Optimization of microwave treatment for storage life enhancement of pearl millet flour

Abstract

Pearl millet contains higher amount of fat content among all other millets. It can be stored for longer duration like months to years without the development of rancidity in whole grain form, but storing in the form of flour is difficult as it has very short shelf life unlike other commercial flours. The development of rancidity is due to high fat content and lipolytic action of enzymes. Apart from enzymatic degradation, oxidative degradation promotes oxidation of free fatty acid (FFA) which leads to the production of peroxides which gives off flavours and bitterness. The study aimed to control both enzymatic and oxidative degradation of flours by giving microwave treatment to grains. The three independent variables such as moisture content (14, 18, 22%), microwave power (600, 800, 1000 W) and time of exposure (75, 85, 95 s) were used for optimizing microwave treatment of pearl millet grains on various attributes of rancidity developing compounds. The optimized condition for microwave processing of pearl millet grains was1000 W power level, 18% moisture content and 93 s time of exposure based on the dependent variables such as lipase, peroxidase, FFA, total phenol were found to be12.018 µM FFA/h/g, 32.843 µM/min/g, 0.29%, 0.569%, respectively.