WO1999003356A1

WO1999003356A1 - Improved tofu food products and methods of manufacture

Info

Publication number: WO1999003356A1
Application number: PCT/CA1998/000685
Authority: WO
Inventors: Ruey Seng Li
Original assignee: Nutra-Well Foods Inc.
Priority date: 1997-07-15
Filing date: 1998-07-15
Publication date: 1999-01-28
Also published as: AU8329198A

Abstract

An improved tofu-okara material for preparing tofu food products including puffed, ready-to-eat tofu snacks, baked goods, pasta and meat substitution products is disclosed. The tofu product contains okara, which is generally discarded during tofu making. Okara improves the nutritional value and decreases the cost of the tofu product. The puffed tofu product preferably contains green peas which increases the nutritional value, palatability and processibility of the product.

Description

IMPROVED TOFU FOOD PRODUCTS AND METHODS OF MANUFACTURE

FIELD OF THE INVENTION

The present invention relates to improved tofu food products and their methods of manufacture. More particularly, it relates to the preparation of ready-to- eat tofu food products containing okara, a by-product in tofu manufacture, and preferably green peas.

BACKGROUND OF THE INVENTION

In recent years, the public has become more aware of the health risks associated with consuming large quantities of food products containing cholesterol and saturated fat, such as animal meat.

Tofu is a digestible and palatable food derived from soybeans, which are an abundant and inexpensive source of vegetable protein. However, soybeans are rarely consumed directly by humans because of their disagreeable beany flavor and the presence of flatulence-causing, water- soluble oligosaccharides. As a result, protein-rich tofu has gained popularity as a nutritious meat substitute which is free of cholesterol . Tofu has been produced from soybeans for over two thousand years in order to remove the unpleasant beany flavor and oligosaccharides from soybean. Modern processing of the soybean to remove undesirable flavors and the flatulence-causing oligosaccharides has yielded soy protein concentrate, soy protein isolate and textured soy protein. Still, according to the report by Calloway et al . (J Food Sci, Vol 36, p 251-255, 1976) , flatus measurement studies indicated that out of all the processed soybean products, only tempeh and tofu from which all carbohydrates (including oligosaccharides) have been removed were found to be non-flatulent . Although tofu is a healthy food product, its use in preparing snacks or other food products has been limited by its physical properties. Tofu consists of 85% water making it difficult to handle and not shelf-stable. The high water content makes it inconvenient and difficult to manipulate, cook and consume. Very few shelf stable ready-to-eat tofu food products have been described. Soy flour or tofu have been processed to form fried or baked dry chips which are hard and structurally unstable. Since soy protein material does not have sufficient starchy content to form puffable products, the dry chips made from them are not crispy and palatable. Moreover, soy protein usually causes hardness in fried, baked or extruded products. In using soy flour in producing a palatable ready-to-eat breakfast cereal, Bedenk et al . (U.S. Patent No. 3,682,647) enhanced the tenderness of the cereal by treating the soy flour with barley malt whereas Olson et al (U.S. Patent No. 3,976,793) used oat and soy flour to form palatable cereal flakes.

In Japan, fried tofu known as aburage is traditionally made by freshly frying seasoned sliced hard tofu in vegetable oil . The aburage contains about 40% moisture and is usually not available in dry shelf stable packaged forms . Aburage has recently been prepared from reprocessed soy protein isolate in combination with starch powder and fat (e.g JP 5-219910, 1993, U.S. Patent No. 3,950,550, and U.S. Patent No. 4,298,628) .

As the tofu manufacturing process is labour- intensive, it would be quite expensive to produce shelf- stable palatable high protein tofu snacks (such as chips) using tofu alone. Soy protein concentrate and soy protein isolate on the other hand are also expensive in addition to the fact that they contain residual flatulence- causing oligosaccharides and are difficult to redissolve . In view of the above, there is a need to develop a method for preparing palatable, nutritious tofu snacks that are shelf-stable using less expensive tofu-okara material that has been sufficiently processed to remove the beany flavor and flatulence causing oligosaccharides from the soybean.

SUMMARY OF THE INVENTION

The present invention provides an improved tofu product that includes okara. Okara is also commonly referred to as tofu residue, tofu refuse, tofu draff and soy pulp, and these terms may be used interchangeably throughout the application. Okara is a by-product in tofu manufacture that results after the filtration of soymilk from the soybean slurry to coagulate tofu. The use of okara in the product not only makes the product less expensive, but also enhances the nutritional value of the product because okara has a higher Protein Efficiency Ratio (PER) value than tofu, has higher content of the amino acid cysteine, higher fibre content and is digestible like tofu. This also allows the effective use of a by-product of tofu manufacture, which otherwise would be disposed of as cheap animal feed or in the worst case, discarded as waste.

In one aspect, the present invention provides a tofu-okara material comprising tofu and okara. The term "tofu-okara material" means a starting material containing tofu and predetermined amount of okara that can be used to prepare edible tofu foods such as tofu chips, cookies, muffins and noodles. The tofu is preferably present in an amount from about 5 to about 60% solid by weight of the finished tofu food product. The okara is preferably present in the ratio of about 0.01:1 to about 6.0:1, more preferably from about 0.05:1 to about 3.0:1, of the solid tofu-okara weight in the tofu- okara material .

