Inhibition of Lipid and Aroma Deterioration in Rice Bran by Infrared Heating

Abstract

This study was aimed to investigate the inhibition of the deteriorations of rice bran by infrared radiation (IR) heating and its effects on the chemical and biological profiles during short-term storage. Freshly milled paddy rice bran was exposed to the IR until the surface temperature reached 85 °C. The results indicated that after 20 days of storage, the activities of relevant enzymes, including lipase, lipoxygenase, and peroxidase all decreased after IR-treated. The rising trend of the free fatty acid content decreased significantly during storage. IR treatment can reduce the oxidation and hydroperoxides of rice bran, which can control the rise of peroxide value till the 15 days of storage (9.7 meq/kg). The contents of palmitic acid (C16:0), oleic acid (C18:1), and linoleic acid (C18:2) were well maintained by IR heating during the whole storage period. The aroma of fresh rice bran was acceptably preserved with abundant amount of aldehydes and alkanes. After quantification of the volatile chemical compounds in rice bran, potential biomarkers specific for rice bran storage should be highlighted, being 3-octen-2-one, acetophenone, 2,4-dimethylcumene, 5,6-dimethylindane, and phytane. This study illustrates that the IR processing can effectively guarantee the stabilization of rice bran in terms of desirable FAs profiles, relevant enzymes activities, and aroma features.