CZ20001335A3 - Method of producing spread - Google Patents

Abstract

A method for producing a milk-based spread, in which milk for cheese production or cream or a mixture thereof is coagulated with acid in the presence of a suitable culture and then subjected to heat treatment at a temperature higher than 58°C for a period longer than 1 second. A culture of exopolysaccharide-producing lactic acid bacteria capable of reducing the graininess of the milk-based spread is used for acidification, wherein the exopolysaccharide-producing lactic acid bacteria satisfy at least a first comparative graininess test compared to a product acidified with non-exopolysaccharide-producing lactic acid bacteria or satisfies a combination of two or more tests for the suitability of using the culture to reduce the graininess of the spread. A food product according to this method, which contains at least 5% by weight of the milk-based spread.

Description

Technical field

The invention relates to a method of producing a spread from milk-based raw materials so that the spread has the desired taste properties.

BACKGROUND OF THE INVENTION

A variety of milk-based spreads are known, particularly those containing acidified milk. These spreads usually consist of a mixture of concentrated milk proteins and fat sources, which are acidified and further processed, optionally whey is removed.

An example of such spreads is e.g. spreads, yoghurt-based spreads, margarines, containing ingredients of acidified milk, fresh cheeses, curd and cream cheese.

Preferred nutritional products are fresh cheeses or other spreads containing at least 5% by weight fresh cheese.

For the purposes of the present invention, a spread is a plastic, spreadable product which can be spread on bread at room temperature without breaking the bread.

Dairy-based spreads are produced, for example, as follows: the milk or cream is adjusted to the desired fat and protein content, and then acidified, for example, by the addition of a bacterial culture and, where appropriate, a fermentation. warms up. As soon as the pH value approaches the isoelectric point for casein, i. approximately 4.6, the protein coagulates and spreads. Then it is still possible. whey may be removed or the spreads may be homogenized.

• 9 • 9 • · · · · · · · · · · · · · · · · · ·

The fat in the spread of this type may be of dairy or other origin and may be partially added after acidification.

Optional ingredients such as butter, cream, spices, salt, herbs or binders and / or structuring agents may be added to the spreads at appropriate stages of production.

If the coagulation of the protein is induced by the combined action of acid and heat, the pH of the coagulation may be substantially higher than 4.6.

Fresh cheese is distinguished from other cheeses in that the coagulation of milk proteins is induced by the action of an acid, e.g. also by heat rather than by enzyme. In addition, the fresh cheese does not ripen, but is ready for consumption as soon as it is finished. In the manufacture of fresh cheeses, rennet can be used, but only in small quantities as an auxiliary component, the main substance being the acid-forming component. Only in this small amount can rennet improve the resulting properties of the product and increase the efficiency of the coagulation process. The primary factor for inducing coagulation is however in combination with heat.

In the manufacture of fresh cheese, whey is usually removed after coagulation and a homogenization step can be carried out during or after it has been removed or the cheese production mixture can be heated.

After the production of spreads of this type has been completed, the spread is filled into cartons or other type of packaging while it is still hot or cooled, allowed to cool and then stored at low temperatures. If necessary, the spread can be removed from the mold or packaging as soon as the spread has reached sufficient strength.

A major problem in the production of milk-based spreads is the fact that an undesirable, less advantageous spread structure may be formed. Such a spread may then appear grainy, flour or chalky to the consumer. This altered spread structure can occur in particular when heat is applied to the mixture during production of the spread.

For purposes of the invention, heat treatment is defined as heating a milk-based spread to a temperature of greater than 58 ° C for more than 1 second.

Usually, heat treatment is used to prolong the shelf life of the products by inactivating lactic acid bacteria, which would otherwise cause further acidification of the product during storage.

In particular, during heat treatment, further coagulation of milk proteins may occur, resulting in unpleasant sensations when consuming such spreads. This degradation of properties is referred to as grain size, flouriness or chalkiness of the spread. Homogenization may be used to modify these properties, but often the results obtained are not entirely satisfactory and the product remains grainy. Such altered spreads are usually not acceptable to consumers.

It would therefore be desirable to find a process for improving the properties of milk-based spreads, particularly those which have been heat-treated.

It has already been proposed to add stabilizers to the spreads to improve their quality. For example, guar gum, gelatin, this locust, starch and the like. However, even the use of these ingredients is usually not acceptable to consumers.

SUMMARY OF THE INVENTION It is an object of the present invention to provide natural ingredients which can be added to milk-based spreads such that the spreads have a satisfactory taste and texture even if they have been produced using heat treatment.

It has also been proposed to include specific types or combinations of bacteria in spreads of this type.

E.g. EP-A-111020 describes the use of a specific combination of bacteria for the preparation of a dense fermented dairy product.

EP-A-639332 describes a process for producing a reduced fat cheddar cheese. In this case, syrup-like bacteria are used. Cheddar is a cheese that is not suitable for bread lubrication. In its production, the milk for the production of this cheese is acidified with the appropriate culture for 30 minutes and then aged for a further 30 minutes in the presence of rennet.

