Varietal and Seasonal Effect of Rice on the Physicochemical Properties of Rice Flakes

Rice-based flakes made from 7 mid-season rice varieties (4 indica and 3 japonica subspecies) and 3 early season indica varieties produced both in early and late season were studied for their main physicochemical characters, including water activity, film thickness, bulk density (BD), ash, reducing sugars (RS), protein, phytic acid, starch, amylose, and rapid visco analyser (RVA) viscosity profile. A significant varietal effect was found for all these parameters (P<0.05 or 0.01) except starch. Strong variety × season interactions were observed but the seasonal effect was less pronounced, and only significant (P<0.01) for RS. The apparent amylose content (AAC) of rice flakes was significantly correlated (P<0.01) with AAC (r=0.99) and several RVA profile parameters [e.g., final viscosity (r=0.92)] of rice flour. For rice flakes, BD was significantly correlated with AAC (r=0.82, P<0.01) and most RVA profile parameters. The study indicates that varietal and environmental effects should be considered simultaneously for optimal production of rice grains for rice flakes manufacturing.