OA16771A - Lactose-reduced milk-related product, and a process and milk processing plant for its manufacture. - Google Patents
Lactose-reduced milk-related product, and a process and milk processing plant for its manufacture. Download PDFInfo
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- OA16771A OA16771A OA1201300062 OA16771A OA 16771 A OA16771 A OA 16771A OA 1201300062 OA1201300062 OA 1201300062 OA 16771 A OA16771 A OA 16771A
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Abstract
The present invention relates to lactosereduced milk-related products, and particularly such products having a long shelf-life. Additionally, the invention relates to a method of producing such products and a milk processing plant for the implementation of the method.
Description
LACTOSE-REDUCED MILK-RELATED PRODUCT, AND A PROCESS AND MILK
PROCESSING PLANT FOR ITS MANUFACTURE
FIELD OF THE INVENTION
The présent invention relates to lactose-reduced milk-related products, and particularly such products having a long shelf-life. Additionally, the invention relates to a method of producing such products and a milk processing plant for 10 the Implémentation of the method.
BACKGROUND
It Is estimated that approx. 70-75% of the adult population of the world suffer from lactose Intolérance. Lactose intolérant individuals are not able to métabolisé lactose and experlence symptoms such as nausea, dlarrhoea, or flatulence when Ingesting lactose-rlch products such as milk. These symptoms often keep lactose Intolérant individuals from eating or drinking lactose-containlng dalry products, and consequently these individuals miss the well-recognlzed nutritional beneflts of 20 such products.
Several approaches for producing lactose-free or lactose-reduced dairy products hâve previously been reported. Normally, such approaches deal with either physical removal of lactose via membrane séparation or chromatography and/or 25 enzymatic digestion of lactose, typically Into galactose and glucose.
Typically, milk-related products are heat treated in order to inactivate undesirable enzymes and destroy pathogenic and spoilage mlcroorganisms. The heating process may additionally cause physical and chemical changes (protein dénaturation, browning, etc.), which posltively or negatively affects the sensory characteristics and nutritional value of the products. Milk-related products may be treated by a range of processes which dlffer in the severity of the heat treatment.
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InteIIecwaI PROpERïy Àw
OAPI ACCREdlTed açenî
The three general types of heat treatment (from mild to severe) are thermization, pasteurisation and sterillzation. Thermization is a mild heat treatment (typically
57-68 degrees C for 15 sec.) sufficient to destroy gram-negatlve psychotroplc végétative microorganisms and Increase the refrigerated shelf-llfe. Pasteurisation (typicatly 72 degrees C for 15 sec.) destroys most of the végétative pathogenic organisms (bacteria, yeasts, and moulds), which may cause food polsoning. Sterillzation Is the most severe heat treatment (typically 121 degrees C for 3 min.) and destroys ail microorganisms (végétative and spores) or renders them incapable of further growth.
To extend the shelf-life of mllk at ambient température beyond several days, It must be heated to higher températures than during pasteurisation and postprocesslng contamination must be eliminated. Températures in excess of 100 degrees C are required, however, this causes undesirable changes in the milk:
decreased pH, calcium précipitation, protein dénaturation, Maillard browning, and modification of casein; these changes are important and affect the sensory characteristics, nutritional value, susceptibllity to foui heat exchangers, and sédiment formation.
Ultra high température (UHT) processing Is well-known In the prior art as a continuous flow process, where the mllk is heated in excess of 135 degrees C, held for approx. 4 sec., rapldly cooled, and aseptlcally packaged. UHT can involve using traditlonal heat exchangers to heat and cool the milk (indirect UHT) or direct mixing of mllk and steam followed by cooling to remove the condensed steam (direct UHT). UHT milk undergoes fewer chemical reactions than sterllized milk, resulting In a product that Is whiter, tastes less caramelised, has reduced whey protein dénaturation, and reduced loss of heat-sensitive vltamlns. Even so, the development of off-flavours, especially stale or oxidized flavour, during storage, is the most important factor limlting the acceptability of UHT milk. This off-flavour development is associated with chemical reactions and changes (e.g. Maillard reaction and browning) that occur during processing and that continue during subséquent storage.
A solution to the above-mentioned problem is presented in WO 2009/000,972, where it Is suggest to heat treat lactose-reduced milk by separating the protein from the carbohydrate and UHT-treating the protein fraction and the carbohydrate fraction separately. The UHT-treated fractions are recombined after the heat treatment to form a long shelf-life lactose-reduced milk.
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SUMMARY OF THE INVENTION
The présent inventors perceived the approach of WO 2009/000,972 as a complicated way of producing long shelf-life lactose-reduced milk, and set out to discover slmpler ways of producing such milk products without compromising the nutrltional or organoleptic quality of the resulting milk product.
Thus, an object of the Invention Is to provide advantageous methods of producing lactose-reduced mllk-related products, and particularly long shelf-life products . Yet an object of the présent invention Is to provide Improved long shelf-life lactose-reduced milk-related products, in comparison to the prior art.
Another object of the présent Invention Is to provide long shelf-life mllk-related products having an improved taste and particularly a reduced cooked taste as well as methods of producing such milk-related products and milk processing plants for implementing said methods.
A further object of the présent Invention is to provide long shelf-life milk-related products which, relative to the long shelf-life milk of the prior art, are healthler for the consumers who Ingest them, as well as methods of producing such improved milk-related products and milk processing plants for implementing said methods. Additional objects and advantages of the invention are described below.
Thus, an aspect of the invention relates to a method of producing a packaged, lactose-reduced milk-related product, the method comprising the steps of:
a) providing a lactose-reduced milk-related feed
b) subjecting a milk derivative derived from said milk-related feed to a High Température (HT)-treatment, wherein the mifk derivative is heated to a température in the range of 140 - 180 degrees C, kept in that température range for a period of at most 200 msec. and then finally cooied,
c) packaging a lactose-reduced mllk-related product derived from the HT-treated milk derivatlve.
As documented in the Examples, the présent method provides lactose-reduced milk having a very long shelf-life, a surprlsingly low furosine value and at the same time a consumer-acceptable taste. To this end it should be noted that the présent method is simpler both to Implement and to operate than e.g. the method described In WO 2009/000,972.
Another aspect of the invention relates to a milk-related product, and particularly a long shelf-life milk-related product, e.g. the mllk-related product obtainable by the method as described herein.
For example, the lactose-reduced milk-related product may hâve a shelf-life of at least 119 days, when kept at 25 degrees C, said lactose-reduced mllk-related product comprising:
- 0.01-2% (w/w) galactose relative to the total weight of the lactose-reduced mllk-related product,
- 0.01-2% (w/w) glucose relative to the total weight of the lactose-reduced milkrelated product,
- at most 0.2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related product, and wherein the mllk-related product has a furosine value of at most 80 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage.
Alternatlvely, the lactose-reduced milk-related product may hâve a shelf-life of at least 70 days, when kept at 5 degrees C, said lactose-reduced milk-related product comprising:
- 0.01-2% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product,
- 0.01-2% (w/w) glucose relative to the total weight of the lactose-reduced mllkrelated product,
- at most 0.2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related product, and wherein the milk-related product has a furosine value of at most 60 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
The présent inventors hâve found that surprisingly it is possible to obtain a long shelf-life milk with furosine values that are even lower than reported in the prior art for comparable milk products.
Yet an aspect of the Invention relates to a milk processing plant for converting a milk-related feed to a milk-related product having a long shelf-life, said plant comprising:
a lactose réduction section adapted to remove lactose from a milk, thereby providing a milk-related feed, a HT-treatment section In fluid communication with said lactose réduction section, which HT-treatment section is adapted to heat a milk-derivative derived from said milk-related feed to a température in the range of 140180 degrees C for a period of at most 200 msec. and subsequently cool the liquid product, and a packaging section for packaging the product of the milk processing plant, which packaging section is in fluid communication with the HT-treatment section.
In the context of the présent invention, the term lactose-reduced milk-related product is used Interchangeably with the term milk-related product and relates to milk-based products which contain most, and preferably ali, of the protein types présent in skim milk. A lactose-reduced milk-related product may additionally contain various amounts of milk fat and milk minerais, and possibly also non-dairy additives such as non-dairy flavours, sweeteners, minerais and/or vltamins. Furthermore, a lactose-reduced milk-related product comprises at most 3% (w/w) lactose.
In the context of the présent invention, the phrase Y and/or X means Y or X or Y and X. Along the same line of logic, the phrase ni, n2, η,.ι, and/or nj means nj or n2 or ... or ni-i or ni or any combination of the components :
m, n2,...nt.i, and nb
The term long shelf-life, when used In the context of the présent invention, relates to products which hâve shelf-llves longer than ordlnary pasteurized milk. Examples of the length of the shelf-life and tests to measure the actual shelf-life ofthe mllk-related product are described herein.
BRIEF DESCRIPTION OFTHE FIGURES
Figure 1 shows a schematic flow diagram of an embodiment of the Invention in which the milk-related feed is subjected to a ΗΤ-treatment and subsequently packaged.
Figure 2 shows a schematic flow diagram of an embodiment of the invention in which at least some of the lactose of the milk-related feed is hydrolysed. After the hydrolysls the resulting product Is subjected to a HT-treatment and subsequently packaged.
Figure 3 shows a schematic flow diagram of an embodiment of the invention In which the milk-related feed Is subjected to a HT-treatment. Subsequently, at least some of the lactose of the product resulting from the HT-treatment Is hydrolysed, and the product containing hydrolysed lactose Is packaged.
Figure 4 shows a schematic flow diagram of an embodiment of the invention in which the milk-related feed is subjected to an enzyme inactivation step and subsequently to a HT-treatment. The resulting product is subsequently packaged.
Figure 5 shows a schematic flow diagram of an embodiment of the invention in which at least some of the lactose of the milk-related feed is hydrolysed and the resulting product Is subjected to an enzyme inactivation step and subsequently to a HT-treatment. The HT-treated product is finally packaged.
Figure 6 shows a schematic flow diagram of an embodiment of the Invention in which the milk-related feed is subjected to an enzyme inactivation step, and in which at least some of the lactose of the HT-treated product is hydrolysed. The product containing hydrolysed lactose Is subsequently subjected to a HTtreatment and packaged.
Figure 7 shows a schematic flow diagram of an embodiment of the Invention in which the milk-related feed Is subjected to an enzyme Inactivation step and subsequently to a HT-treatment. After the ΗΤ-treatment at least some of the lactose of the resulting product Is hydrolysed, and the resulting product, now also containing hydrolysis products of lactose, Is subsequently packaged.
Figure 8 shows a schematic flow diagram of an embodiment of the invention In which the milk-related feed Is subjected to a HT-treatment. Subsequently the resulting product is subjected to an enzyme Inactivation step and packaged.
Figure 9 shows a schematic flow diagram of an embodiment of the Invention in which at least some of the lactose of the milk-related feed Is hydrolysed and the resulting product Is subsequently subjected to a HT-treatment. The HT-treated product is subjected to an enzyme inactivation step and packaged.
Figure 10 shows a schematic flow diagram of an embodiment of the invention In which the milk-related feed is subjected to a HT-treatment. Subsequently, the resulting product Is first subjected to a step of hydrolysing at least some of the lactose of the product, then to an enzyme inactivation step, and finally packaged.
Figure 11 shows a schematic flow diagram of an embodiment of the invention in which the milk-related feed is subjected to a HT-treatment. Subsequently, the resulting product is first subjected to an enzyme Inactivation step, then to a step of hydrolysing at least some of the lactose of the product, and finally the product is packaged.
Figure 12 shows a schematic flow diagram of an embodiment of the Invention where the milk-related feed is prepared using a combination of ultrafiltration (1) and nanofiltration (4).
Figure 13 shows a schematic flow diagram of an embodiment of the invention where the mllk-related feed is prepared using a first sequence of ultrafiltration (1) and nanofiltration (4) followed by a second sequence of ultrafiltration (1) and nanofiltration (4).
Figure 14 shows the furoslne values after 7 weeks of storage of the milk-related products of Example II and furthermore contains a comparison with furoslne values of prior art milk.
Figure 15 shows the furoslne values after 6 weeks of storage of the milk-related products of Example III and furthermore contains a comparison with furoslne values of prior art milk.
Figure 16 shows the furoslne values after 1-12 weeks of storage of the mllkrelated products of Example V and furthermore contains a comparison with furoslne values of prior art milk.
DETAILED DESCRIPTION OF THE INVENTION
Thus an aspect of the Invention relates to a method of produclng a packaged, lactose-reduced mllk-related product, the method comprising the steps of:
a) providing a lactose-reduced milk-related feed
b) subjecting a milk derlvative derlved from said mllk-related feed to a High Température (HT)-treatment, wherein the milk derlvative is heated to a température In the range of 140 - 180 degrees C, kept In that température range for a period of at most 200 msec. and then finally cooled,
c) packaging a lactose-reduced milk-related product derived from the HT-treated milk derivatlve.
In the context of the présent Invention the terms lactose-reduced milk-related feed and milk-related feed are used Interchangeably. A lactose-reduced milkrelated feed comprises at most 3% (w/w) lactose.
The lactose-reduced milk-related feed of step a) may be produced in a number of different ways. For example, some of the lactose-reduced dairy products described in the prlor art may be used. See for example the lactose-reduced dairy products of the patent documents EP 0 203 706, US 4,820,348, WO 2008/000895, US 2010/055286, US 2005/214409A, US 2010/055289, WO 2009/000972, and WO 2009/043356.
In some embodiments of the invention the milk-related feed may for example be prepared using a process step selected from the group consisting of enzymatic hydrolysis of lactose, removal of lactose using ultrafiltration, removal of lactose using nanofiltration, removal of lactose using electrodialysls, removal of lactose using Ion exchange chromatography, and removal of lactose using centrifugation technology.
Alternatlvely, the milk-related feed may for example be prepared using at least two process steps selected from the group consisting of enzymatic hydrolysis of lactose, removal of lactose using ultrafiltration, removal of lactose using nanofiltration, removal of lactose using electrodialysls, removal of lactose using ion exchange chromatography, and removal of lactose using centrifugation technology.
In some preferred embodiments of the invention the provision of the milk-related feed comprises subjecting a mllk to at least one ultrafiltration (UF) step, which leads to the formation of an UF retentate and a UF permeate, and using at least the protein of UF retentate for the formation of the milk-related feed so that milkrelated feed conta Ins at least the protein of UF retentate. The UF retentate typically contains a concentrate of the larger molécules of the mllk, e.g. a concentrate of the proteins, and the smaller molécules In substantially the same concentration. The UF permeate contains substantially no protein but contains water and smaller molécules, such as lactose and Ions, in substantially the same concentration as In the mllk.
The mllk used to préparé the milk-related feed Is preferably bovine mllk.
