Phytochemicals and Antioxidant Properties in Wheat Bran

Abstract

Bran samples of seven wheat varieties from four different countries were examined and compared for their phytochemical compositions and antioxidant activities. Phenolic acid composition, tocopherol content, carotenoid profile, and total phenolic content were examined for the phytochemical composition of wheat bran, whereas the measured antioxidant activities were free radical scavenging properties against 2,2-diphenyl-1-picrylhydrazyl radical, radical cation 2,2‘-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, peroxide radical anion O₂^•-, and oxygen radical and chelating capacities. The results showed that the tested wheat bran samples differed in their phytochemical compositions and antioxidant properties. Ferulic acid, with a concentration range of 99−231 μg/g, was the predominant phenolic acid in all of the tested bran samples and accounted for about 46−67% of total phenolic acids on a weight basis. The concentrations for α-, δ-, and γ- tocopherols were 1.28−21.29, 0.23−7.0, and 0.92−6.90 μg/g, respectively. In addition, lutein and cryptoxanthin were detected in all of the tested bran samples with levels of 0.50−1.80 and 0.18−0.64 μg/g, respectively. Zeaxanthin was detected in the six bran samples, and the greatest zeaxanthin concentration of 2.19 μg/g was observed in the Australian general purpose wheat bran. β-Carotene was detected in four of the tested bran samples at a range of 0.09−0.40 μg/g. These data suggest that wheat and wheat bran from different countries may differ in their potentials for serving as dietary sources of natural antioxidants. Keywords: Antioxidant; wheat; bran; phenolic; phenolic acid; tocopherol; carotenoid; chelating; radical