The Effects of Soy-Sauce (Shoyu) on the Texture of Foodstuffs During the Process of Cooking (Part 2)

Abstract

Further studies were prevailed in order to investigate the factors which made the foodstuffs harder during the process of cooking with shoyu. Soy beans were cooked with the solutions containing major components of shoyu, and the texture of cooked material was measured by curd meter.
1. Sixteen varieties of carboxylic acids as well as two amino acids, such as glutamic acid and aspartic acid contained in shoyu caused the hardness of soy beans when compared with the distilled water.
As for the effects of several kinds of inorganic salts, potassium chloride and sodium chloride made the texture of soy beans softer. On the other hand, calcium chloride, magnesium chloride and ferric chloride gave the opposite results.
2. When soy beans were cooked with the diluted shoyu solution (NaCl : 5 g/dl), which contains one of each carboxylic acid or amino acid (0.1 mole) described above, the results were one and half to two times harder than that which was treated with the diluted shoyu solution only. In case of the treatment with shoyu or with the buffer solution (NaCl : 5 g/dl), which contains three main carboxylic acids in shoyu; lactic acid, succinic acid and acetic acid, thetexture of soy beans became softer than those which were cooked with the plain solution of the above carboxylic acid.