EP-A-196436 describes the use of a mixture of different Streptococcus cremoris bacteria in the manufacture of cottage cheese. In this process, the mixture is neither homogenized nor heat treated.

EP-A-331564 describes the use of a polysaccharide from a specific culture of Streptococcus thermophilus as a thickening agent, e.g. in the manufacture of yoghurt.

US-A-4243684 discloses a method by which the grain size of soft cheeses such as Camembert, Brie, Romadur, Limburg cheese and Muenster can be reduced using specific bacterial cultures.

· · · · · · · · · · · · · · · · · · · · · · · · · ·

In the case of these products, coagulation is primarily achieved by rennet. After coagulation, the mixture for the production of these cheeses is no longer heat-treated. In the case of spreads according to the invention, however, the coagulation is mainly achieved by acidification.

International patent application WO-A-94/12656 describes specific Lactobacillus sake strains which have the ability to produce exopolysaccharides in margarine-like products and also in salad dressings.

FR-A-2154371 refers to fresh cheeses and similar products, eg yoghurts, which are acidified to a certain pH. Since these products are already subjected to heat treatment after coagulation, they usually contain live active lactic acid bacteria.

International Patent Application WO-A-92/02142 describes novel types of bacteria comprising a plasmid containing a DNA fragment that is a codon fragment for a viscosity enhancer of a milk-containing product. Said bacteria may be used for the production of buttermilk, sour cream and cottage cheese. These products contain live bacteria, since they are no longer subjected to any heat treatment after acidification.

EP-A-82581 discloses fermented dairy products such as yoghurts which contain specific lactic acid bacteria and in addition biopolymers. These products are fermented to give the final product which is immediately ready for consumption.

Sebastiani H., DMZ Lebensmittel Industrie und Milchwissenschaft, Volume 115, No. 12, June 9, 1994, p. 586 describes the use of Streptococcus thermophilus strains for the preparation of exopolysaccharides. It has been reported that the strains described herein can be used to ferment milk to acidify it and to produce soft cheese.

Obert G., Magyar Tejgazdasag Kiserleti Intezet,

Pecs, Hungary, Tejipar, Vol. 33, No. 2, pp. 47-48, 1994, discloses the production of cream cheese using a heat-resistant strain of Streptococcus thermophilus to improve the rheological properties of the cheese. The products are packaged at a temperature of 60 ° C at which the bacteria used does not yet die.

In any of the above cases, the specific problem of the structure of products containing coagulated casein and which have been " heat treated.

SUMMARY OF THE INVENTION

It has now surprisingly been found that specific lactic acid bacteria producing exopolysaccharides can be used to produce heat-treated milk-based spreads without producing a product with an unsatisfactory structure.

It has been shown that milk-based spreads, such as fresh cheeses, produced using lactic acid bacteria producing exopolysaccharides can be heat-treated without loss of homogeneity or the formation of an undesirable granular or sand-like spread structure.

Accordingly, the present invention provides a method for producing a milk-based spread, wherein the milk for cheese or cream or a mixture thereof is coagulated by acid treatment in the presence of a suitable culture and then subjected to heat treatment, the culture being lactic acid bacteria producing exopolysaccharides able to reduce the grain of the spread.

• ·

The coagulation by the action of an acid may be optionally. followed by removal of whey and / or homogenization in any order of these steps.

In one embodiment, the invention relates to a process for producing fresh cheese, wherein the cheese milk is coagulated with acid in the presence of a suitable culture followed by whey removal and heat treatment in any order, wherein a culture of lactic acid bacteria producing lactic acid bacteria is used. exopolysaccharides to reduce the grain size of fresh cheese.

A suitable culture for use in the production of spreads of the invention is lactic acid bacteria producing EPS exopolysaccharides and capable of reducing the grain size of the spread. Although EPS producing bacteria may form part of the culture used for acidification, it is preferred that they form at least a substantial part of the culture. Additional cultures may be added to these bacteria, for example to increase the acidification rate of the spread or to modify the resulting taste of the product.

Not all EPS-producing lactic acid bacteria have been found to be suitable for the above purpose. However, one skilled in the art can, by simple experimentation, find out which EPS-producing lactic acid bacteria are suitable for this purpose, in particular by the following procedures.

Probably the most appropriate test (a) to determine the ability to reduce the graininess of a milk-based spread is to compare milk-based spreads, eg fresh cheese, produced using lactic acid bacteria producing EPS and spreads of the same composition produced under the same acidification but using bacteria; not EPS. This test is preferably performed with a low fat spread. It has been shown that a significant reduction in the granularity of the spreads produced by heat treatment can be achieved by the use of said bacteria. The procedure is described in more detail in the example section of the application.

The grain size reduction in test a) is preferably demonstrated by means of a panel of experienced persons. The grain size is graded on a scale of 1 to 5, with a value of 1 representing a smooth homogeneous sample and a value of 5 representing a very granular sample of the type of granular curd or even coarser material. Preferably, at least 8 out of 10 people in the panel should consider that the grain size has been reduced by at least 2 units using the scale so that the culture can be used for this purpose.

