GB2056840A

GB2056840A - Preparing emulsified foods

Info

Publication number: GB2056840A
Application number: GB8025956A
Authority: GB
Original assignee: Nisshin Oil Mills Ltd
Current assignee: Nisshin Oillio Group Ltd
Priority date: 1979-08-10
Filing date: 1980-08-08
Publication date: 1981-03-25
Also published as: FR2462876B1; DE3029896A1; IT1132387B; DE3029896C2; FR2462876A1; CA1140802A; IT8024106A0; GB2056840B

Abstract

A mayonnaise-like food is prepared by solubilising an alcohol- denatured soybean protein with protease until the solubility of the protein in a 10% aqueous solution of trichloroacetic acid is from 8 to 35% by weight, separating water- insoluble materials, and emulsifying the thus-refined soybean protein with edible oil and vinegar. The alcohol may be methanol, ethanol or propanol and the protease may be e.g. pepsin, papain or trypsin.

Description

SPECIFICATION Preparing emulsified foods This invention relates to a process for preparing emulsified, mayonnaise-like foods, by using a specifically refined soybean protein, instead of eggs, as an emulsifier. The term "mayonnaiselike food" means a mayonnaise which does not contain eggs as an emulsifier.

The high level of cholesterol in the blood resulting from eating a large amount of animal foods can cause serious health problems. It has become increasingly desirable to provide foods free of cholesterol.

In conventional mayonnaise, eggs (which contain a large amount of cholesterol) are used as an emulsifier. It has been proposed to prepare mayonnaise-like foods by using soybean protein (which is free of cholesterol) instead of eggs. Examples of such preparations are that using separated soybean protein (reported at the 5th International Congress of Food Science and Technology, Sep. 17-22, 1978, Kyoto, Japan) and that involving subjecting soybean protein to lactic fermentation and using the resulting lactic acid instead of vinegar (Japanese Patent Publication No. 51-32705).

However, these methods have various disadvantages. Firstly, the soybean protein, in spite of effecting purification, deodorization and decolouration is not sufficiently flavoursome to provide an effective substitute for eggs and the product therefore exhibits a flavour and colour peculiar to soybean, even when seasoned. Secondly, conventional soybean protein provides only a low degree of emulsification at the acidic pH of mayonnaise. Thirdly, the resulting mayonnaise tends to have less satisfactory properties on extrusion from a plastic tubular container than an eggemulsified mayonnaise. For example, the former may be too soft or have a hard, gel-like form in which the surface is rough or split.

According to the present invention, a process for preparing a mayonnaise-like food comprises solubilising an alcohol-denatured soybean protein with protease until the solubility of the protein in a 10% aqueous solution of trichloroacetic acid is from 8 to 35% by weight, separating waterinsoluble materials, and emulsifying the thus-refined soybean protein together with edible oil and vinegar.

In the process of the invention, an alcohol-denatured soybean protein is refined to remove the odour and colour peculiar to soybean. Mayonnaise-like foods prepared therefrom can have a flavour and organoleptic properties similar to egg-emulsified mayonnaise.

The alcohol denaturation causes the protein to become water-insoluble. The higher the degree of denaturation, the lower the solubility of the protein in water, and vice versa.

It is known that the emulsifying power of soybean protein is increased to some extent by hydrolysis with an enzyme. It has been found that, when soybean protein whose water-solubility has been reduced by alcohol denaturation is solubilised by enzymolysis, its emulsifying power and emulsification stability can be improved.

The starting soybean protein which may be used in this invention may be a defatted soybean flour or a soybean protein prepared therefrom, e.g. an extracted soybean protein or an isolated soybean protein.

The starting soybean protein is washed with an alcohol, and preferably with water containing an alcohol. Suitable alcohols include methanol, ethanol and propanol; ethanol is preferred. By this washing, the flavour and colour of the protein are markedly reduced. A high level of denaturation is preferred because it has a favourable influence upon the subsequent emulsification stability.

The alcohol washing can be carried out by conventional methods. e.g. by using water containing 50 to 80% of an alcohol and a weight ratio of solvent to soybean protein of 5:1 to 20:1. The washing temperature is preferably below the boiling point of the solvent. Alternatively, alcohol vapour may be used.

