GB1597783A

GB1597783A - Soy protein

Info

Publication number: GB1597783A
Application number: GB18246/78A
Authority: GB
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1977-05-09
Filing date: 1978-05-08
Publication date: 1981-09-09
Also published as: JPS5414541A; IT7823142A0; DE2819626A1; FR2390108A1; BE866830A; NL7804948A

Description

(54) MODIFIED SOY PROTEIN (71) We, THE PROCTER & GAMBLE COMPANY, a company organised under the laws of State of Ohio, United States of America, of 301 East Sixth Street, Cincinnati, Ohio 45202, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a process for preparing a soy protein binder of enhanced functionality.

Heretofore, much work has been done to provide satisfactory analog food products. Meat analogs, egg analogs and cheese analogs are simulated food products generally formed from vegetable proteins, notably soy protein, and other sources, for example, feathers, and other animal by-products.

To prepare a meat analog, the protein source is generally "texturized" to impart to the material the chewy toughness and mouth feel associated with meat.

The texturized protein may be in the form of fibers, chunks or other physical forms.

Binding agents are added to the product to hold the texturized protein in the shape or form of the food being imitated, i.e., patty, loaf, etc. Coloring, fat and flavor are then added to the texturized protein and the entire mass is shaped to resemble the desired meat product.

In the case of cheeses or egg analogs, the protein material is texturized to give a smooth, less tough and chewy texture so that the final product, when the binding agent, coloring, fats and flavor are added, will resemble the cheese or egg product.

Heretofore, the really suitable binding materials for meat analog products and naturally extended meat products have involved the use of egg white. Egg white is an excellent binding material, but its supply is limited and the cost variable.

A preferred binder would be one derived from an abundant vegetable source, for example, soy protein. One such binder is described in U.S. 3,953,611, issued to Youngquist, 1976, which describes a protein binder comprising 7S soy protein isolate. The 7S isolate is a particular fraction of soy protein which can be isolated from native soy protein.

Soy protein itself will function as a binder when solubilized in water at a pH above 9. This highly alkaline pH range is not acceptable in a food product because of the off-flavor. In U.S. 4,000,323, issued to Youngquist, 1976, a method of using soy protein as a binder is described. A leavening acid is mixed with the particulate texturized protein material and a soy protein binder having a pH above 9. On heating, the soy protein heat-sets to bind the texturized protein material and the leavening acid automatically provides a pH within the acceptable meat flavor range, 5.5 to 7.5.

In one aspect of the present invention may provide a soy protein isolate which functions as a binder material at an acceptable meat pH range of 5.5 to 7.5 without the need for isolation of the 7S fraction.

In another aspect the present invention may provide a soy protein binder material which functions at a pH within the acceptable meat flavor range of 5.5 to 7.5 without the use of leavening acids.

According to the present invention we provide a method for preparing a modified soy protein material comprising heating an aqueous solution of soybean proteinaceous material at the temperature and a pH range within the area defined by the points ABCD of the figure for a period of from 15 to 60 minutes. The invention also encompasses the modified soy protein material thus made, its use as a binder in food analog products, and the food analog containing said binder, both "set" and "non-set".

The figure illustrates the pH range and temperature range at which the modification of the soy protein material to provide a binder takes place. The area defined by the points ABCD, the non-shaded area, represents the pH and temperatures at which the binder protein is produced. The shaded area represents the conditions under which the protein produced by the heat/pH treatment is not an acceptable binder.

A soy protein material which functions effectively as a binder is prepared by the method herein described.

By "modified soy protein material" is meant a protein material which will function as a binder, especially in a food analog product. The binder material heatsets at normal cooking temperatures when used as a 30% (or greater) aqueous dispersion in a food analog product. The heat-setting is irreversible, under normal conditions of use, i.e., the binder does not liquefy upon cooling or upon re-heating after it has been heat-set. The non-heat set modified soy protein material is readily soluble in water in the normal range of foods, 5.5 to 7.5, and is readily formulated into foods.

