FLAVORED SOYBEAN PRODUCT

Technical Field of Invention

The present invention deals with a process and product having a yogurt-like consistency made by that process using soy milk as a principal ingredient. The final product contains no cow's milk nor is the product subjected to the inoculation of yogurt-like cultures or enzymes.

Related Applications

The present application is a continuation-in-part of U.S. Patent Application Serial No. 561,554, filed on December 14, 1983.

Background of the Invention The United States is the world's largest producer of soy beans, yet less than 15% of America's non- exported soy protein ever reaches the market for human consumption. Of this quantity, only approximately 1% to 2% is consumed directly as soy bean foods, while about 13% is fed to animals and thus reaches the marketplace for human consumption in the form of meat and dairy products. Such a situation is particularly disappointing in view of the fact that soy beans produce over 33% more protein from an acre of land than any other known crop and twenty times as much usable protein as is raised on an acre dedicated to the grazing of beef cattle or the growing of their fodder.

There have been a number of attempts made to provide food products for direct human consumption based upon soy as a major component. Each prior attempt, however, has been largely unsuccessful principally because prior products have continued to

exhibit the characteristic beany taste quite familiar to those who have eaten tofu and other soy bean based products. Unless a taste has been acquired for such products, most consumers find the taste objectionable. More recent attempts, such as those disclosed in U.S. Patent Nos. 4,325,977, 3,950,544 and German Patent No. 2,406,600 have involved the manufacture of soybean-based products presumably as substitutes for dairy-based yogurt but, in each instance, yogurt-like technology was employed, which, it is believed, has resulted in a lack of commercial success for such efforts. In each instance, the starting ingredients have been treated by an enzyme or otherwise inoculated with a yogurt-like culture, which has been found to be non-conducive to the preparation of suitable non-dairy food products.

Prior efforts have further proven unsuccessful in attempting to change the texture of tofu or other soy- based products. Although tofu is a high protein, low calorie food which has no cholesterol or lactose, it is normally manufactured as a white block of bean curd, which is rather hard and grainy. Such a product does not readily lend itself as an ingredient for a food product having a creamy or yogurt-like consistency. It is thus an object of the present invention to provide a novel food product made from soy which is non-dairy, has no cholesterol or lactose.

It is yet another object of the present invention to provide a food product made from soy which has a taste and texture similar to that of yogurt and which is substantially devoid of the bean-like taste traditionally associated with soy products of the past.

It is yet a further object of the present invention to provide a food product made of soy which contains no dairy products nor inoculating cultures and

which would still possess a taste and texture not unlike yogurt.

It is still a further object of the present invention to provide a food product made of soy which possesses a good shelf-life and which is simple to manufacture using a relatively low cost process suitable for mass production.

These and further objects of the present invention will be more readily appreciated when considering the following disclosure.

Summary of the Invention

In its broadest sense, the present invention involves a process for the manufacture of a-high protein soy-based food product and the yogurt-like product made from that process. The phrase "yogurt- like" is intended to embody a consistency from a liquid to custard like product. Commercially available yogurts have been found with a broad range of consistencies. The process comprises providing a quantity of soy milk and adding to that soy milk an amount of a stabilizer to form a solution. The solution is then heated to pasteurizing temperatures after which time the solution is cooled to promote the formation of a gel. During the processing of the product, an acidic medium is added to reduce the pH, enhance the flavor and thicken the solution. To this product can be added various flavorings such as sweeteners and fruit-based materials as desired.

Detailed Description of the Invention Virtually any commercially available soybean milk can be employed as a principal ingredient for use herein. Although the process for producing soy milk is well known, it is noted that, generally, soybeans are first washed until clean and then soaked in water until

they swell to about twice their normal size. The soybeans are ground then heated in steam to about 200 ^β F or in a pressure cooker to approximately 230 ^β F for a length of time to deactivate the trypsin inhibitor and to destroy the lipoxgenase enzyme. The juice is then separated from the beans and the shells and fibers discarded.

In the practice of the present invention, it has been recognized that the soy milk should possess a Brix level between approximately 4 to 14 and, more preferably, between 7 and 11. Brix levels directly affect the taste and texture of the finished product. In the composition which will be described in the following text, approximately 70% to 86% by weight and most preferably approximately 80% by weight soymilk is employed on a fruit free basis.

To the soy milk is added a stabilizer which is intended to perform a number of functions in the practice of the present invention. As noted above, it is intended that the present product be acidified for reasons which will be more fully explained hereinafter. However, when acidification takes place, it is antici¬ pated that the soy proteins found in the soy milk insolubilize and denature, resulting in products with a chalky texture with separation of the coagulated proteins. It is theorized that the stabilizers of the present invention interact with the soy protein and prevent such results when acids are added to the soy milk. Either a single stabilizer or a system of stabilizers can be employed herein. It is the intent to employ stabilizers comprising a member selected from the group consisting of starches, gelatin, pectin, agar, gums and mixtures thereof. Of the variously available gum products, it is contemplated that a gum be employed comprising a member selected from the group

consisting of carrageenan, guar, locust bean, xanthan gum and mixtures thereof.