In one embodiment, a starchy material is added to the tofu-okara material. The starchy material is preferably present in the ratio of about 0.1:1 to about 6.0:1, more preferably from about 0.5:1 to about 4.5:1, of the solid tofu weight in the product.

In a preferred embodiment, the tofu-okara material additionally contains a vegetable, preferably green peas. The vegetable is preferably present in the ratio of about 0.01:1 to about 2.5:1, more preferably from about 0.2:1 to about 1.0:1.0, of the solid tofu weight in the product . The inclusion of a vegetable has been shown to improve the processibility, the taste, texture, reduced oil absorption on frying and nutritional content of the product .

In another aspect, the present invention relates to a method for preparing a tofu-okara material comprising:

(a) preparing an aqueous soybean or soy flour mixture and heating the mixture at a temperature from about 80°C to about 100°C for preferably 15-25 minutes;

(b) adding a coagulant to the aqueous soybean or soy flour mixture; and

(c) separating the solids from the liquids to obtain a tofu-okara material.

The term "soy flour" includes all available soy flours such as full fat, low fat and defatted soy flours. When soybeans are used, they are preferably soaked in water for approximately 6 to 24 hours, most preferably overnight, prior to their use. "Soy bean juice" refers to the soy milk or liquid separated from a heated aqueous mixture of soybean or soy flour. It is assumed to contain no okara.

It is preferable to use soy flour and to coagulate the suspension of soy flour without filtering out the insoluble residue okara so that both okara and tofu will be co-coagulated from the soy bean slurry, preferably at pH 6.7-8.5. This eliminates the soybean soaking, grinding and okara separation steps which are normally required if whole soybean is used. This process simplification also reduces the cost of operation. Okara, like tofu, is free of oligosaccharides after the co- coagulation and filtration steps. Okara is generally present in about 20-35% by weight of soybean or soy flour. Therefore, to prepare a tofu-okara material with a higher okara content, additional okara of desirable amount can be added. To prepare a tofu-okara material with a lower okara content, additional soybean juice from which okara has been filtered can be added or a selected amount of okara can be removed from the aqueous soybean or soy flour mixture.

It is often advantageous in preparing puffed tofu snacks, such as tofu chips, according to the present invention to proceed through a storage- stable, intermediate "half product". By this is meant a shaped gelatinized preformed product which has not yet been subjected to sufficient heat to cause the product to puff. Accordingly, in another aspect, the present invention provides a method of preparing such a half product, comprising the steps of:

(a) preparing an aqueous soybean or soy flour mixture and heating the mixture at a temperature from about 80°C to about 100^CC;

(b) adding a coagulant to the aqueous soybean or soy flour mixture; (c) separating the solids from the liquids to obtain a tofu-okara material;

(d) adding a starchy material to the tofu-okara material ;

(e) adding water to the starchy material and the tofu-okara material in a weight ratio of 3:1 to 30:1 of the tofu-okara material;

(f) gelatinizing; and

(g) drying to form the half product.

It is to be noted that "gelatinization" or "gelatinizing" herein refers to the process of heating a starch-water slurry, causing tangential swelling of the starch.

In a further aspect, the present invention provides a method of preparing a puffed tofu snack comprising:

(a) preparing an aqueous soybean or soy flour mixture and heating the mixture at a temperature from about 80^CC to about 100°C;

(b) adding a coagulant to the aqueous soybean or soy flour mixture;

(c) separating the solids from the liquids to obtain a tofu-okara material;

(d) adding a starchy material to the tofu-okara material ;

(f) gelatinizing the tofu-okara material and starchy material to prepare a tofu-okara dough;

(g) drying the tofu-okara dough to about 20-55% moisture;

(h) machining the tofu-okara dough;

(i) drying the machined product to 2-15% moisture; and (j) frying the dried machined tofu product to obtain a puffed tofu snack. Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples while indicating preferred embodiments of the invention are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in relation to the drawings in which:

Figure 1 is a graph showing the effect of increasing the green pea content of a tofu chip dough (without okara) on the machineability at higher moisture % of the tofu chip dough.

Figure 2 is a graph showing the effect of increasing the green pea content of the tofu chip dough (with okara) on the improved machineability at higher moisture % of the chip dough.

Figure 3 is the graph showing the reduction in the oil absorption of a tofu chip after frying by increasing the green pea content in the tofu chip dough described in Figure 2.

DETAILED DESCRIPTION OF THE INVENTION

As hereinbefore mentioned, the present invention relates to an improved tofu-okara material, and a method for its manufacture. The improved tofu-okara material contains okara which is a byproduct of tofu manufacture. The invention also includes edible products prepared with the tofu-okara material.

Okara, despite its nutritional advantages such as high protein and fibre content, has not widely been utilized in food products partly due to its rough mouth feel and non smoothness in texture. In preparing dry tofu powder containing okara, Terada et al . (U.S. Patent No. 4,427,710) micronized curded soy milk mixture without separating okara and spray drying. This process did not include the filtration step to remove the oligosaccharides although it overcame the problem of making the okara more smooth by micronizing. Okara was used in rice cake production (U.S. 4,505,942 to Ito et al . ) and in the recipe for making healthy cakes using baking powder, eggs and other ingredients (U.S. 5,128,165 to Wakana et al . ) .

The present inventor has developed a method for using okara without having to micronize or pulverize the okara mixture to colloidal particle size. Instead, the inventor has found out that by coagulating the okara-soy protein in the pH range of 6.7-8.5, a smoother and more palatable tofu-okara material can be achieved and the material can be filtered without difficulty. Micronization causes a problem in filtering off the oligosaccharide-containing liquid phase ("soy whey").

