Optimization and evaluation of foxtail millet (&lt;em&gt;Setaria italica&lt;/em&gt;) bran oil by supercritical carbon dioxide extraction

M Pang,L L Cao,S J He,S T Jiang

doi:10.3989/gya.0239151

Abstract

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 °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 °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.

Highlights

Foxtail millet (Setaria italica) is one of the most important cereal crops in semi-arid areas all over the world (Zohary et al, 2012)
With respect to foxtail millet bran, there are still few reports in spite of the fact that the oil from foxtail millet bran has proved to be rich in polyunsaturated fatty acids (PUFA), especially linoleic acid and several lipid bioactive compounds (Liang et al, 2010; Pang M, 2014)
Did we establish an economical, convenient and no risk of solvent contamination extraction process for foxtail millet (Setaria italica) bran, and we evaluated the physicochemical properties, fatty acid compositions and sterols of foxtail millet bran oil (FMBO) obtained by supercritical fluid extraction (SFE) and solvent extraction (SE)

Summary

Introduction

Foxtail millet (Setaria italica) is one of the most important cereal crops in semi-arid areas all over the world (Zohary et al, 2012). In China, foxtail millet is planted as one of the major grain sources. Foxtail millet bran, which consists of an anatomical pericarp layer, an aleurone layer and cereal germ, makes up about 8%–10% of millet quality. Several studies regarding foxtail millet have been reported. The potential effects of antioxidant activity estimations for foxtail millet insoluble fibers were confirmed by using different in vitro tests (Bangoura et al, 2013). The protein, total carbohydrates and crude fat contents of foxtail millet were rapidly and accurately investigated by near infrared spectroscopy (Chen et al, 2013). The purification and characterization of foxtail milletderived peptides with antioxidant and antimicrobial activities were investigated (Amadou et al, 2013). With respect to foxtail millet bran, there are still few reports in spite of the fact that the oil from foxtail millet bran has proved to be rich in polyunsaturated fatty acids (PUFA), especially linoleic acid and several lipid bioactive compounds (Liang et al, 2010; Pang M, 2014)

Methods

Results

Conclusion