In some preferred embodiments of the invention the provision of the milk-related feed comprises at least one nanofiltratlon or reverse osmosls step, which provides a permeate comprising water, and optionally also salts of mono- or divalent Ions, which permeate Is added to the retentate of the at least one ultrafiltration. In even more preferred embodiments of the invention, the permeate of the abovementioned ultrafiltration step Is subjected to a nanofiltration or reverse osmosis step, and the permeate of the nanofiltration or reverse osmosis is added to the retentate of the at least one ultrafiltration.
Useful examples of such processes are shown In Figs. 12 and 13.
In Fig. 12 a milk is pumped to an ultrafiltration unit (1) and separated Into an ultrafiltration retentate (2) and an ultrafiltration permeate (3). The ultrafiltration permeate (3) is pumped to a nanofiltration unit (4) and separated Into a nanofiltratlon retentate (6) and a nanofiltration permeate (5). The nanofiltration permeate, which prlmarily comprises water and salts of mono- or divalent Ions, Is mixed with the ultrafiltration permeate (3) and the mixture is used as milk-related feed. More details on how to implement such a process can be found in WO 2009/043356.
In Fig. 13 a modification of the process of Fig. 12 is shown. Instead of using the mixture (7) of the ultrafiltration retentate (2) and the nanofiltratlon permeate (5) directly as milk-related feed, it is sent through a second combination of ultrafiltration (1) and nanofiltratlon (4). The second ultrafiltration retentate (2') is combined with the second nanofiltration (5') and this mixture Is used as milkrelated feed.
In some preferred embodiments of the invention the provision of the milk-related feed of step a) Involves the steps of al) subjectlng a milk to ultrafiltration (UF), thereby obtaining a UF retentate and a UF permeate, a2) subjecting the UF permeate to nanofiltratlon (NF), thereby obtaining an NF retentate and an NF permeate, a3) mixing the NF permeate and the UF retentate, thereby obtaining lactose-reduced milk mixture,
a4) optionally, repeating steps al)-a3) once or twice, each time replacing the first milk of step al) with the latest lactose-reduced milk mixture, and a5) using the latest lactose-reduced milk mixture as the milk-related feed.
The milk used to préparé the milk-related feed may be e.g. a skimmed milk or seml-skimmed milk. The milk fat content of the milk used to préparé the milkrelated feed may be at most 5% (w/w), preferably most 3.5% (w/w), and even more preferably at most 2% (w/w). For example, the fat content of the milk used to préparé the milk-related feed may be at most 1.5% (w/w). Preferably the fat content of the milk is at most 0.5% (w/w). Even more preferably the fat content of the milk Is at most 0.1% (w/w).
The ultrafiltration and nanofiltration processes are well-known In the art. The membrane used for nanoflltratlon may for example hâve a pore size in the range of 10'3 -102 micron. The membrane used for ultrafiltration may for example hâve a pore size in the range of 10’2 -10'1 micron.
In some embodiments ofthe invention the lactose-reduced milk-related feed comprises at most 3% (w/w) lactose relative to the total weight of the lactosereduced milk-related feed. For example, the lactose-reduced milk-related feed may comprise at most 2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related feed, preferably at most 1% (w/w), and even more preferably at most 0,5% (w/w) lactose relative to the total weight of the lactosereduced milk-related feed.
Even lower levels of lactose may be désirable, thus In some embodiments of the invention the lactose-reduced milk-related feed comprises at most 0.2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related feed. For example, the lactose-reduced milk-related feed may comprise at most 0.1% (w/w) lactose relative to the total weight ofthe lactose-reduced milk-related feed, preferably at most 0.05% (w/w), and even more preferably at most 0.01% (w/w) lactose relative to the total weight of the lactose-reduced milk-related feed.
In some embodiments ofthe Invention the lactose-reduced milk-related feed comprises 0.01-2% (w/w) glucose relative to the total weight ofthe lactose11 reduced mllk-related feed. For example, the lactose-reduced mllk-related feed may comprise 0.02-1.5% (w/w) glucose relative to the total weight of the lactosereduced milk-related feed, preferably 0.05-1% (w/w), and even more preferably
0.1-0.5% (w/w) glucose relative to the total weight of the lactose-reduced milkrelated feed.
Sometlmes lower levels of glucose may be désirable, thus In some embodiments of the invention the lactose-reduced mllk-related feed comprises 0.01-0.5% (w/w) glucose relative to the total weight of the lactose-reduced milk-related feed. For example, the lactose-reduced mllk-related feed may comprise 0.02-0.3% (w/w) glucose relative to the total weight of the lactose-reduced milk-related feed, preferably 0.04-0.2% (w/w), and even more preferably 0.05-0.1% (w/w) glucose relative to the total weight of the lactose-reduced milk-related feed.
In some embodiments of the Invention the lactose-reduced milk-related feed comprises 0.01-2% (w/w) galactose relative to the total weight of the lactosereduced milk-related feed. For example, the lactose-reduced milk-related feed may comprise 0.02-1.5% (w/w) galactose relative to the total weight of the lactose-reduced milk-related feed, preferably 0.05-1% (w/w), and even more preferably 0.1-0.5% (w/w) galactose relative to the total weight of the lactosereduced milk-related feed.
Lower levels of galactose may be désirable, thus In some embodiments of the invention the lactose-reduced mllk-related feed comprises 0.01-0.5% (w/w) galactose relative to the total weight of the lactose-reduced milk-related feed. For example, the lactose-reduced milk-related feed may comprise 0.02-0.3% (w/w) galactose relative to the total weight of the lactose-reduced milk-related feed, preferably 0.04-0.2% (w/w), and even more preferably 0.05-0.1% (w/w) galactose relative to the total weight of the lactose-reduced milk-related feed.
In some preferred embodiments of the Invention, the milk-related feed comprises a total amount of mono- and disaccharides in the range of 0.5 - 4% (w/w) relative to the total weight of the milk-related feed. For example, the milk-related feed may comprise a total amount of mono- and disaccharides in the range of 0.7 - 3.5% (w/w) relative to the total weight of the mllk-related feed, preferably in the range of 1 - 3.2% (w/w), and even more preferably in the range of 1-3% (w/w) relative to the total weight of the mllk-related feed.
The mllk-related feed provided in step a) is preferably a liquid milk-related feed.
As used herein the term milk-related feed includes lactose-reduced whole milk, skim milk, fat-free milk, low fat milk, full fat milk, or concentrated milk.
Fat-free milk is a non-fat or skim milk product. Low-fat milk is typically defined as milk that contains from about 1% to about 2% fat. Full fat milk often contains about 3.25% fat. As used herein, the term milk is also intended to encompass mllks from animal and plant sources.
Animal sources of milk Include, but are not limited to, human, cow, sheep, goat, buffalo, camel, llama, mare and deer.
In a preferred embodiment of the Invention, the mllk-related feed comprises bovine milk.
Plant sources of milk include, but are not limited to, milk extracted from soybean. In addition, the term milk-related feed refers to not only whole milk, but also skim milk or any liquid component derived therefrom, such as whey or milk sérum. By whey or milk sérum is meant the milk component remaining after ail, or a substantial portion of the milk fat and casein contained in milk, are removed. The term whey also encompass so-called sweet whey which is the byproduct of rennet-based cheese production, and acid whey which Is the byproduct of the acidification of milk, which typically takes place during the production of caselnate or quark and cream cheese.
In an embodiment of the Invention, the milk-related feed of step a) comprises at most 60% w/w milk fat. An example of such a milk-related feed is cream double.
In another embodiment of the Invention, the mllk-related feed of step a) comprises at most 40% w/w milk fat. An example of such a milk-related feed is whipplng cream,
In yet an embodiment of the invention, the mllk-related feed of step a) comprises at most 20% w/w milk fat. An example of such a milk-related feed is single cream/table cream containing approx. 18% w/w milk fat.
In a further embodiment of the Invention, the mllk-related feed of step a) comprises at most 4% w/w mllk fat. An example of such a mllk-related feed Is full fat mllk which typieally contains 2-4% w/w mllk fat, and preferably approx. 3% w/w mllk fat.
In a further embodiment of the invention, the milk-related feed of step a) comprises at most 2% w/w milk fat. An example of such a milk-related feed Is seml-sklm milk which typieally contains 0.7-2% w/w mllk fat, and preferably 11.5% w/w milk fat.
In an additional embodiment of the invention, the milk-related feed of step a) comprises at most 0.7 w/w mllk fat. An example of such a mllk-related feed is sklm mllk which normally contains 0.1-0.7% w/w milk fat, and preferably 0.30.6% w/w mllk fat, such as approx. 0.5% w/w milk fat.
In a preferred embodiment of the Invention, the mllk-related feed of step a) comprises at most 0.1% w/w milk fat. An example of such a milk-related feed is skim-milk having a fat content in the range of 0.05-0.1% w/w.
In the context of the présent Invention, when a composition is said to comprise, contain or have X % (w/w) of a specified component, the weight percentage of the specified component is calculated relative to the total weight of the composition unless it is stated otherwise.
The mllk-related feed normally comprises water, and may e.g. comprise at least 50% (w/w) water, preferably at least 70% (w/w) water, and even more preferably at least 80% (w/w) water. For example, the milk dérivative may comprise at least 85% (w/w) water, preferably at least 90% (w/w) water, and even more preferably at least 95% (w/w) water.
In a particularly preferred embodiment of the invention, the mllk-related feed of step a) comprises lactose-reduced mllk. The mllk-related feed may e.g. consist of lactose-reduced milk.
In some embodiments of the invention, the milk-related feed of step a) comprises 2.5-4.5% w/w casein, 0.25-1% w/w mllk sérum protein, and 0.01-3% w/w milk fat. In some preferred embodiments of the Invention, the mllk-related feed of step
a) comprises 2.5-4.5% w/w casein, 0.25-1% w/w milk sérum protein, and 0.11.5% w/w mllk fat. In other preferred embodiments ofthe invention, the mllkrelated feed of step a) comprises 2.5-4.5% w/w casein, 0.25-1% w/w milk sérum protein, and 0.01-0.1% w/w milk fat.
In the context of the présent Invention the term mllk sérum protein relates to the non-caseln proteins of raw bovine mllk.
The method of the invention may preferably be used for treating fresh milkrelated feed, i.e. milk-related feed based on mllk which has recently been milked from the source of the milk-related feed, e.g. from cows. For example, it may be preferred that the milk-related feed is at most 48 hours old, I.e. at most 48 hours slnce milking, and more preferably at most 36 hours old, such as at most 24 hours old.
It is preferred that the milk-related feed is of good quality and normaily the milkrelated feed comprises at most 100,000 colony forming units (cfu)/mL, preferably at most 50,000 cfu/mL, and even more preferably at most 25,000 cfu/mL. It may even be preferred that the milk-related feed comprises at most 10,000 cfu/mL, such as at most 7,500 cfu/mL.
The milk-related feed of step a) may comprise one or more additives. For example, the one or more additives may contain a flavour. Useful flavours are e.g. strawberry, chocolaté, banana, mango, and/or vanllla.
Alternatively, or In addition, the one or more additives may contain one or more vltamins. Useful vltamlns are e.g. vitamln A and/or vitamin D. Other vitamins such as vitamln B, C, and/or E may also be useful.
Alternatively, or in addition, the one or more additives may also contain one or more minerais. An example of a useful minerai Is the milk minerai supplément Capolac MM-0525 (Aria Foods Ingrédients Amba, Denmark). Another useful additive Is whey protein.
In a preferred embodiment ofthe Invention, the milk-related feed of step a) has been pasteurised and possibly also homogenized.
Step b) of the invention involves subjecttng a milk dérivative derived from said milk-related feed to a High Température (HT)-treatment, wherein the milk dérivative is heated to a température in the range of 140 - 180 degrees C, kept in that température range for a period of at most 200 msec, and then finally cooled,
In the context of the présent invention, when a milk dérivative is derived from mllk-related feed It means that at least 80% (w/w) of the solids of the milkreiated feed are included in the milk dérivative. For example at least 90% (w/w) of the solids of the milk-related feed may be included in the milk dérivative, preferably at least 95% (w/w), and even more preferably at least 99% (w/w) of the solids. It should be noted that some of the solids of the milk-related feed may be présent in the milk dérivative In the same form as in the milk-related feed or they may hâve been modified, e.g. by heating, oxldation or enzymatic dégradation. For example, some of the solids of the milk-related feed may be présent in the milk dérivative In hydrolyzed form or denatured form. For example, some of the lactose of the milk-related feed may for example be présent in the milk derlvatlve In the form of glucose and galactose, which are the hydrolysis products of lactose. Some proteins, which were in their native form in the milkrelated feed, may be présent In the milk derlvatlve in a denatured form.
When a milk dérivative is derived from a mllk-related feed, It is furthermore preferred that a substantial amount of the water of the mllk-related feed is Included In the milk dérivative. For example, at least 80% (w/w) of the water of the mllk-related feed may be Included In the milk dérivative. Alternatively, at least 90% (w/w) of the water of the milk-related feed may be included in the milk dérivative, preferably at least 95% (w/w), and even more preferably at least 99% (w/w) of the water, such as e.g. substantially ail water of the milk-related feed.
In the context of the présent invention, the term solids relates to the molécules that would remain if ail water was removed from the milk. The term solids includes carbohydrates, proteins, peptides, milk fat, minerais, acids, vitamlns and other small, non-water molécules.
The milk derlvatlve may for example contain a substantial amount of the mllkrelated feed. For example, the milk derlvatlve may be identical to the milk-related feed. Alternatively, the milk derlvative may essentially consist of the milk-related feed.
In the context of the présent Invention the term essentially consist of means that the mentloned product or composition consists of the mentloned components as well additional optlonal components which do not materially affect the basic and novel characteristlcs of the Invention.
In some preferred embodiments of the Invention derlving the milk dérivative from the mllk-related feed Involves subjecting the mllk-related feed to an enzyme Inactivation step.
The enzyme Inactivation step may for example comprise adjustlng the température of the milk-related feed to a température in the range of 70-95 degrees C and keeping the température of the milk-related feed In that range for a period in the range of 30-500 seconds.
In some preferred embodiments of the invention deriving the milk derlvative from the mllk-related feed Involves hydrolysing at least some of the lactose of the mllkrelated feed.
The hydrolysis of lactose may for example comprise contacting the mllk-related feed with a lactase enzyme.
In some embodiments of the Invention the hydrolysis is performed after the enzyme Inactivation step.
In other embodiments of the invention the enzyme inactivation step is performed after the hydrolysis.
In some embodiments of the Invention deriving the milk derivatlve from the mllkrelated feed furthermore Involves adding a lipid source to the milk-related feed.
In some embodiments of the Invention the milk derlvative comprises at most 3% (w/w) lactose relative to the total weight of the milk derlvative. For example, the milk dérivative may comprise at most 2% (w/w) lactose relative to the total weight of the milk derlvative, preferably at most 1% (w/w), and even more preferably at most 0.5% (w/w) lactose relative to the total weight of the milk derlvative.
