Gelation characteristics and morphology of corn starch/soy protein concentrate composites during heating

The formation of corn starch (CS) and soy protein concentrate (SPC) composite during heating has been investigated using thermal and rheological analysis. SPC did not exhibit endothermic peak in differential scanning calorimetry (DSC) thermogram. Adding CS at low mass percentage (16.7%) to SPC resulted in a reduction of storage modulus (G') from 7.72 to 3.63 kPa at 50 degrees C. The DSC thermogram showed that the peak temperature was raised to 73.5 degrees C, compared with 70 degrees C for CS. The gelatinization of starch granules played an important role on the rheological properties of the composite during heating. Scanning electron microscopy and light microscopy with the aid of histological technique revealed the microstructure of CS/SPC composites. The observation illustrated that starch granules lost integrity and formed a gel with SPC at the temperature of maximum G (T-G'max). The effect of starch mass percentage on the structural change of the composite was discussed. (c) 2006 Elsevier Ltd. All rights reserved.