Determination of antioxidant components in rice bran oil extracted by microwave-assisted method

Bioresour Technol. 2008 Jul;99(11):4910-8. doi: 10.1016/j.biortech.2007.09.067. Epub 2007 Nov 8.

Abstract

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.

MeSH terms

  • Antioxidants / analysis*
  • Antioxidants / isolation & purification*
  • Biphenyl Compounds / metabolism
  • Chemistry Techniques, Analytical / methods*
  • Free Radical Scavengers / metabolism
  • Free Radicals / metabolism
  • Hydrazines / metabolism
  • Microwaves*
  • Picrates
  • Plant Oils / chemistry*
  • Rice Bran Oil
  • Solvents
  • Temperature
  • Vitamin E / isolation & purification
  • alpha-Tocopherol / isolation & purification
  • gamma-Tocopherol / isolation & purification

Substances

  • Antioxidants
  • Biphenyl Compounds
  • Free Radical Scavengers
  • Free Radicals
  • Hydrazines
  • Picrates
  • Plant Oils
  • Solvents
  • Vitamin E
  • gamma-Tocopherol
  • 1,1-diphenyl-2-picrylhydrazyl
  • alpha-Tocopherol
  • Rice Bran Oil