Even lower levels of lactose may be désirable, thus in some embodiments of the Invention the mllk derlvative comprises at most 0.2% (w/w) lactose relative to the total weight of the mllk derlvative. For example, the mllk derlvative may comprise at most 0.1% (w/w) lactose relative to the total weight of the mllk derlvative, preferably at most 0.05% (w/w), and even more preferably at most 0.01% (w/w) lactose relative to the total weight of the mllk derivatlve.
In some embodiments ofthe Invention the mllk derlvative comprises 0.01-2% (w/w) glucose relative to the total weight of the milk derlvative. For example, the milk derlvative may comprise 0.02-1.5% (w/w) glucose relative to the total weight ofthe mllk derivatlve, preferably 0.05-1% (w/w), and even more preferably 0.1-0.5% (w/w) glucose relative to the total weight of the mllk derivatlve.
Sometimes lower levels of glucose may be désirable, thus in some embodiments of the Invention the mllk derivatlve comprises 0.01-0.5% (w/w) glucose relative to the total weight of the mllk derlvative. For example, the milk derlvative may comprise 0.02-0.3% (w/w) glucose relative to the total weight of the milk derivatlve, preferably 0.04-0.2% (w/w), and even more preferably 0.05-0.1% (w/w) glucose relative to the total weight of the milk dérivative.
In some embodiments of the invention the milk derlvative comprises 0.01-2% (w/w) galactose relative to the total weight of the milk dérivative. For example, the mllk derivatlve may comprise 0.02-1.5% (w/w) galactose relative to the total weight ofthe milk derivatlve, preferably 0.05-1% (w/w), and even more preferably 0.1-0.5% (w/w) galactose relative to the total weight of the milk derlvative.
Lower levels of galactose may be désirable, thus in some embodiments of the invention the milk derlvative comprises 0.01-0.5% (w/w) galactose relative to the total weight ofthe milk dérivative. For example, the milk derivatlve may comprise 0.02-0.3% (w/w) galactose relative to the total weight of the milk derivatlve, preferably 0,04-0.2% (w/w), and even more preferably 0.05-0.1% (w/w) galactose relative to the total weight of the mllk dérivative.
In some preferred embodiments of the Invention, the milk dérivative comprises a total amount of mono- and dlsaccharides in the range of 0.5 - 4% (w/w) relative to the total weight of the milk dérivative. For example, the milk dérivative may comprise a total amount of mono- and dlsaccharides In the range of 0.7 - 3.5% (w/w) relative to the total weight of the milk dérivative, preferably in the range of 1 - 3.2% (w/w), and even more preferably in the range of 1-3% (w/w) relative to the total weight of the milk dérivative.
In some preferred embodiments of the invention the température of the milk dérivative immediately before the HT-treatment Is In the range of 60-85 degrees C, preferably in the range 62-80 degrees C, and even more preferably In the range of 65-75 degrees C. Preliminary experlments Indlcate that if the température of the milk dérivative is in these température ranges, less foullng occurs In the HT-treatment system.
In an embodiment of the Invention, the milk dérivative conslsts of the milk-related feed of step a).
However, In another embodiment of the Invention, the milk-related feed has been added one or more additlves, e.g. a milk fat, prior to the HT-treatment and in this case the milk dérivative comprises both the one or more additlves (e.g. milk fat) and the milk-related feed.
In an embodiment of the Invention, the milk dérivative comprises at least 50% (w/w) milk-related feed of step a), preferably at least 75% (w/w) milk-related feed, and even more preferably at least 85% (w/w) milk-related feed. For example, the milk dérivative may comprise at least 90% (w/w) milk-related feed of step a), preferably at least 95% (w/w) milk-related feed, and even more preferably at least 97.5% (w/w) milk-related feed.
The milk derlvative normally comprises water and may e.g. comprise at least 50% (w/w) water, preferably at least 70% (w/w) water, and even more preferably at least 80% (w/w) water. For example, the milk derlvative may comprise at least 85% (w/w) water, preferably at least 90% (w/w) water, and even more preferably at least 95% (w/w) water.
In a preferred embodiment of the invention, the milk dérivative furthermore comprises one or more lipid sources.
The one or more lipid sources may for example comprise a vegetable fat and/or a vegetable oil. It is furthermore possible that the one or more lipid sources conslst of a vegetable fat and/or a vegetable oil. This Is typically the case when the milkrelated product Is a so-called filled milk, I.e. a milk product wherein at least a portion of the original milk fat has been replaced with a non-dalry lipid source such as vegetable oll or vegetable fat.
The vegetable oil may e.g. comprise one or more oils selected from the group consisting of sunflower oll, corn oll, sesame oil, soya bean oil, palm oil, linseed oil, grape seed oil, rapeseed oll, olive oil, groundnut oil and combinations thereof.
If a vegetable fat is desired, the vegetable fat may e.g. comprise one or more fats selected from the group consisting of palm oil-based vegetable fat, palm kernel oil-based vegetable fat, peanut butter, cacao butter, coconut butter, and combinations thereof.
In a preferred embodiment of the invention, the one or more lipid sources comprlse(s), or even conslst(s) of, a milk fat source.
The milk fat source may e.g. comprise one or more lipid sources selected from the group consisting of a cream, a cream double, an anhydrous butter fat, a whey cream, a butter oll, a butter oil fraction, and combinations thereof.
Production of long shelf-life milk typically Involves UHT-treatment of the milk fat fraction of the milk. The présent Inventors hâve found that even though the UHTtreated milk fat, e.g. cream, Is only added to the long shelf-life milk in relatively small quantifies, it may still contribute to an undesired cooked taste. The présent inventors hâve additionally found that one may subject the milk fat, e.g. cream, to mllder thermal treatment, than what is normally done, without losing the long shelf-life of the milk.
Thus, in a preferred embodiment of the Invention, the one or more lipid sources, e.g. the milk fat source, such as cream, hâve been heat-treated by adjusting the température of the lipid source(s) to a température in the range of 70-100
degrees C for a period of 2-200 seconds. For example, the one or more lipld sources may be heat-treated by adjusting the température of the lipid source(s) to a température In the range of 70-85 degrees C for a period of 100-200 seconds. Alternatively, the one or more lipid sources may be heat-treated by adjusting the température of the lipid source(s) to a température in the range of 85-100 degrees C for a period of 2-100 seconds.
In another preferred embodiment of the Invention, the one or more lipid sources, e.g. the milk fat source, such as cream, hâve been heat treated by adjusting the température of the lipid source(s) to a température In the range of 100-180 degrees C for a period of 10 msec. - 4 sec.
For example, the one or more lipid sources may be heat-treated by adjusting the température of the lipid source(s) to a température In the range of 100-130 degrees C for a period of 0.5-4 seconds. Alternatively, the one or more lipid sources may be heat-treated by adjusting the température of the lipid source(s) to a température in the range of 130-180 degrees C for a period of 10 msec. - 0.5 seconds.
Alternatively, the HT-treatment described In the context of step b) may e.g. be used for separate heat-treatment of the one or more lipid sources.
The HT-treatment of step b) involves heating the milk derlvative to a température In the range of 140-180 degrees C, preferably 145-170 degrees C, and even more preferably 150-160 degrees C.
In an embodiment of the Invention, the HT-treatment of step b) involves heating the milk derlvative to a température In the range of 140-170 degrees C, preferably 145-160 degrees C, and even more preferably 150-155 degrees C.
In another embodiment ofthe Invention, the HT-treatment of step b) involves heating the milk derlvative to a température in the range of 150-180 degrees C, preferably 155-170 degrees C, and even more preferably 160-165 degrees C.
In yet an embodiment ofthe Invention, the milk derlvative has a température in the range of 70-75 degrees C when provided to step b).
The high température of the HT-treatment may e.g. vary at most +/- 2 degrees C from the Intended température, preferably at most +/- 1 degrees C, and even more preferred at most +/- 0.5 degrees C, such as at most +/- 0.25 degrees C.
In a preferred embodiment of the invention, the température of the milk derlvative Is kept in the HT-temperature range for a period of at most 200 msec., preferably at most 150 msec., and even more preferably at most 100 msec.
For example, the température of the milk derlvative may be kept in the HTtemperature range fora period of 10-200 msec., preferably 25-150 msec., and even more preferably 30-100 msec.
In another embodiment of the invention, the température of the milk derlvative Is kept in the HT-treatment température range for a period of 10-100 msec., preferably 25- 90 msec., and even more preferably 30-70 msec.
The relationship between the process parameters and the time In which the température of the milk derlvative Is kept In the HT-treatment température range, sometimes referred to as the holding time, Is typically provided by the equlpment manufacturer.
If not, the holding time may be determined as outlined below:
1. Calculate the heat capaclty of the feed from the milk derlvative via empirical formulas
2. Calculate the required energy (kg/hour steam) to raise the feed température from the preheating température to the desired heat treatment température
3. Calculate the excess steam (used for transport) by subtractlng the required heating steam flow from the total steam flow
4. Détermine the exact volume of the holding cell
5. Détermine the volumétrie flow rates of material into and through the process unit, including any volumétrie changes (for example heating steam condensation)
6. Calculate the holding time by dlvldlng the holding cell volume by the volumétrie flow rate.
In a preferred embodiment ofthe invention, the duration ofthe HT-treatment,
Including heating, holding, and cooling the milk derivative, is at most 500 msec., preferably at most 300 msec., and even more preferably at most 200 msec., such as at most 150 msec.
For example, the duration ofthe HT-treatment, Including heating, holding, and cooling the milk derivative, may be at most 400 msec., preferably at most 350 msec., and even more preferably at most 250 msec., such as at most 175 msec.
The duration of the HT-treatment, including heating, holding, and cooling the milk derivative, may be calculated as the duration of the perlod(s) wherein the température of the milk derivative is at least 95 degrees C.
The cooling of step b) preferably cools the milk derivative to a température of at most 90 degrees C, such as at most 70 degrees C. In an embodiment of the invention, the milk derivative is cooled to a température In the range of 2-90 degrees C, preferably In the range of 70-95 degrees C, and even more preferably in the range of 72-85 degrees C.
In a preferred embodiment of the Invention, the duration of the cooling of the HTtreatment is at most 50 msec., preferably at most 10 msec., and even more preferably at most 5 msec., such as 1 msec.
The heating of the HT-treatment of step b) must be able to rapidly increase the température of the milk derivative. Such rapld température increases may be accomplished by contacting the milk derivative with steam. Thus, in a preferred embodiment of the invention, the heating of the HT-treatment is performed by contacting the milk derivative with steam. There are different techniques available for contacting the milk derivative with steam. One of these Is direct steam Injection In which steam is injected into the liquid to be heated. Another technique is steam Infusion wherein the liquid to be heated Is Infused into a steam-fllled chamber.
The température of the steam is typically somewhat higher than the desired treatment temperate of the HT-treatment, for example at most 10 degrees C higher than the desired treatment temperate of the HT-treatment, preferably at most 5 degrees C higher, an even more preferred at most 3 degrees C higher.
For example, the heating of the HT-treatment may comprise contacting the milk derivatlve with steam, and It should be noted that other energy sources may contrlbute to the heating as well.
In an embodiment of the Invention, the heating of the HT-treatment comprises, or conslsts of, subjecting the milk derivatlve to electromagnetic energy. Examples of useful electromagnetic energy are IR radiation and/or microwave radiation.
It is also important that the heated milk derivatlve Is rapldly cooled as part of the HT-treatment, and in a preferred embodiment of the Invention, the cooling of the HT-treatment comprises, or conslsts of, flash cooling.
In the context of the présent invention, the term flash cooling is the cooling obtained by Introducing, e.g. spraying, a hot liquid or aérosol into a vacuum chamber, whereby parts of the liquid evaporates and rapldly cools the remalnlng liquid.
Examples of useful HT-treatment Systems are e.g. the Sanlheat™-system Gea Nlro (Denmark), the Llnlent Steam Injection (LSI™)-system of Gea Nlro (Denmark) or the Instant Infusion System (IIS) of Invensys APV (Denmark).
Example for useful HT-treatment Systems are e.g. found In the International patent applications WO 2006/123,047 Al and WO 98/07,328, which both are incorporated herein by reference for ail purposes.
General aspects of high température treatment are e.g. found in Thermal technologies in food processing ISBN 185573558 X, which Is Incorporated herein by reference for ail purposes.
Step c) of the method involves packaging a lactose-reduced milk-related product derived from the HT-treated milk derivatlve.
In the context of the présent invention, when a milk-related product Is derived from HT-treated milk dérivative it means that at least 80% (w/w) of the solids of the HT-treated milk dérivative are included in the milk-related product. For example, at least 90% (w/w) of the solids of the HT-treated milk derivatlve may
be Included in the milk-related product. Preferably at least 95% (w/w) of the solids of the HT-treated mllk derlvative are included in the milk-related product. Even more preferably at least 99% (w/w) of the solids of the HT-treated mllk derivatlve are Included in the milk-related product. It should be noted that some of the solids of the HT-treated mllk derivatlve may be présent In the milk-related product In the same form as In the HT-treated mllk derivatlve, or some of them may hâve been modified, e.g. by heating, oxidation or enzymatic dégradation. For example, some of the solids of the HT-treated mllk derlvative may be présent In the milk-related product in hydrolysed form or denatured form. For example, some of the lactose of the HT-treated mllk derivatlve may for example be présent In the milk-related product In the form of glucose and galactose, which are the hydrolysis products of lactose. Some proteins, which were in their native form in the HT-treated mllk derlvative, may be présent in the milk-related product in a denatured form.
When a milk-related product Is derived from a HT-treated milk derivatlve, it Is furthermore preferred that a substantiel amount of the water of the HT-treated mllk derivatlve is included in the milk-related product. For example, at least 80% (w/w) of the water of the HT-treated mllk derlvative may be Included In the milkrelated product. Alternat!vely, at least 90% (w/w) of the water of the HT-treated milk derlvative may be included In the milk-related product, preferably at least 95% (w/w), and even more preferably at least 99% (w/w) of the water, such as e.g. substantially ail water of the HT-treated milk derivatlve.
The milk-related product may for example contain a substantiel amount of the HTtreated milk derivatlve. For example, the milk-related product may be Identical to the HT-treated mllk derlvative. Alternative^, the milk-related product may essentially consist of the HT-treated mllk dérivative.
In some preferred embodiments of the Invention derlving the lactose-reduced milk-related product from the HT-treated milk derivatlve involves subjecting the HT-treated milk derlvative to an enzyme inactivation step.
The enzyme inactivation step may e.g. comprise adjusting the température of the
HT-treated milk derivatlve to a température in the range of 70-95 degrees C and keeping the température of the HT-treated milk derlvative in that range for a period in the range of 30-500 seconds.
