The influences of coagulation conditions and storage proteins on the textural properties of soy-curd (tofu)

The contribution of storage proteins (e.g., 7S, 11S) in soybean (variety Raja Basa) on the textural properties of tofu was investigated. Applying glucono-δ-lactone (GDL) as coagulant, the protein recovery was varied, dependent on coagulant concentration (p ≤ 0.05). Different coagulants yielded different proportions of 11S/7S storage protein ratios (p ≤ 0.05). Curd coagulated with CaSO 4 ·2H 2 O lacked 7S subunits. The amount of 7S was up to 8.35% of the total storage proteins. This led to increased 11S/7S storage protein ratio and consequently increased curd hardness and gumminess (23.34 and 9.10 N, respectively). An upsurge of 11S/7S storage protein ratio resulted in a higher number of covalent bonds from disulfide bonding as 11S protein contains more total cysteine groups than 7S. Conclusively, this study shows 11S/7S storage protein ratio apparently has a contribution on the textural properties of curd especially on the characteristics of hardness and gumminess.