Effect of microwave and air drying of parboiled rice on stabilization of rice bran oil

Abstract

Two rice varieties, Giza 175 (short grain) and Giza 181 (long grain) were parboiled by soaking the grains at room temperature for 20 hours and steaming for 15 min then dried either at room temperature or by microwave. The results indicated that air and microwave drying significantly increased oil extraction in both rice bran varieties. Parboiling followed by air or microwave drying produced a slight change on protein, fiber and ash content of rice bran and reduced the development of free fatty acids (F.F.A.) in oil bran. Microwave samples have less F.F.A. content than the corresponding samples air dried. Oils from the cold stored rice bran presented lower F.F.A. than the corresponding oil bran stored at room temperature. The ratio between total unsaturated fatty acids and total saturated ones (Tu/Ts) decreased after air and microwave drying. Results also show that air drying increased the ratio of total hydrocarbons and total sterols (Tu/Ts) in both varieties while microwave decreased it.