Study on textual properties and rheological characteristics of tofu prepared from whole soybeans with magnesium chloride

Whole soybean curd was manufactured using ultrafine grinding technology and coagulant which called magnesium chloride and microbial transglutaminase,the texture properties and rheological characteristics of whole soybean curd were researched during the gel formation. The results showed that gel strength of the whole soybean curd reached the maximum of 221 g at 0.4%(w/w) magnesium chloride with 7U/g(protein),transglutaminase,2.2 times stronger than the traditional gluconate-α-lactone soybean tofu,with a slightly lower water holding capacity of 70% than the traditional gluconate-α-lactone soybean tofu,and the tofu showed a typical soybean curd texture. In the low shear stage,viscosity of whole soymilk was much lager than viscosity of traditional soymilk.Storage modulus(G′) increased rapidly during gel formation of both types of soybean curd. G ′ value of whole soybean curd eventually reached 3020 Pa while traditional gluconate- α- lactone soybean curd was only 1300 Pa. Loss modulus(G″) underwent a similar course as a function of time,but its values remained much lower than G′,which clearly indicated an elastic gel formation. The results of scanning electron microscope showed that whole soybean curd nested with fiber and formed a more loose gel network,which corresponded to a lower water holding capacity.