Thus, the simplified coagulation of tofu together with okara and the utilization of additional okara in the product reduces the cost of production and enhances the nutritional quality of the tofu product .

The conventional production of tofu involves extracting soy milk from soaked soybean with ten times its weight of water and coagulating with calcium sulfate, glucono delta lactone or nigari . Tofu is obtained as a soft fragile curd containing about 85% water after compression to remove the whey which contains flatulence- causing oligosaccharides. After the soy milk is removed, an insoluble tofu residue known as okara or tofu draff results and is usually discarded as waste or sold cheaply or given free of charge to people who use it as animal feed. This inefficient utilization of tofu by-product is not only a waste of the nutritive material but also causes environmental concern, because for every 50 kg of tofu, about 20 kg of okara will be produced. In fact okara has 17% by weight of the original soybean protein. It contains higher quality protein (as measured by PER, Protein Efficiency Ratio) than any other fraction in the tofu making process, largely due to its high content of cysteine :

Okara also has higher fibre content:

Okara has been under-used probably because of its high biological instability due to high moisture retentiveness and its texture as well as the unpleasantness to the palate. Because of its high fibre content, its presence will affect the cohesiveness and the texture as well as the palatability of the tofu. As the tofu-okara material for tofu food products of this invention would not need to be as tender as the wet tofu, there should not be a problem in including okara in the tofu-okara material to make the use of tofu less expensive . Not only can okara be incorporated in the preparation of the food products of this invention, it is also found that the tofu-okara materials of this invention can be processed without the step of okara removal, thus simplifying and making the process more cost effective. Moreover, by carrying out the coagulation at pH 6.7 to pH 8.5, the tofu-okara material with okara naturally present or with okara added externally is found to be softer and more tender than that coagulated without pH adjustment.

A variety of soybean-derived raw materials can be used in the present invention, such as whole soybean, full fat soy flour, low or defatted soy flour and soy protein concentrate. The finished tofu products prepared from this tofu-okara material are found to be as palatable as those made from tofu alone. Thus the combination of okara in tofu and the simplification of tofu coagulation without the okara removal step make the process cost effective and at the same time solve the problem of waste utilization.

In one aspect, the present invention provides a tofu-okara material comprising tofu and okara. The invention also provides a method of preparing a tofu- okara material comprising:

(a) preparing an aqueous soybean or soy flour mixture and heating the mixture at a temperature from about 80°C to about 100°C; (b) adding a coagulant to the aqueous soybean or soy flour mixture at a pH from about 6.7 to about 8.5; and

(c) separating the solids from the liquids to obtain a tofu-okara material.

The aqueous soybean or soy flour mixture should be heated in step (a) for a period of time sufficient to remove the flatus-causing oligosaccharides in the soybean or soy flour. Preferably, the aqueous material is heated for 15-25 minutes. The coagulant may be any suitable coagulant including calcium sulfate, glucona delta lactone or nigari, preferably calcium sulfate. The coagulant is generally added in an amount from about 1 to about 6% by weight of the soybean. The material is preferably separated in step (c) using filtration or centrifugation. The separated tofu-okara material can further be dried, pulverized or spray dried to give shef- stable powders.

Soy flour and whole soybeans generally contain 20- 35% okara by weight. Additional okara may be added to the tofu-okara material if a product with higher okara content is desired. On the other hand, if a product with lower okara content is desired, some of the okara can be removed, or additional soybean juice that has had the okara removed may be added.

For ready-to-use tofu products to be shelf stable without using preservatives, their moisture content should be less than 12%. Ready-to-eat, shelf-stable tofu snacks are preferably in the puffed dry form. Pure tofu by itself is very hard when dried. Moreover, in spite of tofu being bland in taste in the wet form, some beany taste develops when the tofu is dehydrated by heat. As tofu is fairly expensive compared to other snack food raw materials such as potato, corn and wheat, it is also the object of this invention to make tofu snacks more affordable by the cost-effective utilization of the nutritious tofu by-product okara or tofu draff, which would otherwise be disposed of as animal feed or as industrial waste.

As mentioned above, tofu has to be in a puffed, low moisture form to become a palatable ready-to-eat snack food. Starchy materials and tofu-okara materials may be blended and gelatinized to form a tofu-okara dough. In the context of this description and the present invention, "tofu-okara dough" refers to gelatinized or non-gelatinized tofu/okara/starch mixtures with various degrees of water conten . Those mixtures having lower water content have a physical form like that of a conventional dough, while those with higher water content will be more like a batter or even a slurry.

This tofu-okara dough has a wide range of applications. The dough may be dried and fried to cause puffing for example. Consequently, the present invention also provides a method of making a tofu-okara dough comprising:

(a) preparing an aqueous soybean or soy flour mixture and heating the mixture at a temperature from about 80°C to about 100°C;

(b) adding a coagulant to the aqueous soybean or soy flour mixture at a pH from about 6.7 to about 8.5;

(c) separating the solids from the liquid to obtain a tofu-okara material;

(d) adding a starchy material to the tofu-okara material ;

(e) adding water to the starchy material and the tofu-okara material in a weight ratio of 3:1 to 30:1 of the tofu-okara material; and

(f) gelatinizing the tofu-okara material and starchy material to prepare a tofu-okara dough. The starchy material can be selected from a wide range of starchy materials including rice, glutinous rice, tapioca, corn, potato, wheat, barley, rye, oat, sweet potato and arrowroot .

