Effect of heat treatment on physicochemical properties of rice flour (utilization for cooking and food processing of heat-treated rice flour part I)

Abstract

Effects of heat-dry or heat-moisture treatment on physicochemical properties of rice flour were investigated. The particle size and the degree of damaged starch of heat-dry treated (HDT) rice flour were smaller than the untreated and heat-moisture treated (HMT) rice flours. To α-amylase hydrolysis HMT rice flour was less resistant than those of untreated and HDT rice flours. Swelling-power and solubility of HDT and HMT rice flours were considerably suppressed. The peak viscosity in the RVA viscograms decreased with increasing temperature of heat-dry and heat-moisture treatments. The onset temperature of gelatinization in heating DSC curves shifted to higher temperatures with increasing temperature of heat-moisture treatment. The alteration of the thermal properties of HMT rice flour was attributed to the changes in rigidity of starch granules and their surroundings during the treatment. The X-ray diffraction patterns of HMT rice flour indicated that amylose-lipid complexes were formed during the heat-moisture treatment.