The highly functional modified soy protein herein is characterized by a distribution of ultracentrifuge sedimentation constants between 2 and 7, the majority of the protein being 2S to 4S.

The sedimentation constant has been defined by Svedberg, T. and Pederson, K.O., The Ultracentrifuge, Clarendon Press, Oxford, England (1940).

dx, /dt S= w2x wherein x equals distance from center of rotation; t equals time; w equals angular velocity; and dx/dt equals the velocity of component i.

A second physical characteristic of the modified soy protein isolate prepared by the invention herein is the -gel strength. A gel strength of 1.3 to 3.5 is characteristic of the product produced by this process. The gel strength or hardness is measured using a Brabender Texturometer. Hardness Unit H.U.) values for this instrument are calculated by the equation: H.U.=height of first peak/voltage input As used herein, "texturized protein material" means a plurality of edible protein particles which have a hydration capacity of from about I to 4 times their weight of water, and when hydrated remain particulate (maintain their structural integrity) and have a chewy texture.

By the term "chewy texture" herein is meant the physical characteristics of a texturized protein material which causes such materials, when masticated, to present the properties of resilience, elasticity and resistance to shear which are characteristic of meat. This chewy texture is preferably evaluated subjectively by chewing the protein; however, this texture of the protein material can be expressed in shear press values. Suitable texturized protein material for use herein includes protein material having a shear press value in the range of 300 to 1 500 pounds determined according to the method disclosed in U.S. Patent 3,778,522, granted December 11, 1973, to Strommer.

By "soybean proteinaceous material" is meant the whole soybean or any part thereof which contains a protein material, including both full fat and defatted soybean material. Preferred soybean proteinaceous material includes defatted soy flakes, meal or flavor, soy isolate and soy concentrates.

All percentages herein are by weight, unless otherwise specified.

To prepare the modified soy protein material (binder) of the present invention a source of soybean protein or soybean proteinaceous material is mixed with water having a pH in the range within the area defined by the points ABCD of the figure.

Soybean protein isolate or concentrate are suitable for use herein. In addition, other suitable soybean proteinaceous materials are defatted soybean flakes, meal or flour. The soybean proteinaceous material is preferably defatted before use herein.

Generally, the ratio of water to the soybean proteinaceous material is a ratio of 10:1 to 35:1. When soybean meals or concentrates are used. a ratio of 10:1 to 20:1 is preferred, and a ratio of 15:1 is highly preferred. When soybean isolate is used, a ratio of 25:1 to 35:1 is preferred, and a ratio of 30:1 is highly preferred.

The pH is adjusted using a food approved acid or base. An acid or base which would leave a toxic residue is not acceptable in the practice of this invention.

Acids which are suitable for use in this invention are acetic acid, lactic acid, citric acid, hydrochloric acid, among others. Bases which are useful in the practice of this invention are alkali metal hydroxides, e.g., sodium hydroxide, potassium hydroxide, alkali metal carbonates, e.g., potassium carbonate, sodium carbonate, lithium carbonate, calcium carbonate, among others. For those on a low sodium diet, it is preferred to use the non-sodium alkali metal base to produce a modified soy protein binder of a low sodium content.

The pH range is approximately from 6.5 to 11.0. At these pH's the soybean protein is solubilized and most of the non-proteinaceous material is insoluble.

Some of the carbohydrate material present will dissolve with the protein but these materials remain in solution when the protein is precipitated.

In a preferred method, the pH is adjusted to 7.5 to 9.5.

To aid in the solubilization of the soybean protein, the soybean proteinaceous material can be slurried with the water. The slurry can be heated concurrently with the solubilization to the temperatures and pH's within the area defined by the points ABCD of the figure.

In a variation, the soy protein material can be solubilized and then heated. The heat treatment is from 15 minutes to 60 minutes, preferably 30 to 45 minutes.

The temperature selected depends on the pH of the solution. The temperatures may range from about 450C to about 950 C. The pH and temperature are selected so that parameters are within the area defined ABCD of the figure.