A number of other tests have been developed to determine which lactic acid bacteria producing EPS will be suitable for reducing the graininess of milk-based spreads that have been heat-treated. Combining two or more of these assays will provide greater assurance that the bacteria of interest are suitable for this purpose.

A second suitable test (b) for determining the grain-reducing ability of milk-based spreads, e.g., fresh cheese, is to determine the degree of granularity of the product by determining the particle size distribution in the diluted spread of the spread. The granularity of the spread is reduced if the number of larger sized particles is reduced. The bulk particle size distribution is preferably such that less than 10, particularly preferably less than 7% by volume of the particles have a diameter greater than 18 microns. This procedure is also used in the example section.

The ability of the EPS-producing lactic acid culture to reduce the graininess of the milk-based spreads can be further determined by examining the EPS-producing culture. Appropriate test c) for this: 99 999 * 9 9 9 9 9 999 * 99 9 999 99 9

9 9 9 9 9

99 and the determination is to determine the value of the modulus of elasticity G ´ and G ”as a function of the temperature of the milk sample fermented with different lactic acid bacteria producing EPS. G 'and G' values are very sensitive values for protein coagulation in these samples. A sudden change in the value of G 'and G' during slow heating of the sample shows the coagulation of a portion of the protein by heat. Protein particles formed during heating have been shown to be the main cause of the granularity of milk-based spreads. Thus, from the changes in G 'and G' values as the temperature increases, it is possible to deduce the ability of the EPS-producing culture to prevent protein aggregation during the spreading of the spread, thereby reducing its graininess. In particular, the relatively flat curve profile for changes in G 'and G' values at a temperature range of 40 to 60 ° C demonstrates the ability of bacteria to reduce the grain size of the spread.

The following equation can be used to determine the change in Theological Parameters by determining the values of G 'and G':

Reduction factor = = 100% * [logG '(40 ° C) -logG' (6G 'C)] / log G' (40 'C), with G' given in Pa.

This reduction factor indicates the dependence of log G 'on temperature for the temperature range of 40 to 60 ° C.

The abovementioned reduction factor is preferably less than 35 and particularly less than 30%. This procedure is also used in the example section of the application.

Another suitable procedure d) is to determine the loss of water from a milk sample fermented with various EPS-producing lactic acid bacteria. Samples prepared using suitable EPS-producing cultures are less sensitive to heat. Thermal • · ·· • 9

For example, processing in this test may mean heating to 80 ° C for 1 hour. In the case of suitable cultures, the water loss after this treatment at pH 4 is less than 20% by weight, particularly preferred is a minor water loss of up to 5% by weight after treatment at a pH of the product of about 4.

Another suitable test e) is to determine the charge of exopolysaccharide molecules. It has been found that the presence of uncharged exopolysaccharides is typical of the ability of the culture to reduce the grain size of milk-based spreads during heat treatment.

Also, a method for determining the charge of EPS molecules is described in the Examples section of the application.

Another suitable test f) is to determine whether EPS-producing bacteria form a capsule around the bacteria. This assay can be performed, for example, using a laser microscope and a conventional protein dyeing agent, such as rhodamine.

When the bacteria are surrounded by a layer of EPS substantially free of protein, the cultures are suitable for use in reducing the graininess of the milk-based spreads.

The EPS layer around the bacteria is referred to as the capsule.

Thus, the fact that the bacteria are encapsulated by an EPS layer demonstrates that bacteria of this type are suitable for reducing the graininess of the milk-based spread.

Test f) is preferably used for samples that have not been subjected to greater shear. For specimens processed at high shear, this test is less suitable since the sheath may be broken by shear.

·······················. .

· · * * Β β β β β β β β β β β β

Another suitable test for determining the grain-reducing ability is to determine the hardness of the milk-based spread before and after its pasteurization. Usually, the spread of the spread is greatly increased after this treatment. Hardness during the application is defined as the maximum resistance that can be measured when penetrating the product. Preferably, the change in hardness when using a culture of lactic acid bacteria producing EPS is relatively small compared to a product in which this type of culture has not been used.

Accordingly, in a preferred embodiment of the invention, the present invention relates to a process for the production of a milk-based spread, comprising adding to a milk for cheese or cream or a mixture thereof a culture in the presence of acid coagulation, wherein the culture used is lactic acid bacteria , producing exopolysaccharides, which are free of charge and form a capsule around the bacteria.

It has been found that particularly suitable EPS producing cultures are Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766.

However, in view of the above guidance, it will be apparent to those skilled in the art that other suitable cultures will be able to identify.

In the course of the application, where a range a) to b) is indicated, this range also includes both a) and b).

The milk-based spread as the final product preferably has a dry matter content of 5 to 80%, and in particular 15 to 65% by weight.

The fat content of the milk-based spread is in the range of 0 to 60%, preferably 0 to 40% by weight.

···· · ··· ·

9 · to to to to to to to to to to to to to to to to toto toto toto toto toto toto toto toto toto • ·· · ·

The fat content of the spread may be up to 80, preferably 0 to 75% by weight of the dry product of the resulting product. Particularly suitable products may be obtained when the fat is 10-75%, and more preferably 40-60% by weight of the dry matter.