Rice powder, especially waxy rice powder, is preferred as it results in better puffing. It also provides better nutritional enhancement because rice protein contains a relatively higher methionine level . Tofu protein is relatively deficient in methionine.

Pre-gelatinized starchy materials can also be used in which case, the gelatinization step (f) can be omitted. The commercial pre-gelatinized starches such as Bana-Snak™ from National Starch and X-Pand-R™ from A.E Staley can also be used. Gelatinized starch can also be used in combination with the un-gelatinized starchy materials. The starchy material can be from a single source or can be a combination of the above-mentioned starchy materials . Preferably the starchy material is a mixture of the flours of glutinous rice, tapioca, rice, corn, potato in the weight ratio of 16:7:7:5:8 to 8:3:3:0:0, preferably to 12:5:5:3:3.

Pregelatinization of the starchy material with or without other components in the desired amount of water is carried out by steaming, cooking, pressure-cooking, low pressure heat extrusion, oven heating, microwave heating or infra-red heating. The dough is partially dried to a moisture content from about 20 to about 55% and then the dough is formed or sheeted. The gelatinized dough is usually quite sticky at room temperature and can be coated at the desired thickness on to non-stick surfaces and dried to the half product or the pre-formed product. The gelatinized dough can also be partially dried to the desired moisture level 20-50% (preferably 25-45% moisture content) whereby the dough can be machined that is sheeted between rollers to any desired thickness . The gelatinized dough can also be frozen to give a frozen form of any shape which can be sliced to give chips of desired thickness. The starchy material can also be blended with the other components of the product to form a batter which can be coated to desired thicknesses on metal surfaces (preferably Teflon™ coated) and heat-gelatinized briefly at higher temperature and then dried by hot air current at lower temperature to provide a formed gelatinized sheet (half product) in a continuous manner. In this case the gelatinization, forming and drying steps are carried out at the same time.

After drying to a moisture content of less than 15%, preferably less than 10%, a shelf stable tofu-okara dough or preformed product is obtained.

The preformed tofu half product can be fried to prepare a puffed tofu snack such as tofu chips. Consequently, the present invention also provides a method of preparing a tofu snack comprising:

(c) separating the solids from the liquids to obtain a tofu-okara material;

(d) adding a starchy material to the tofu-okara material ;

(f) gelatinizing the tofu-okara material and starchy material to prepare a tofu-okara dough; (g) drying the tofu-okara dough to about 20-55% moisture; (h) machining the tofu-okara dough; (i) drying the machined product to 2-18% moisture; and (j) frying the dried machined tofu product to obtain a puffed tofu snack.

The term "machining" includes shaping, sheeting, slicing, stamping, cutting or otherwise forming the tofu- okara dough into a desired shape.

In order to prepare puffed tofu chips, the dried preformed tofu-okara dough is deep fried in vegetable oils, preferably soya oil, canola oil, corn oil or peanut oil, at 170-200°C for 2-25 seconds. Palm oil, coconut oil can also be used. The extra oil coated on the puffed chips can be drained off or partially removed by centrifuging. Seasonings from 0 to 20% by weight of the product can be incorporated in the dough or topically coated on to the products after frying.

The expanded tofu product with or without okara and containing starchy material acquires a slight beany taste as the tofu solid content of the product increases and also on frying to puff. It has a powdery texture and slight starchy taste . Any beany or starchy taste is not noticed when seasoning ingredients such as garlic, onion, barbecue flavors are incorporated.

To improve its texture as well as its taste, a vegetable (such as green pea, carrot, spinach, taro, potato and sweet potato) can be incorporated into the tofu-okara material of this invention. A preferred vegetable is green pea. Preferably, raw green pea is used as it does not contain any flatulence-causing oligosaccharides. The addition of green peas to the tofu-okara material and starchy material unexpectedly improved the machineability of the tofu-okara dough. The machinable moisture level for sheeting the dough was increased by approximately 4-5% which reduces the drying time to ease the machining step as shown in Figures 1 and 2. Also unexpectedly, tofu chips containing green peas had a significant improvement in taste and reduction in oil absorption over chips without green peas . The puffed tofu snack containing green peas has very tender texture and very pleasant nut or egg-like sweet flavor. The inclusion of green peas not only increases the nutritive value but also imparts a very appealing greenish color to the product. The oil absorption of the product containing green peas is found to be reduced as shown in Figure 3. Green pea can be incorporated in the amount from 0.01:1 to 2.5:1, preferably 0.2:1 to 1:1, of the tofu solid weight. As the amount exceeds the ratio limit, ratio, the puffing property of the product decreases and the product becomes harder. Taro is also found to impart pleasant taro flavor to the product. However, it requires much higher taro content in the product to acquire significant pleasant taro flavor. Carrot imparts reddish color and carrot flavor to the product . The sweet potato imparts its pleasant sweet flavor to product but the product tends to soften during frying. Potato (boiled) gives a flavorful product. However, the oil absorption of the product increases. Spinach in small amounts imparts a greenish color and slight green leaf flavor to the product. However, at higher levels of spinach, slight bitterness develops. It is found that green pea in admixture with carrot, spinach and potato can also be effective as above.

