Azis Boing Sitanggang

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 CaSO4·2H2O 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.

Physicochemical characteristics of starch from Indonesian Numbu and Genjah sorghum (Sorghum bicolor L. Moench)

Abstract Within this study, several physicochemical properties of starch from Indonesian Numbu and Genjah sorghum (Sorghum bicolor L. Moench) were investigated. This characterization is of importance to find the prospective applications of those starches. Based on the analyses of pasting, and gelatinization properties, starch from Numbu was suitable as an ingredient for dairy products, mayonnaise and salad dressings, while Genjah could be properly used as ingredient for noodles, soup and sauces. For both types of sorghum, the starch gelatinization temperatures were 75.97 and 77.30°C, respectively for Numbu and Genjah variety. It was higher compared to corn starch (i.e. 62–72°C). Herein, these starches conclusively require a longer cooking time and a larger thermal energy whenever used as ingredients for producing food products.