The protein thus obtained is substantially free of the taste and odour peculiar to soybean and improved in colour, but its solubility is decreased by the alcohol denaturation and it is therefore unsuitable for the preparation of mayonnaise-like foods. The alcohol-denatured protein is then dispersed in water and the pH is adjusted as desired. An acidic, neutral or alkaline protease such as pepsin, Bilprase (from Nagase Sangyo, Japan), papain, trypsin or Alkalase (from the Novo Company, Denmark) is then added to effect enzymolysis, while stirring slowly. At this stage, the pH and temperature are preferably the optimum values for the promotion of the enzymatic reaction.

For adjusting the pH, acids or salts suitable for use in food, e.g. hydrochloric acid, acetic acid, sodium bicarbonate, or water, may be used. By way of example, using pepsin as an enzyme, the pH may be adjusted to the optimum value (about 2.0) by adding hydrochloric acid. An enzyme preparation may then be added, to start the enzymolysis. After having reached the desired level of enzymolysis, sodium hydroxide is added to effect neutralization, and the enzyme is then inactivated, suitably by heating and preferably using a plate-type heat exchanger.

The enzymatic reaction is stopped when the solubility of the protein in a 10% aqueous solution of trichloroacetic acid (hereinafter referred to as "10% TCA solubilisation rate") has reached 8 to 35, and preferably 8 to 15, % by weight.

A 10% TCA solubilisation rate may be measured as follows: 2 g of a sample of a powdered protein, after enzyme treatment, are dissolved in 48 g of water, and 50 g of a 20% aqueous TCA solution are added thereto with shaking. The resulting precipitate is centrifuged and 10 g of the supernatant solution are sampled. The Nitrogen content (Ns) is measured in accordance with the Kjeldahl method.

The total nitrogen content (Nt) of the protein powder is also measured and the 10% TCA solubilisation rate is calculated from its equivalence to 1 0Ns/ 1 00Nt.

If the TCA solubilisation rate is too low, proteins made insoluble by the alcohol denaturation cannot be recovered in the subsequent extraction and filtration step, so that the yield of refined protein is reduced and the emulsification stability of the food products is not improved. If the TCA solubiiisation rate exceeds 35% by weight, bitter peptides are formed in the enzymolysis products, which have an undesirable influence upon the flavour of mayonnaise-like foods.

After inactivation of the enzyme, water-insoluble materials are filtered off to obtain a solution of refined soybean protein, to which edible oil, vinegar and, if desired, seasoning may be directly added and emulsified together to prepare a mayonnaise-like food. If desired, the refined protein may be dried to a powder and redissolved before emulsification. By way of example, seasonings such as salt, sodium glutamate, nucleic acid-type seasonings or sugar and, if desired, pastes may be dispersed and dissolved in the solution of the refined protein. Natural colouring matters, oil-soluble spcices and herbs and tocopherol may first be dissolved in an edible oil. The soybean protein solution and edible oil thus obtained may be emulsified by means of an emulsifier such as a paddle mixer, agitator, Homomixer (from Tokushukika Kogyo, Japan) or colloid mill.The resulting emulsion may be mixed in a colloid mill to further advance homogensation.

Preferably, the food obtained by the process of the invention contains between 0.5 and 2.5% by weight of the refined soybean protein as dry. At this content level, and if the partial hydrolysis is conducted until the TCA solubilisation rate is from 8 to 15% by weight, the smoothness and form-maintaining property of the food when extruded from a plastic tubular container can be especially high.

Of the following Examples, some illustrate the invention. All parts and percentages are by weight. Viscosity measurements were conducted in a Brookfield BM Viscometer.

Example 1 20 g of a slightly denatured, defatted soybean were washed with 200 g of an aqueous 60% w/w solution of ethanol in a sealed tank at 50"C for 30 minutes. After filtration, 32 g of cake were obtained and transferred to a pressure-reduced drier. After drying at 70"C, 1 3.5 g of a powdered, concentrated soybean protein were obtained. The product contained 6.5% water and 67% dry weight protein and had a Nitrogen Solubility Index (NSI) od 11.0%.

The entire product was then added to 1 50 1 of warm water (60"C) in a tank provided with a jacket, and dispersed while stirring. Dilute ammonia was added to a pH of 9.0. The solution was heated to 55"C and maintained at this temperature. When 50 g of Bilprase SP-4 were added and reacted at 55"C for two hours, the pH slowly decreased to 7.5. The 10% TCA solubilisation rate was then 20%. This solution was heated by means of a plate-type heat exchanger to 1 20 C and then cooled. After centrifuging, 1 20 1 of a solution containing 7.3% solids were obtained.