The tofu-okara material of this invention has a wide variety of uses . In combination with starchy material and green pea, it can be fried and puffed to prepare tofu chips as well as crackers and croutons. It can be incorporated into baked goods such as muffins, cookies, cakes, pretzels and breads. It can also be incorporated into pasta products such as noodles and wrappers. It can also be processed to be used as a meat replacement material for the preparation of patties or sausages, for example . In general it can serve as a valuable nutritious food replacement which is free of cholesterol for the preparation of various food products . Because of the higher protein content, the products are more tasty than conventional products that do not contain tofu.

Tofu snacks containing green pea and okara prepared as described above, have good taste and mouth feel, texture, lower oil content but above all more nutritional value than conventional potato chips . The chips are free of cholesterol and added hydrogenated fat and they contain healthy tofu components made available conveniently in the form of shelf stable snack foods. Moreover, the unique simplified process of preparing the tofu-okara material containing okara, not only makes the tofu food product processing more cost effective but also enhances the nutritive value of the product and helps utilize valuable tofu byproduct.

The following non-limiting examples are illustrative of the present invention:

PREPARATION OF A TOFU-OKARA MATERIAL

EXAMPLE 1

(A) 300 g of soy beans (Grain Processing Enterprises) were soaked with 1200 g water at room temperature overnight. After draining off water, the soaked beans were pulverized with 3 kg water. The mixture was heated at 80-100° C for 15-20 minutes and filtered through a cloth bag to give 493 g okara (tofu draff) which was dried with warm air to 82.5 g yellowish white powder after pulverization. It had a 94.32% solid content. The filtrate (bean juice) was heated to 80- 100°C and while stirring gently, a freshly prepared suspension of 7.5 g calcium sulfate (Terra Alba, Pharmaceutical Grade) in 150 g water was added. Coagulation occurred in 2 minutes. The curd was pressed in the cloth bag under a load of 3.2 kg for 2 hours to give 501 g hard tofu having a solid content of 28.85%.

(B) 300 g of soy beans (Grain Processing Enterprises) were soaked with 1200 g water at room temp overnight. After draining off water, the soaked beans were pulverized with 3 kg of water and the mixture was heated at 80-100°C for 15 minutes. Then it was treated with sodium bicarbonate to a pH of 7.2 and the mixture was filtered through a cloth bag to give 516.3 g okara having total solid of 77.1 g. This okara was more soft and tender to the palate than that in Example 1 (A) . The filtrate bean juice was reheated to 80- 100°C and a freshly prepared suspension of 10.5 g calcium sulfate (Terra Alba, Pharmaceutical Grade) in 150 g of water was added while stirring gently. Curding occurred in 3 minutes . The curd was pressed in the cloth bag under a load of 3.2 kg for 2 hrs to give 700 g of hard tofu (19.43% solid) . This tofu was found to be more spongy and tender than that in Example 1 (A) .

(C) Same as Example 1(A) except that the step of filtering okara was omitted. Calcium sulfate suspension was added to the bean juice with okara in it. 919.2 g of tofu-okara material (solid content 24.58%) was obtained. It was less cohesive and not as palatable as the tofu of Example 1 (A) .

(D) Same as Example 1 (B) except that okara was not removed prior to coagulation of the mixture at pH 7.24.

A less cohesive tofu-okara material 1078 g (solid content 19.88%) was obtained. It was found to be more soft and tender than the tofu curded with okara in Example 1 C . EXAMPLE 2

(A) 300 g of full fat soy flour (Grain Processing Enterprises) was dispersed in 2070 g water and heated at 80-100°C for 20 min and while stirring gently, a freshly prepared suspension of 7.5 g calcium sulfate (Terra Alba, Pharmaceutical Grade) in 150 g water was added. Curding occurred in 7 min. A tofu-okara material of 1031 g (21.32% solid content) was obtained after straining through a cloth bag under a load of 3.2 kg for 2 hours .

(B) Same as 2 (A) except that the pH of the mixture was adjusted with sodium bicarbonate to 7.04 prior to the addition of the suspension of 10.5 g of calcium sulfate in water. A tofu-okara material of 772 g (25.41% solid content) was obtained. It tasted more tender and was softer than that in Example 2 (A) .

EXAMPLE 3

(A) 300 g of low fat soy flour (Grain Processing Enterprises) was dispersed in 2070 g water and heated at 80-100°C for 20 min. Then a freshly prepared suspension of 7.5 g of calcium sulfate (Terra Alba, Pharmaceutical Grade) in 150 g water was added while stirring the mixture gently. The mixture thickened in 10 min. After stirring gently for 10 more min, it was pressed in a cloth bag under a load of 3.2 kg for 3 hours. A tofu- okara material of 1048 g (21.94% solid content) was obtained .

(B) Same as Example 3 (A) except that prior to the addition of the suspension of 11.5 g calcium sulfate in 150 g water, the pH of the mixture was adjusted to 6.92 with sodium bicarbonate. A tofu-okara material of 975 g

(22.41% solid content) was obtained. It tasted softer and more tender than that in Example 3 (A) . (C) Same as Example 3 (B) except that 50 g of okara powder from Example 1 (A) was added to the mixture at pH 7 prior to calcium sulfate addition. A tofu-okara material with extra okara content was obtained weighing 1246.4 g (22.96% solid content). It tasted more tender than okara in Example 1(A) and the tofu-okara material in Example 3 (A) .

