Property changes of frozen soybean curd during frozen storage in “Kori-tofu” manufacturing process

It is generally accepted that the microstructure of frozen food changes even in freeze-storage due to the recrystallization of ice crystals. Kori-tofu is a traditional processed food in Japan, which is made from soybean curds availing refrigeration techniques to add an elastic texture. The elastic texture of soy bean curds which is Kori-tofu materials occurs during frozen-storage under subzero temperature, however, these mechanism have not clear. In this study, aiming to discuss the mechanism of the hard texture arising in soy bean curds during the freeze storage periods, characteristics changes in soy bean curds during frozen storage period such as texture, water holding capacity, ice crystal and frozen concentrated phase were investigated with time. In addition, how a character of soy protein changes was examined. The result indicated that the change in the balance of hydrophilic and hydrophobic region induced by dehydration with ice recrystallization at first stage of storage plays an important role in forming the new protein-protein interaction especially for amphipathic protein as α and α′subunit of β-conglycinin.