Studies on Reduction of Moya (aging) Period in Kori-tofu Making Process

Abstract

To make kori-tofu, fresh tofu is frozen and then kept -1--3°C in a storage room for about 3 weeks. During this period called Moya, original tofu changed into unique structure like sponge but it is extremely time consuming. Standing on the viewpoint that ionized SH groups can promote protein denaturation by freezing and cause the formation of spongy structure, present paper deals with practical trials to reduce Moya period.Blowing of nitrogen gas into soymilk before heating caused the increase of SH groups and promoted to form spongy structure, while blowing of oxygen gas caused the decrease of SH groups and prevented the formation of spongy structure. Addition of 5×10-4M sodium suifite to soymilk before coagulation also promoted the increase of SH groups and also the formation of spongy structure, consequently, Moya period can be reduced. But this adding amounts is limited by food regulation.It may be concluded that to reduce Moya period and prepare Kori-tofu in good quality, it is important to make tofu with a care for preventing soymilk from decrease of SH groups.