PREPARATION OF A TOFU PRODUCT EXAMPLE 4

(A) A tofu-okara dough containing 450 parts of commercial tofu (Heng Lee Food Products Company Limited) , 120 parts of glutinous rice flour, 50 parts tapioca flour, 50 parts rice flour, 30 parts corn flour, 30 parts of potato flour, 18 parts of onion powder, 10 parts of garlic powder, 18 parts of sugar and 8 parts of salt was prepared with different amounts of added grean peas.

The material was steam-gelatinized and partially dried by warm air current at 30-60°C to the optimum dough moisture content for machineability. Figure 1 shows that by increasing the green pea content of the tofu-okara dough, the machineability of the dough at high moisture content is improved.

(B) A tofu-okara dough containing 150 parts of tofu-okara material coagulated from low fat soy flour without okara separation (21.82% solid), 81.7 parts of the starchy material (containing the flours of glutinous rice, tapioca, rice, corn and potato in the ratio of 120:50:50:30:30 by weight) and 16 parts of seasoning (onion powder, garlic powder, sugar and salt in the ratio of 18:10:18:8 by weight) and 85-100 parts of water. The dough was steam-gelatinized and partially dehydrated by a warm air current at 30-60°C to the optimum moisture content for machineability. Figure 2 shows that by increasing the green peas content of the tofu-okara starting material (containing okara) , the machineability of the dough at high moisture content is improved.

(C) Chips were prepared by forming and dehydrating the product of Example 4(B) and deep frying the dried chips (half products) from Example 4(B) in soya oil at 170°-200°C for 4-12 seconds. Figure 3 shows that by increasing the green pea content in the tofu-okara material, the amount of oil absorbed by the chips is reduced .

PREPARATION OF TOFU CHIPS EXAMPLE 5

(A) 450 g of commercial tofu (Heng Lee Food Products Co. Ltd, water content 87.11%) was pulverized in a blender and blended with a starchy powder containing 120 g of glutinous rice flour, 50 g of rice flour, 50 g of tapioca flour, 30 g of corn flour and 30 g of potato flour and a flavoring mixture containing 18 g onion powder, 10 g garlic powder, 18 g sugar and 8 g salt. The batter was then steamed for 30 min. The steamed dough was cooled to room temperature and spread in a layer to about 16" x 12" area between 2 plastic sheets. After peeling off the top plastic film it was then partially dried by hot air current to a moisture content of 32.88%, after which it could be sheeted in the pasta machine (Grazia, using slit #6 or 20 mil gap) . The sheets were roll -imprinted with a circular roller cutter to rectangles of the size 1.5 cm x 1 cm and hot air dried. The preformed chips were then deep fried in soybean oil at 180-200°C to give puffed chips with a fat absorption of 13.86%.

(B) Same as Example 5 (A) except that 120 g of frozen greeh peas (Green Giant) was added to tofu in the blender for pulverization. The partially dried dough was found to be machinable in the pasta machine at a moisture level of 37.48%. The puffed chips, after deep frying, were found to absorb 7.9% of oil. These chips were found to be more palatable and tender than those in Example 5(A) .

EXAMPLE 6

(A) A pregelatinized starchy dough was prepared by steaming a batter of 61.3 g of glutinous rice flour, 26 g of rice flour, 26 g of tapioca flour, 15.3 g of corn flour and 15.3 g of potato flour for 30 min. The sticky dough was then blended with a puree of 230 g of tofu (Heng Lee Food Products Co Ltd) and 61.3 g of frozen green peas and then mixed with a mixture of the flavoring ingredients containing 9.2 g onion powder, 5.1 g of garlic powder, 9.2 g of sugar and 4.1 g of salt. 163 g of water was added to form a uniform paste. It was spread onto a polyethylene surface and hot air (30-55°C) dried to a moisture content of 33.44%. Then it was sheeted in a pasta machine (Grazia, thickness #6 or 20 mil gap) and cut to form 1.5 cm x 1 cm size chips. They were deep fried in canola oil to give puffed light greenish chips having an oil absorption of 13.09%. It had a pleasant sweet nutty and egg-like flavor and tender texture .

(B) 106 g of tofu-okara material curded at pH 6.92 without okara removal from Example 3 (B) was blended with a puree of 42 g frozen green peas in 38 g water and 24 g pre-gelatinized starch Expand R™ (A.E Staley) in the Kitchen-Aid Mixer. The dough was frozen in a tubular plastic bag overnight in the freezer. The frozen greenish dough was then sliced to give chips of approximate 1-2 mm thickness and hot air dried (30-55°C) . After deep frying in soya oil, a puffed chips with an oil absorption of 16.59% was obtained. It had a tender and pleasant, slightly beany flavor. EXAMPLE 7

(A) A puree containing 450 g of tofu (Heng Lee Foods Products Co. Ltd) , 100 g of green peas, 10 g of carrot and 25 g of spinach was blended with a starchy composition containing 120 g of glutinous flour, 50 g of rice flour, 50 g of tapioca flour, 30 g of corn flour, potato flour, 18 g of onion powder, 10 g of garlic powder, 18 g of sugar and 8 g of salt, to form a greenish batter. 120 g of this batter was cast onto a cookie tray by scraping with an aluminum plate along plastic cord spacers (thickness 2.40 mm) . This coating was then heated in a kitchen electrical oven at 350°F for 5 min. The gelatinized coating was then hot air dried at 35-55°C to give a greenish sheet which was deep fried in canola oil. Puffed greenish chips with an oil absorption of 17.17% resulted. The chips were crisp, tender, had a uniform texture and were tasty.

