WO1990009107A1

WO1990009107A1 - A spreadable water-in-oil emulsion

Info

Publication number: WO1990009107A1
Application number: PCT/DK1990/000032
Authority: WO
Inventors: Jørgen Madsen; Peter Finn Pedersen
Original assignee: Grinsted Products AS
Current assignee: Grinsted Products AS
Priority date: 1989-02-10
Filing date: 1990-02-08
Publication date: 1990-08-23
Anticipated expiration: 1991-08-10
Also published as: AU5100390A; DK60689D0

Abstract

A spreadable and stable water-in-oil emulsion to be used in a similar way as margarine and low fat spreads is very poor in fat, contains only 12-30 %, preferably 16-25 % fatty phase, calculated on the weight of the emulsion, whereas margarine contains 80 % and usual low fat spreads 40 %. The low fat content is made possible by using as emulsifier only distilled monoglycerides or monodiglycerides of C12-22, preferably C16-18 fatty acids and having an iodine value of 50-150, preferably 100-110. Calculated on the weight of the emulsion the amount of emulsifier is 0.35-4.0 %, preferably 0.75-1.5 %. The emulsion is prepared according to usual margarine technology without using special equipment or special mixing or emulsifying technology.

Description

A SPREADABLE WATER-IN-OIL EMULSION

Field of the Invention

The present invention relates to a spreadable water- in-oil emulsion which as the emulsifier contains only-' distilled monoglycerides or mono-diglycerides of edible ^ci₂-₂₂ fatty acids. The emulsifier is present in the fatty phase of the emulsion.

With the expression "spreadable" is meant that the emulsion must be non-liquid at room temperature and temperatures up to 30^βC such that it is sensed as having a consistency fairly like that of butter, margarine and the low fat, margarine-like products commonly sold under the name low fat spread ("minarine") . With the designation "monoglycerides" there is aimed in accordance with usual terminology at mixtures of esters of fatty acids with glycerol in which substantially only one of the hydroxyl groups of the glycerol is esterified, whereas with "mono- diglycerides", likewise in accordance with usual terminology, there is aimed at esters of fatty acids with glycerol in which either one or two of the hydroxyl groups of the glycerol is/are esterified. Distilled monoglycerides normally contain at least 90% of monoglyceride.

Background of the Invention

Butter and common margarine usually contain about 80% fat or oil (in the present specification there will be made no distinction between "fat" and "oil") mainly consisting of triglycerides, i.e. glycerol in which all three of the hydroxyl groups are esterified with fatty acids, which may be saturated or more or less unsaturated. Meagre margarines including low fat spreads usually contain about 40% fat or oil, in principle of the same kinds as are used in ordinary margarines. Low fat spread has been commercially available in Europe since the 1960-years and although the product may by now be considered as accepted by the public, the fat consumption in the majority of countries and not least in Denmark must still be considered as too high seen from a health point of view.

However, it is technically difficult to prepare water-in-oil emulsions having a substantially lower fat content than the current low fat spread products and especially it is difficult to prepare them in a manner such that they are stable at temperatures substantially above refrigerator temperature, notably at room temperature such as, e.g., 22°C, and the water-in-oil emulsion will not be sensed as butter- or margarine-like.

In the patent literature there may be found various information on margarine-like or low fat spread-like products having a lower content of fat than low fat spreads. Thus, from European patent application publication No. 256 712 there is known a spreadable water-in-oil emulsion containing 18-35% fat in the continuous phase; the disperse phase, i.e. the aqueous phase, contains at least 8% by weight of milk proteins and 0.1-1.2% by weight of modified, preferably pre-gelatinized starch. These ingredients are stated to make possible the low fat contents and must be assumed to act as stabilizers.