The quantity of the stabilizer employed will be determined by the type of stabilizer and the intended consistency of the final product. For a yogurt-like consistency, it is generally recommended that 0.12%- 0.48% by weight gums, such as guar gum, locust bean gum or agar, be employed. The preferred concentration of these gums is 0.20 to 0.35% by weight. When gelatin, having a bloom in the range of 225 to 275, high methoxy pectin, such as Hercules Genu JM or other stabilizers of this type are employed, generally recommended concentrations range from 0.35 to 0.90% by weight. Concentrations of 0.60 to 0.80% by weight are preferred. Food grade starches, such as Purity D and Firmtex produced by National Starch and Chemical, are employed at concentrations of 1.0 to 3.0% by weight, preferably at 1.25 to 2.00% by weight. All percentages are calculated on a fruit-free basis. The preferred process is one which employs a combination of stabilizers such as gelatin and locust bean gum; gelatin and starch; agar and starch; agar and gelatin; gelatin, locust bean gum and starch; and gelatin, starch and high methoxyl pectin. It is possible to reduce the concentration of individual stabilizers when combinations of stabilizers are employed. Alternatively, higher concentrations of total stabilizer, providing greater stability, are possible without adversely affecting product consistency. The preferred combinations are 0.50 to 0.60% by weight gelatin and 0.3 to 0.4% by weight locust bean gum; 0.6 to 0.8% by weight gelatin and 0.80 to 1.50% by weight starch; or 0.5 to 0.6% by weight gelatin, 0.2 to 0.3% by weight locust bean gum and 0.80 to 1.50% by weight starch.

It is intended that an acid be added to the food product to reduce the pH thereof, preferably below approximately 4.5. In doing so, the flavor of the product is improved, particularly when fruits or fruit flavors are blended with the acidified soy milk blend. Although most acids appear satisfactory, citric acid has been found to be more complimentary to many fruit flavors. Lactic, acetic, gluconic, malic, fumaric, hydrochloric, phosphoric and sulfuric acids have also been found to be quite acceptable in reducing the pH of the solution. The step of pH reduction can be carried out either before or after the heating step as described hereinafter.

In an attempt to lower the bacteria count of the product and thus increase its shelf life, it is contemplated that the solution be heated in a step akin to the pasteurization of traditional dairy products. A secondary purpose for the heating of the solution is to hydrate stabilizing agents. However, prolonged heating at high temperatures, for example, above 185 ^β F, can adversely affect the flavor and texture of the final product. As such, it is recommended in practicing the present invention that the solution be heated to approximately 180° to 185 ^β F and held at that elevated temperature for only approximately 25 to 30 seconds. At lower temperatures, such as from 155" to 160 ^* F the pasturization times would be increased upwards of approximately 30 minutes.

Subsequent to "pasteurization", it is intended that the present composition be chilled, which has the effect of promoting the gelation of the solution. As such, it is intended that the solution be brought to a temperature no greater than approximately 70 ^β F. Long term storage of the product should be maintained at refrigeration temperatures. Speed in the temperature

reduction step will minimize the growth of bacteria in the final product and will thus enhance its shelf life.

Sugar, corn syrups, fructose or other nutritive and non-nutritive sweeteners can be employed as flavor enhancers to improve the overall palatability of the product. A product with sweetness equivalent to that obtained with approximately 9% to 12% sugar is preferred. An acceptable but less sweet product can be produced with from approximately 5% to 9% sucrose or appropriate concentrations of other sweeteners. Other ingredients such as salt employed in concentrations from approximately 0.1 to 0.5%, vanilla at concentrations of approximately between 0.05 to 0.5%, lemon oil or juice at concentrations of 0.01 to 2.5% and natural or artificial flavoring systems, commonly referred to as protein masking agents, can be added to modify, and depending upon the desired final flavor, improve the overall acceptance of the product. It has particularly been found that lemon oil is quite effective in substantially eliminating any of the residual bean-like taste which traditionally accompanies a soy-based product.

Fruit flavors in an amount less than approximately 3.0% and frozen or heat processed fruit can be added to produce, again, a more appealing product. Heat processed fruit is preferred at concentrations ranging from approximately between 2% to 15% of the product as the heating process destroys microorganisms and enzymes which might otherwise shorten its shelf life. Fruit pieces, as opposed to fruit flavors add to the visual appeal of the product and give added natural flavor impact. Although not crucial to the practice of the present invention, it is highly recommended that the product can further be homogenized before the addition of fruit to insure even distribution of ingredients. Any commercial homogenzation apparatus can be employed

herein and, as stated previously, the use of homogenization is clearly an optional expedient.

