Effects of hydrothermal processes on antioxidants in brown, purple and red bran whole grain rice (Oryza sativa L.).
The impacts of parboiling and wet-cooking, alone and in combination, on the concentrations of lipophilic antioxidants (vitamin E and γ-oryzanol), soluble (including proanthocyanidins and anthocyanins) and cell wall-bound phenolics, and antioxidant capacities in whole grain rice from six cultivars having different bran colours were investigated. Parboiling rough and brown rice increased the concentrations of lipophilic antioxidants in whole grain rice but decreased the concentrations of total phenolics and antioxidant capacities found in the soluble fraction. After hydrothermal processing of purple bran rice, the retention of extractable anthocyanins was low, but was high for simple phenolics. For proanthocyanidins found in red bran rice, the extractable oligomers with a degree of polymerization (DP) less than 4, increased up to 6-fold; while for oligomers with DP⩾4 and polymers, there was a significant decrease that was positively correlated with the DP and the temperature of the processing methods. The presence of hulls helped to retain water-soluble antioxidants during parboiling.
Food Science and Technology Program, Department of Agriculture, Food, and Resource Sciences, University of Maryland Eastern Shore, Princess Anne, MD 21853, USA.
Byungrok
B
Min
Dale Bumpers National Rice Research Center, Agricultural Research Service, United States Department of Agriculture, 2890 Hwy 130 E., Stuttgart, AR 72160, USA.
Anna
A
McClung
Dale Bumpers National Rice Research Center, Agricultural Research Service, United States Department of Agriculture, 2890 Hwy 130 E., Stuttgart, AR 72160, USA. Electronic address: ming.chen@ars.usda.gov.
Ming-Hsuan
MH
Chen
D000872:Anthocyanins / Q000032:analysis; D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D005511:Food Handling; D007502:Iron Chelating Agents / Q000494:pharmacology; D012275:Oryza / Q000737:chemistry*; D010636:Phenols / Q000032:analysis; D010666:Phenylpropionates / Q000032:analysis; D010936:Plant Extracts / Q000032:analysis; D024505:Tocopherols / Q000032:analysis; D014810:Vitamin E / Q000032:analysis
D000872:Anthocyanins; D000975:Antioxidants; D007502:Iron Chelating Agents; D010636:Phenols; D010666:Phenylpropionates; D010936:Plant Extracts; D014810:Vitamin E; D024505:Tocopherols; C013172:gamma-oryzanol
Anthocyanins; Antioxidant; Antioxidant capacity; Black rice; Parboil; Proanthocyanidins; Purple rice; Red rice; Vitamin E; Wet-cook