From European patent application publication No. 237 120 there is known a spreadable water-in-oil emulsion containing 10-35% by weight of fatty phase, the aqueous phase having a viscosity of at least 20 mPa.s at a shear rate of 17090 sec.^-1 and a temperature of 5^βC; this is obtained by the presence of 1-25% by weight of a hydrocolloid as gel-forming component in the mixture constituting the aqueous (dispersed) phase. The hydrocolloid may for example be a hydrolyzed starch derivative, gelatin, carrageenan or mixtures thereof, and moreover the aqueous phase may contain non-gel-forming components such as non- gel-forming starch hydrolyzate or maltodextrin. From British patent application publication No.

2 150 585 there is known a spreadable water-in-oil emulsion containing a fat phase of 20-90% by weight and containing in the aqueous phase 1-25% (calculated on the entire weight of the emulsion) of separate granules of native, crystalline starch or agglomerates thereof, 80-100% of said granules having a diameter of less than 25 μm. The spreadable water-in-oil emulsions thus known accordingly contain protein and/or hydrocolloid in the aqueous phase. It would be desirable, however, to avoid such microbiologically degradable material in the aqueous phase because it may give rise to microbiological growth whereas known emulsifiers on a fatty basis in the fat phase rarely give problems of that kind.

There is also known spreadable water-in-oil emulsions which contain monoglycerides or mono-diglycerides as the only emulsifier. Thus, European patent application publication No.. 98 664 relates to a process for producing a water-in-oil emulsion having a low fat content, defined as below 60%, which is characterized in forming an emulsion from a fatty phase and an aqueous phase, which emulsion is thereupon subjected to shearing forces to cause a phase reversal by the aid of a device, e.g. a Votator A- or C-unit, which is interiorly coated with or prepared of a hydrophobic material, preferably polytetrafluorethylene, whereby the fat crystallizes. According to Example 1 of that specification there is formed a stable (it is not stated in which temperature range) water-in-oil emulsion having a fatty phase of 21% of the weight of the emulsion and composed of fats having specified dilatation values. The only emulsifier is 0.55% of monoglyceride, Hymono Sf 44. It has an iodine value of probably about 40 and a content of monoglyceride of perhaps 90%. This emulsion depends on the particular production technique described in the publication.

From German accepted patent specification No. 23 45 798 there is known another process for the production of spreadable water-in-oil emulsions poor in calories, containing no particular stabilizing agent and having a fat content of 30-60%; as the (apparently only) emulsifier there is employed monoglyceride blends containing saturated and unsaturated fatty acids in a weight ratio of 1.5:1 to 10:1, preferably 1.6:1 to 8:1 and moreover there are special limitations with respect to the ratio between the amount of stearic acid and the amount of saturated fatty acids, and with respect to the ratio between the amount of linolic acid and the amount of unsaturated fatty acids having a code number which when multiplied by 100 is at least 110. Accordingly it is not possible by this known process to produce margarine-like or low fat spread-like products having a lower fat content than 30%.

Disclosure of the Invention

It is the object of the invention to provide a water- in-oil emulsion of the kind defined by way of introduction and which has a lower fat content than 30% and may be prepared by using apparatus which is conventional in the margarine industry, its aqueous phase not containing substrates for microbiological growth, it being at the same time not necessary to ensure any special balancing of the fatty acids in the mono- or mono-diglycerides.

It has been surprisingly found according to the invention that this may be achieved when the fatty phase constitutes 12-30% of the weight of the emulsion and the emulsifier has an iodine value of 50-150 and is present in an amount corresponding to an amount of monoglyceride of 0.35-4.0% of the weight of the emulsion, the aqueous phase being free of added protein and hydrocolloid.

There are no particular limitations with respect to the compositions of the fats (triglycerides) in the fatty phase, which may contain both saturated and unsaturated fatty acids and be composed as it is usual for margarine and low fat spreads. Thus, it is possible to use fat blends containing animal or vegetable oils and fats, partially and/or fully hardened oils and fats, or butter oil.

According to the invention the fatty phase may expediently constitute 16-25% of the weight of the emulsion. Even when complying with the abovementioned conditions it may be difficult to maintain stable a product containing less than 16% fatty phase at temperatures of, e.g., 30-35^βC. As fatty acid residues the emulsifier may contain predominantly residues of fatty acids containing 16-18 carbon atoms. As is clear from the iodine values mentioned above the fatty acid residues are both saturated and unsaturated. Distilled monoglycerides and mono-diglycerides of this kind are produced industrially in large amounts and are easy of access.

