Optimization and evaluation of foxtail millet (Setaria italica) bran oil by supercritical carbon dioxide extraction

A Box-Behnken central composite design combined with the response surface methodology (RSM) was used to optimize the parameters of a supercritical fluid extraction (SFE) of foxtail millet bran oil (FMBO). Results showed that a maximum oil yield of 7.97% was achieved under the optimal conditions with an extracting pressure of 30.03MPa, extracting temperature of 47.93 degrees C; and an extraction time of 2.3 h. The quality of the oil obtained from SFE and solvent extraction (SE) was evaluated by proximate analysis to include physicochemical properties, fatty acids and sterol compounds. The FBMO obtained from SFE showed a much lower phospholipid (0.188 mg/g) content and a preferable color compared to the oil from SE, while it contained a higher content of total sterols, 1.55%. The thermal gravimetric analysis results showed one major regime of weight loss over a temperature range of 300-500 degrees C. The results show that FBMO obtained by SFE can be a promising nutritional source for food fortification and is understood to have more potentially healthy biological properties.