The effect of single screw conveyor stabilization on free fatty acids, α-tocoferol, and γ- oryzanol content of rice bran

The benefit of rice bran to human health is already wellknown. It is a rich source of fiber, vitamin B1, tocoferol and γ-oryzanol. Unfortunately, freshly milled rice bran has a short shelf life because of its high triaclyglycerol content, which tends to decompose into free fatty acids (FFA). The last are responsible for off flavor development during rice bran storage. In this research, hot screw conveyor was used to stabilize fresh rice bran. The effects of several stabilization parameters, those are conveyor temperature and conveyor rotation speed to the content of FFA, α-tocopherol, and γ-oryzanol of rice bran stored at 37°C for two weeks were observed. The results showed that after two weeks of storage, an increase of total FFA in unstabilized rice bran (39.91%) was significantly higher as compared to the stabilized one (6.75%). Overall, it was concluded that the best treatment for rice bran stabilization was obtained at 120°C with a screw speed of 15 Hz. The treatment was chosen because it gave minimum loss of tocopherol and oryzanol (4.74% and 22.28%) and FFA content less than 10%.