According to the invention there may expediently be so much emulsifier present in the fatty phase as to correspond to an amount of monoglyceride of 0.4-3.5%, preferably 0.75-1.5% of the weight of the emulsion. In some cases lower amounts of monoglyceride may cause separation of water from the emulsion, and higher amounts can only cause an improved stability of the emulsion in special cases.

According to the invention the iodine value of the emulsifier may expediently be 90-120 and with especial advantage be 100-110 which has proven to give the emulsion a particularly high stability.

The pH value of the aqueous phase may well be the same as the pH of usual margarines and low fat spreads, i.e. from 4 up to the point of neutrality. Advantageously it is at least 5.5 and especially about 6.0. Since there are no hydrocolloids or proteins present in the aqueous phase there is no need for the preserving effect which is normally to be achieved by the aid of the addition of acid, and the very low fat content renders it possible to achieve the refreshing taste caused by the acid by means of a low amount of acid. As acid one can employ those commonly used in margarine and low fat spreads, e.g. lactic acid or especially citric acid. In some countries a rather acidilous taste of margarine and simlar spreads is appreciated, and for these a pH of the aqueous phase of about 4 may be useful. Experiments with a low fat spread containing 40% fatty phase have shown that the pH does not influence its stability when the aqueous phase does not contain protein. The same holds true the very low fat emulsion according to the present invention.

The present emulsion is mainly meant to be used as a substitute for margarine or low fat spread and therefore contains additives that are usual for such products. Thus, it may contain salt (i.e. sodium chloride) in an amount which is customary for such products, i.e. 0-2.5 of the weight of the emulsion. For instance carotin may be present in the fatty phase in known manner. It functions, a.o., as a provitamin and both the aqueous phase and the fatty phase may furthermore contain vitamins in current amounts. Known margarines and low fat spreads contain flavouring and taste-giving substances the kind and composition of which are usually considered trade secrets and consequently are not disclosed. They are most frequently present in the fatty phase. Because of the very limited amount of fatty phase in the present emulsion it is expedient according to the invention that flavouring agents are present in the aqueous phase as well as the fatty phase. They may be of any of the kinds commonly used in margarine and low fat spreads.

Experiments In the following the emulsion according to the invention will be more fully elucidated by the aid of some experiments.

In these there was used a laboratory installation having two emulsion tanks alternatingly in use and each having a volume of 6 litres and each provided with a propeller stirrer the speed of rotation of which may be varied in a non-stepwise manner from 0 to 2400 revolutions per minute (rpm). An experimental high pressure pump from Gerstenberg & Agger A/S, Frederiksberg, Denmark, type 2-30-4 having a continuously variable performance of 0-98 kg/h was used for pumping the emulsion through the cooling and kneading unit of the installation. The standard capacity of the pump is 50 kg/h; when capacity is mentioned in connection with the experiments described hereinbelow there is aimed at the amount of emulsion which was actually pumped through the installation per hour in the given experiment. The cooling and kneading unit was a socalled experimental perfector manufactured by Gerstenberg & Agger A/S. The type of apparatus is wellknown in the margarine industry and is usually called surface-scraping heat, exchangers. The cooling medium is liquid ammonia the evaporation temperature and hence the cooling effect of which may be varied. In all of the experiments there was employed two cooling pipes and the rotor velocity in the cooling pipes was about 970 rpm.