Preferred parameters for the process herein are pH's in the range of 7.5 to 9.5 and temperatures of from 60"C to 850C.

The soluble proteinaceous material is separated from any insoluble material by centrifugation or other conventional methods. The insoluble soy material can be separated before heating or after the heating step.

The modified soy protein material can be isolated from solution by any standard technique. Isoelectric precipitation using a food approved acid to lower the pH to about 4.5 is a preferred method. Any of the acids mentioned above for adjusting the pH are useful at this step.

A second mode of isolation of the protein comprises salting out by the addition of a water-soluble salt. In similar mode, a water soluble organic solvent which is not toxic and is food approved can also be used. Preferred solvents for precipitating the protein are ethanol, methanol, 2-propanol and acetone.

If soybean isolate, containing about 90 /O protein is used, the pH of the solution is adjusted to 6.5 to 7.0 after heating, and the mixture is simply freeze-dried, using standard techniques to recover the modified protein. When other soybean proteinaceous material, i.e., meal, flour or concentrates are used, the carbohydrate material present in the protein solution contaminates the product.

The modified soy protein material isolated from the above process is a highly functional protein. When a 5% concentration of the modified soybean protein material in water is centrifuged at 1700 rpm for 30 minutes, greater than 900to of the protein is found in the supernatant liquid. A protein isolate from soy meal under the same conditions produces only about 5060% of the protein in the supernatant liquid.

When a ca 30% (wt.), or higher, aqueous dispersion of the modified soy protein material is heated to about 65"C, or higher, for about 30 minutes, an irreversible gel is formed, i.e., the modified soy protein material heat-sets and binds in a manner which is-substantially equally effective to the 7S protein and egg white binders known in the art.

The formation of an irreversible gel upon heating is desirable in a product which acts as a binder for meat analog or food analog products. If the product is heat set to give the product the appearance and physical characteristics of cooked food, then the binder material must be such that it does not melt upon cooling, or if the product is to be reheated, does not melt at those temperatures. The protein herein meets these requirements.

Table I gives the gel strength values of the modified soy protein material prepared by the above described process. A gel strength below about 1.3 is too soft and does not provide the desired texture and mouthfeel during mastication. A gel strength above about 3.5 is too tough and is therefore unacceptable.

TABLE I Heat Treatment Gel Strength (H.U.) "C for One Hour pH 30% Protein 45 8.5 0.5' 45 11.0 2.65 50 6.5 0.3' 50 10.5 1.65 55 8.5 0.7' 55 10.5 2.10 65 7.5 1.50 65 8.5 1.39 65 9.5 2.0 65 10.5 2.90 65 11.0 a,b 70 10.5 a, b 75 8.5 3.35 75 9.5 b 85 7.5 2.48 a-sulfurous odor upon isoelectric precipitation bflakey, non-uniform, non-cohesive gel due to incomplete hydration of protein c-not suitable for binder As mentioned above, a gel strength of 1.3 to 3.5 H.U. is acceptable for use as a binder in a food analog product.

To form a food analog product the binder is mixed with a protein material. The protein can be derived from an animal source, for example, a meat, egg, or milk, from an animal by-product, for example, feathers or keratinous material, or from a vegetable source such as oil seeds, leguminous plants, cereals, and grasses, for example alfalfa.

To prepare a meat analog, the protein is usually texturized. Vegetable protein is texturized by any conventional method, preferably by extrusion. The texturized protein solids are mixed with water and trace amounts of color added if desired. In addition, diluents can be added, for example, starch. The starches may be derived from cereal grains, for example, wheat, corn, rice, or from vegetables, for example, potatoes, arrowroot and other sources.

For use as a binder material in a food analog, the modified soy protein material prepared by the present process is first mixed with water to form a tacky paste. The ratio of water to dry protein material ranges from 1:1 to 4: 1. The hydrated modified soy protein material, i.e. binder, is then mixed together with the protein to form the food analog. In the case of a meat analog, the texturized protein material and the binder are then formed into a suitable shape, for example, a patty or loaf form. On dry weight basis, the ratio of protein to binder can suitable range from 3:1 to 11:1.