Particularly preferred products can be obtained using 0 to 40% fat, with a dry matter content of 15 to 65% by weight, and a homogenization step.

Milk fat is the preferred fat, but vegetable fat may also be used instead of some or all of the milk fat.

Preferably, however, the spreads according to the invention comprise at least 30% by weight of milk fat based on the total amount of fat and in particular at least 60% by weight of milk fat based on the total amount of fat.

Although it is very advantageous to prepare a smooth, grain-free surface using only EPS-producing lactic acid bacteria, other ingredients such as 0.1 to 5% by weight of binder and / or structuring agent and / or stabilizing agent may be added to the spread, preferably 0.1 to 3 and in particular 0.3 to 3 are used

1.5% by weight of these substances. Preferred binder or structuring agent or stabilizing agent are whey proteins, which may be added in the form of whey protein concentrate, carboxymethylcellulose, gelatin and mixtures thereof.

By adding these binders and / or structuring and / or stabilizing agents, a very good stability of the resulting product, e.g., fresh cheese at a higher temperature, can be achieved and a stable product without fat or water output is obtained. Total amount of stabilizing or structuring agents or binders

99 * 9 9

9 9 9 9 9 9

9 9

9999 99

99

9 9

9 9 99 • · · ·

99

However, it is 0.1% by weight, and no such agent is particularly preferably used.

The above optional ingredients are added to the milk-based spread after acidification. If the whey is separated, the optional ingredients are preferably added after the whey has been separated.

In one embodiment, a spread according to the invention is prepared in a process in which:

acidifying milk or cream or combinations thereof containing lactic acid bacteria producing exopolysaccharides; and. other cultures for acidification to induce coagulation,

b. with whey removal and, if necessary. additional folders are added in any order,

c. The product is packed into containers.

In a preferred embodiment of the process, in step b) the whey is removed after the heat treatment has been completed.

The milk or cream or a combination thereof used in step a) may be ordinary milk or cream, standardized for a certain protein and / or fat content, depending on the desired end product. It may also be milk reconstituted from powdered milk. The milk or cream may contain other materials such as buttermilk, skimmed milk, vegetable fat milk, and the like. The starting milk or cream may also be pasteurized and / or processed at a higher temperature and / or homogenized.

The milk or cream is acidified by a culture of lactic acid bacteria producing exopolysaccharides and, where appropriate, by the addition of the milk. a small amount of rennet is added.

· A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A • · · »· * A *

Preferably, the coagulation is induced by the action of acid rather than by the combined action of acid and heat. That is, the acid milk in which the coagulation has occurred preferably has a pH of 4.5 to 5.0 and in particular 4.6 to 4.9.

Acidification and coagulation can be stopped using the heat treatment according to step b), e.g. to a temperature higher than 58 ° C for 5 minutes.

The whey is removed preferably by ultrafiltration UF or centrifugation in a conventional separator.

The heat treatment in step b) can serve to achieve a more consistent consistency of the coagulated milk and to pasteurize the product. The heat treatment can be used before or after whey removal. The heat treatment to achieve a firmer consistency can be combined with the treatment to stop acidification.

The heat treatment according to step b) is preferably carried out at a temperature higher than 60 ° C, the usual range being 65 to 100, preferably 70 to 80 and especially 75 to 80 ° C.

It may further be advantageous to homogenize the coagulated milk, for example by passing it through a homogenizer. Homogenization can be used when the product is at a higher temperature. The homogenization is preferably carried out in a homogenizer, e.g. at a pressure of at least 5 MPa, preferably 7.5 to 50 MPa, in particular 10 to 30 MPa.

According to another embodiment of step b), the whey is removed after the heat treatment is completed, after which the material is subjected to a further heat treatment and homogenized.

• 4 ·

444 • 4 · 4

4445 44 • 4 «4

4 4

4,444 • 4 of 4 «

4 4 4

4 »

44 * 4 4 4 • 4 4 4 • 4 4 * 4 4

44

The composition of the milk or cream and subsequent processing may be selected such that the product obtained may be packaged without the use of other ingredients after step a) or with the use of certain flavor, aroma or appearance-altering ingredients such as salt, spices, herbs and the like.

The herbs and other materials formed by the separable particles that are intended to remain recognizable in the final product are preferably added later during production, preferably before extrusion.

If these particles are to be used, it is especially desirable for paste-like hygiene reasons to pasteurize the resulting product after the addition of these materials. When materials of this type are to be deposited on the surface of the product, part or all of the resulting product may be sprinkled with a layer of said materials, e.g., particles of herbs, nuts, and the like.

Ingredients which may not be discernible in the final product, such as salt or spices, may be added at an earlier stage of the process, but preferably only after the whey has been removed if this is part of the process.

Similarly, when additional ingredients are added, e.g. cream, butter, vegetable fat, structuring and / or stabilizing agents and / or binders, these ingredients are added at different stages of the process, but preferably also after optional whey removal.

The products of the invention may be mixed with other food products. The invention therefore also relates to various spreads containing the products according to the invention. The amount of such acidified product in the final product is preferably greater than 5% by weight.

