Gelatinization of rough rice is an important unit operation in the rice parboiling process. The possibility of applying far-infrared (FIR) radiation for gelatinization of rough rice was investigated in this study. The soaked rough rice was exposed to FIR radiation at 5 s intervals up to 30 s and moisture content, degree of gelatinization & color of rice were measured. The moisture content of rough rice immediately after exposing to FIR radiation was in the range of 27.8±0.1 - 21.4±0.6 % and it decreased with the increase of exposure time. The degree of gelatinization increased with exposure time and was in the range of 20.51% and 100%. The optimum degree of starch gelatinization of 40% was achieved in an exposure time of 20 s. The yellowness index was in the range of 21.95 – 34.54. The lightness (L*) of soaked rough rice exposed to FIR radiation was decreased with time from 60.30 to 52.72.
Tropical Agricultural Research Vol. 26 (4): 707 – 713 (2015)