Preferably, this ratio is 5:1 to 10:1, and most preferably, 5:1 to 7:1.

In addition to the binder material, water and protein granules or fibers, other adjuvants may be added to a meat analog mixture before heat setting the product.

For example, fat, either liquid or solid from a variety of sources, flavor, flavor enhancers, flavor precursors, coloring, salt, and other seasonings may be added.

The additional adjuvants are then mixed with dry or hydrated protein and the hydrated binder phase before the formation of the product.

The food analog products made using the soy protein modified material of this invention as the binder are heat-set by any conventional method. For example, heating in the presence of moist steam, autoclaving, frying, baking and microwaving. The low temperatures at which the binder material of the instant invention heat-sets makes it possible for the food analog to be heat-set prior to consumption.

The following examples are illustrative of the invention but are not meant to be limiting thereof.

EXAMPLE I Defatted soy flakes were added to an aqueous solution of potassium hydroxide having a pH of 10.5; the ratio of water:flake being 15:1. The mixture was heated for one hour at 55"C, during which time, the solution was stirred continuously.

After the heat treatment, the mixture was centrifuged. The supernatant liquid containing the modified soy protein was retained and the residue discarded. The protein was isolated by isoelectric precipitation using one normal hydrochloric acid to lower the pH to about 4.5.

The acid solution was centrifuged and the supernatant liquid discarded. The residual solid material is the modified soy protein isolate. This material was dispersed in water and the pH adjusted to neutrality using potassium hydroxide.

The mixture was then freeze-dried to produce a dry, neutral proteinaceous material.

Ultracentrifuge analysis showed the material to consist mainly of 2S soy protein fraction. The material is 90% protein (determined by Kjeldahl nitrogen values).

A 30% dispersion of the protein was prepared. This solution was heated at 65"C for 30 minutes. The gel which formed had a gel strength of 2.0 H.U. when measured with a Brabender Texturometer.

When the defatted soy flakes in Example I are replaced by soy concentrate or soy isolate, similar results are obtained.

When soy concentrate is used to replace the defatted soy flakes of Example I, and the ratio of water flake is adjusted to 30:1, similar results are obtained.

EXAMPLE II All-Vegetable Meat Analog Ingredient Weight (gms) Percent of Total Flavor extruded soy protein granules 34.0 29.47 Protein material from Example I 6.0 5.20 Coloring 0.05 0.04 Solid "Crisco" (Trade Mark) 17.34 15.03 Water 58.0 50.26 Total Weight 115.39 100.00 The modified soy protein material is prepared as in Example I, the color additive and 50 grams of water are mixed mechanically for 20 seconds to prepare the binder.

The "Crisco" and 8 grams of water are heated in a hot water bath until the "Crisco" melted. Texturized flavored vegetable protein granules are prepared according to the method described by Liepa and Slone, U.S. Patent 3,840,679 (1974) and are coated with the "Crisco" water mixture.

The binder mixture is then added to the texturized flavor granules mix and blended in a beaker using a spatula. A shaped patty, 4 1/2 inch round, 3/8 inch thick is prepared from the binder and granular mixture. The patty is wrapped in a plastic material and allowed to sit at room temperature for about 10 minutes to hydrate.

The formed patty is fried in a covered electric skillet at 280"F for 5 minutes on each side.

A product approximating in texture and in taste, a fried all-beef hamburger is produced.

EXAMPLE III A commercial soy protein isolate is dissolved in an aqueous solution of potassium hydroxide, the pH being 9.5, the ratio of water to soy flake being about 12:1. The solution is then heated to 65"C for 35 minutes, during which time the mixture is stirred continuously.