Comparative Example 1

Three products were formulated with soy milk. Product A contained 76% soy milk, 6% sugar, 0.6% 250 bloom gelatin and 1.0% modified tapioca starch. Product B contained 76% soy milk, 6% sugar, 0.56% 250 bloom gelatin and 0.37% locust bean gum. Lastly, Product C contained 76% soy milk and 6% sugar with no stabilizers. All products were heated to 190 ^β F, homogenized and cooled to varying degrees before citric acid was added to reduce the pH of the product to approximately 4.3. Upon addition of the acid to sample C, the proteins coagulated, separated from the aqueous portion of the sample and produced a chalky, grain texture. This typical phenomonen occurred even when the sample was cooled to 45 ^β F before adding the acid. In contrast, products A and B showed no signs of protein coagulation except when the product temperature equalled or exceeded 145 ^β F at the time the acid was added. Stabilized samples A and B developed a slightly chalky texture when acid was added, while the product temperature was 145 ^β F or 175 ^β F.

The stabilizer thus appears to do more than a simple binding of water and prevention of separation due to the viscosity of the product. This is indicated by the fact that a high methoxy pectin such as that available by Hercules sold under the trademark GENU when used in concentrations of approximately 0.4% to 0.8% in a blend containing 76% soy milk and 6% sugar, effectively prevented coagulation of the protein during heat treatment and acidification, but had no significant effect on the viscosity of the soy milk and sugar blend.

Example 2

Approximately 2 grams of 250 bloom gelatin were mixed with approximately 50 ml of boiling water until dissolved. The gelatin mixture was then added to approximately 250 ml of soy milk, together with 20 g of sugar in 0.5 ml of lemon oil. The mixture was then heated to 180 ^β F and held at that temperature for approximately 30 seconds, at which time the temperature was quickly reduced to approximately 37 ^* F. Approximately 1.5 ml of lactic acid was then added to the chilled mixture and the solution stirred by an impeller for approximately 20 seconds. The lactic acid brought the pH of the solution to approximately 4.15 at which time pasteurized fruit was blended into the product under continuous stirring. The product was then poured into cups.

Example 3

A dry blend was prepared containing 5.0 grams gelatin, 60.0 grams sugar, 250 milligrams salt, 1.6 grams starch and 1.5 grams citric acid (dry weight basis). After blending 497.6 grams soy milk was added while constantly mixing at which time the solution was slowly heated to approximately 180 ^* F. After maintaining the temperature for approximately 30 seconds, the solution was quickly cooled and 8.1 grams of flavoring was added. The resultant product was homogenized, 3 to 4% fruit pieces added and the final product put in cups and refrigerated.

Although it is not intended that the present invention be limited to a specific theory of operation, it is believed that the various stabilizers operate in one of two fundamental ways—each to protect the coagulated protein found in the acidified soy milk. The first process relies upon the addition of sufficient thickeners to the soy milk to develop a high

enough viscosity to prevent separation of the coagulated protein. The viscosity which is required is typical of that produced when 2% by weight starch is added to soy milk and the product heated to permit hydration and gelation of the starch. Any of the typical starches or most gums, if present in adequate concentration, will produce sufficient viscosity. The required viscosity will depend upon the density and size of the coagulated protein particles. As an alternative is the addition of appropriate concentrations of stabilizers to prevent the coagula¬ tion of the soy protein at its isoelectric point. This does not require the development of high viscosities prior to adding acid, however, the temperature of solu- tion should generally be kept below approximately 120 ^β F and preferably below approximately 60°F during acid addition. It has been noted, as presented above, that stabilizers such as gelatin at a concentration of approximately 0.8% by weight, high methoxy pectin at a concentration of approximately 0.8% by weight, guar gum at a concentration of approximately 0.15% by weight and locust bean gum at a concentration of approximately 0.2% by weight have been found to be effective in pre¬ venting coagulation of the soy protein. Because of the diversity of these stabilizers, it is believed that other, stabilizers such as pectins, carboxymethyl cellulose, xanthan gums, carageenan, agar, micro- crystalline cellulose, furcelleran, ghatti and tragacanth gum would be equally effective at appropriate concentrations.

Lastly, it has been found that the basic ingre¬ dients recited above can be combined in the manufacture of a frozen custard or dessert product. Although the ingredients and process are as previously recited, as a final process step, the food product would be poured into a thermutator and chilled and dashed until the

product reaches the desired dull finish at approxi¬ mately 25 ^β F. Dashing could be continued without refrigeration until the desired overrun is achieved in the range of approximately 30 to 50%.