The Comparative Study of Parboiled Rice Production between Traditional Method and Microwave Method

Abstract

A parboiling process for high-quality rice is important to consume and export. This research was to study and compare the parboiling processes of Thai jasmine rice 105 between a traditional and a microwave technique. The paddy in the conventional method was soaked in the water temperature of 70 and 80 °C with the holding time of 60, 120 and 180 min and steamed at the temperature of 100 °C for 5, 10 and 15 min. The results showed that the steeping with 80 °C for 180 min caused the head rice yield of 65.47 % without chalky grain and the L* and b* values of 64.48 and 19.83, respectively. For soaking by the microwave, the microwave power was varied in the ranges from 400, 440 and 480 W for the duration of 80, 105 and 130 min and after that steamed the paddy as the traditional method. The microwave power of 440 W, the holding period of 160 min for the soaking process and the steaming time of 5 min were suitable conditions. The parboiled rice had the whole grain of 64.02 % with the L* and b* of 60.63 and 16.12, respectively, and the 1.33 % of chalky kernels. Moreover, the characteristics of the whole kernel, chalky grain, values of color space and whiteness from the two techniques were compared and showed no statistically significant (p<0.05). However, the microwave process could reduce the parboiling time and energy consumption.