In some preferred embodiments of the invention deriving the lactose-reduced milk-related product from the milk dérivative Involves hydrolysis at least some of the lactose of the HT-treated milk derlvative.
The hydrolysis of lactose may e.g. comprise contacting the HT-treated milk derlvative with a lactase enzyme.
In some preferred embodiments of the invention the hydrolysis is performed after the enzyme inactivation step.
In other preferred embodiments of the invention the enzyme Inactivation step is performed after the hydrolysis.
The packaging of step c) may be any suitable packaging techniques, and any suitable container may be used for packaging the milk-related product of the Invention.
However, in a preferred embodiment of the invention, the packaging of step c) Is aseptie packaging, i.e. the milk-related product is packaged under aseptie conditions. For example, the aseptie packaging may be performed by using an aseptie filling system, and it preferably involves filling the milk into one or more aseptie container(s).
Examples of useful containers are e.g. bottles, cartons, bricks, and/or bags.
The packaging is preferably performed at or below room température. Thus, the température of the lactose-reduced milk-related product is preferably at most 30 degrees C during the packaging, preferably at most 25 degrees C and even more preferably at most 20 degrees C, such as at most 10 degrees C.
The température of the lactose-reduced mllk-related product during packaging may for example be in the range of 2-30 degrees C, and preferably in the range of 5-25 degrees C.
In an embodiment of the Invention, the lactose-reduced mllk-related product comprises at Ieast 50% (w/w) HT-treated milk dérivative of step b), preferably at Ieast 75% (w/w) HT-treated milk dérivative of step b), and even more preferably at Ieast 85% (w/w) HT-treated milk derlvatlve of step b). For example, the lactose-reduced mllk-related product may comprise at Ieast 90% (w/w) HTtreated milk derivatlve of step b), preferably at Ieast 95% (w/w) HT-treated milk derivatlve of step b), and even more preferably at Ieast 97.5% (w/w) HT-treated milk derivatlve of step b).
The lactose-reduced milk-related product normally comprises water, and may e.g. comprise at Ieast 50% (w/w) water, preferably at ieast 60% (w/w) water, and even more preferably at Ieast 70% (w/w) water. For example, the lactose-reduced milk-related product may comprise at Ieast 75% (w/w) water, preferably at Ieast 80% (w/w) water, and even more preferably at Ieast 85% (w/w) water.
In a preferred embodiment of the Invention, the lactose-reduced milk-related product comprises at Ieast 90% (w/w) water.
Additionally, the lactose-reduced mllk-related product may contain the same additives as the mllk-related feed and/or the milk dérivative.
Another aspect of the Invention relates to a mllk-related product obtainable by the method of the invention. For example, the mllk-related product may be the HTtreated milk dérivatives of step b) or alternatively, it may be the packaged lactose-reduced milk-related product of step c).
For long shelf-life milk products, undeslred enzyme activity may be just as problematlc as microbial growth, and it Is therefore preferred that the method of the invention also comprises an enzyme Inactivation step.
In a preferred embodiment of the Invention, said enzyme inactivation step comprises adjusting the température of the liquid to be treated to a température in the range of 70-95 degrees C for a period In the range of 30-500 seconds.
For example, the température of the liquid to be treated may be adjusted to a température in the range of 70-80 degrees C for a period in the range of 30-500 seconds, preferably 40-300 seconds, and even more preferably 50-150 seconds.
In a preferred embodiment of the Invention, the température of the liquid to be treated Is adjusted to a température In the range of 70-75 degrees C for a period in the range of 30-500 seconds, preferably 40-300 seconds, and even more preferably 50-150 seconds.
Alternatively, the température of the liquid to be treated may be adjusted to a température in the range of 75-85 degrees C for a period in the range of 30-500 seconds, preferably 40-300 seconds, and even more preferably 50-150 seconds.
Alternatively the température of the liquid to be treated may be adjusted to a température in the range of 80-95 degrees C for a period in the range of 10-300 seconds, preferably 25-200 seconds, and even more preferably 30-100 seconds.
Such a température treatment has proven to reduce the activity of enzymes, such as plasmin, as well as pro-enzymes, such as plasmlnogen.
The enzyme inactivation step should preferably reduce the combined activity of plasmin and plasminogen of the treated liquid by at least 60% relative to the 20 activity ofthe untreated liquid, preferably by at least 65%, and even more preferably by at least 70%.
The combined activity is a measure of the activity of plasmin in the milk-related product plus the activity that can be gained from converting plasminogen Into 25 plasmin. The combined activity Is determined according to analysis G of Example
I.
Some embodiments ofthe invention require even lower levels of combined plasmin and plasminogen activity, and for such embodiments the enzyme
Inactivation step should preferably reduce the combined activity of plasmin and plasminogen of the treated liquid by at least 80% relative to the activity of the untreated liquid, preferably by at least 85% and even more preferably by at least 90%.
In preferred embodiments of the invention, the enzyme inactivation step should reduce the combined activity of plasmin and plasminogen of the treated liquid by
at least 95% relative to the activity of the untreated liquid, preferably by at least
97.5%, and even more preferably by at least 99%.
In an embodiment of the Invention, the combined activity of plasmin and plasmlnogen of the milk-related product is at most 8.000 mlcroUnlts/mL, preferably at most 5.000 microUnits/mL and even more preferably at most 3.000 microUnits/mL.
In the context of the présent invention, a plasmin activity of one Unit (U) Is the plasmin activity which can produce 1 micromol p-Nltroanlllne per minute at 25 degrees C, pH 8.9, using Chromozyme PL (Tosyl-Gly-Pro-Lys-4-nltranillde acetate) as substrate.
In another embodiment ofthe Invention, the combined activity of plasmin and plasmlnogen of the milk-related product is at most 2.500 mlcroUnits/mL, preferably at most 1.000 microUnits/mL, and even more preferably at most 750 mlcroUnlts/mL. It may even be preferred that the combined activity of plasmin and plasmlnogen of the milk-related product Is at most 600 mlcroUnlts/mL, preferably at most 400 microUnlts/mL, and even more preferably at most 200 microUnits/mL.
The enzyme inactivation step may be performed during different stages of the method, for example, before the hydrolysls of lactose, before the HT-treatment, and/or before the packaging.
As mentioned herein, the method of the invention may involve a step of hydrolyslng at least some of the lactose into glucose and galactose. The hydrolysis of lactose may e.g. comprise contactlng the lactose with a lactase enzyme.
A number of different lactase enzymes are commercially available and an example of a useful lactase enzyme Is e.g. Lactozym® Pure (Novozymes, Denmark).
The enzyme preferably contacts the composition which contains the lactose, e.g. the milk-related feed and/or the HT-treated milk dérivative.
In some embodiments of the invention the enzyme Is added to the milk-related feed and/or the HT-treated milk dérivative. The enzyme may e.g. be présent In 29
the milk-related feed and/or the HT-treated milk dérivative in dissolved form, e.g.
as single enzyme molécules or as soluble aggregates of enzyme molécules.
In other embodiments of the Invention the lactase enzyme is separate from the mllk-related feed and/or the HT-treated milk derlvative, but brought in contact with the lactose by contacting the enzyme with the mllk-related feed and/or the HT-treated milk dérivative. For example, enzyme immobllised on a stationary solid phase may be used. Examples of useful stationary solid phases are e.g. a filter, a packed bed of enzyme-containlng particles, or similar structures.
Alternatively, the solid phase may e.g. be a free flowlng, particulate solid phase, e.g. organic or inorganlc beads, forming part of the liquid.
The température of the liquid, In which lactose Is to be hydrolysed, is preferably kept relatively low to avold unwanted microbial growth. In some embodiments of the Invention the température ofthe liquid, e.g. the milk-related feed or the HTtreated milk derlvative, during the hydrolysis is in the range of 1-15 degrees C. The température of the liquid during the hydrolysis may e.g. be in the range of 212 degrees C, preferably in the range of 3-10 degrees C, and even more preferably in the range of 4-8 degrees C.
The duration of the hydrolysis dépends on the used activity of the enzyme and well as In which form (e.g. Immobilised or added to the liquid) it Is used. It is preferred that the hydrolysis takes at most 48 hours, and preferably at most 24 hours, such as at most at most 12 hours. The hydrolysis may for example take place in a cooled tank in which the liquid, e.g. the milk-related feed or the HTtreated mllk derlvative, 1s mixed with the enzyme.
Details relating to the industrial use of enzymes including immobilisation techniques and suitable solid phase types can be found in Biocatalysts and Enzyme technology, Klaus Buchholz et al., ISBN-10: 3-527-30497-5, 2005, Wiley VCH Verlag GmbH, which Is incorporated herein by reference for ail purposes.
The présent Inventors have seen Indications that, contrary to what one would expect, performlng the lactose hydrolysis reaction prior to the HT-treatment provided products having an acceptable taste desplte the presence of reactive monosaccharfdes during the HT-treatment of the mllk derlvative. Thus, in
preferred embodiments ofthe invention, the hydrolysis of lactose Is performed prior to the HT-treatment of the milk dérivative.
In some embodiments of the Invention the lactase enzyme is still présent and active in the milk-related product when the milk-related product is packaged. This approach simplifies the process and saves the time and costs for operating hydrolysis tanks or continuous hydrolysis reactors.
In other embodiments of the Invention the lactase enzyme has been Inactlvated prior to the packaging, e.g. by one of the heating or inactivation steps already mentioned herein or using an additional heating step.
In some embodiments of the invention the method furthermore involves physically separating mlcroorganisms from the milk-related feed, and thereby obtaining a partly sterilised milk dérivative. This séparation actually removes microorganlsms from the milk-related feed contrary to other stérilisation techniques which only kill the mlcroorganisms and leave the dead microorganlsms in the milk.
In the context of the présent invention, the term microorganlsms relates to e.g. bacteria and bacterial spores, yeasts, moulds and fungal spores.
The physical séparation may e.g. remove at least 90% of the mlcroorganisms of the milk-related feed, preferably at least 95% of the microorganlsms, and even more preferably at least 99% of the microorganlsms of the milk-related feed.
In an embodiment of the Invention, the physically séparation Involves bactofugation of said milk-related feed.
In another embodiment ofthe invention, the physically séparation involves microfiltration of said milk-related feed.
In a preferred embodiment of the invention, the microfiltration is performed using a filter having a pore size In the range of 0.5-1.5 micron, preferably in the range of 0.6-1.4 micron, even more preferably In the range of 0.8-1.2 micron.
These pore size ranges hâve been found to be advantages as they retain most of the microorganisms of the milk-related feed with substantially no alteration of the protein composition of milk derivate.
In an embodiment of the Invention, the used mlcrofilter is a cross-flow microfilter.
Suitable microfiltration system can e.g. be found In Tetra Pak Dalry processing Handbook 2003 (ISBN 91-631-3427-6), which Is incorporated herein by reference for ail purposes.
In yet an embodiment of the invention, the physical séparation involves both bactofugatlon and microfiltration of said milk-related feed.
In an embodiment of the Invention, the bactofugatlon comprises the use of at least one bactofuge, preferably at least two bactofuges in sériés, and even more preferably at least three bactofuges in sériés.
The physical séparation is preferably performed at, below, or slightly above ambient température. Thus, the température of the milk-related feed may be at most 60 degrees C during the physical séparation, e.g., at most 40 degrees C, such as at most 20 degrees C, or at most 10 degrees C.
The température of the milk-related feed during physical séparation may for example be in the range of 2-60 degrees C, and preferably in the range of 25-50 degrees C.
Suitable bactofuges, Including one one-phase or two-phase Bactofuges, can e.g. be found In Tetra Pak Dalry processing Handbook 2003 (ISBN 91-631-3427-6), which Is incorporated herein by reference for ail purposes.
However, In some embodiments of the Invention derivlng the milk dérivative from the milk-related feed does not Involve physically separating microorganisms from the milk-related feed.
In other embodiments of the invention derivlng the milk dérivative from the milkrelated feed does not Involve physically separating microorganisms from any milkrelated stream of the method.
Different exemplary embodiments ofthe invention are shown in Figs. 1-11. Note that these figures do not show all the details of the depicted process embodiments and that the embodiments may contain various additional process steps, such as
e.g. température adjustments, homogénisation, and storlng.
Figure 1 shows a schematic flow diagram of an embodiment of the Invention in which the mllk-related feed is subjected to a ΗΤ-treatment. In this case the milk derlvative Is, or essentlally consists of, the mllk-related feed. The HT-treated milk derivatlve obtained from step c) is subsequently packaged. In this embodiment of the Invention the milk-related product Is, or essentlally consists of, the HT-treated milk derivatlve.
Figure 2 shows a schematic flow diagram of an embodiment of the Invention in which at least some of the lactose of the milk-related feed is hydrolysed. In this embodiment the milk derivatlve Is the mllk-related feed which has been modified by hydrolysing at least some of the lactose. The milk derivatlve Is subjected to a ΗΤ-treatment, and the resulting HT-treated milk derivatlve Is subsequently packaged. In this embodiment of the invention the milk-related product Is, or essentlally consists of, the HT-treated milk derivatlve.
Figure 3 shows a schematic flow diagram of an embodiment of the invention in which the milk-related feed is subjected to a ΗΤ-treatment. In this embodiment of the Invention the milk derivatlve is, or essentlally consists of, the mllk-related feed. Subsequently, at least some of the lactose of the HT-treated milk derivatlve Is hydrolysed. In this embodiment of the invention the milk-related product is, or essentlally consists of, the HT-treated milk derlvative, which contains the hydrolysed lactose. After the hydrolysis the milk-related product is finally packaged.
Figure 4 shows a schematic flow diagram of an embodiment of the invention fn which the milk-related feed Is subjected to an enzyme inactivation step. In this embodiment of the Invention the milk dérivative Is, or essentlally consists of, the enzyme Inactivated milk-related feed. The milk derlvative Is subjected to a ΗΤtreatment and the resulting product is subsequently packaged. In this embodiment of the Invention the milk-related product Is, or essentlally consists of, the HT-treated milk derivatlve.
Figure 5 shows a schematlc flow diagram of an embodiment of the invention in which at least some of the lactose of the mllk-related feed Is hydrolysed and the resulting product is subjected to an enzyme inactivation step. In this embodiment the milk derivatlve Is the hydrolysed, enzyme Inactivated mllk-related feed. The milk derivatlve is subsequently subjected to a ΗΤ-treatment and packaged. In this embodiment of the Invention the mllk-related product Is, or essentially consists of, the HT-treated milk dérivative.
Figure 6 shows a schematlc flow diagram of an embodiment of the invention In which the milk-related feed is subjected to an enzyme Inactivation step and in which a least some of the lactose of the resulting product Is hydrolysed. In this embodiment the milk derivatlve is the mllk-related feed which has been subjected to enzyme inactivation and subséquent hydrolysls of lactose. The milk dérivative is subjected to a ΗΤ-treatment and finally packaged.
