Abstract
We have found that qualities of cooking black soy-beans are markedly affected on direct contact with the metal of iron. The following results were obtained :
1) It was found that considerable amounts of iron were absorbed onto the boiling soy beans, exhibiting black color beautifully. This color, however, disappeared clearly on the addition of sodium bicarbonate. On the other hand, discoloration did not proceed when both table salt and iron powder were present together.
2) With the addition of table salt or the salt plus sodium bicarbonate black soy beans in cooking do not harden at all even in the process of seasoning.
3) The use of iron prevents black soy beans from being infiltrated with seasoning agents. On the other hand, in the presence of sodium bicarbonate of wood ash, soy beans soften and are fully impregnated with seasoning agents.
4) Bubbling due to heating can also be prevented by the addition of table salt.
