**3.2 Soybean paste**

312 Soybean – Genetics and Novel Techniques for Yield Enhancement

paste is consumed in large different ways in different countries. It is used as the base for sauces served with meat, seafood, poultry, or vegetable dishes in China, while it is used as

Soy sauce is recognized as Jiang-you in China, Shoyu in Japan and Ganjang in Korea. There are two types of soy sauce based on the color. One type of soy sauce is an all purpose liquid seasoning, characterized by a strong aroma, a myriad flavor, and a deep red-brownish color. The other type is in a lighter brown color used mainly for cooking when the original flavor and color of the foodstuff need to be preserved. The difference in aromas observed between Japanese and Chinese styles of soy sauce are ascribed to the different ratios of wheat and soybeans used and the existence of pasteurized process (Fukushima, 1979). The salt concentration of soy sauce is around 16-17%, and the pH is around 4-5 (Shibasaki and

Fermented whole soybean products are known as Dou-chi in China, Natto in Japn, and Tempeh in Indonesian (Ogawa et al., 2004), which are much different from their counterparts. These products are solid, and the shape of cooked whole soybean particles is kept as it is. Although these products from different countries share this common characteristic, they have distinctive qualities because of the different bacterial and fungal

Sufu (Fu-ru, or Dou-fu-ru in Chinese) is a fermented soybean curd and a highly flavored, soft creamy product originating in China. It is a cheese-like product consumed as a side dish mainly with breakfast rice or steamed bread (Han et al., 2001). It has a long history and written records date back to the Wei Dynasty 220–265 AD in China. Several types of sufu can be distinguished, according to processing method or according to color and flavor.

Fermentation of soybean is complicated and time-consuming. High amount of salt used for the manufacture and the acid environment inhibit the growth of microorganism and enzyme activity. Therefore, starter is used to shorten the natural fermentation period. Soybean is full of protein and carbohydrate, thus the starter should produce or contain various hydrolytic enzymes such as protease and amylase with strong activity in solid or

Microorganisms used as soybean fermentation starters include bacteria, molds and yeasts. The first procedure for soybean fermentation is the preparation of Qu (in Chinese) or called koji (in Japanese). Koji is a source of microorganisms and their enzymes for converting the carbohydrates and proteins into sugars, peptides, and amino acids, etc. contained in the materials. The nutrients which were produced through the action of these enzymes will be used by yeasts and lactic acid bacteria during further fermentation period (Abe et al., 2006).

the base for soups in Japan and Korea (Fukushima, 1979).

**2.2 Soy sauce** 

Hesseltine, 1962).

**2.4 Soybean curd** 

submerged cultures.

**3.1 Microorganisms** 

**2.3 Fermented whole soybean products** 

communities in these products (Kim et al., 2010).

**3. Starters for the fermented soybean product** 

Cultures of *Aspergillus oryzae*, which known as a seed mold, are commonly used as starter for the production of soybean paste (Fukushima, 1979). Rice or barley is steamed and inoculated with *Aspergillus oryzae* to make koji. After completion of fermentation, the resulting koji is mixed with salt, cooked whole soybeans, pure cultured yeasts, lactic acid bacteria, and water, and then kept for an appropriate period for the second fermentation. The resulting aged mixture is mashed and packaged as miso. In general, miso is a paste of bright yellow to dark brown color. Whiter miso contains more rice than soybeans, whereas the darker miso contains 50 to 90% soybeans (Abe et al., 2006). The molds produce amylases and proteases which hydrolyze the cereal starch and the proteins in soybeans and cereals.