Figure 7 shows a schematlc flow diagram of an embodiment of the invention In which the milk-related feed is subjected to an enzyme Inactivation step and subsequently to a ΗΤ-treatment. The milk dérivative of this embodiment Is, or essentially consists of, the enzyme inactivated milk-related feed. After the HTtreatment at least some of the lactose of the HT-treated milk derivatlve is hydrolysed, and the resulting milk-related product, now also containing hydrolysls products of lactose, is subsequently packaged.
Figure 8 shows a schematlc flow diagram of an embodiment of the invention in which the milk-related feed is subjected to a ΗΤ-treatment. In this embodiment the milk dérivative is, or essentially consists of, the mllk-related feed. Subsequently, the resulting HT-treated milk derivatlve is subjected to an enzyme Inactivation step and packaged. In this embodiment the mllk-related product Is, or essentially consists of, the enzyme inactivated HT-treated milk derivatlve.
Figure 9 shows a schematlc flow diagram of an embodiment of the Invention In which at least some of the lactose of the mllk-related feed Is hydrolysed and subsequently subjected to a HT-treatment. In this embodiment the milk derivatlve is, or essentially consists of, the milk-related feed containing hydrolysed lactose,
The resulting HT-treated milk dérivative Is subjected to an enzyme inactivation step and packaged. Thus, the milk-related product of this embodiment Is, or essentially consists of, the enzyme Inactivated, HT-treated milk dérivative.
Figure 10 shows a schematic flow diagram of an embodiment of the invention in which the milk-related feed Is subjected to a HT-treatment. In this embodiment the milk dérivative Is, or essentially consists of, the milk-related feed. Subsequently, the resulting HT-treated milk derivatlve is first subjected to a step of hydrolyslng at least some of the lactose of the HT-treated milk dérivative, then to an enzyme inactivation step, and flnally packaged. The milk-related product of this embodiment is, or essentially consists of, the hydrolysed, enzyme Inactivated HT-treated milk derivatlve.
Figure 11 shows a schematic flow diagram of an embodiment of the Invention in which the milk-related feed Is subjected to a HT-treatment. In this embodiment the milk derivatlve is, or essentially consists of, the milk-related feed. Subsequently, the resulting HT-treated milk derivatlve Is first subjected to an enzyme inactivation step, then to a step of hydrolysing at least some of the lactose of the HT-treated milk derivatlve, and flnally the product is packaged. The milk-related product of this embodiment Is, or essentially consists of the enzyme inactivated, hydrolysed HT-treated milk derivatlve.
An advantage of the présent invention Is that It provides a more CO2-friendly, fresh-tasting milk. Due to Its long shelf-life and robustness to higher températures, the présent milk-related products can be transported at ambient température instead of at 5 degrees C. Low température logistlcs are highly energy consumlng and typically require transportation of a relatively higher number of small, cooled loads of product, than a comparable ambient température logistic set-up. Milk-related products of the présent Invention may therefore be produced and transported to the retallers with a lower CO2 émission than prior art miik products having a similar fresh taste.
The présent Inventors hâve additionally found that the method of the invention surprlslngly Increases the time a milk processing plant, In which the method has been implemented, can operate before the plant has to be cleaned. This 1s percelved as advantageous and allows for cost savings in the production of the milk products.
As will be clear to the person skilled in the art, the method may contain one or more additional step(s), such as a homogénisation step, a storage step, a mixing step, température adjustment step, a pasteurisation step, a thermizatlon step, a centrifugation step as well as combinations thereof.
Yet an aspect of the invention relates to a packaged, lactose-reduced milk-related product obtainable by the method according to any of the preceding daims. The milk-related product may be packaged in a container as described herein.
An additional aspect of the invention relates to a milk-related product as such, preferably having a long shelf-life and low level of cooked taste.
The shelf-life of a product Is typically described as the time for which the product can be stored without the quality falllng below a certain minimum acceptable level. This is not a very sharp and exact définition and it dépends to a large extent on the perception of minimum acceptable quality.
In the context of the présent invention, the term shelf-life means the time in which the milk-related product can be stored, hermetically sealed, at a spécifie température before an undesirable event occurs.
In an embodiment of the invention, the undesirable event is that the milk-reiated product is found to be non-sterile. A non-sterile milk-related product is a product which does not contain microorganisms capable of growlng in the product at normal non-refrtgerated conditions at which the food is llkely to be held during manufacture, distribution and storage. Non-sterility and microbial presence or growth may e.g. be detected according to Marth, E. H., ed. 1978. in Standard methods for the examination of dairy products. Am. Publ. Health Assoc., Washington, DC.
Hydrophobie peptides, which are products of proteolytfc dégradation of milk proteins, are known to give rlse to an undesirably bltter taste. Thus, in an embodiment of the Invention, the undesirable event Is that the milk-related product is found to contain at least 1 mg/L hydrophobie peptides having a molar weight in the range of 500-3000 g/mol, such as at least 20 mg/L, or such as at least 50 mg/L hydrophobie peptides having a molar weight In the range of 5003000 g/mol.
In another embodiment of the Invention, the undeslrable event Is that the milkrelated product Is found to contain at least 100 mg/L hydrophobie peptides having a molar weight In the range of 500-3000 g/mol, such as at least 200 mg/L, or such as at least 500 mg/L hydrophobie peptides having a molar weight In the range of 500-3000 g/mol.
In a further embodiment of the invention, the undeslrable event is that the mllkrelated product Is found to contain at least 750 mg/L hydrophobie peptides having a molar weight In the range of 500-3000 g/mol, such as at least 1000 mg/L, or such as at least 2000 mg/L hydrophobie peptides having a molar weight In the range of 500-3000 g/mol.
The concentration of hydrophobie peptides having a molar weight In the range of 500-3000 g/mol of the mllk-related product Is determined as described In Kai-Ping et al, J. Agrlc. Food Chem. 1996, 44, 1058-1063. The mllk-related product Is used as sample and, following Kai-PIng et al., the obtained 500-3000 g/mol molecular weight fraction Is subsequently analysed via analytical HPLC on a C18 column. The resulting chromatogram is used to détermine the concentration of hydrophobie peptides having a molar weight in the range of 500-3000 g/mol of the milkrelated product.
In yet an embodiment of the Invention, the undeslrable event is that the mllkrelated product is found to hâve an undeslrable sensory property using sensory testlng according to ISO 22935-1:2009, ISO 22935-2:2009, and ISO 229353:2009 which relate to sensory analysis of milk and milk products. Sensory propertles, such as Visual appearance, consistency, odour, and taste, are preferably tested.
It Is preferred to combine two or more of the different types of undeslrable events for the détermination of shelf-life.
Thus, in a preferred embodiment of the invention, the shelf-llfe is determined by the first occurrence of an undesired event selected from the group consisting of: the mllk-related product Is found to be non-sterile, and
- the mllk-related product ts found to contain at least 1 mg/L hydrophobie peptides having a molar weight in the range of 500-3000 g/mol.
In another preferred embodiment of the invention, the shelf-life is determined by the first occurrence of an undesired event selected from the group consisting of:
- the milk-related product Is found to be non-sterlle,
- the milk-related product is found to contain at least 1 mg/L hydrophobie peptides having a molar weight In the range of 500-3000 g/mol, and
- the milk-related product Is found to hâve an undeslrable sensory property.
In yet a preferred embodiment ofthe invention, the shelf-life is determined by the first occurrence of an undesired event selected from the group consisting of:
- the milk-related product is found to be non-sterile, and the milk-related product Is found to hâve an undeslrable sensory property.
In an embodiment ofthe invention, the shelf-life of said milk-related product is at least 30 days, when kept at 25 degrees C.
In another embodiment of the invention, the shelf-life of said milk-related product is at least 49 days, when kept at 25 degrees C the first 21 days after packaging and at 5 degrees C the subséquent time.
In yet an embodiment of the invention, the shelf-life of said milk-related product is at least 70 days, when kept at 5 degrees C.
In an additional embodiment ofthe invention, the shelf-life of said milk-related product is at least 119 days, when kept at 25 degrees C.
In another embodiment of the Invention, the shelf-life of said milk-related product is at least 182 days, when kept at 25 degrees C.
The milk-related product of the invention appears to hâve a relatively low content of denatured beta-lactoglobulln. For example, at most 50% (w/w) ofthe betalactoglobulin of the milk-related product may be denatured relative to the total amount of both denatured and non-denatured beta-lactoglobulln. Preferably, at most 40% (w/w) of the beta-lactoglobulln of the milk-related product Is denatured relative to the total amount of both denatured and non-denatured betalactoglobulln, preferably at most 35% (w/w), and even more preferably at most 30% (w/w).
In preferred embodiments of the invention, at most 30% (w/w) of the betalactoglobulin ofthe milk-related product Is denatured relative to the total amount of both denatured and non-denatured beta-lactoglobulln, preferably at most 25% (w/w), and even more preferably at most 20% (w/w
The degree of dénaturation Is measured according to Analysis C of Example I.
In an embodiment of the invention, the milk-related product comprises at most 60% w/w milk fat. An example of such a mllk-related product Is cream double.
In another embodiment of the Invention, the milk-related product comprises at most 40% w/w milk fat. An example of such a milk-related product is whipping cream.
In yet an embodiment of the Invention, the mllk-related product comprises at most 20% w/w milk fat. An example of such a mllk-related product Is table cream containing 18% w/w milk fat.
In a further embodiment of the Invention, the mllk-related product comprises at most 4% w/w milk fat. An example of such a milk-related product Is full fat milk which typically contains 2-4% w/w milk fat, and preferably approx. 3% w/w milk fat.
In a further embodiment of the Invention, the milk-related product comprises at most 1.5 w/w milk fat. An example of such a mllk-related product is semi-skim milk which typically contains 0.7-2% w/w milk fat, and preferably 1-1.5% w/w milk fat.
In an additional embodiment of the invention, the milk-related product comprises at most 0.7 w/w milk fat. An example of such a mllk-related product Is skim milk which normally contains 0.1-0.7% w/w milk fat, and preferably 0.3-0.6% w/w milk fat, such as approx. 0.5% w/w milk fat.
In a preferred embodiment of the Invention, the milk-related product comprises at most 0.1% w/w milk fat. An example of such a mllk-related product Is skim-milk having a fat content In the range of 0.05-0.1% w/w.
In some embodiments of the invention, the mllk-related product comprises 2,54.5% w/w caseln, 0.25-1% w/w milk sérum protein, and 0.01-3% w/w milk fat. In some preferred embodiments of the invention, the milk-related product comprises 2.5-4.5% w/w caseln, 0.25-1% w/w milk sérum protein, and 0.1-1.5% w/w milk fat. In other preferred embodiments of the invention, the mllk-related product comprises 2.5-4.5% w/w caseln, 0.25-1% w/w milk sérum protein, and 0.01-0.1% w/w milk fat.
The mllk-related product normally comprises water, and may e.g. comprise at least 60% (w/w) water, preferably at least 70% (w/w) water, and even more preferably at least 80% (w/w) water. For example, the milk-related product may comprise at least 85% (w/w) water, preferably at least 87.5% (w/w) water, and even more preferably at least 90% (w/w) water.
In some embodiments of the Invention the lactose-reduced mllk-related product comprises at most 3% (w/w) lactose relative to the total weight of the lactosereduced mllk-related product. For example, the lactose-reduced milk-related product may comprise at most 2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related product, preferably at most 1% (w/w), and even more preferably at most 0.5% (w/w) lactose relative to the total weight of the lactose-reduced mllk-related product.
Even lower levels of lactose may be désirable, thus in some embodiments of the Invention the lactose-reduced milk-related product comprises at most 0.2% (w/w) lactose relative to the total weight of the lactose-reduced mllk-related product. For example, the lactose-reduced mllk-related product may comprise at most 0.1% (w/w) lactose relative to the total weight of the lactose-reduced mllk-related product, preferably at most 0.05% (w/w), and even more preferably at most 0.01% (w/w) lactose relative to the total weight of the lactose-reduced mllkrelated product.
In some embodiments of the Invention the lactose-reduced mllk-related product comprises 0.01-2% (w/w) glucose relative to the total weight of the lactosereduced mllk-related product. For example, the lactose-reduced milk-related product may comprise 0.02-1.5% (w/w) glucose relative to the total weight of the lactose-reduced mllk-related product, preferably 0.05-1% (w/w), and even more
preferably 0.1-0,5% (w/w) glucose relative to the total weight of the lactosereduced milk-related product.
Sometimes lower levels of glucose may be désirable, thus in some embodiments of the Invention the lactose-reduced milk-related product comprises 0.01-0.5% (w/w) glucose relative to the total weight of the lactose-reduced milk-related product. For example, the lactose-reduced milk-related product may comprise 0.02-0.3% (w/w) glucose relative to the total weight of the lactose-reduced milkrelated product, preferably 0.04-0.2% (w/w), and even more preferably 0.050.1% (w/w) glucose relative to the total weight of the lactose-reduced milkrelated product.
In some embodiments of the invention the lactose-reduced milk-related product comprises 0.01-2% (w/w) galactose relative to the total weight of the lactosereduced milk-related product. For example, the lactose-reduced milk-related product may comprise 0.02-1.5% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product, preferably 0.05-1% (w/w), and even more preferably 0.1-0.5% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product.
Lower levels of galactose may be désirable, thus In some embodiments of the invention the lactose-reduced milk-related product comprises 0.01-0.5% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product. For example, the lactose-reduced milk-related product may comprise 0.02-0.3% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product, preferably 0,04-0.2% (w/w), and even more preferably 0.05-0.1% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product.
The milk-related product may furthermore contain any of the additlves mentioned herein.
In one exemplary aspect, the milk-related product may hâve a shelf-life in the range of 4 to 6 months, when stored at a température of no more than 35 degrees C.
In a second exemplary aspect, the milk-related product may hâve a shelf-life In the range of 20 days to 60 days when stored at a température of no more that 8 degrees C.
Milk secreted by healthy cows is basically stérile, but the Introduction of bacteria into milk from a variety of sources, Including exterlor and interior of the udder, soil, bedding, manure, milking equipment and storage tanks, Is generally unavoldable. Although, according to Pasteurized Milk Ordinance (PMO) standards, the total bacterial count (TBC) of Grade A raw milk for an Individual producer should not exceed 100,000 cfu/mL (FDA, 2001, Grade A Pasteurized Milk Ordinance., U.S. Dept. of Health and Human Services, Public Health Service. Publication No. 229. Washington, DC.), an Idéal spécification for the bacterial count Is < 7500. Following pasteurisation, the recommended bacterial count should not exceed 20,000 cfu/ml. After UHT processing, e.g. at 149 degrees C for 3 seconds, no mlcroorganism/spore Is capable of survival, as measured by standard plate count tests (Glllis et al., J Dalry Sci.1985 2875-9).
