Stabilization of rice bran milling fractions using microwave heating and its effect on storage

Abstract

Rice bran tends to become rancid during storage if it is not stabilized. In commercial rice mills, bran is removed in phases using battery of polishers and different fractions of rice bran are produced. The stabilization reduces peroxidase, lipases, lipoxygenase and auto-oxidation enzymatic activities. The bran fractions were stabilized by continuous microwave heating at different treatment combinations (850, 925 and 1000W; 3, 4.5 and 6min) and stability of bran fractions were analysed in terms of Free Fatty Acid (FFA), Acid value (AV) and Peroxide value (PV) for 90days at the interval of 15days. As power and exposure time increases the FFA, AV and PV are found to be low during storage period. The rancidity level was high in last milling bran fraction and as milling progressed, the rancidity level also increased and it was similar throughout the storage. The bran fractions processed at 925W to 3min found to be the suitable condition for stabilization of rice bran milling fractions.