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Effects of Milling on the Physicochemical Characteristics of Waxy Rice in Taiwan¹

¹Presented in part at the AACC 82nd Annual Meeting, San Diego, CA, October 1997. ²Department of Food Science, National Chung-Hsing University, Taichung, Taiwan 40227, R.O.C. ³Corresponding author. E-mail: slu@dragon.nchu.edu.tw ⁴Institute of Chemistry, Academia Sinica, Nankang, Taipei, Taiwan, R.O.C.

Three types of mills and six milling methods were employed to mill two waxy rice varieties (TCSW1, long grain; TCW70, short grain), and the physicochemical and functional properties of rice flour were examined. The results showed that dry-milling maintained a higher level of the chemical components than other milling methods. Wet-milling slightly increased solubility as test temperatures increased, and significantly increased swelling power at 75 and 85°C for TCSW1 and TCW70, respectively. Hammer and semi-dry hammer milling gave higher percentages of coarse particles (100–300 μm); cyclone and turbo milling led to a more even particle-size distribution, and the wet-milling gave the finest particles (10–30 μm). Dry hammer-milled rice had higher gelatinization and pasting temperatures, and semi-dry grinding milling resulted in the lowest pasting temperature, setback viscosity, and enthalpy value among the mills. The final quality of the two waxy rice varieties was profoundly affected by the mill type and milling method.