Study on the composition of rice bran oil and its higher free fatty acids value

摘要

The compositions of rice bran oils (RBO) and three commercial vegetable oils were investigated. For refined groundnut oil, refined sunflower oil, and refined safflower oil, color values were 1.5-2.0 Lovibond units, unsaponifiable matter contents were 0.15-1.40%, tocopherol contents were 30-60 mg%, and FFA levels were 0.05-0.10%, whereas refined RBO samples showed higher values of 7.6-15.5 Lovibond units for color, 2.5-3.2% for unsaponifiable matter, 48-70 mg% for tocopherols content, and 0.14-0.55% for FFA levels. Of the four oils, only RBO contained oryzanol, ranging from 0.14 to 1.39%. High-oryzanol RBO also showed higher FFA values compared with the other vegetable oils studied. The analyses of FA and glyceride compositions showed higher palmitic, oleic, and linoleic acid contents than reported values in some cases and higher partial glycerides content in RBO than the commonly used vegetable oils. Consequently, the TG level was 79.9-92% in RBO whereas it was > 95% in the other oils studied. Thus, refined RBO showed higher FFA values, variable oryzanol contents, and higher partial acylglycerol contents than commercial vegetable oils having lower FFA values and higher TG levels. The higher oryzanol levels in RBO may contribute to the higher FFA values in this oil.