··· ··· ···· · ······················································ »·

A preferred product of the invention is fresh cheese which can be consumed as such.

It is also possible to mix this fresh cheese with, for example, butter, yogurt, margarine, vegetable fat spread, cottage cheese, coarse-grained cottage cheese, mozzarella, cream cheese and the like. The two components of the resulting mixture may be mixed homogeneously or inhomogeneously such that the fresh cheese and the other component are in a combined package forming a spread. The composite products preferably comprise at least 5, more preferably at least 15, and most preferably at least 50% by weight fresh cheese of the invention.

Most preferred products of the invention contain more than 90% by weight fresh cheese.

The products according to the invention are preferably stable for long periods of storage.

Longer storage for these products means the possibility of storage for at least three weeks, preferably at least 6 weeks and in particular at least 8 weeks, while not increasing the acidity of the product during storage and also not changing the taste or texture compared to the product just after termination of production.

This long shelf life can be achieved, for example, by using a heat treatment after coagulation using a sufficiently high temperature and a sufficiently long time to kill substantially all bacteria so that the acidity of the product no longer increases in the finished package. It has been found that heat treatment at too low a temperature used for too short a time may not destroy all bacteria. On the other hand, if the temperature is too high for a long time, the structure of the product may be undesirably changed. For this reason, the heat treatment is preferably carried out at a temperature above 60 ° C, particularly preferably at a temperature of 65 to 100 and even more preferably at a temperature of 70 to 80 ° C. This heat treatment preferably takes several seconds to 20 minutes, preferably 10 seconds to 15 minutes and particularly preferably 1 to 5 minutes.

The product of the invention is preferably substantially free of live lactic acid bacteria.

The following examples are intended to illustrate the invention. Throughout the Example, all proportions and percentages are by weight.

DETAILED DESCRIPTION OF THE INVENTION

General procedures

By way of example, the following standard procedure for producing spreadable fresh cheese will be used.

Preparation of preliminary culture

The sterile skim milk is inoculated using 0.5% of the culture stored at -80 ° C. It is a culture grown in skimmed milk, diluted with sterile 10% glycerol to a final content of 6% glycerol. The inoculated sterile skim milk is fermented for 16 hours at 35 ° C for mesophile culture and at 37 ° C for thermophile culture.

Preparation of fresh cheese

The raw milk is pasteurized at 72 ° C for 30 seconds. The milk is then adjusted to a fat content of 2.5% by weight. A pre-culture is then added, namely 1% by weight mesophilic lactic acid bacteria or 2.5% by weight thermophilic lactic acid bacteria and also 0.001% by weight rennet. In addition, 1% by weight of another acidification culture may be added to increase the acidification rate of the spread composition, e.g., Streptococcus thermophilus. The milk is acidified to pH 4.8 at 23 ° C for about 16 hours for mesophile culture and at 43 ° C for about 3 hours for thermophile culture. The product is then heated at 60 ° C for 5 minutes, then subjected to ultrafiltration to remove a portion of whey until a dry matter content of 28% by weight is reached. 0.7% by weight of salt is then added and the product is further heat-treated at 75 ° C for 10 minutes. The product is then homogenized in a homogenizer at a pressure of 20 MPa and filled into containers.

The resulting product contains about 10 wt% fat, wt% protein and about 28 wt% dry matter.

The following examples describe the performance of procedures to determine whether lactic acid bacteria cultures are suitable for reducing the grain size of the spreads. If test (a) is used to determine this capability, it is not necessary to use the second test. Test a) was used in Examples I and IV.

If any of tests (b) to (f) are used, then at least two of these tests must be used to obtain a reliable result. This means that the results of the two tests of Examples II, III, V and VI need to be evaluated together before making a final decision on the ability of the EPS producing culture to reduce the graininess of the milk-based spreads.

Example I

Two fresh cheeses were prepared according to the general procedure.

· * * · · · · · • ·

Fresh cheese A was prepared using 50 parts, 1% by weight of Lactobacillus delbrueckii subsp. bulgaricus 291 and 50 parts, 1% by weight of Streptococcus thermophilus filant as a thermophile organism. The milk was acidified at 43 ° C until pH 4.8.

Fresh B cheese was prepared using 2.5% Lactococcus lactis subsp. cremoris H414. Acidification was carried out at 23 ° C until pH 4.8.

Both products were evaluated as described above a) to evaluate their grain size. Product A according to the invention was evaluated as having a substantially reduced grain size compared to product B prepared in a known manner.

Example II

Three milk samples were prepared as follows:

Sterile skim milk was fermented using 1% culture by weight.

Sample C was fermented at 37 ° C using Lactobacillus delbrueckii subsp. bulgaricus 291 to pH 3.8.

Sample D was fermented at 37 ° C using Lactobacillus helveticus NCDO 766 to pH 3.7.

Sample E was fermented at 20 ° C using Lactococcus lactis subsp. cremoris H414 to pH 4.2.

G 'and G' shear measurements were performed with a Carrimed CSL 500 rheometer at a temperature increase of 10 to 60 ° C at a rate of 2.5 ° C per minute. The results are shown in Fig. 1. The X-axis shows the temperature in degrees Celsius and the Y-axis shows the G / G ”values on the logarithmic scale.

