Abstract: This study aimed to investigate the effect of coagulation temperature on gelling properties and molecular forces of tofu coagulated with glucono-δ-lactone. Through dynamic rheological and texture analysis, the dynamic viscoelastic properties and texture properties of tofu were studied during its coagulation process. The effect of coagulation temperature on chemical forces of tofu was explored by using a sequential extraction procedure. The results showed that with the increase in coagulation temperature, the elastic modulus (G’) and viscosity modulus (G”) increased rapidly. At 85 ℃, the coagulation reaction only took about 1.8 s to reach maximum gel strength and the final G’max was 143.5 kPa. Hydrophobic interaction, disulfide bonds, hydrogen bonds and ionic bonds were the major chemical forces in tofu. With the increase in coagulation temperature, the proportions of ionic bonds and hydrogen bonds decreased significantly, while the proportions of hydrophobic interactions and disulfide bonds increased. The chemical forces were significantly related to the textural properties of tofu gels. At higher coagulation temperature, the main chemical forces were hydrophobic interaction and disulfide bonds, and higher gel elasticity, hardness, adhesiveness and cohesiveness were obtained. This study provides theoretical support for the development of high temperature coagulated tofu processing technology.

Key words: tofu coagulated with glucono-δ-lactone; coagulation temperature; rheological property; texture characteristics; chemical forces