The long shelf-life of the mllk-related product of the présent invention is due to low residual level of viable microorganisms. When measured immediately following processing and packaging (under aseptie conditions) the product has a viable spore count, measured as colony forming unlts/mill(litre (cfu/ml) of at most 1,000 cfu/ml, more preferably 500 cfu/ml, 100 cfu/ml, 50 cfu/ml, 10 cfu/ml, 1 cfu/ml or <1 cfu/ml. Preferably the product has a viable spore count between 0 and 1,000 cfu/ml, more preferably between 0 and 100 cfu/ml, 0 and 50 cfu/ml, or 0 and 10 cfu/ml.
In a preferred embodiment of the Invention, the milk-related product contains 0 cfu/ml, i.e. the milk-related product Is preferably stérile.
Suitable methods for determining the viable spore count in milk or mllk-derlved products are known In the art: For example standard plate count tests are described by Marth, E. H., ed. 1978. in Standard methods for the examination of dalry products. Am. Publ. Health Assoc., Washington, DC. According to a standard method, milk samples are plated on a medium of Milk Agar (Oxoic), and colonies are counted after 3 d incubation at 30 degrees C (Health protection agency (2004) Plate count test at 30 degrees C. National Standard Method D2 IlSue 3, www.hpa42
standardmethods.ora.uk/Ddf sops.asp. Alternatively, spore counts can be determined by direct microscopie count using bright-fleld microscopy and Thoma countlng chamber procedures.
Many volatile compounds generated during the thermal processing of milk hâve been associated with cooked, stale, and sulfurous notes In milk and are considered as off-flavours by most consumera. Heat treatment is known to be the direct cause of Type 2 reactions leading to off-flavour compounds, such as aldéhydes, methyl ketones, and various sulfur compounds, which are barely détectable In the raw milk.
Levels of total ketones detected in raw milk (circa 6 microgram and 11 microgram total ketones per kg of 1% and 3% raw milk respectively) and pasteurised milk are not stgnificantly different, but may be Increased by as much as 12 fold in UHT milk (circa 78 microgram and 120 microgram total ketones per kg of 1% and 3% UHT milk respectively). The major ketone contrlbutors are 2-heptanone and 2nonanone, whose concentration is 34 and 52 times higher, respectively, in UHT milk than In raw and pasteurized samples. These levels correspond to circa 22 microgram and 34 microgram 2-heptanone per kg of 1% and 3% UHT milk respectively; and circa 35 microgram and 53 microgram 2-nonanone per kg of 1% and 3% UHT milk respectively). The other contrlbutors are 2,3-butanedlone, 2pentanone, and 2-undecanone.
Since aroma impact is not only dépendent on concentration, but also on sensory threshold, the odour activity value (OAV = concentration/sensory threshold) must be taken into account. The calculated odour activity values reveal that 2,3butanedione, 2-heptanone, 2-nonanone, 2-methylpropanal, 3-methylbutanal, nonanal, decanal, and dimethyl sulfide are Important contrlbutors to the offflavour of UHT milk.
In some exemplary embodiments of the invention, the natural organoleptlc properties of raw/pasteurised milk are preserved in the long shelf-llfe milk-related product of the présent invention due to the low level of volatile off-flavor compounds in the product. In partîcular the milk product obtained immediately following processing and packaging (under aseptie conditions) contains a détectable total ketone level measured in units of microgram total ketone per kg of 1% fat (or 3% fat) milk of at most 60 (100), more preferably at most 50 (80),
(60), 30 (40), 20 (20) and 10 (10) microgram total ketone. Preferably, the détectable total ketone level measured in units of microgram total ketone per kg of 1% fat (or 3% fat) milk lies within the range of between 6 - 60 (8 - 100), more preferably 6 - 50 (8 - 80), 6 - 40 (8 - 60), 6 - 30 (8 - 40), 6 -20 (8 - 20) or
-10 (8 - 10) microgram total ketone.
In some exemplary embodiments of the invention, the milk product obtained Immediately following processing and packaging (under aseptie conditions) contains a détectable 2-heptanone level measured in units of microgram total 2heptanone per kg of 1% fat (or 3% fat) milk of at most 15 (25), more preferably at most 10 (20), 7 (15), 5 (10) or 2 (5) microgram 2-heptanone. Preferably, the détectable 2-heptanone level measured In units of microgram total ketone per kg of 1% fat (or 3% fat) milk lies within the range of between 1 - 15 (1 - 25), more preferably 1 - 10 (1 - 20), 1-7(1- 15), 1 - 5 (1 - 10) or 1 -3 (1 - 5) microgram 2-heptanone.
In some exemplary embodiments of the invention, the milk product obtained immediately following processing and packaging (under aseptie conditions) contains a détectable 2-nonanone level measured in units of microgram total 2nonanone per kg of 1% fat (or 3% fat) milk of at most 25 (40), more preferably at most 20 (30), 15 (25), 10 (15) or 5 (10) microgram 2-nonanone. Preferably, the détectable 2-nonanone level measured in units of microgram 2-nonanone per kg of 1% fat (or 3% fat) milk lies within the range of between 0.2 - 25 (0.2 40), more preferably 0.2 - 20 (0.2 - 30), 0.2 - 15 (0.2 - 25), 0.2 - 10 (0.2 - 15) or 0.2 -5 (0.2 - 10) microgram 2-nonanone.
Headspace solid-phase microextraction (HSSPME) combined with gas chromatography provides a fast and reliable technique for the extraction and quantitative analysis of volatile components in dairy foods (P. A. VazquezLandaverde et al., 2005 J. Dairy Sci. 88:3764-3772). For example, mass spectra of milk volatiles can be obtained using an Agllent 6890 gas chromatograph equipped with a 5973 quadrupole mass analyzer detector (Agilent Technologies, Inc., Wilmington, DE). The SPME fiber is exposed to the headspace of 20 g of a milk sample in a 40-mL amber glass vial for 3 h at 35 degrees C and then inserted in the GC-mass spectroscopy injection port for 5 min. under splitless conditions. A DB-5 caplllary column (30 m x 0.32 mm i.d., 1-microm film thickness; J&W Scientific, Folsom, CA) provides chromatographie séparation. The oven
température program is maintained at 35 degrees C for 8 min., increased to 150 degrees C at a rate of 4 degrees C /min., then increased to 230 degrees C at a rate of 20 degrees C/min., and flnally held at 230 degrees C for 20 min. Hélium is used as the carrier gas at 2.5 mL/mln. The injector, detector transfer line, and Ion source températures are 250, 280, and 230 degrees C, respectively. Electron Impact ionizatlon at a voltage of 70 eV and m/z range of 35 to 350 is collected at 4.51 scans/s. The instrument control and data analysis is performed using enhanced ChemStation software (Agtlent Technologies, Inc.). The volatile compounds in milk are identified by comparing mass spectra and rétention times with those of authentic compounds.
Heat treatment of milk is the cause of Type 1 reactions leading to the dénaturation, dégradation, and inactivation of whey proteins, enzymes, and vltamins. The Maillard reaction plays a key rôle in such Type 1 reactions. This reaction can be monitored by measuring the furoslne (epsilon-N-2-furoylmethyl-Llysine) and lactulose (4-0-beta-galactopyranosyl-D-fructose) values and the furosine/lactulose ratio in a product. In the early Maillard reaction, lactose reacts with protein-bound lysine to the protein-bound Amadori product (1-deoxy-lamino-) lactulosyllysine. Furoslne is an artificial amino acid that arises from acid hydrolysis of the Amadori product. Furoslne can therefore be used as a molecular marker to quantlfy the extent (and progress) of the Maillard reaction and available lysine. Furoslne as such Is normally not présent in détectable levels In milk products.
Similarly, the mllk product obtained Immediately following processing and packaging (under aseptie conditions) contains a détectable level of lactulose measured in units of mg/mllliliter (ml) milk of at most 30 mg/ml milk product, more preferably at most 20, 10, 5, or 2 mg/ml. Preferably, the détectable lactulose level measured In units of mg lactulose per ml of milk product Iles within the range of between 0-30 mg/ml, more preferably 0 - 20, 0 - 10, 0 - 5 or 0 - 2 mg/ml lactulose.
In some preferred embodiments of the invention, the milk-related product has a furosine value of at most 80 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage. The furosine value of a milk-related product may be determined according to Analysis F of Example I.
For example, the milk-related product may hâve a furosine value of at most 70 mg/100 g protein on day 49 after the production when kept at a température of degrees C during storage or even more preferred a furosine value of at most mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage.
Even lower furosine values may be preferred, thus the milk-related product may hâve a furosine value of at most 50 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage. For example, the milk-related product may hâve a furosine value of at most 40 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage or even more preferred a furosine value of at most 30 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage.
In other preferred embodiments of the invention, the milk-related product has a furosine value of at most 60 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
For example, the milk-related product may hâve a furosine value of at most 50 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage or even more preferred a furosine value of at most 40 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
Even lower furosine values may be preferred, thus the milk-related product may hâve a furosine value of at most 30 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage. For example, the milk-related product may hâve a furosine value of at most 20 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage or even more preferred a furosine value of at most 10 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
As mentioned, the formation of the Amadori product in the Maillard reaction leads to a loss of lysine available for digestion. Therefore, the nutritional value of the
présent milk-related products Is perceived to be better than prior art lactosereduced milk due to the lower furosine values and thus higher bioavailability of lysine.
Although fat-soluble vitamlns In milk are minimally affected by heat treatment, the water-soiuble vitamlns can be partially destroyed. Consequently, UHT processing reduces B vitamlns by 10%, folie acid by 15%, and vitamln C by 25%. The long shelf-llke milk of some exemplary embodiments of the présent invention has a vitamln C content that Is reduced by less than 20% during production processing.
Hydroxymethylfurfural (HMF) is a recognlsed marker of heat-damaged milk, where levels of HMF In UHT milk are reported to range from 4-16 micromol/l. Singh et al., Lait (1989) 69 (2) 131-136. A long shelf-life milk-related product obtained immediately following processing and packaging (under aseptie conditions) contains a détectable level of HMF measured (n units of 1 micromol /L milk at most 6 mlcromol/l HMF, more preferably at most 5, 4, 3, 2 or 1 micromol/L HMF. Preferably, the détectable HMF level measured in units of micromol HMF per I of milk product lies within the range of between 0-6 mlcromol/l, more preferably 0-5, 0-4, 0-3 or 0-2 micromol/l.
Methods for determining furosine and lactulose levels in milk or milk-derlved products are known In the art: Both HPLC or enzymatic assays, as well as frontface fluorescence spectroscopy methods are described by Kulmyrzaev et al., 2002 in Lait 82: 725-735. Methods for determining HMF levels in milk are described by Singh et al., Lait (1989) 69 (2) 131-136.
The milk-related product can additionally be characterised using one or more the analysis described in Example I.
The milk related product may for example be a lactose-reduced mllk-related product having a shelf-life of at Ieast 119 days, when kept at 25 degrees C, said lactose-reduced milk-related product comprising:
- 0,01-2% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product,
- 0.01-2% (w/w) glucose relative to the total weight of the lactose-reduced milkrelated product,
- at most 0.2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related product, and wherein the milk-related product has a furosine value of at most 80 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage.
In a preferred embodiment ofthe invention, the lactose-reduced milk-related product has a shelf-life of at least 182 days, when kept at 25 degrees C.
The lactose-reduced milk-related product may hâve a furosine value of at most 60 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage.
Altematively, the milk-related product may be a lactose-reduced milk-related product having a shelf-life of at least 70 days, when kept at 5 degrees C, said lactose-reduced milk-related product comprising:
- 0.01-2% (w/w) galactose relative to the total weight ofthe lactose-reduced milk-related product,
- 0.01-2% (w/w) glucose relative to the total weight ofthe lactose-reduced milkrelated product,
- at most 0.2% (w/w) lactose relative to the total weight ofthe lactose-reduced milk-related product, and wherein the milk-related product has a furosine value of at most 60 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
The lactose-reduced milk-related product may for example hâve a furosine value of at most 50 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
An additional aspect of the invention relates to a milk processing plant for converting a milk-related feed to a milk-related product having a long shelf-life, said plant comprising a lactose réduction section adapted to remove lactose from a milk, thereby providing a milk-related feed,
a ΗΤ-treatment section In fluid communication with said lactose réduction section, which HT-treatment section is adapted to heat a milk-derivative derlved from said milk-related feed to a température in the range of 140180 degrees C for a period of at most 200 msec. and subsequently cool the llquid product, and a packaging section In fluid communication with the HT-treatment section for packaging the product of the milk processing plant.
In the context of the présent invention, the term fluid communication means that the sections which are in fluid communication are so arranged that that liquid can be moved from one section to the other. This is typically implemented by interconnecting the relevant sections ofthe plant with pipes, and pumps and/or valves.
The mllk processing plant is suitable for implementing the method of the présent Invention.
The lactose réduction section typically contains one or more Systems adapted to physically removing lactose from a milk-related feed. For example, the lactose réduction section may comprise sériés of ultrafiltration Systems and nanofiltration Systems as deplcted In Fig. 12 or Fig. 13.
The HT-treatment section may comprise one or more ofthe HT treatment Systems mentioned herein and the packaging section will typically contain a commercially available packaging or filling system.
The packaging section Is preferably an aseptie filling system.
In addition to the above-mentioned sections, the milk processing plant may contain pumps, valves, piping, homogeniser, heater, etc. which ali are well-known units for the person skilled in the art and are commercially available as well. The plant may furthermore contain an enzyme inactivation section adapted the heat a llquid to a température as described herein in the context of the enzyme activation step. The enzyme inactivation section may for example comprise one or more plate heat exchanger(s).
The plant may furthermore contain an lactose hydrolysis section adapted to hydrolyse lactose in a liquid at a température as described herein In the context of the hydrolysis. The lactose hydrolysis section may for example comprise a température controlled tank or a continuous flow enzyme reactor.
The plant may furthermore comprise a physical séparation section capable of removing microorganisms from the milk-related feed. The physical séparation section may e.g. contain one or more of the microfiltration Systems mentioned herein, and alternatively or In addition, it may contain one or more of the bactofuges mentioned herein.
EXAMPLES
Example I - Methods of analysis
Analvsls A: Sensorv testing
A sensory profile or QDA, Quantitative Descriptive Analysis, Is a description of the sensory properties of a product as well as the Intensity of properties. It is an established method that contains a list of attributes, normally in the order that they are percelved, and an Intensity value for each attribute. Sensory profiling is described in ISO 13299:2003 and in ISO 22935-1:2009, ISO 22935-2:2009, and ISO 22935-3:200 which relate to Sensory analysis of milk and milk products.