4.0 1 of a 5% protein solution were prepared from a 5.0 I sample of the 1 20 1 solution. 100 g of sugar, 200 g of salt and 50 g of seasoning were added thereto and dissolved. 5 kg of soybean salad oil were then added slowly and emulsified while maintaining the temperature at 30"C. 1.0 kg of vinegar was added slowly and emulsified. Finally, a colloid mill was used to obtain a mayonnaise-like food.

Example 2 The 11 5 1 of the centrifuged solution remaining after removal of the 5 I sample used in Example I were concentrated and spray-dried to obtain 7.5 kg of refined soybean protein. This powder was free of any beany flavour, bright white in colour and highly water-soluble. It contained 7.0% moisture and 83.5% protein (dry weight). It had a NSI value of 95% and a 10%. TCA solubilisation rate of 26%. It was used to prepare 4.0 1 of a 5% protein solution, and subsequently a mayonnaise-like food, by the procedure described in the final paragraph of Example 1.

Example 3 Defatted soybeans were extracted with water by the conventional method, to remove residues.

Whey was removed by an acid precipitation, and this was followed by neutralisation and heating. Spray-drying was carried out to obtain separated soybean protein powder. The powder contained 6.0% water and 89% protein (dry weight). It has an NSI value of 93% and a 10% TCA solubilisation rate of 26%. A mayonnaise-like food was prepared from this powder in the same manner as in Example 1.

Example 4 A part of the separated soybean protein powder of Example 3 was dissolved in water to prepare a 5% w/w solution. Papain (The Pharmacopoeia of Japan) was added to this solution and enzymolysis was conducted at pH 7 and 50"C for three hours. After heat sterilisation, spraydrying was carried out to obtain an enzymolysed, isolated soybean protein. This product contained 6.5% water and 88% protein (dry weight). It had a NSI value of 95% and a 10% TCA solubilisation rate of 27.0%. It was made up into a mayonnaise-like food in the same manner as in Example 1.

Table 1 shows various properties of the products of Examples 1 to 4.

Table 1 Emulsification Viscosity Example Stability (cps) Flavour Chewiness 1 Stable 45,000 Good 2 Stable 45,000 Good Fine 3 Stable 60,000 Peculiar Rough 4 Stable 50,000 Peculiar Fine In a forced degradation text on the above products, in which the emulsification stability was evaluated by allowing the product to stand at 40"C, the products of Examples 3 and 4 exhibited oil separation after one and two weeks, respectively. The product of Example 2 and a conventional egg-emulsified mayonnaise were stable after four weeks.

In a taste test, twenty blindfold panellists tasted the product of Example 1 and a commercially available egg-emulsified mayonnaise. Nine preferred the former and eleven the latter.

Example 5 5 kg of defatted soybean were washed with a 10food ratio of a 75% w/w aqueous alcohol at 55"C and filtered. The washing and filtering were repeated twice. After drying at room temperature, 3.4 kg of concentrated soybean protein were obtained. This product contained 8.0% water and 69.8% protein (dry weight). It had a NSI value of 14%.

The concentrated soybean protein was treated with enzyme in the same manner as in Example 1 for 30 minutes. The enzyme was inactivated by heat treatment. The 10% TCA solubilisation rate of the product was 10%.

A refined soybean protein solution was obtained by centrifuging. Water was then added to form a 4% protein solution. 100 g of sugar, 200 g of salt, 20 g of sodium glutamate, 2 g of nucleic acid-type condiments, 20 g of yeast extract and 11 g of tamarind seed gum were added to 2.3 1 of the protein solution. The mixture was fed to a jacketed tank and dissolved, with stirring. The temperature was elevated to 90-95"C for 20 minutes and then reduced to 30"C.

In 5.5 kg. of salad oil, 40 g of carrot oil, 5 g of mustard oleoresin of 5 g of tocopherol were dissolved. The salad oil thus obtained was added to the above protein solution in the tank over five minutes while stirring by means of an impeller type stirrer. The stirrer was then replaced by a Homomixer to effect emulsification. 0.6 kg of apple vinegar with 100 grains were then added slowly with stirring. The resultant product was then subjected to a colloid mill to prepare a mayonnaise-like food.

