Rheological and textural characteristics of black soybean touhua (soft soybean curd) prepared with glucono-δ-lactone

Viscoelastic studies on the mixture of black soymilk and glucono-δ-lactone (GDL) have been done to analyse the gelation process of touhua. The isothermal gelation curves of touhua were well predicted by first-order reaction kinetics. The saturated storage modulus ( G sat ′ ) of touhua was affected by the solids content, coagulation temperature and GDL concentration. The G sat ′ value was proportional to the 1.68th power of solids content. The rate constant of gelation increased with increasing coagulation temperature and GDL concentration, but decreased with increasing solids content of soymilk. The gelation time decreased with increasing coagulation temperature and GDL concentration, and increased with increasing solids content. The hardness and adhesiveness values of packed touhua, measuring by textural profile analysis, increased with increasing solids content, GDL concentration and coagulation temperature. The storage modulus of touhua, during gelation, correlated positively with the textural characteristics of the packed touhua.