For the sample C according to the invention, the graph for the G 'value in Pa as a function of temperature is more or less flat, with the G value at 10 ° C being approximately 200 Pa and the G value at 60 ° C being 25.3 Pa. The graph for the G value in Pa as a function of temperature also had a flat pattern, with the G value at 10 ° C being approximately 50 Pa and the G value at 60 ° C being approximately 10 Pa.

These flat profiles of the G 'and G' curves are proof of the stability of the sample against the effects of temperatures.

G '(40 ° C) = 61.8 Pa G' (60 ° C) = 25.3 Pa Reduction factor = 22%

A reduction factor of less than 35% is conclusive for cultures suitable for reducing the graininess of milk-based spreads.

In the case of Sample D according to the invention, the graph for G 'values in Pa also had a more or less flat course with temperature, with G' at 10 ° C being approximately 50 Pa and G 'at 60 ° C approximately 10 Pa. The graph for the G value in Pa as a function of temperature also had a flat pattern, with the G value at 10 ° C being approximately 12 Pa and the G value at 60 ° C being approximately 3 Pa.

This flat curve of the G 'and G' values is again conclusive for the temperature resistance of the sample.

G '(40 ° C) = 21.2 Pa

G '(60 ° C) = 9.4 Pa

Reduction factor = 27%

A reduction factor of less than 35% is conclusive for cultures suitable for reducing the graininess of milk-based spreads.

In the case of Sample E, which is a comparative sample, a drop in the graph for G 'is observed as a function of temperature, in particular between 40 and 50 ° C, with G' at 10 ° C being approximately 50 Pa, at 40 ° 25 Pa and at 50 ° C approximately 3.5 Pa and at 60 ° C only 2 Pa. The G 'value was about 10 Pa at 10 ° C, about 9 Pa at 40 ° C, about 2 Pa at 50 ° C, and about 2 Pa at 60 ° C.

G '(40 ° C) = 23.8 Pa

G '(60 ° C) = 2.9 Pa

Reduction factor = 66%.

A reduction factor greater than 35% is conclusive for cultures not suitable for reducing the graininess of milk-based spreads.

According to test c), cultures producing exopolysaccharides suitable for use in the preparation of the spreads according to the invention can be selected by measuring the temperature profile of G 'and G' as a function of the temperature described above. The above-defined reduction factor should preferably be less than 30% for this purpose.

Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 are cultures suitable for use in reducing the graininess of milk-based spreads.

Example III

Sterile skim milk was fermented by adding 1% pre-culture as described for Samples C to E of Example II. Sample F was obtained by seeding sterile skimmed milk supplemented with 0.35% yeast extract, 0.35% ·

9 9 9 99 99

9999 99 peptone, 1% glucose and 50 mg / l manganese sulphate using 0.5% Lactobacillus sake culture 0-1 stored at -80 ° C after cultivation in the above dairy medium, diluted with sterile 10% glycerol to a final glycerol concentration of 6%. The thus prepared pre-culture was grown for 16 hours at 20 ° C and was then used to prepare sample F by seeding with a supplemented milk medium of 1% pre-culture followed by fermentation until a pH of 4.3 was reached.

Samples C to F were then heated at 80 ° C for one hour and water loss was determined. The results of this experiment are summarized in Table 1 below.

Table 1. Water loss after heating to 80 ° C for 1 hour.

Sample Water loss in% at pH 4 C 10 D 0 E 25 F 60

By assay D, cultures of exopolysaccharide-producing bacteria suitable for the preparation of the milk-based spreads of the invention can be selected by measuring the water loss after heating as described above. The loss of water after heat treatment at a pH of about 4, less than 20% by weight is indicative of suitable EPS-producing lactic acid bacteria strains. Preferably, there is practically no water loss.

Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 are cultures suitable for use in reducing the graininess of milk-based spreads.

· • ·

From the results of this test, it can be concluded in combination with the results of Example II that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 are cultures suitable for use in reducing the graininess of milk-based spreads.

Example IV

The raw milk is pasteurized at 90 ° C for 15 minutes. Prepare two fresh cheeses according to known procedures. Fresh cheese D according to the invention is prepared using a thermophile culture of Lactobacillus delbrueckii subsp. bulgaricus 291 and Streptococcus thermophilus filant in a 1: 1 ratio. Comparative fresh H cheese was prepared using Flora Danica mesophile culture (ex Chr. Hansen’s).

The resulting products were subjected to a) grain size tests. Sample G was found to have a significantly reduced grain size when compared to Sample H.

Example V

The average particle diameter was measured as follows: approximately 0.5 g of fresh cheese was dispersed in approximately 25 ml of water. The suspension was stirred for 20 minutes. The Helos / SUCELL is adjusted to an optical concentration between 15 and 20%. The measurement time was 10 seconds, the focal length was 200 mm, and the resolution time was 1000 ms.

Two fresh G and H cheeses were prepared as in Example IV.

The volume concentration of the individual particles as a function of their diameter is shown in Fig. 2.