Examples 6 and 7 The procedure of Example 5 was repeated twice except that the enzymatic treatment time was increased to two and five hours respectively. The respective 10% TCA solubilisation rates were 25% and 41%.

Table 2 sets out the results of analyses on the refined soybean protein solutions obtained in each of Examples 5, 6 and 7. Table 3 sets out the results of tests on the final products of each of Examples 5, 6 and 7.

Table 2 Solids Content wrt Soybean Solids Protein Concentrated Example Solution (g) Content (%) Content (%) Soybean (%) Flavour 5 780 5.6 4.0 44 Good 6 830 7.0 5.6 58 Good 7 870 7.9 6.8 69 Slightly Bitter Table 3 Forced Degradation Test, at 40"C Just before After one After 1.5 Example Flavour test month months 5 Good Good Oil risen Oil off 6 Good Good Good Good 7 Slightly bitter Good Good Oil off Example 8 1 3.5 kg of the powdered, concentrated soybean protein obtained in Example 1 were added to 150 1 of warm water (60"C) in a tank provided with a jacket and dispersed, with stirring. Caustic soda was added to a pH to 8.5.

50 g of Bioprase SP-4 were added and enzymolysis was conducted for 30 minutes at 55"C and the pH was then adjusted to 9.5 by caustic soda. The enzyme was inactivated by heating at 90"C for 1 5 minutes.

10 1 of the resulting solution were centrifuged to remove water-insoluble materials. The protein solution thus obtained had a 10% TCA solubilisation rate of 7.5%.

The protein solution was neutralized (pH 7.0) with hydrochloric acid. After spray-drying, about 9 kg of refined soybean protein were obtained, from which a mayonnaise-like food was prepared using the following ingredients: Soybean Salad Oil 550 g Vinegar 150 9 Seasonings 30 9 Spices and Herbs 10 g Refined Soybean Protein 1 5 g Tamarind Gum 2 g Water 243 g The seasonings, spices and herbs, refined soybean protein and Tamarind gum were dispersed in water. The soybean salad oil was added dropwise and emulsified with a Homomixer. After adding the vinegar, further emulsification was conducted and 1 kg of mayonnaise-like food was obtained.

Examples 9 to ii The procedure of Example 8 was repeated three times except that the enzymolysis time was increased to 60, 90 and 1 20 minutes, respectively. The respective TCA solubilisation rates of the protein solutions thus obtained were 12.5%, 14.5% and 21%.

Examples 12 and 13 The procedures of Examples 9 and 11 were repeated, respectively, but the amount of refined soybean protein in the mayonnaise-like food was reduced to 5 g and the amount of water increased to 253 g.

Examples 14 and 15 The procedures of Examples 9 and 11, respectively, were repated except that the amount of refined soybean protein in the mayonnaise-like food was increased to 25 g and the amount of water decreased 233 g.

Table 4 gives results of the analyses of the foods prepared in Examples 8 to 1 5. The emulsification stability test was conducted at 45"C for one week. The form maintenance and smoothness were analysed by squeezing 200 g of the product from a plastic container.

Table 5 Emulsification Viscosity Form Example Stability (cps) Maintenance Smoothness 8 Water Off 120,000 Good Hard 9 Good 80,000 Good Good 10 Good 60,000 Good Good 11 Good 25,000 Flagging Soft 12 Oil Off 35,000 Flagging Soft 1 3 Good 150,000 Breakable Hard 14 Oil Off 15,000 Flagging Very Soft 1 5 Good 130,000 Breakable Hard

Claims

1. A process for preparing a mayonnaise-like food, which comprises solubilising an alcoholdenatured soybean protein with protease until the solubility of the protein in a 10% aqueous solution of trichloroacetic acid is from 8 to 35% by weight, separating water-insoluble materials, and emulsifying the thus-refined soybean protein with edible oil and vinegar.

2. A process according to claim 1 wherein the soybean protein has been denaturated by washing with water containing from 50 to 80% by weight of an alcohol.

3. A process according to claim 1 or claim 2 wherein the solubility of the protein in a 10% aqueous solution of trichloroacetic acid is from 8 to 15% by weight.

4. A process according to any preceding claim wherein the food contains between 0.5 and 2.5% by weight of the refined soybean protein as dry.

5. A process according to claim 1 substantially as described in any of the illustrative Examples.