Process Parameters Optimization for Continuous Infrared Rice Bran Stabilizer and Assessment of Their Impact on Quality and Shelf Life

Background: Rice bran is the most valuable by-product of the rice milling operation. The FFA level rises immediately after milling and bran oil becomes hazardous for consumption owing to its lower pH, rancid flavor and soapy taste. Methods: A continuous-type infrared rice bran stabilizer was designed and process parameters such as moisture content, thickness, power density and treatment time were optimized for their impact on FFA content of bran, capacity and energy demand of the stabilizer using response surface methodologies. Under constant power density and moisture content, it has been confirmed that the capacity decreases with infrared exposure time. Result: The capacity was minimum (6.7 kg/h) at 0.5 cm thickness and 5 min exposer times, whereas it was maximum (40.2 kg/h) at 1 cm bed thickness and 3 min exposer time. The energy demand rose as the power density and time of exposure increased while the bed thickness and moisture content remained constant, whereas the FFA lowered nonlinearly as the power density and exposure time increased. FFA content was shown to be low at lower bed thickness and moisture content and to increase slowly as thickness and moisture content increased to 0.8 cm and 15% (w.b), respectively. However, when bed thickness and moisture level increase further, FFA content raised dramatically.