Phytochemical content and antioxidant activity of six diverse varieties of whole wheat
2010
Okarter, Neal | Liu, Chang-Shu | Sorrells, Mark E. | Liu, Rui Hai
The phytochemical content and antioxidant activity of six diverse varieties of whole wheat are reported. The free phenolic content ranged from 255 (KanQueen) to 499 (Roane)μmol gallic acid equivalents/100g DW. The bound phenolic content ranged from 582 (Roane) to 662 (Cham1) μmol gallic acid equivalents/100g DW. The bound fraction contributed 53.8-69.7% of the total phenolic content of the wheat varieties analysed. Ferulic acid was the predominant phenolic acid found in whole wheat. Total ferulic acid content ranged from 310.8 (Caledonia) to 496.1 (KanQueen)μmol ferulic acid/100g DW. The percentage of ferulic acid found in the insoluble-bound fraction ranged from 87.4% (Caledonia) to 97.2% (KanQueen). Other phenolic acids, p-coumaric acid, syringic acid, vanillic acid, and caffeic acid were also detected. Lutein was the predominant carotenoid found in the whole wheat varieties analysed. Zeaxanthin, β-carotene, and β-cryptoxanthin were also detected. Mainly α- and β-tocopherols and α- and β-tocotrienols were found in all varieties of whole wheat though γ-tocopherol was detected in all but two varieties. β-Tocotrienol was the predominant form of vitamin E found in all varieties of whole wheat. The antioxidant activity was assessed using the oxygen radical absorbance capacity (ORAC) assay. The ORAC of the free fraction ranged from 1958 to 3749μmol Trolox equivalents/100g DW. The ORAC of the bound fraction ranged from 3190 to 5945μmol Trolox equivalents/100g DW. Total phenolic content was correlated with oxygen radical absorbance capacity (R ² =0.810; p <0.001). The phytochemicals found in whole grains may be responsible for the health benefit of whole grain consumption.
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