(B) 100 g of the batter from Example 7 (A) was cast in the same way on a polyethylene surface (circular shape) and steamed 5 min in a kitchen steamer and then hot air dried to give a smooth, tough, greenish sheet. On deep frying, a puffed greenish chip with an oil absorption of 17.92% was obtained. It was crisp, tender and tasted good.

EXAMPLE 8

(A) 200 g of the thawed frozen tofu-okara material containing extra okara from Example 3(C) was blended with 100 g of starchy mixture (140 g of glutinous rice flour: 55 g of rice flour, 55 g of tapioca flour: 15 g of corn flour: 15 g of potato flour: 18 g of onion powder: 10 g of garlic powder: 18 g of sugar: 8 g of salt) in 106.7 g of water to form a dough which was steamed for 30 min. After cooling to room temp, the dough was flattened between two polyethylene films. The top film was peeled off and the wet dough sheet was hot air dried to a moisture content of 32.89% after which the dough could be sheeted and cut to the desired sizes in a pasta machine (Grazia, #7 slit, 12 mil gap) . Before frying, it was further dried to a moisture content of less than 15%. After deep frying in soya oil, a reddish white chip with a moderate crispness and an oil absorption of 11.41% was obtained. It had a noticeable gritty mouth feel and a mild taste.

(B) Same as in Example 8 (A) except that 72 g of frozen green peas pureed in the water portion were added into the formulation. The dough was found to be machineable at a moisture content of 40.39%. After deep frying in soya oil, a pale greenish chip with an oil absorption of 11.43% was obtained. It had a pleasant, sweet nutty flavor and did not have significant gritty mouth feel .

PREPARATION OF TOFU COOKIES

EXAMPLE 9

(A) To a blend of 158 g of sifted all purpose flour, 158 g of granulated sugar, 2.5 g of sodium bicarbonate and 1 g of salt, were added 70 g vegetable shortening (Crisco, Golden) , 50 g of low fat tofu curded with okara in it as in Example 3 (B) , egg white separated from one large egg, 0.5 teaspoon of vanilla and 22 g water. The mixture was blended in a Kitchen-Aid Mixer gently at slow speed to form a batter which was filled into a Mirro Cookie Press to make bar cookies. The baking was carried out in an electrical oven at 320°F for 10 min. Tasty, tender cookies of yellowish color were obtained.

PREPARATION OF MUFFINS

EXAMPLE 10

(A) 1.4 g of lecithin were dispersed in 140 g of warm soya oil and cooled to room temperature. 175 g of granulated sugar and 175 g brown sugar were then added and stirred at high speed in a Kitchen-Aid Mixer for about 1 min. A blend of the dry ingredients consisting of 320 g all purpose flour, 7 g of baking powder

(Nabisco, ingred: starch, mono calcium phosphate and sodium bicarbonate) and 4 g of baking soda (USP Grade) , 3.5 g of salt, 12 g skim milk powder and 1 g of cinnamon powder was then added to the mixture. 200 g of carrot and half of the drained pineapple chunks in a 19 oz . can

(Dole Foods of Can Ltd.) were blended in a food processor and then added to the mixture. 1 teaspoon of artificial vanilla flavor and 250 g of tofu-okara material curded from low fat soy flour at pH 7.16 along with the externally added okara from Example 1 (A) as described in Example 3 (C) were added and blended at slow speed in a Kitchen-Aid mixer. The batter was then baked in a kitchen electrical oven at 360°F for 30 min to give 14 muffins. The muffins had good taste and did not have any gritty mouth feel or adhesion to the palate.

PREPARATION OF PASTA

EXAMPLE 11

(A) 250 g of full fat soy flour tofu-okara material curded without okara separation at pH 7.04 as in Example 2(B), 426 g of all purpose flour, 1 tablespoonful of soya oil, 2 teaspoonful of salt, 46 g water and one whole extra large egg were blended in a Kitchen-Aid mixer at medium speed to a dough which could be sheeted and stripped on the pasta machine (Grazia, #6 slit, 20 mil gap) to give noodles of good palatability .

PREPARATION OF TOFU PATTIES

EXAMPLE 12

(A) 320 g of raw potato was boiled and mashed and 202 g of low fat tofu-okara material curded at pH 6.92 from Example 3(B) were added. Then 25 g rice flour, 20 g bread crumb, 22.5 g soya oil, 3 g onion powder, 2.5 g salt, 20 g soy sauce, 1.5 g black pepper and one whole egg were added and blended at medium speed in a Kitchen- Aid mixer to give a uniform dough. The dough was divided, pressed and fried to give tasty tofu-potato patties .

While the present invention has been described with reference to what are presently considered to be the preferred examples, it is to be understood that the invention is not limited to the disclosed examples. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims .

All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

Claims

CLAIMS :

1. A tofu-okara material comprising tofu and okara.

2. A tofu-okara material according to claim 1, wherein said okara is present in the ratio of 0.01:1 to 6.0:1 of the tofu by weight .

3. A tofu-okara material according to claim 1 or claim 2, having a moisture content of 0.1 to 15%.

4. A tofu-okara material according to claim 1 or claim 2, further comprising a vegetable in the ratio of 0.01:1 to 2.5:1 of the tofu material by weight.

