Rice bran real-time stabilisation technology with flowing microwave radiation: its impact on rancidity and some bioactive compounds

A pilot-scale real-time flowing microwave drum (PRFM) heating system was designed and adopted to stabilise rice bran (RB) for retarding rancidity. Meanwhile, the influence of PRFM radiation on fat-soluble bioactive compounds of RB were evaluated. Results revealed that PRFM processing could effectively inactivate lipase (LA) and lipoxygenase (LOX) of RB in minutes. The RB sample irradiated at 4 kW for 10 min with PRFM acquired the optimal stabilisation effect, and its residual LA activity was 7.94% and LOX was completely destroyed. The free fatty acids content and peroxide value of RB sample treated at optimal condition only increased by 1.06% and 5.32 meq O2/kg rice bran oil at 35 °C for 60 days, respectively. No significant decrease in fatty acid, tocopherols and γ-oryzanol content were noticed in bran sample treated at optimal condition. Therefore, PRFM radiation would be used as a practical and real-time technology for stabilising RB on-line.