Thus, according to test (b), a reduction in the grain size of the fresh cheese can be demonstrated by reducing the amount of larger particle size. The bulk particle size distribution is preferably such that the cheese contains less than 7% by volume of particles larger than 18 microns.

Figure 2 shows that fresh cheese in sample G, acidified with a culture of Lactobacillus delbrueckii subsp. bulgaricus 291 contains 5% of particles larger than 18 microns. That is, this culture is suitable for reducing the grain size of fresh cheeses.

Combining this result with the result of Example II or Example III, it can be concluded that the culture can be used to reduce the granularity of fresh cheeses.

Comparative sample H contains approximately 9% of particles larger than 18 microns, which means that the culture is not suitable for reducing the graininess of the milk-based spreads.

Example VI

The following fermented milk samples were prepared by the method of Example II / III: sterile skim milk was always fermented by adding 1% by weight of culture.

Sample C was fermented at 37 ° C using Lactobacillus delbrueckii subsp. bulgaricus 291 up to pH 3.8.

Sample D was fermented at 37 ° C with a culture of Lactobacillus helveticus NCDO 766 up to pH 3.7.

Sample E was fermented at 20 ° C with a culture of Lactococcus lactis subsp. cremoris H414 to pH 4.2.

Sample F was fermented with a Lactobacillus sake culture of 0-1 at 20 ° C to pH 4.3.

99

9 • 99

9 9

9 9

9999 99

99 • 9 9 • · ·· ♦

9

9 9 9

99

99 * 9 9 9

9 9 9 •

9 9 9 «φ

Example VIA

EPS can be isolated and purified from the fermentation broth as follows. The protein is separated from the fermentation broth by addition of trichloroacetic acid up to a concentration of 4%. After careful mixing, the culture is allowed to stand for 30 minutes at room temperature. The mixture is centrifuged at 13,000 g for 30 minutes and the clear supernatant is collected. The EPS obtained is precipitated by adding 1.5 volumes of cold ethanol. The precipitate was separated, redissolved and then dialyzed against demineralized water for two days at 20 ° C. The water is changed twice a day. The material obtained is lyophilized and then stored dry.

Two different procedures may be used to determine the EPS charge as described in test (e).

1. A solution of positively charged chitosan polysaccharide with a concentration of 0.5% by weight in water at a pH in the range of 4 to 5 is formed. It is important that the chitosan is completely dissolved to form a clear solution. An equal amount of EPS solution, also having a concentration of 0.5% by weight, is added to this clear solution. The two solutions were mixed at room temperature. If a precipitate is formed, it can be concluded that the added EPS contained a charge. If the solution remained clear, it was a non-charged EPS, indicating that the culture from which it was isolated may be a suitable culture to reduce the graininess of the milk-based spreads.

2. Another way of detecting a possible EPS charge is by electrophoresis on a Zetasizer 3 (Malvern). In this way, the mobility of the isolated EPS during electrophoresis can be monitored. An aqueous solution of isolated EPS at a concentration of 0.1% by weight was placed in the electrophoretic cell. In case that

99 * · measured mobility during electrophoresis is basically zero, running on EPS without charge.

Both experiments described above were performed on EPS isolated from samples C, D and F.

Using EPS isolated from samples C and D, a clear solution was obtained in the first experiment and no movement in the electric field was observed in the second experiment. Depending on these results, it can be concluded that EPS produced by a culture of Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 has no charge.

Using EPS isolated from sample F, a precipitate was formed in the first experiment. In a second experiment, the EPS from sample F was shown to move towards the positive electrode. It can be concluded that EPS isolated from Lactobacillus sake 0-1 carries a negative charge.

According to the results of test (e), the production of uncharged exopolysaccharides demonstrates that the culture producing this substance is suitable for use in reducing the graininess of milk-based spreads.

Example VIB

Milk samples C to E are fermented to pH to obtain samples for the CSLM laser microscope according to test f) as described above.

5.5 and then heat-treated for 5 minutes at 60 ° C to terminate acidification. The heated samples are then plated onto microscope plates for CSLM microscope.

Protein and bacteria are stained with rhodamine B. This staining is carried out in a conventional manner, e.g. according to Nizo Nieuws 1995, No. 8, A A A A A A A A A A

A A A

AA ** AA ** AA

A A A A A A A

A A A A

A · A * AA * A A I A A A

A · A A

pp. 13-15, Μ. E. Marie and P. Zoon. It is important that the pH of the samples is maintained above the pH for protein aggregation, preferably above pH 5.5.

The samples were monitored under a microscope. EPS is not directly visible because it does not stain, but appears as a dark cover.

A BioRad MRC600 (Confocal Scanning Laser Microscope) was used for this assay.

The results of this test are shown in Figures 3A-3C. All images are 65 microns wide.

Giant. 3A relates to Lactobacillus delbrueckii subsp. bulgaricus 291, FIG. 3B refers to Lactobacillus helveticus NCDO 766 and FIG. 3C refers to Lactococcus lactis subsp. cremoris H414.

