14B-37

J. M. AWIKA¹, L. W. Rooney, and E. L. Suhendro. (1) Soil and Crop Sciences, Texas A&M University, Cereal Quality Laboratory, College Station, TX 77843-2474

There is strong evidence that various phenols found in plants provide several health benefits to man by acting as natural antioxidants. Development of foods with high levels of these compounds is of prime importance. Some sorghum varieties contain tannins and other phenols concentrated in the outer layers of the kernel; they could provide a natural source of antioxidants for foods. Our objective was to isolate sorghum fractions with the highest levels of tannins and total phenols and determine their antioxidant capacities relative to blue berries. ATx623*SC103 (brown), a type III high tannin sorghum, Tx430 (black), a black variety high in anthocyanins and ATx631*RTx436 (white), a food type sorghum, were abrasively milled to remove successive bran fractions which were analysed for tannins (Vanillin-HCl) and total phenols (Folin-Ciocalteu). Oxygen radical absorbance capacity (ORAC) assays were performed to determine antioxidant power of these fractions relative to other products. Phenol contents in whole grain samples were 0.16, 0.52 and 0.77 mg/100 mg (gallic acid equivalent) for white, black and brown sorghums respectively. Fractionation achieved maximum values of 0.28, 1.9 and 4.63 mg/100 mg phenols in the white, black and brown sorghum brans respectively. Blue berries have a phenol content of 1.46 mg/100 mg on a dry matter basis. Only the brown sorghum had catechins, with levels of 2.37 and 18.32 mg/g CE in whole grain and bran respectively. The sorghum brans had ORAC values of 20.8 (white), 132.8( (black) and 176.8 (brown) (U mol TE/g) compared to blue berries with a value of 116.4 (U mol TE/g). Sorghums (especially high tannin types) are a rich source of catechins and total phenols; the bran gives high concentrations of these compounds with antioxidant power similar to berries. These fractions could be a good source of antioxidants and other nutrients in foods.