Optimization of Microwave Oven Roasting of Peanuts Using Response Surface Methodology

This study aimed at determining the optimum conditions for roasting of peanuts in a microwave oven using response surface methodology (RSM). Peanuts were heated in microwave oven for 2 minutes at 100% power (432W) continuously for removing seed coats prior to roasting. Roasting experiments were conducted using a central composite design in RSM to evaluate the effect of sample weight, microwave power level and exposure time on the changes in peanut crispness, color, crushing force and energy from the respective quadratic response surface models. The optimum conditions for roasting of peanuts in the microwave oven were determined as 257 g sample weight, 77.8% power level (336 W) and 5.5 minutes of roasting time resulting in the crispness score of 8.78. The microwave power level was the most significant factor followed by the roasting time and sample weight. The optimally roasted peanuts indicated total color difference in CIEL*a*b* color space, crushing force and energy to be 11.98, 38.7 N and 0.026 J, respectively. Keyword: Microwave roasting, Peanuts, CCD, RSM, Optimization