Quality characteristics of fermented cheese analogs produced using roasted soy flour and different fermentation times with rice straw

To improve the nutritional and physiological functionality of cheese analogs, fermented cheese analogs treated with Flavourzyme® were developed and the effects of roasting soy flour and fermentation time (1, 2, and 3 days) with rice straw on their quality characteristics, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), isoflavone content, and antioxidant activity were examined. Heat coagulation was the highest for the unroasted and roasted soy flour groups fermented for 1 day, with the unroasted group having higher values than the roasted group, regardless of fermentation time. The daidzein and genistein contents were the highest in the soy flour and roasted soy flour groups fermented for 2 days and 1 day, respectively. The antioxidant activity and heat extension were the highest for the soy flour group and roasted soy flour group fermented for 1 day, respectively. In the SDS-PAGE patterns, protein subunits of P26 in roasted soy flour groups were consistently decomposed by increasing the fermentation time. The yield and pH in both groups decreased as fermentation time increased. The adhesiveness of the soy flour group was highly increased by fermentation, and the cohesiveness, springiness, and appearance of the roasted soy flour group were improved by fermentation. The optimum fermentation time for the fermented cheese analogs was 1 day, as higher yields, heat coagulation, heat extension, lightness, dE, cohesiveness, and springiness were obtained. Between the two groups fermented for 1 day, the soy flour group showed better heat coagulation, genistein content, antioxidant activity, cohesiveness, springiness, and adhesiveness; however, the roasted soy flour group showed better yield and heat extension.