Morphological and physicochemical properties of rice starch dry heated with whey protein isolate

Abstract

The effect of dry heating treatment with whey protein isolate (WPI) on the morphological and physicochemical properties of rice starch (RS) was investigated. Scanning electron microscopy results demonstrated that WPI-mediated aggregation of RS granules was more pronounced as the dry heating time increased, which was further confirmed by analysis of the particle size distribution. Differential scanning calorimetry results showed that dry heating treatment in the presence of WPI significantly decreased the gelatinization temperature of RS but without affecting the gelatinization enthalpy change. X-ray diffraction and Fourier transform infrared spectroscopy analysis demonstrated that the long and short range orders of RS were partially damaged following dry heating treatment and the incorporation of WPI. In addition, a significant increase in the oil-binding ability was observed in the dry heated starch samples, which was more pronounced under the combination of dry heating with WPI. These phenomena could be attributed to the interaction of RS with WPI, the aggregation and denaturation of WPI, and the disruption of hydrogen bonds within starch during the treatment process.