Abstract
The effects of soy protein isolate (SPI) on the gelatinization of rice flour (RF) were studied as a function of mixing ratio by compression measurements, differential scanning calorimetry (DSC), and confocal scanning laser microscopy. The total concentration was 16.7%w/w, and the SPI/RF ratios ranged from 0:10 to 10:0. Gels with SPI/RF ratios of 0:10 to 4:6 showed a decrease in Young's modulus, compression stress, and compression energy with increasing SPI concentration. On the other hand, gels with SPI/RF ratios of 7:3 to 10:0 showed an increase in the above-mentioned values as the SPI concentration increased. The concentration- dependent graph of Young's modulus appeared to follow a convex downward curve. The DSC endothermic peak appearing upon the gelatinization of RF shifted slightly to higher temperatures while the enthalpies of the SPI/RF mixtures decreased with increasing SPI concentration. The results of the compression test and DSC changes suggested that SPI inhibited RF gelatinization. The results of confocal laser scanning microscopy confirmed the phase separation of SPI and RF mixture.
