Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2003
Publication Date: 10/2/2003
Citation: Awika, J.M., Rooney, L.W., Wu, X., Prior, R.L., Cisneros-Zevallos, L. 2003. Screening methods to measure antioxidant activity of sorghum (sorghum bicolor) and sorghum products. Journal Of Agricultural And Food Chemistry. 51(23):6657-6662.
Interpretive Summary: The measurement of total antioxidant components in whole processed foods is important from the standpoint of selecting appropriate varieties of foods as well as to help understand the effects of various cooking, baking and processing techniques on the antioxidants in foods. Dietary antioxidant intake has been related to health outcomes and thus having a convenient analytical method for assessing antioxidant capacity is important. In this study, specialty sorghums, their brans and baked and extruded products were analyzed for antioxidant capacity using three different methods. The oxygen radical absorbance capacity assay (ORAC) was used as the benchmark. For the sorghum samples analyzed, the other two methods were highly correlated with ORAC. Antioxidant capacity as determined by any of the 3 methods was correlated to the content of a particular class of compounds called phenolic, which generally account for a large amount of the antioxidants in most foods.
Technical Abstract: Specialty sorghums, their brans, and baked and extruded products were analyzed for antioxidant activity using three methods: oxygen radical absorbance capacity (ORAC), 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS), and 2,2-diphenyl-1-picrylhydrazyl (DPPH). All sorghum samples were also analyzed for phenolic contents. Both ABTS and DPPH correlated highly with ORAC (R2 = 0.99 and 0.97, respectively, n = 18). Phenol contents of the sorghums correlated highly with their antioxidant activity measured by the three methods (R2 0.96). The ABTS and DPPH methods, which are more cost effective and simpler, were demonstrated to have similar predictive power as ORAC on sorghum antioxidant activity. There is a need to standardize these methods to allow for data comparisons across laboratories. Keywords: Sorghum; antioxidant; phenols; ORAC; ABTS; DPPH