Sample/quaiity of sample:
To be able to conduct the test there must be samples for training available before the test. For the actual test there must be a sufficient amount of each sample. They should also be of représentative quality.
The numbers of samples that can be evaluated during one session dépend on the nature of the sample and the amount of attributes to be evaluated. If only a few attributes are to be evaluated, more samples can be included In the test, and vice versa. Normally a maximum of ten samples are evaluated In one session.
Panel leader:
The panel leader Is responslble for trainlng the panel and the design and performance of the test. The requlrements of a panel leader Is described in ISO 13300-1:2006
Assessors:
The assessors In the panel are chosen because of their ability to detect flavours at low concentration. The recrultment process Is described In ISO 8586-1:1993, They are tralned for a certain type of products, In this case milk. Before a sensory profile test the panel trains several times with the products and attributes that are to be tested. The aim of the trainlng is to obtain a uniform way of using the scale and understandlng the meaning of the scale.
For each test a panel of 6-12 assessors Is used to evaluate the products.
Evaluation room:
The room where the trainlng and the test are performed should meet the requirements stated in ISO 8589:2007.
Présentation of samples:
The samples should be served bllnd with a three-digit code, the servlng order randomized. Samples are served In small plastic pots with lid on (Aseptlsk provburk 100 ml from www.kemikalla.se art. No. 165555).
Scale and trainlng session:
A continuous linear scale with anchored end points Is used. The end points are described as nothing at ail of the attribute = 0, respectively very, very strong intenslty of the attribute =10. The task for each assessor Is to mark the scale to indlcate the intenslty of each attribute. For bolled/cooked flavour the panel has agreed that low pasteurlzed milk (72 degrees C/15 sec, 1.5 % fat) has the value 0, extended shelf-life (ESL) milk (Direct steam injection 127 degrees C/2 sec,
1.5% fat) 2.5 and UHT (Direct steam Injection 143 degrees C/6 sec, 1.5% fat) 7,5 on the scale. The numbers are not shown to the assessors during the test.
During the tralnlng period the assessors will learn about how to identlfy the attributes and how to evaluate them, by look, smell, taste etc. They will also establlsh a common way of evaluating each attrlbute, e.g. bolled flavour for ESL milk Is 2.5 on the scale. One or more individual évaluation Is also done during the training period to evaluate each assessor's ability to perform the test.
The test:
Each session starts with trainlng/revlew of the panel. Three known samples are used first; low pasteurlzed milk (72 degrees C/15 sec, 1.5 % fat), long shelf-life milk (Direct steam injection 127 degrees C/2 sec, 1.5 % fat) and UHT (Direct steam Injection 143 degrees C/6 sec, 1.5 % fat), which all hâve spécifie positions on the scale. After that, the panel receives one or two unknown samples, which they through consensus décidé where to put on the scale (calibration of panel).
The panel should be informed about the number of samples to evaluate and any other information that might be necessary. FIZZ Software is used for the évaluation. During the test one sample at a time is served to the assessors. The task for the panel Is then to look/feel/smell/taste the product and the put a mark on the scale for each attrlbute. It is also possible for the assessor to write a comment on each sample. They should rlnse the mouth with water between attributes and samples.
References for Analysis A:
ISO 22935-1:2009, ISO 22935-2:2009, and ISO 22935-3:2009 which relate to sensory analysis of milk and milk products.
ISO 13299:2003 Sensory analysis -- Methodology — General guidance for establishlng a sensory profile
ISO 13300-1:2006 Sensory analysis — General guidance for the staff of a sensory évaluation laboratory — Part 1: Staff responsibilitles
ΙΞΟ 8586-1:1993 Sensory analysis — General guidance for the sélection, trainlng and monitorlng of assessors — Part 1: Selected assessors
ISO 8589:2007 Sensory analysis -- General guidance for the design of test rooms
Stone, H and Sidel, J.L (2004) Sensory Evaluation Practices. Tragon Corporation, California, ISBN0-12-672690-6
Analysis B - particle size distribution:
Particle size In a milk sample Is determined using a Malvern apparatus running a Mastersizer 2000 program where average particle diameter Is measured in terms of mean diameter (mlcrometer) by volume.
Analysis. C: Denatured beta-lactoglobulin
The détermination of the degree of dénaturation of beta-lactoglobulin of a processed milk product requires a sample of the unprocessed milk derivatlve and a sample of the processed milk product. Each sample Is analysed according to ISO 13875:2005(E) Liquid milk - Détermination of acid-soluble beta-lactoglobulin content to détermine the amount of acid soluble beta-lactoglobulin In the samples - expressed In the unit mg/L sample.
The degree of dénaturation (DD) of beta-lactoglobulin of the milk product is calculated via the formula:
DD = 100%*(BLGr - BLGh)/BLGr
Wherein:
DD Is the degree of dénaturation (DD) of beta-lactoglobulin.
BLGr Is the content of beta-lactoglobulin in the untreated milk derivatlve (mg/L). BLGh Is the content of beta-lactoglobulin In the processed milk product to which the degree of dénaturation relates (mg/L).
Analysis D: Lactulose détermination:
Lactulose content In a milk sample is measured by an enzymatic assay, defined by the International Organisation for Standards, given publication No: ISO 11285:2004(E); IDF 175: 2004 (E).
Analysis E:_Hydroxy Methyl Furfural (HMF) Quantification by HPLC
The content of HMF, as well as the content of HMF and Its precursors, in a milk sample is measured In parallel, together with a set of HMF standards, according to the following protocol:
HMF standards: 1 to 60 microM Hydroxy Methyl Furfural (HMF) aqueous solutions are prepared from 0.5 mM and 1.2 mM HMF standard aqueous solutions In milli Q water.
Préparation of milk sam pies to be analysed: A 9% (weight/volume) aqueous solution is prepared from a milk sample and the solution Is then stirred for at least 1 hour. A 10 ml sample Is taken from this solution, which is then transferred to a 50 ml flask, to which 5 ml 0.15 M oxalic acid is then added to give Milk HMF sample.
Sample Pre-treatment: Quantification of HMF, and HMF and Its precursors respectively In a Milk HMF sample are analysed separately, where the samples receive the following pre-treatment:
1) A Milk HMF sample is left for 60 min. at room température prior to quantlfying the content of HMF In the sample as Is;
2) A Milk HMF sample Is cooked for 60 min. under lld to convert HMF precursors into HMF, followed by cooling to 5 degrees C, prior to quantlfying the content of HMF Including precursors in the sample.
After cooling the samples, 5 ml 40% TCA (trlchloracetic acid) is added to each of the above pre-treated samples, as well as to each HMF standard and blank control sample, which each are then fndlvldually filtered through 0.22 micrometer filters, and the filtrate is then subjected to HPLC analysis as follows.
Samples (20 mlcroL volume) are Injected into an HPLC, equipped with an Apex II
ODS Smicrometer (vydac), and separated with a mobile phase comprising:
Eluent A: H2O, 0.1% TFA; and Eluent B: 90% acetonitrile, 10% H2O and 0.1%
TFA In the following gradient:
| Time [min] | Flow [ml/mln] | %A | %B | Curve |
| 0,01 | 1,00 | 100,0 | 0,0 | 6 |
| 2,00 | 1,00 | 100,0 | 0,0 | 6 |
| 10,00 | 1,00 | 93,0 | 7,0 | 6 |
| 11,00 | 1,00 | 100,0 | 0,0 | 6 |
| 15,00 | 1,00 | 100,0 | 0,0 | 6 |
| 16,00 | 0,00 | 100,0 | 0,0 | 6 |
HMF, is detected at 284 nm, and the HMF peak area for each sample chromatogram Is determined, together with the peak areas of the HMF standards that are used to calculate the slope of the calibration curve, which Is forced through 0.0.
HMF in a sample is calculated as follows:
HMF [microgram/lOOg] = (Samplepeakarea* MWHMf* VDlssO|Vement)/(Slope* mSample)
Where :
Samplepeakarea = Peak area of HMF in the sample chromatogram
Slope - The slope of the calibration curve msampie = The weighed sample amount [g] Voissoivement = Total volume dissolvement, (10 ml.) MWhmf = 126.1 g/mol
Analvsis F - Détermination of the furoslne-value:
The milk sample Is hydrolysed over-nlght In HCl solution at 105 degrees C; and one aliquot of the hydrolyzate was used to détermine the total Nitrogen content; and another aliquot was passed through a C18 column to separate out the furosine, which was then determined by HPLC-DAD and quantitated with respect to a furosine standard.
Analysis G - Plasmln/plasmlnogen détermination:
Plasmin activity in milk samples and plasmln-derlved activity after activation of plasmlnogen by urokinase were determined by measurlng the concentration of the 5 fluorescent product AMC (7-amldo-4-methyl coumarln) released by plasmin from the spécifie non-fluorescent coumarin peptide N-succinyl-L-alanyl-L-phenylalanylL-lysyl-7-amido-4-methyl coumarln [1].
Plasmin and plasmlnogen assays were carried out as previously described by Saint 10 Denis et al. [2]. One millilitre of milk sample was pre-incubated for 10 min. at 37 degrees C with 1 mL of 100 mmol/L Tris-HCI buffer, pH 8.0, containing 8 mmol/L EACA and 0.4 mol/L NaCI to dlssoclate plasmin from caseln micelles.
Plasmlnogen was previously converted Into active plasmin [3, 4, 5] by a 60 min.
IS incubation at 37 degrees C of 1 mL milk sample In the presence of 1 mL urokinase solution (200 Ploug U/mL In 100 mmol/L Trls-HCI buffer, pH 8.0, with 8 mmol/L EACA and 0.4 mol/L NaCI). Incubations were performed at 37 degrees C In a Vbottom microtube.
The incubated reaction mixture consisted of 200 mlcrollter of prepared milk samples mixed with 200 mlcrollter of 2.0 mmol/L N-succlnyl-L-alanyl-LρΙΐθηγΐ3ΐ3ηγΙ-ίΊγ3γΙ-7-3πη1άο-4-ηΊβΙΐΊγ1 coumarln (dissolved In 20% v/v dimethyl sulfoxyde and 80% v/v 60 mmol/L Tris-HCI buffer, pH 8.0, with 0.25mol/L NaCI). After 10 min. pre-Incubatlon to stabllize the température at 37 degrees C, the rate of peptide hydrolysls was determined by measurlng the fluorescence of released AMC during Incubation, at 3 time points over an Interval of 5 to 90 min., dependlng on the plasmin or plasmln-derlved activity In the sample.
For each measurement, 100 microliter of reaction mixture was mixed in a cuvette 30 with 1 mL of dlstilled water and 1 mL of Clarlfying Reagent (registered trademark) to stop any enzymatlc reaction. These steps enabled direct spectrofluorometrlc measurements (ex = 370 nm, em = 440 nm) without interférence of milk turbldity.
Plasmlnogen content was calculated by subtracting native plasmin activity from the total plasmin activity after plasmlnogen activation by urokinase. Each sample was analyzed In duplicate. The increase in fluorescence intenslty during incubation 56
was linear up to 4 h. A similar reaction mixture without mllk sample was used as a control to détermine spontaneous hydrolysis of the coumarln peptide, which was negllgible in ail experiments.
References to Analysis G:
[1] Pierzchala P.A., A new fluorogenlc substrate for plasmin, Biochem. J. 183 (1979)555-559.
[2] Saint-Denis T., Humbert G., Gaillard J.L., Enzymatic assays for native plasmin, plasminogen and plasmlnogen actlvators in bovine mllk, J. Dairy Res. 68 (2001) 437-449.
[3] Korycka-Dahl M., Ribadeau-Dumas B., Chene N., Martal J., Plasmin activity In milk, J. Dairy Sel. 66 (1983) 704-711.
[4] Richardson B.C., Pearce K.N., The détermination of plasmin in dairy products, N. Z. J. Dairy Sel. Technol. 16 (1981) 209-220.
[5] RollemaH.S.,Visser S., Poil J.K., Spectrophotometrlc assay of plasmin and plasmlnogen in bovine mllk, Mllchwlssenschaft 38 (1983) 214-217.
Example II: Lactose-reduced and hydrolyzed milk product (hydrolyzed after ΗΤ-treatment, ambient storage)
Low-pasteurized sklm mllk (72 degrees C for 15 s) was ultraflltered (UF) at 10 degrees C with a concentration factor of 2 thereby produclng a UF permeate containing water, lactose and other small molécules of skimmed mllk, and a UF retentate containing the protein fraction ofthe skimmed milk as well as water and smaller molécules such as lactose. The UF permeate was subsequently nanofiltered (NF) at 10 degrees C with a concentration factor of 4 thereby producing a NF permeate containing water and small Ions and a NF retentate containing lactose and water.
UF retentate and NF permeate were combined and mixed at 5 degrees C to obtain a lactose-reduced mllk feed. The fat content of the feed was adjusted to approx. 1.5 % (w/w) by addition of high-pasteurlzed cream.
The feed contained approx. 1.5 % (w/w) milk fat, approx. 4.1 % (w/w) protein and approx. 2.4 % (w/w) lactose. The dry matter content of the feed was approx.
% (w/w).
The feed was subjected to an enzyme inactivation step (indirect heating to 85 degrees C for 120 s or 90 degrees C for 120 s) and was subsequently heated to a température of 155 degrees C for approx. 0.1 s using steam Infusion (Instant Infusion System, Invensys APV, Denmark). The heat-treated feeds were subsequently cooled to 80 ± 3 degrees C and homogenlzed aseptlcally (2 step 160/40 bar). The products were further cooled to 5 degrees C and stérile filtered lactase (Maxllact LG2000) was added to a concentration of 0.0167 % (w/w) before the milk products were filled aseptlcally in glass bottles.
The packed milk products was stored dark at ambient température for 180 days. After 7 days of storage the lactose content was <0.01 % (w/w).
This way lactose-reduced milk products were prepared containing 1.5 % (w/w) milk fat, 4.1 % (w/w) protein, < 0.01 % (w/w) lactose and approx. 3 % (w/w) carbohydrates (glucose and galactose), The dry matter content was 9.1-9.2 % (w/w).
Maillard reaction
Nutrltlonal quality and progress of the Maillard reaction In the milk products were measured by monitoring the furosine value during the storage. The furosine values were determined as described In Analysis F of Example I. The obtained results were compared with normal skim milk, lactose-hydrolyzed skim milk and the milk products disclosed In the example 3 and example 4 of the International patent application WO 2009/000972.
The milk products according to example 3 and 4 of WO 2009/000972 were prepared using ultrafiltration and nanofiitration to obtain a milk base with a low lactose content (< 0.5 %) and a lactose fraction. These two fractions were heat treated separately (direct UHT, 146 degrees C for 4 s) and combined afterwards. As the heat treatment of the milk base and lactose fraction is performed separately, furosine formation and Maillard reaction is reported to be reduced.
