LAUSR

Wheat germ (WG) is a nutritional milling byproduct of wheat with short shelf-life. This study investigated hot air-assisted radio frequency (HA-RF) stabilizing treatment of WG. Physicochemical properties, enzyme activities and nutritional quality of HA-RF stabilized WG were evaluated and compared with WG stabilized by fluidized bed heating. Results indicated HA-RF heating to 100 °C with 15-min holding at 100–105 °C or heating to 110 °C with 6-min holding at 110–115 °C reduced lipase activity to about 10%. HA-RF inactivation of lipase, peroxidase, polyphenol oxidase and lipoxygenase was more effective in WG with initial moisture content of 14.5% or 20.0%, but less effective in WG with moisture content of 10.0%. For oils extracted from HA-RF stabilized WG with moisture content of 14.5%, peroxide and acid values were stable after storing at 25 °C for 3 days. After both HA-RF and fluidized bed stabilizations, color of WG and WG oils became darker, lipid content increased and reducing sugar content decreased, while extraction oil yield and protein content had no significant change ( p  > 0.05). HA-RF heating had no influence on α-tocopherol content, but fluidized bed stabilization decreased it from 299.42 mg/kg to 236.73 mg/kg. HA-RF heating had no distinct effects on amino acid and fatty acid composition. This study indicated that HA-RF heating had great potential in WG stabilization.