Author
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Luthria, Devanand - Dave |
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LIU, KESHUN - US Department Of Agriculture (USDA) |
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Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/4/2013 Publication Date: 10/1/2013 Citation: Luthria, D.L., Liu, K. 2013. Localization of phenolic acids and anliokidant actnity in sorghum karnels. Journal of Food Science. 5:1751-1760. Interpretive Summary: Information on distribution of phenolic acids within a sorghum grain is of significant value to food manufacturers as phenolic acids are known to influence the organoleptic and health benefits associated with the consumption of whole grain cereals. This manuscript describes extraction and analysis of phenolic acids and antioxidant capacity of 11 pearling fines and the corresponding 10 pearled kernels from two genotypes (white and red) of sorghum grains. All fractions, plus the original kernels were analyzed by two independent assay procedures, phenolic acids content by high performance liquid chromatography and antioxidant capacity by ferric reducing antioxidant power (FRAP) assays, to study the distribution of phenolic acids and antioxidant activity within sorghum grains. Four phenolic acids identified in all fractions were caffeic, p-coumaric, ferulic, and sinapic acids. Data showed that the distribution of phenolic acids and antioxidant capacity in two genotypes of sorghum was non-homogeneous. Around 60% of the phenolic acids and the antioxidant capacity were recovered in the initial three pearling fine fractions (within 16% surface removal). The concentrations of the phenolic acids decreased significantly with sequential pearling. Significant correlation (R2 > 0.98) between total phenolic acids content and antioxidant capacity as determined by FRAP assay was observed in two sorghum genotypes when all fractions were included except first pearling fine fraction from the red sorghum grain which contained anthocyanins that were not analyzed in the current study. Hence one should be cautions in using only colorimetric antioxidant assay results, these results should always be coupled with detailed phytochemical analysis using chromatographic separation for better accuracy and health claims. The information gained in this study will be of significant value to cereal producers and consumers as phenolic acids are known to influence the organoleptic and health beneficial properties of sorghum grain. Technical Abstract: Two genotypes (white and red) of sorghum grains were sequentially pearled into 11 pearling fines and the corresponding 11 pearled kernels to study the distribution of phenolic acids within sorghum grains. All fractions, plus the original kernels were analyzed by two independent assay procedures, phenolic acids content by high performance liquid chromatography and antioxidant capacity using ferric reducing antioxidant power (FRAP) assay. Four phenolic acids identified in all fractions were caffeic, p-coumaric, ferulic, and sinapic acids. Data showed that the distribution of phenolic acids and antioxidant capacity in two sorghum genotypes was not homogeneous. Around 60% of the phenolic acids and the antioxidant capacity were recovered in the initial three pearling fine fractions that constituted about 20% surface removal. The concentrations of the phenolic acids decreased significantly with sequential pearling. Significant correlation between total phenolic acids and antioxidant capacity was observed with all fractions except the first pearling fine fraction from the red sorghum which contained anthocyanins, which were not analyzed in the current study. Hence one should be cautions using only colorimetric antioxidant assays. The antioxidant activity should always be coupled with detailed phytochemicals analysis for better accuracy and health claims. |
