Effects of different heat-moisture treatments on the physicochemical properties of brown rice flour

We evaluated the effect of heat-moisture treatment (HMT) on the main chemical components, physical properties, and enzyme activities of two types of brown rice flour: high-amylose Koshi-nokaori and normal-quality Koshiibuki. Five different HMTs using brown rice (moisture content was 12.0%) were assessed: 0.1 MPa/120 degrees C for 5 or 10 min, 0.2 MPa/134 degrees C for 5 or 10 min and 0.3 MPa/144 degrees C for 10 min. HMT, decreased the alpha-amylase and lipase activities, and fat acidity, and slightly increased the dietary fiber and resistant starch levels. After 2 months' storage at 35 degrees C, rice samples that were treated with 0.2 MPa/134 degrees C or 0.3 MPa/144 degrees C for 10 min had a lower fat acidity than untreated samples, which would be useful for long-term storage and export of rice flour. And HMT exhibited inhibition of retrogradation in the pasting and physical properties, which is profitable to promote the qualities of the rice products.