Properties of Nonwaxy Rice Flours with Different Soaking Time and Particle Sizes

摘要

Effects of soaking time and particle size on physicochemical properties of nonwaxy rice flour were investigated. Nonwaxy rice grains were soaked at 4°C for 0, 1, 12, and 24 hr, dried at room temperature, and milled. Resulting flours were passed through 45-mesh (<355 μm, IL45) and 100-mesh (<150 μm, IL100) sieves and separated into <40 μm and 40-100 μm series. IL45 series showed higher amount of large particles (40-100 μm) than IL100 series. As the soaking time increased, protein and ash contents decreased, and amylose content, water-binding capacity, swelling power, and solubity of nonwaxy rice flours increased. Swelling power and solibility of nonwaxy rice flours also increased between 65-85°C. Water-binding capacity, swelling power, and solubility of IL100 series were higher than those of IL45 series. 12 hr-soaked nonwaxy rice flour pastes showed higher peak viscosity and breakdown but lower setback and visicosity at 95 and 50°C than 1 hr-soaked ones. X-Ray diffractograms of nonwaxy riceflours were not affected, whereas surface appearance was affected, by soaking time and particle size.