The solution is then cooled to room temperature, and the protein isolated by isoelectric precipitation, a pH of 4.5 is achieved by the addition of one normal hydrochloric acid. This mixture is then centrifuged and the supernatant liquid discarded. The protein material, which is the residue, is then dispersed in water and the pH adjusted to about 6.6. When a 30% solids dispersion of this material is gelled at 550 C, the gel hardness is 2.0 H.U. when measured with a Brabender Texturometer.

When the protein material is used to replace the binder in Example II, a patty with similar characteristics is obtained.

EXAMPLE IV All Vegetable Sausage Analog Ingredient Weight (gms) Percent of Total Texturized granules 25.00 48.92 Flavor 1.00 1.96 Color 0.10 0.19 Solid "Crisco" 15.00 29.33 Protein material from Example 1 3.00 13.70 Water 7.00 5.90 51.10 100.00 The modified soy protein material is prepared as in Example I. The color additive, flavor components, protein binder and water are mixed mechanically for about 30 seconds to prepare the binder.

The texturized protein granules, containing about 60 water and 10% fat and prepared according to the method described by Yang and Olsen, U.S. Patent 3,814,823 (1974), are coated with the "Crisco" which had been heated in a hot water bath until melted.

The binder mixture is then added to the texturized granules and blended in a beaker using a fork. A shaped patty, 2 3/4 inch round, 3/8 inch thick is prepared from about 45 grams of the granule and binder mixture. The formed patty is fried in a covered electric skillet or griddle at 300"F for 3 1/2 minutes on each side. A product similar in texture and taste to a pork sausage is produced.

WHAT WE CLAIM IS: 1. A method for preparing a modified soy protein material comprising heating an aqueous solution of soybean proteinaceous material at the temperature and pH range within the area defined by the points ABCD of the figure for a period of from 15 to 60 minutes.

2. A method according to Claim I wherein said proteinaceous material is heated for 30 to 45 minutes.

3. A method according to Claim 2 wherein the pH is from 7.5 to 9.5.

4. A method according to Claim 3 wherein said proteinaceous material is heated within the range from 600C to 850C.

5. A method according to Claim 2 wherein said proteinaceous material is defatted soybean meal or flour, soy isolate or soy concentrate.

6. A method according to Claim 5 wherein said proteinaceous material is defatted soybean meal or flour or soy isolate and wherein the ratio of water to said proteinaceous material is from 10:1 to 20:1.

7. A method according to Claim 5 wherein said proteinaceous material is soy concentrate and the ratio of water to concentrate is 25:1 to 35:1.

8. A method for preparing a modified soy protein material according to Claim 1 comprising the additional steps of: (1) isolating the modified soy protein material from the solution; and (2) adjusting the pH of the modified soy protein material to from 6.5 to 7.0.

9. A method according to Claim 8 wherein said solubilized proteinaceous material is defatted soybean meal or flour, soy isolate or soy concentrate.

10. A method according to Claim 9 wherein said modified soy protein material is isolated by isoelectric precipitation.

II. A method according to Claim 10 wherein said modified soy protein is isolated by addition of a physiologically acceptable water-soluble salt or organic solvent.

12. A modified soy protein material prepared according to the method of

Claims

Claim 1.

13. A modified soy protein material prepared according to the method of Claim 8.

14. A food analog product comprising protein material and modified soy protein material prepared by the method of Claim 1.

15. A meat analog according to Claim 14 wherein said protein material comprises texturized protein material.

16. The meat analog product of Claim 15 wherein said texturized protein material is selected from the group consisting of texturized vegetable protein or texturized animal protein.

17. A product according to Claim 15 wherein said texturized vegetable protein is derived from soybean, cottonseed, or peanuts.

18. A product according to Claim 16 wherein said texturized protein material is selected from the group consisting of soybean protein isolate, soybean protein concentrate, and cottonseed isolate.

19. A product according to Claim 15 wherein said texturized protein is an animal protein selected from the group consisting of meats. fish, poultry and keratinous animal by-products.

20. A product according to Claim 14 which is heat-set.

21. A method according to Claim 1, when carried out substantially as described in Example I or III.

22. A product according to Claim 13, substantially as described in Example II or IV.