Infrared radiation and hot air-assisted radio frequency heating rice bran extends its shelf life

學生姓名: 薛家瑜
指導教授: 張正明
學期: 110下
摘　　要: Rice bran (RB), a by-product of rice milling industry has limited uses despite its nutritional value. Thermal treatment is the most common method used for stabilizing RB. Therefore, the purpose of this study is to use infrared radiation (IR) heating and hot air-assisted radio frequency (HA-RF) heating to analyze the fatty acid, antioxidant activity, color, and so on, to explore the effect on the storage stability of rice bran. Rice
bran was heated at 100°C, 120°C, 140°C by IR for 5, 10, 15, 20 minutes, respectively, and stored at 20°C.When compared with the control, heating rice bran with IR significantly inhibited the free fatty acids (FFA) content in rice bran, while heating at 140°C for 15 minutes was the most effective in inhibiting lipase activity and preventing rice bran rancidity without changing γ-oryzanol content and fatty acid composition. The
rice bran was heated with low-temperature hot air-assisted radio frequency (LT-RF) and high-temperature hot air-assisted radio frequency (HT-RF), respectively, for 15 minutes at 100-105°C, and 6 minutes at 110-115°C. Compared with the control, rice bran heated with HA-RF reduces lipase (LA) and polyphenol oxidase (PPO) activities by 20 –30%. Rice bran treated with HA-RF showed darker color, higher content of free flavonoids and antioxidant capacity than extruded rice bran (ERB). HA-RF had no significant effect on protein, lipid, tocotrienol, tocopherol content, and fatty acid composition. Comparing with ERB, HA-RF treatment had less damage to rice bran structure. In summary, using IR and HA-RF to heat rice bran can effectively prolong its storage period.