Fermented tofu

Tofu is inexpensive, nutritious, versatile, and can be served as a meat or cheese substitute. Yet, compared with meat or cheese, tofu contains fewer calories because of its higher protein/fat ratio. Tofu is also cholesterol-free, lactose-free, and lower in saturated fat. Because of its bland taste and porous texture, tofu can be prepared with virtually any other food. It is frequently served in soups or separate stir-fried dishes with meat and/or vegetables. Tofu can also be further processed into secondary products such as deep-fried tofu, savory tofu, and fermented tofu (sufu). 

Tofu is very versatile as a food it can be served fresh or cooked with vegetables and/or meat in thousands of different dishes and soups. It can also be further processed into various secondary tofu products, including deep-fried tofu, savory tofu (Fig. 14.2), grilled tofu, frozen tofu, dried-frozen tofu, fermented tofu, etcetera. In most cases, these processed tofu products have different characteristics, end uses, and commercial identities from the original plain tofu discussed previously. 

Soybean-Based Cheese. In tofu cheese manufacture, the soybeans are cooked to give soy milk, then formed into a curd using calcium sulfate, and pressed to give tofu. The tofu is inoculated y ctinomucor elegans fermented, salted, and aged to form sufu (soft cheese) (17). This product is widely used ia the Orient and is gaining acceptance ia the United States. 

It is a highly hydrated gelatinous product with a bland taste. The texture characteristics of the curds vary from soft to firm, depending on the processing conditions. Thus, tofu can be easily incorporated with other foodstuffs and used in nearly every culinary context from salad to dessert and from breakfast foods to dinner entrees. Tempeh is made by fermenting cooked soybeans with a mold, Rhizopus oligosporus. 

Based on processing technology, the soybean foods that have been consumed in East Asia may be classified into two general types non-fermented and fermented (2-8) as shown in Table I. Names of these foods and the details of preparing and serving such foods may vary from country to country. Among them, soybean curd (tofu) and soy sauce have been the most widely consumed in the Orient. 

Before 1990 the composition of isoflavones in soy foods was thought to be largely determined by whether the food had been fermented. Fermented foods (e.g., miso and tempeh) contain the unconjugated isoflavones agycones, while non-fermented food (e.g., tofu, soy flower, and soy milk) contain the conjugated glucoside. Subsequent experiments have demonstrated that fermentation of soy decreased the isoflavone content of the food product, but increased the urinary isoflavonoid recovery, suggesting that fermentation increases availability of isoflavones in soy (Slavin et al., 1998). 

Enzyme Digestibility and Yield of Soy Sauce. There are various kinds of traditional soybean protein foods in the Orient. In addition to soy milk, tofu, kori-tofu and yuba described so far, there are fermented soy sauce, miso, natto, sufu and temphe. Soy sauce was introduced into Japan during the 7th century by Buddhist priests and has been developed into the present-day Japanese type of soy sauce, characterized by an excellent aroma and flavor, through centuries of artistry. Recently, fermented soy sauce has become popular with Western people. 

Tofu wastewater, containing 5.0-8.0 gT1 soluble starch and 0.3-0.4 gT1 sugars, (Table 1) generated 0.9 1 H2/l wastewater, along with some organic acid, during 26 h of fermentation (Fig. 3). Due to the higher concentration of soluble starch in Tofu wastewater compared to the Makkoli wastewater, it took an additional 6-8 h to reach the maximum H2 production... 

Figure 3 Anaerobic fermentation patterns from Tofu wastewater by C. butyricum NCI B 9576. O pH hydrogen production A starch V reducing sugar...

Such traditional soybean foods as tofu (soybean curd) and tempeh have little flatus activity (42). In the case of tofu, oligosaccharides are presumably eliminated during the course of its preparation, and, in the case of tempeh, enzymes produced by the mold (Rhizopus) during fermentation probably hydrolyze the oligosaccharides. As might be expected because of their low carbohydrate content (< 1%), soy protein isolates are devoid of flatus activity (43). It follows that textured meat analogs made from isolated soy protein are most likely free of flatus activity. 

USE In the production of soybean oil. As food and feed -stuff. Debittered soybean flour contains practically no starch and is widely used in dietetic foods. Soybean meal obtained after expressing the oil is a preferred source of protein for feedstuffs. Other products are soybean lecithin, genistin, monosodium glutamate, soybean milk, soy sauce tofu, a soybean curd ntiso, a fermented mixture with barley or rice nutio, which is soybean cheese. Soybean proteins are used also in the adhesive and plastics industries. 

In general, traditional soyfoods, also known as Oriental soyfoods, are classified as non-fermented and fermented. Non-fermented soyfoods include soymilk, tofu, soy sprouts, yuba (soymilk film), okara (soy pulp), vegetable soybeans, soynuts and toasted soy flour, whereas fermented soyfoods include soy sauce, miso (fermented soy... 

This reaction, called alcoholic fermentation, is important in producing some foods, as shown in Figure 23.28. Alcoholic fermentation is needed to make bread dough rise, form tofu from soybeans, and produce the ethanol in alcoholic beverages. Another use of the ethanol is as an additive to gasoline, as shown in Figure 23.29. 

Soy-based products that are not fermented (soy milk, tofu, textured soy protein, hydrolyzed vegetable protein, soy protein concentrate, meat analogs, unfermented soy sauce )... 

Sufu could be described as fungal fermented and matured tofu. Sufu is a popular breakfast ingredient in China. It gives flavour and taste to the bland soya milk, vegetables and fried dough of breakfast. The process could be divided in stages preparing... 

Food, Beverages, Food Additives, and Supplements. Industrial fermentation plays a major role in the production of food. Food products traditionally made by fermentation include dairy products (cheeses, sour cream, yogurt, and kefir) food additives and supplements (flavors, proteins, vitamins, and carotenoids) alcoholic beverages (beer, wines, and distilled spirits) plant products (bread, coffee, soy sauce, tofu, sauerkraut) and fermented meat and fish (pepperoni and salami). 

Isoflavones (2) have usually been found as small amount phytochemicals from the legumes, grains and vegetables, and their processed foods such as traditional tofu and Indonesian tempeh which is a traditional soy product originally from Indonesia [Indonesian tempeh is made by a natural culturing and controlled fermentation process that binds soybeans into a cake form of similar to a very firm vegetarian burger patty], miso, natto, soya milk, bean curds and bean sprouts. 

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