Characterization of soy protein hydrolysates produced by varying subcritical water processing temperature

The objective of this study was to investigate the effect of subcritical water processing (SWP) temperature on the hydrolysis pattern and quality characteristics of soybean protein hydrolysates. Two common cultivars of soybean were subjected to SWP at temperature ranging from 150 to 250 degrees C and pressure of 22 MPa. The highest free amino group content and yield were obtained at a processing temperature of 190 degrees C for both the cultivars (p < 0.05). Gel electrophoresis analysis exhibited low molecular mass hydrolysates at this processing temperature. Increasing processing temperature generated lower molecular mass peptides, as revealed by gel permeable chromatography. The color parameters L*, a* and b* were also highly influenced by the elevated processing temperatures, particularly at 190 degrees C. Increasing the processing temperatures of soybean hydrolysates also affected the viability of murine macrophage. The optimization of processing temperature could produce peptide fractions for food applications.