Influences of Waxy Rice Protein Network on Physical Properties of Waxy Rice Flour Composites

Abstract

The roles of waxy rice protein network as a binder on thermal, pasting and microstructural characteristics of waxy rice flour (WF)-mungbean starch (MB) were demonstrated. The presence of WF, even at one-tenth of the total solid, lowered both enthalpy of gelatinisation and enthalpy for retrogradation reversal of the WF-MB flour composite compared to those of MB (P<0.05). The timedependent shear-thinning characteristics at 95°C of WF, WF-MB and MB indicated that the composites with high ratio of WF to MB resisted shear the most (P<0.05) during Rapid Visco Analysis (RVA). Confocal Laser Scanning Microscopy (CLSM) showed the swollen MB granules were bound by the protein network of WF after heat treatment. The resistance to shear during pasting of WF-MB composites, compared to those of WF or MB alone, were likely to be due to the binding of the swollen MB granules via interfacial interactions between WF protein network and the protein at the envelope of MB granules. This study highlighted the influences of microstructural alteration, through network formation of proteins, on the bulk pasting profiles and thermal properties of both starch and flour.