Abstract: A radio frequency (RF) heating system was employed to treat fresh rice bran for the purpose of improving its stability. Optimization of operating parameters for reduced relative activity of lipase was carried out using a combination of one-factor-at-a-time method and response surface methodology. The results showed that the optimal operating conditions were as follows: spacing distance between RF plates 10.5 cm, temperature 92 ℃, and treatment time 5.3 min. Under these conditions, the relative activity of rice bran lipase was as low as 18.25%. was After being stored at 35 ℃ for 6 weeks, the relative activity of lipase increased from 18.35% to only 22.63%, the acid value was only 22.32% as compared to that of untreated rice bran at the same storage period, and the peroxide value remained below the threshold of 5 mmol/kg. The protein content of rice bran decreased slightly but not significantly during storage. The water-holding capacity of rice bran protein reached its maximum after one week of storage, which increased by 37% in the treated rice bran compared with the untreated rice bran. Therefore, RF treatment could not only extend the storage life of rice bran, but also enhance the functional properties of rice bran protein. This study provides a good theoretical basis for expanded application of rice bran.

Key words: radio frequency heating; rice bran; relative lipase activity; storage stability; rice bran protein