5. A tofu-okara material according to claim 4, wherein said vegetable is green pea.

6. A tofu-okara dough comprising a tofu-okara material according to claim 1 or claim 2 and a starchy material .

7. A tofu-okara dough according to claim 6, wherein said starchy material is present in the ratio of about 0.1:1 to about 0.8:1 by dry weight of the tofu-okara dough.

8. A tofu-okara dough according to claim 6, further comprising a vegetable in the ratio of 0.2:1 to 1:1 by weight of the tofu-okara solids.

9. A tofu-okara dough according to claim 8, wherein said vegetable is green pea.

10. A tofu-okara dough according to claim 6, wherein said starchy material is selected from the group consisting of rice, glutinous rice, corn, potato, tapioca, oat, wheat, barley and arrowroot or mixtures thereof .

11. A tofu-okara dough according to claim 6, wherein said starchy material is pre-gelatinized.

12. Use of a tofu-okara dough according to claim 7 to prepare an edible puffed tofu product selected from the group consisting of chips, crackers, croutons, cereals and extruded puffed snacks .

13. Use of a tofu-okara material according to claim 1 or claim 2 to prepare an edible tofu product selected from the group consisting of muffins, cookies, cakes, donuts, bagels, breads, pretzels, noodles, sauces, spreads, non- dairy creamers, breaded coatings, extruded puffed snacks, cereals, puddings, soups, meat and milk substitute products, drinks and drink mixes.

14. A method of preparing a tofu-okara material comprising:

(a) preparing an aqueous soybean or soy flour mixture and heating the mixture at a temperature from about 80┬░C to about 100┬░C;

(b) adding a coagulant to the aqueous soybean or soy flour mixture,- and

(c) separating the solids from the mixture to obtain a tofu-okara material.

15. A method according to claim 14, further comprising the step of drying the separated tofu-okara material.

16. A method according to claim 14 or claim 15, wherein the aqueous mixture in step (a) is heated for about 15 to 25 minutes.

17. A method according to claim 14 or claim 15, wherein the aqueous soybean or soy flour mixture is adjusted to a pH of 3 to 9.

18. A method according to claim 14 or claim 15, wherein the aqueous soybean or soy flour mixture is adjusted to pH from 6.7 to 8.5.

19. A method according to claim 14 or claim 15, wherein said coagulant is selected from the group consisting of calcium sulfate, glucono-delta-lactone, nigari or mixtures thereof.

20. A method according to claim 14 or claim 15, wherein said coagulant is calcium sulfate.

21. A method according to claim 14 or claim 15, wherein said coagulant is present in an amount from about 1% to about 6% by weight of soybean or soy flour.

22. A method according to claim 14 or claim 15, further comprising adding additional okara in step (a) .

23. A method according to claim 14 or claim 15, further comprising adding soy bean juice in step (a) .

24. A method according to claim 14 or claim 15, further comprising filtering off a predetermined amount of okara from the heated aqueous soybean or soy flour mixture in step (a) .

25. A method of preparing a tofu-okara half product comprising:

(a) preparing a tofu-okara material according to the method of claim 14 ;

(b) adding a starchy material to the tofu-okara material ; (c) adding water to the starchy material and tofu- okara material in a weight ratio of 3:1 to 30:1 of the tofu-okara material;

(d) gelatinizing the product of step (c) ;

(e) forming the product of step (d) into a desired shape ,- and

(f) drying to about 2 to 18% to form a tofu-okara half product.

26. A method according to claim 25, in which the aqueous mixture of the starchy material and tofu-okara material in step (c) is cast onto a release surface.

27. A method according to claim 25, in which gelatinization in step (d) comprises thermal extrusion at reduced pressure.

28. A method according to claim 25, in which forming in step (e) comprises freezing and slicing the frozen gelatinized tofu-okara dough.

29. A method according to claim 25, in which the gelatinized material in step (d) is partially dried to moisture content of 20 to 55% prior to the step of forming.

30. A method of preparing a puffed tofu-okara snack comprising:

(a) preparing half product according to claim 25;

(b) frying said half product in vegetable oil at about 170┬░C to about 220┬░C.

31. A method according to claim 25, further comprising adding a vegetable material to the tofu-okara material in step (a) or to the tofu-okara dough in step (d) after gelatinization .

32. A method according to claim 31, wherein said vegetable material is selected from the group consisting of carrot, spinach, green pea, snow pea, edible seaweed or mixtures thereof .

33. A method according to claim 31, wherein said vegetable material is fresh or frozen green peas.

34. A method according to claim 31 wherein said vegetable material is added in a finely divided form.

35. A method according to claim 25, further comprising adding a fiber material to the tofu-okara material in an amount from about 0.1 to about 10% by weight of the puffed product.

36. A method according to claim 35, wherein said fiber material is selected from wheat bran, corn bran or oat bran.

37. A method according to claim 25, further comprising adding a protein enhancing material to a tofu-okara material in an amount from about 0.1 to about 20% by weight of the puffed product.

38. A method according to claim 37, wherein said protein enhancing material is selected from wheat gluten, wheat germ, corn germ, caseinates, whey solids, soy protein isolate and soy protein concentrate.

39. A method according to claim 30, further comprising adding a seasoning internally or externally in an amount from about 0.1 to about 20% by weight of the puffed product .