Figure 14 shows the furosine value of Example II milk related products compared to the milk products and reference milk of example 3 and 4 of WO 2009/000972.
The milk products produced In Example II had much lower furosine values than comparable prior art milk products, even though carbohydrate and proteins were not heat treated separately.
Détermination of the plasmin activity
Proteolytlc activity In the présent milk products was monitored by analyzing plasmin activity (analysis G).
No proteolysls was observed during storage and the plasmin system was therefore effectively Inactivated by the processing described in this Example.
Conclusion
The surprisingly low furosine values of the présent milk products demonstrate that the présent lactose-reduced milk products are less prone than the lactose-reduced milk of the prior art to having sensory defects related to the Maillard reaction, and particularly to sensory defects which occur during long time storage. The formation of the Amadori product in the Maillard reaction leads to a loss of lysine available for digestion. Therefore, the nutritlonal value of the milk products of Example II Is furthermore perceived to be better than for the prior art lactosereduced milk due to a higher bioavailability of lysine.
Example III: Lactose-reduced and hydrolyzed milk product (hydrolyzed before HT-treatment, ambient storage)
Two other lactose-reduced milk products were produced as outline in Example II, but by performing the hydrolysis of lactose before the heat treatment.
Thus, prior to the heat treatment, the feed was transferred to a tank and Lactase (Maxilact LG2000) was added to a final concentration of 0.175 % (w/w). Lactose hydrolysis was performed at 10 ± 1 degrees C for > 20 h to reach a lactose concentration of < 0.01 % (w/w). After this, the lactose-reduced feed was subjected to the same enzyme inactivation step and heat treatment as described
In Example II.
The product was filled aseptlcally In glass bottles and was stored dark at ambient température for 180 days.
This way, a carbohydrate-reduced lactose hydrolyzed milk product was prepared containing 1.4 % (w/w) milk fat, 3.7 % (w/w) protein, < 0.01 % (w/w) lactose and approx. 3 % (w/w) carbohydrates. The dry matter content was 8.3-8.4 % (w/w).
Maillard reaction:
Figure 15 shows the furoslne value of the présent lactose-reduced milk products Furoslne formation and Maillard reaction seems to increase when the hydrolysls Is performed before the heat treatment. The furoslne values of the milk reiated products of Example III were sllghtly hlgher than In the milk reiated products of Example II, but stlll significantly lower than the furoslne values disclosed In examples 3 and 4 of WO 2009/000972.
Proteolytic actlvl.ty:
The plasmln system was Inactivated In Example III milk reiated products (< 20 pU/ml) and no proteolysis was observed during storage.
Sensorv testing:
The milk reiated products prepared In Example III both had a consumer acceptable taste at day 180, and appeared to hâve lower degree of off-flavour than the reference (UHT treated, hydrolyzed milk).
Conclusion:
Hydrolysls prior to the heat treatment Increases the extent of the Maillard reaction due to a hlgher amount of reducing sugars compared to post-hydrolyzed milk products. The différence in the furoslne values of the présent milk products compared to example I milk products is surprisingly low, which shows that the hydrolyzation step in the process can be placed before or after the heat treatment step without major changes in the sensory and nutritional quality of the resulting milk products.
Example IV: Lactose-reduced and hydrolyzed milk product (hydrolyzed before HT-treatment, cold storage)
As In example III, the lactose reduced feed for the milk product was hydrolyzed prior to the heat treatment. The lactose reduced feed was subjected to an enzyme inactivation step (indirect heating to 74 degrees C for 30 s) and was subsequently heated to a température of 155 degrees C for approx. 0.1 s using steam infusion.
The heat-treated feed was cooled to approx. 67 degrees C and homogenized aseptlcally (2 step 160/40 bar). The product was further cooled to 5 degrees C and filled aseptlcally in glass bottles. The product was cold (5-8 degrees C) and dark for 60 days.
This way, a lactose-reduced milk product was prepared containing 1.4 % (w/w) fat, 3.8 % (w/w) protein, < 0.01 % (w/w) lactose and approx, 3 % (w/w) carbohydrates. Dry matter content was 8.4 % (w/w).
Maillard reaction:
The progress ofthe Maillard reaction and the nutrltlonal value ofthe milk product were monitored by measuring the furosine value of the milk product. The Furosine value was compared to carbohydrate-reduced hydrolyzed ESL milk (in Kallioinen, H., Tossavainen, O. (2009): Changes during storage of lactose hydrolyzed extended shelf life milk. DMZ, Lebensmittellndustrie und Milchwissenschaft 130 (14): 47-50).
The milk product showed a slightly lower furosine value than the ESL reference during the storage period.
Proteolytic activity:
Plasmln activity in the milk product was considerably reduced, but plasmin was not completely Inactlvated, but no proteolysis or bitter taste was observed during the storage period.
Dénaturation of beta-lactoglobulln:
The degree of dénaturation of beta-lactoglobulln was determined according to
Analysis C of Example I, and the présent milk product had a degree of dénaturation of beta-lactoglobulln of 31.4%.
Sensory testing:
The sensory quallty of the milk product was compared to a lactose-reduced ESL milk (direct steam Injection at 127 degrees C for 2 s) after 7, 28 and 60 days of storage. A newly produced ESL reference was used for comparison on every sensory profiling.
The milk product showed equal sensory quallty relative to the fresh reference and kept it's fresh taste during the entire storage period of 60 days.
Conclusion:
The low furosine values and the good sensory properties of the présent milk product during the entire storage period show, that the présent milk product has a surprisingly longer shelf-life without any decrease In quallty than prior art lactosereduced milk products.
Example V: Lactose-reduced and hydrolyzed milk product (hydrolyzed after HT-treatment, ambient storage)
Two milk products similar to example II were produced on a different production plant using a modified process. The lactose reduced feed contained approx. 1.8 % (w/w) fat, approx. 3.8 % (w/w) protein and approx. 2.7 % (w/w) lactose. The dry matter content of the feed was approx. 9.3 % (w/w).
The feed was subjected to an enzyme Inactivation step (indirect heating to 85 degrees C for 120 s or 90 degrees C for 120 s). The feed then was cooled to 72 degrees C and was subsequently heated to a température of 155 degrees C for approx. 0.1 s using steam infusion. The heat-treated feed was cooled to 71 degrees C and homogenlzed aseptically (2 step 160/40 bar). The product was further cooled to approx. 20 degrees C and stérile filtered lactase (Maxllact LG1000) was added to a final concentration of 0,02 % (w/w).The milk products were filled aseptically in Tetra Bric packages.
The packed milk products were stored at amblent température. After 7 days of storage the lactose content was < 0.01 % (w/w).
This way, two lactose reduced mllk products were prepared containing 1.8 % (w/w) fat, approx. 3.9 % (w/w) protein, < 0.01 % (w/w) lactose and approx. 3 % (w/w) carbohydrates. Dry matter content was 9.4 % (w/w).
Maillard reaction
Figure 16 shows the furosine values of the présent lactose reduced milk products compared to the mllk products and reference milk of example 3 and 4 of WO 2009/000972 ('972). Compared to example II mllk products, the milk products show a higher furosine content. This can be due to the cooling of the product after the enzyme Inactivation step, which leads to an increased heat load of the product.
The mllk products of example V stlll had clearly lower furosine values compared to the references during the observed storage period.
Proteolytlc. activity:
The plasmln system was effectlvely Inactivated In Example V milk related products (< 20 μϋ/ml) and no proteolysls was observed during storage.
Sensorv testing:
Sensory profiling of the milk products was performed after 7, 28 and 60 days of storage. The présent mllk products had better organoleptic properties than the UHT reference, particularly with respect to cooked flavour and mllk flavour. An Informai sensory test (using a 4 person panel) was performed 84 days after production and conflrmed that the présent milk products stlll had a good, consumer-acceptable taste.
Conclusion:
The surprislngly low furosine values of the présent milk products demonstrate that the présent lactose-reduced mllk products are less prone than the lactose-reduced milk of the prlor art to having sensory defects related to the Maillard reaction.
The different processlng plant and the cooling step prlor to the heat treatment resulted In a slight rise In the furosine values of the présent mllk products compared to example II mllk products. However, the cooling step allowed an optimum température for both the steam Infusion heat treatment and the
homogenlzation of the mllk products. In addition to that, the sensory quality of the product was found to be better than the reference,
Besldes the better furosine values, the process is slmpler and more robust than the processes used In the prior art. Compared to the process described in the International patent application WO 2009/000972, the process described in example V (and in the other examples described herein) requires less energy and is not prone to cross-contamination, as the feed is not separated into a milk base and a lactose fraction and recomblned after the high température treatment.
Example VI: Lactose-reduced and hydrolyzed milk product (hydrolyzed before HT-treatment, cold storage)
In addition to example IV, two milk products were produced with the same process and processing plant as described in example V.
The lactose reduced feed contained 1.8 % (w/w) fat, approx. 3.9 % (w/w) protein and approx. 2.8 % (w/w) lactose. The dry matter content of the feed was approx. 9.5 % (w/w). Prior to the heat treatment, the feed was transferred to a tank and lactase (Maxilact LG5000) was added to a final concentration of 0.07 % (w/w). Lactose hydrolysis was performed at 10 ± 1 degrees C for > 20 h to reach a lactose concentration of < 0.01 % (w/w).
The lactose reduced feed was subjected to an enzyme inactivation step (indirect heating to 74 degrees C for 45 s or 80 degrees C for 45 s). After this the feed was cooled to 72 degrees C and was subsequently heated to a température of 155 degrees C for approx. 0.1 s using steam infusion. The heat-treated feed was cooled to 71 degrees C and homogenized aseptically (2 step 160/40 bar). The products were further cooled to approx. 8 degrees C and filled aseptically in Tetra Bric packages. The products were stored cold (5-8 degrees C).
This way, two lactose reduced milk products were prepared containing 1,8 % (w/w) fat, approx. 4 % (w/w) protein, < 0.01 % (w/w) lactose and approx. 3 % (w/w) carbohydrates. Dry matter content was 9.5 % (w/w).
Maillard reaction:
The furosine values of the présent milk products were similar to the furoslne value of a freshly produced ESL reference during the observed storage period of 60 days.
Proteolvtic actlvltv:
Plasmln activity in the milk products was considerably reduced, but plasmln was not completely Inactivated. No proteolysis or bltter taste was observed during the storage period.
Dénaturation of beta-lactoalobulln:
The degree of dénaturation of beta-lactoglobulln was determlned according to Analysis C of Example I, and the présent milk products had a degree of dénaturation of beta-lactoglobulln of 41 and 45%, respectively.
Sensorv testlno:
Like the milk products of example IV, the présent milk products were compared to a newly produced lactose reduced ESL reference. Sensory proflling was performed after 7, 28 and 60 days of storage. Throughout the storage period, the milk products surprislngly had sensory proprieties similar to the fresh ESL reference. An informai sensory test (using a 4 person panel) was performed 98 days after production and conflrmed that the présent milk products still had a good, consumer-acceptable taste.
Conclusions!
The low furosine values and the good sensory properties of the présent milk product during the entire storage period show, that the présent milk products hâve a surprislngly longer shelf-llfe without any decrease in quality than prior art lactose-reduced milk products.
Claims (17)
1. A method of producing a packaged, lactose-reduced milk-related product, the method comprising the steps of:
a) providing a lactose-reduced milk-related feed,
b) subjecting a milk derlvative derived from said milk-related feed to a High Température (HT)-treatment, wherein the milk derlvative Is heated to a température In the range of 140 - 180 degrees C, kept In that température range for a period of at most 200 msec., and then flnally cooled,
c) packaging a lactose-reduced milk-related product derived from the ΗΤ-treated milk derlvative.
2. The method according to any of the preceding claims, wherein derivlng the milk dérivative from the milk-related feed Involves subjecting the milk-related feed to an enzyme inactivation step.
3. The method according to any of the preceding claims, wherein derivlng the milk derlvative from the milk-related feed Involves hydrolyslng at least some of the lactose of the milk-related feed.
4. The method according to claims 2 and 3, wherein the hydrolysis is performed after the enzyme inactivation step.
5. The method according to claims 2 and 3, wherein the enzyme inactivation step is performed after the hydrolysis.
6. The method according to any of the preceding claims, wherein derivlng the lactose-reduced milk-related product from the HT-treated milk derlvative Involves subjecting the HT-treated milk derlvative to an enzyme inactivation step.
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7. The method according to any of the preceding daims, wherein deriving the lactose-reduced milk-related product from the mllk dérivative Involves hydrolyslng at least some of the lactose of the HT-treated mllk derlvative.
8. The method according to daims 6 and 7, wherein the hydrolysis is performed after the enzyme inactivation step.
9. The method according to daims 6 and 7, wherein the enzyme inactivation step Is performed after the hydrolysis.
10. The method according to any of the preceding daims, wherein the mllk dérivative comprises lactose In an amount of at most 3% (w/w) relative to the weight of the mllk derlvative.
11. The method according to any of the preceding daims, wherein the mllk derlvative comprises glucose In an amount in the range of 0.01-2% (w/w) relative to the weight of the milk derlvative.
12. The method according to any of the preceding daims, wherein the mllk derlvative comprises galactose in an amount in the range of 0.01-2% (w/w) relative to the weight of the milk dérivative.
13. A lactose-reduced milk-related product having a shelf-life of at least 119 days, when kept at 25 degrees C, said lactose-reduced mllk-related product comprising:
- 0.01-2% (w/w) galactose relative to the total weight of the lactose-reduced mllk-related product,
- 0.01-2% (w/w) glucose relative to the total weight of the lactose-reduced milkrelated product,
- at most 0.2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related product, and wherein the milk-related product has a furosine value of at most 80 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage.
14. The lactose-reduced milk-related product according to claim 13 having a shelflife of at least 182 days, when kept at 25 degrees C.
15. The lactose-reduced milk-related product according to claim 13 or 14, which has a furoslne value of at most 60 mg/100 g protein on day 49 after the production when kept at a température of 25 degrees C during storage.
16. A lactose-reduced milk-related product having a shelf-life of at least 70 days, when kept at 5 degrees C, said lactose-reduced milk-related product comprising:
- 0.01-2% (w/w) galactose relative to the total weight of the lactose-reduced milk-related product,
- 0.01-2% (w/w) glucose relative to the total weight ofthe lactose-reduced milkrelated product,
- at most 0.2% (w/w) lactose relative to the total weight of the lactose-reduced milk-related product, and wherein the milk-related product has a furoslne value of at most 60 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
17. The lactose-reduced milk-related product according to claim 16, which has a furosine value of at most 50 mg/100 g protein on day 49 after the production when kept at a température of 5 degrees C during storage.
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Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US61/367,131 | 2010-07-23 | ||
| DKPA201070540 | 2010-12-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| OA16771A true OA16771A (en) | 2016-01-04 |
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