The fat mixtures employed in the experiments may be characterized as follows by NMR analyses carried out on a Bruker Minispec P 20 apparatus with parallel temperature adjustment of the fat blends before the analysis:

Temperature NMR-values

(content of solid fat)

5°C 15-60% 10^βC 10-50% 20°C 5-25% 30^βC 0-7% 35"C 0-4% 40^βC 0-2%

There was used 3 or 4 kg of emulsion in the individual experiments and all percentages are calculated for experimental portions of these sizes. In the experiments all percentages are calculated on the entire weight of the emulsion and "parts" are parts by weight where the entire fat blend is set at 100 parts. The emulsifying takes place alternatingly in the two tanks each having a capacity of 6 litres, and the velocity of the rotation is decreased gradually with the emptying of the emulsifying tank.

It is known from other experiments and from the production of low fat spreads that the viscosity of the emulsion increases with decreasing emulsifying temperatures, with intensification of the stirring and with increased dosage of monoglyceride of unsaturated fatty acids. In all of the experiments there was aimed at and obtained a water- in-oil emulsion but the experiments have moreover shown that a too high stirring velocity, especially at a low dosage of distilled monoglyceride of saturated fatty acids, may cause a tendency to phase reversal to form an oil-in-water emulsion. However, it could be re-reversed to a water-in-oil emulsion either by the use of still higher stirring velocities or in the experimental perfector.

In all of the experiments 4 ppm of carotin (calculated on the weight of the emulsion) was present in the fatty phase.

The first series of experiments was carried out at an emulsifying temperature of about 50^βC and moderate stirring. The quantitative composition of the finished emulsion was:

Exp. Distilled monoglyceride, No. iodine value about 105

1 0.5% 2 0.8% 3 1.0% 4 1.3% 5 2.0% 6 0.5% 7 0.8% 8 1.0% 9 1.3% 10 2.0%

Fat blend: 25 parts of hardened soybean oil, m.p. 41^βC

75 parts of liquid soybean oil

Aqueous phase a: 73.0% water

b: 78.0% water

Flavouring 100 ppm flavour for the aqueous phase agent: +100 ppm flavour for the fatty phase

The temperature of the ammonia was -10°C and the capacity was 40 kg/h.

The assessment after storage at 5^βC for 3 days by spreading with a knife on a piece of cardboard gave the following results:

Emulsion from exp. No.

1 separates in the aqueous and fatty phases

2 rather good, separates a little 3 excellently stable

4 excellently stable

5 excellently stable, a little soft

6 separates a little

7 excellently stable 8 excellently stable

9 excellently stable

10 excellently stable

The assessment method employed is a very critical one which gives an impression of the look of the product (colour, smoothness, grittiniess, uniformity, whether it is coherent or separates into the aqueous and fatty phases, etc.), its consistency (hard or soft, greasy) and spreadability. Even if the product is found by this test to separate into the aqueous and fatty phases by spreading, it may well be a stable water-in-oil emulsion in the packing and behave like a normal margarine or low fat spread and may even be used for spreading on bread. The products are normally tested after storage at 5^βC; if the product is found stable at spreading on cardboard after storage at 5^βC it will also be stable after storage at a higher temperature. A product which separates into the aqueous and fatty phases at spreading after storage at 5°C may be stable after storage at a higher temperature, e.g. 10°C or 20^βC. This is due to the fact that after an increased storage temperature a larger amount of crystals are molten and thereby the fatty phase becomes softer. The products found by the test to "separate" or "separate a little" are stable in the packing and are usable and spreadable on bread.

At the assessment of the taste the stable samples were found to be well aromatic and to give a good mouth feel. Judged microscopically the distribution of water showed an excellent, uniform distribution of the water droplets. By far the most of them had a diameter below 10 μm. A further series of experiments were carried out to test the products after storage at 5^βC, 10^βC and 20^βC. The emulsifier was the same as in experiments Nos. 1-10 and aqueous phase a) was employed. The amount of the distilled monoglyceride was:

Exp . No . Amount of emulsifier

11 0 . 8%

12 0 . 5%

13 0.4% 14 0 . 3% The product of experiment No. 14 separated after the experimental perfector. The others were tested by the spreading test on cardboard described above after 3 days' storage. The results were

The product tested in experiment No. 12 was satisfactory after storage at 10^βC and 20^βC; that tested in experiment No. 13 was less satisfactory with respect to stability at spreading but had a satisfactory look in the packing.

