Preparation and investigation of the processing characteristics of transglutaminase cross-linked soy protein isolate-whey protein polymer

To investigate the effects of transglutaminase (TGase) treatment on the processing characteristics and structure of soy protein isolate (SPI)-whey protein (WP) polymers, the solubility, emulsification activity, emulsion stability, and other properties of enzyme-treated protein blends were determined. The obtained results revealed that the processing characteristics of the SPI-WP hybrid protein systems were superior to those of SPI and WPI. After the TGase treatment, the maximum emulsification activity and emulsion stability were equal to 50 m(2)/g and 45%, respectively. The infrared spectrum of the produced polymer exhibited a slight red shift; the differential scanning calorimetry peak shifted to low temperature, and the polymer heat capacity increased, indicating that the internal polymer groups were exposed while the protein structure was changed. Scanning electron microscopy observations revealed that the hybrid protein gel possessed a regular three-dimensional meshwork structure, suggesting that TGase treatment considerably enhanced its functional properties. The research effectively improves the processing characteristics of SPI and WP and increases the application range of both in food.