Effects of Heat Treatment of Soymilk, Coagulants and Yeast Inoculation on the Texture of Soy-curds

Abstract

The conditions of curd preparation from soymilk suitable for making cheese-like fermented soy protein foods were examined. The curd frolm soymilk treafed by ultra high temperature heating method (135°C, 2 sec.) showed too low hardness, springiness and chewiness to make fermented soy protein foods. Seven coagulants including 4 kinds of salts and 3 kinds of acids, and lactic fermentation using Streptococcus thermophilus as a starter were tested for preparing curd from soymilk. The curds coagulated by the aid of calcium sulfate, δ-D-gluconic lactone and lactic fermentation were excellent in respect of texture of curds at cutting stage and whey separation. Preparation of curd was carried out with inoculation of Saccharomyces fragils and then the pressed curds were incubated for 40 days at 20°C. Hardness, cohensiveness, springiness and chewiness of the curds were measured during the incubation. The curd by lactic fermentation with inoculation of lactic starter and yeast gave the most smooth body like cheese along with the decrease of hardness, springiness and chewiness during the incubation.