Determination of antioxidant components in rice bran oil extracted by microwave-assisted method.
Rice bran oil was extracted by microwave-assisted extraction with isopropanol and hexane using a solvent-to-rice bran ratio of 3:1 (w/w). The experiments were done in triplicate at 40, 60, 80, 100, and 120 degrees C with a total extraction time of 15 min/sample. The oil components were separated by normal-phase HPLC and quantified with a fluorescence detector. The radical scavenging capability of the oil was tested with DPPH and was expressed as mumol Trolox Equivalent Antioxidant Activity. The increase in total vitamin E with temperature from 40 to 120 degrees C was 59.63% for isopropanol and 342.01% for hexane. Isopropanol was the best solvent for the extraction of gamma-tocopherol and gamma-tocotrienol as compared with hexane for both microwave-assisted and conventional solvent extraction. Isopropanol was better for oil yield extraction at high temperatures. Samples extracted with isopropanol at 120 degrees C had higher antioxidant activity. No differences in oil yield, total vitamin E, and antioxidant activity of oil was noticed between the two methods (microwave-assisted and solvent extractions), at 40 degrees C. No degradation of alpha-tocopherol was noticed during the process.
Zigoneanu
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Louisiana State University, Agricultural Center, BAE Department, Baton Rouge, LA 70803, United States.
Williams
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Xu
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Sabliov
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D000975:Antioxidants / Q000032:analysis* / Q000302:isolation & purification*; D001713:Biphenyl Compounds / Q000378:metabolism; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D016166:Free Radical Scavengers / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism; D006834:Hydrazines / Q000378:metabolism; D008872:Microwaves; D010851:Picrates; D010938:Plant Oils / Q000737:chemistry*; D000073879:Rice Bran Oil; D012997:Solvents; D013696:Temperature; D014810:Vitamin E / Q000302:isolation & purification; D024502:alpha-Tocopherol / Q000302:isolation & purification; D024504:gamma-Tocopherol / Q000302:isolation & purification
D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D005609:Free Radicals; D006834:Hydrazines; D010851:Picrates; D010938:Plant Oils; D012997:Solvents; D014810:Vitamin E; D024504:gamma-Tocopherol; C004931:1,1-diphenyl-2-picrylhydrazyl; D024502:alpha-Tocopherol; D000073879:Rice Bran Oil