In addition to these experiments, moreover the same distilled monoglyceride was tested at high concentrations and otherwise as described.

Exp. Distilled monoglyceride, Fat Aqueous No. iodine value about 105 blend phase

15 3.0% 22.0% a) 16 4.0% 16.0% b)

After storage for 3 days at 5^βC the product tested in experiment No. 15 was found excellently stable at spreading on cardboard. The product tested in experiment No. 16 separated at spreading after storage for 3 days at 5^βC, was excellently stable at the spreading test after storage for 3 days at 10^*C; and after storage at 20^βC for 3 days was a 'little too soft at the spreading test; a few droplets of oil were present at the surface.

A next series of experiments was carried out to elucidate the importance of the capacity and the temperature of the ammonia. The aqueous phases a) and b) from experiments Nos. 1-16 were used; there was employed an amount of emulsifier corresponding to 1.0% distilled monoglyceride having an iodine value of about 105, and 24% and 19%, respectively, of fat blend as well as flavour as used in experiments Nos. 1-10. The weight of the portions was 4 kg.

The assessment after spreading with a knife on cardboard after storage at 5^βC gave the following results:

Exp. Nos. 17-19 and 21-24: Excellently stable, excellently spreadable

Exp. No. 20: A little free water on the surface, looks slightly separated but the free water may be worked into the product anew

The assessment of the taste of emulsions Nos. 17-24 gave the result that they were well aromatic and gave a rather good mouth feel. At 18^βC the products were a little softer but otherwise gave the same results.

This series of experiments showed that the technological conditions during the preparation of the emulsion do not have any significant influence on the properties of the emulsion. The next series of experiments was carried out in order to assess whether the content of salt is important for the stability of the emulsion; and in order to determine the lower limit of the fatty phase in the emulsion that still makes it possible to obtain a water-in-oil emulsion. The weight of each portion was 3 kg. The salt, sodium chloride, was dissolved in the water. The emulsifier was employed in an amount (calculated on the weight of the emulsion) corresponding to 1.0% distilled monoglyceride having an iodine value of about 105. The fat blend was as in experiments Nos. 1-10 and so was the addition of flavouring agent. The capacity was 50 kg/h and the ammonia temperature -10^βC. The emulsions were prepared to have the following compositions:

The assessments showed that the emulsions of experiments Nos. 25 to 30 were excellently stable at spreading after storage at 5^βC. The emulsion of experiment No. 31 gave a very small amount of free water but it could be easily worked into the product anew during the spreading. In a further series of experiments the distilled monoglyceride was replaced by mono-diglycerides containing from 40% to 60% monoglyceride, and the dosage was such that the amount of emulsifier corresponded to about 1% of distilled monoglyceride. In these experiments the fat blend and the aqueous phase were as in experiments Nos. 1-10 and the mode of preparation as in experiments Nos. 25-31. The compositions of the emulsions were as follows

Exp.No. 32 1.7% 60% mono-diglyceride iodine value 113 " " 33 1.7% 60% mono-diglyceride iodine value 113 " " 34 2.5% 40% mono-diglyceride iodine value 118

"^' " 35 2.5% 40% mono-diglyceride iodine value 118 " " 36 2.5% 43% mono-diglyceride iodine value 128 " " 37 1.8% 54% mono-diglyceride iodine value 124

The emulsions formed were excellently stable when spread after storage at 5°C and they had a good flavour. These experiments show that it is well possible to use mono- diglycerides instead of pure monoglycerides.

The mono-diglyceride employed in emulsions Nos. 36 and 37 was based on safflower oil. Since linolic acid constitutes 75-80% of the fatty acids in safflower oil (the remainder being substantially oleic acid) there is no reason to doubt that a monoglyceride containing linolic acid as the only fatty acid would be usable as the emulsifier in the emulsion according to the invention. The iodine value of such an emulsifier would be 143; if based on linolenic acid its iodine value would be still higher.

