Viscosity of Rice Flour: A Rheological and Biological Study

Abstract

Rice breeders frequently use rapid visco analysis (RVA) as in index of rice quality. Potentially, viscosity curves could also be used to predict the sensory properties of a sample of rice or the processing properties of rice when used as an ingredient. The aim of this study is to determine the contribution of the main components of rice flourstarch and protein polymers and lipidsto the viscosity curve, accounting for biological and rheological contributions, and interactions with water. By deconstructing the rice flour, resistance to shear is generally the primary factor that affects rheological processes in the RVA, often masking the physical processes of cooking. Thus, higher concentrations of water reveal more about the true biological and physical processes of the transition from a powder to paste. Proteins contribute to peak height, offset thixotropy, and contribute to the final viscosity. Starch−lipid complexes can mask differences in the molecular structures of amylose and amylopectin, and removing lipids alters the structure of the paste significantly, which consequently alters viscosity curves. Keywords: Viscosity; rice; starch; proteins; lipids