Potential of supercritical carbon dioxide extraction for high recovery of bioactive compounds and antioxidant activities of pigmented rice bran

Abstract

This study explores the effectiveness of supercritical carbon dioxide extraction (SCC) in comparison with simple maceration (SPM) in extracting pigmented rice brans. The effects of rice variety and extraction solvents were also studied. It was found that extraction time for SCC is 90 min while it takes 7 days for SPM. SCC provides higher quality and quantity of rice bran extracts (RBE) and their bioactive compounds than SPM. As a cosolvent in SCC, ethanol is the most suitable for most rice bran varieties followed by the 60:40 ethanol-hexane mixture. Both SCC and SPM demonstrate that glutinous rice brans possess higher antioxidant content and activity than the non-glutinous varieties. The antioxidant activities of all tested pigmented rice brans are free radical scavenging activity and reducing power. All varieties showed significantly higher concentrations of γ-oryzanol than α-tocopherol. The highest yields of γ-oryzanol and α-tocopherol from SCC (2,096.34±25.11 and 27.42±0.78 mg%, respectively) are significantly higher than that from SPM (1,828.28±23.61 and 23.22±0.91 mg%, respectively). Our findings suggest that SCC with ethanol as a cosolvent is a green extraction method with higher potential than SPM in terms of recovery of high bioactive compounds and antioxidant activity of pigmented rice bran.

Keywords

• Supercritical fluid extraction
• Rice bran extract
• Tocopherol
• Oryzanol
• Free radical scavenging
• Reducing power