In a still further series of experiments emulsifiers having a lower iodine value were tested, and in such a way that emulsifier was present in an amount of 1% distilled monoglyceride. These emulsifiers were prepared by blending monoglycerides having higher and lower iodine values. The iodine value of the monoglycerides was in experiment No. 38 about 80, experiment No. 39 about 70, and experiment No. 40 about 60.

Otherwise the composition of the blends was as in experiment No. 8, yet the capacity was 50 kg per hour.

The emulsions from experiments Nos. 38-40 were well stable at spreading and had a good taste. These experiments thus show that it is possible to obtain good results by using emulsifiers having iodine values rather much lower than the preferred values of 100-110.

A final series of experiments had for its purpose to investigate the stability of the emulsions at higher temperatures when using a number of different fat blends; the following fat blends were tested:

A) 25 parts of hardened soybean oil, m.p. 41°C 75 parts of liquid soybean oil

B) 2 parts of fully hardened palm oil, m.p. 60^*C

23 parts of hardened soybean oil, m.p. 41^βC 75 parts of liquid soybean oil

C) 15 parts of hardened soybean oil, m.p. 41"C 30 parts of hardened soybean oil, m.p. 35^*C

55 parts of liquid soybean oil

D) 5 parts of hardened soybean oil, m.p. 41^*C 55 parts of butter oil 40 parts of liquid soybean oil

E) 100 parts of butter oil

In these experiments the aqueous phases a) and b) from experiments Nos. 1-10 were employed; the emulsifier was 1% distilled monoglyceride having an iodine value of about 105. The ammonia coolant had a temperature of -10^*C and the capacity was 50 kg/h.

The fat blends had the following analyses:

B

Iodine value (fat blend)

and the composition of the emulsions were as follows:

The experimental emulsions Nos. 41-50 were stored at 5^βC, 18^*C, 25^βC and 35^βC, respectively, to judge the separation of oil from the emulsions. At 25^βC they were all stable for up to a week without separation of oil and at heating at 35^βC emulsions Nos. 43, 44, 46, 49 and 50 were stable at least for 25 hours without separation of oil. Industrial Use of the Invention

It is expected that the invention will cause the manufacture of low fat spreads having a still lower fat content than has hitherto been commercial practice and hence contribute to improving the general health of the populatons.

Claims

Patent Claims

1. A spreadable water-in-oil emulsion containing as emulsifier only distilled monoglycerides or mono- diglycerides of edible fatty acids containing 12-22 carbon atoms, characterized in that the fatty phase constitutes 12- 30% of the weight of the emulsion and that the emulsifier has an iodine value of 50-150 and is present in an amount corresponding to an amount of monoglyceride of 0.35-4.0% of the weight of the emulsion, the aqueous phase being free of added protein and hydrocolloid.

2. An emulsion as claimed in claim 1, characterized in that the fatty phase constitutes 16-25% of the weight of the emulsion.

3. An emulsion as claimed in claim 1, characterized in that the emulsifier as fatty acid residues contains predominantly residues of fatty acids containing 16-18 carbon atoms.

4. An emulsion as claimed in anyone of the preceding claims, characterized in that the emulsifier is present in an amount corresponding to an amount of monoglyceride of 0.4-3.5% of the weight of the emulsion.

5. An emulsion as claimed in claim 4, characterized in that the emulsifier is present in an amount corresponding to an amount of monoglyceride of 0.75-1.5% of the weight of the emulsion.

6. An emulsion as claimed in anyone of the preceding claims, characterized in that the iodine value of the emulsifier is 90-120.

7. An emulsion as claimed in claim 6, characterized in that the iodine value of the emulsifier is 100-110.

8. An emulsion as claimed in anyone of the preceding claims, characterized in that the pH of the aqueous phase is 4 to 7.

9. An emulsion as claimed in claim 8, characterized in that the pH of the aqueous phase is approximately 6.

10. An emulsion as claimed in anyone of the preceding claims, characterized in that flavouring agents are present in the aqueous phase as well as the fatty phase.