In Figures 3A and 3B, EPS can be seen as a dark wrap around bacteria. The protein stained with rhodamine B is visible as colored spots.

In Fig. 3A and Fig. 3B, it can be clearly seen that EPS forms a layer around the bacteria. There is essentially no protein in this layer.

In Figure 3C, no uncoloured coatings can be observed around the bacteria, and the EPS is located all over the area outside the bacteria. Cases cannot be identified.

From the results it can be concluded that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 produce a sheath-forming EPS, which is evident in cultures suitable for reducing the graininess of milk-based spreads. Lactococcus lactis subsp. cremoris H414 produces free EPS, which means that it is not a culture suitable for reducing the grain size of the milk-based spreads of the invention.

When combining the test results e) and f), i. combining the results with Examples VIA and VIB, it can be concluded that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 are suitable cultures for reducing the graininess of milk-based spreads.

Claims (15)

PATENT CLAIMS A method for producing a milk-based spread, wherein the milk for cheese or cream production or a mixture thereof is coagulated with an acid in the presence of a suitable culture and then subjected to a heat treatment at a temperature of more than 58 ° C for more than 1 second. by using a culture of lactic acid bacteria producing exopolysaccharides and capable of reducing the grain size of the milk-based spread, whereas lactic acid bacteria producing exopolysaccharides meet a combination of two or more of the following tests, provided that test a) is used , no further testing is needed, (a) a milk-based spread is produced in a conventional manner using EPS-producing lactic acid bacteria, and the granularity of the resulting product is compared to that of a product produced in the same way but acidified with non-EPS lactic acid bacteria, the ability of bacteria to reduce the grain size of the spread, (b) a milk-based spread is formed and the granularity of the resulting product is determined by determining the volume of large particles in the diluted dispersion of the spread, wherein the particle size distribution is less than 10% by volume, preferably less than 7% by volume. demonstrates its ability to reduce the graininess of the milk-based spread, (c) determine the value of module G 'and the value of module G' as a function of temperature for dairy samples prepared using different lactic acid bacteria producing EPS, with a relatively flat course of dependence of G 'and G' at a temperature between 40 and 60 ° C is conclusive for the ability of bacteria to reduce the graininess of milk-based spreads. * 999 9 9 9 9 * ·· 99 99 99 9 9 99 99 (d) the water loss after heat treatment at 80 ° C for one hour is determined for dairy samples fermented with different EPS-producing lactic acid bacteria cultures, where a water loss of less than 20% by weight is conclusive for cultures suitable for reducing grain size based on spreads milk, (e) the possible charge of exopolysaccharide molecules is determined, whereby the production of uncharged EPS is indicative of the ability of the culture to reduce the graininess of the milk-based spread, (f) the presence of an EPS capsule around the bacterium shall be determined by means of a laser microscope for serial examination of samples, the encapsulation of bacteria in the EPS being indicative of the ability of the culture to reduce the graininess of the milk-based spread. Method according to claim 1, characterized in that whey is separated after the coagulation of the milk. Method according to claim 1 or 2, characterized in that after spreading the spread is homogenized. Method according to one of Claims 1 to 3, characterized in that, in carrying out test (c), a reduction factor is defined whose value of less than 35%, preferably less than 30%, is conclusive for cultures suitable for reducing the grain size of the spreads. . Method according to any one of claims 1 to 4, characterized in that the EPS produced by lactic acid bacteria is substantially uncharged in test e) and forms a capsule around the bacteria in test f). • 9 9999 * 9 ** 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 • · · · ί ί · · · · · Method according to any one of claims 1 to 5, characterized in that the lactic acid bacteria producing exopolysaccharide meet the conditions of all tests a) to f). Method according to one of claims 1 to 6, characterized in that the culture producing exopolysaccharide is selected from Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 or a mixture of these cultures. Method according to one of claims 1 to 7, characterized in that the milk or cream for the production of cheese or a mixture of these materials is heated to a temperature of 8 to 100 ° C for 1 to 60 minutes, preferably to a temperature of 85 to 100 ° C. 95 ° C for 5 to 20 minutes prior to acid coagulation. Method according to one of Claims 1 to 8, characterized in that the milk-based spread has a dry matter content of 5 to 70%, preferably 15 to 65% by weight. Process according to any one of claims 1 to 9, characterized in that the fat content of the spread is in the range of 0 to 40% by weight and the dry matter content is 15 to 65% by weight. Method according to one of claims 1 to 10, characterized in that the milk-based spread contains 0.1 to 5% by weight of a binder and / or a structuring agent and / or a stabilizing agent from the group of whey protein, locust bean gum bread, carboxymethylcellulose, gelatin or mixtures thereof. 9 »9 9 9» «« 9 9 9 9 «« «« «« «« «« Process according to any one of claims 1 to 11, characterized in that the acidification of the milk for spreading is stopped by the use of a heat treatment. Food product comprising at least 5% by weight of a milk-based spread prepared by the process according to claims 1 to 12. Food product comprising at least 5% by weight fresh cheese prepared by the process according to any one of claims 1 to 12. 15. A food product as claimed in claim 14 comprising at least 90% by weight fresh cheese.