http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Sorghum varieties grown in Texas between 1998 and 2002, as well as processed sorghum products, were analyzed for antioxidant potential using three methods; oxygen radical absorbance capacity (ORAC), 2,2' -azinobis (3-ethyl-benzothiaziline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). Phenolic antioxidants from these samples were separated and characterized by HPLC. Two extraction solvents, 1% HCl in methanol (Me-HCl), and 70% aqueous acetone (Ac-aq), were compared. The Me-HCl generally extracted sorghum antioxidants better than Ac-aq. This effect was more significant in black sorghums than brown sorghums. The ORAC activities (Trolox equivalents, TE) among black and brown sorghum brans were high (1,000 - 3,100 [u]mol TE/g) compared to common fruits and vegetables (80-900 [u]mol TE/g). Retention of antioxidant activity after processing was 57 - 78% for baked, and 70 -100% for extruded sorghum products relative to raw samples. Antioxidant values by the ORAC method were 2-3 times higher than ABTS or DPPH values for the sorghums. However, the three methods correlated highly with one another (R² > 0.95). The ABTS method was overall the most suitable for sorghums. Brown sorghum grains and brans had high procyanidin contents (21-58 mg/g) compared to blueberry (20 mg/g), as measured by HPLC. Polymers with DP>10 were the major procyanidin constituents (66-84%) of brown sorghums. The relative ratio of oligomers (DP<10) to polymers (DP>10) increased significantly in processed products. Black sorghum brans had high anthocyanin content (4.5-11.0 mg/g) compared to commercial sources (0.8-10.0 mg/g). Luteolinidin and apigeninidin were the major anthocyanins in the black sorghums, accounting for about 50% of total anthocyanins. The red sorghum bran had high levels of naringenin (1.0 mg/g) compared to the other sorghum brans (0.17-0.26 mg/g). Specialty sorghums are a rich source of different phenols with high antioxidant potential and are a commercially viable source of these compounds for foods or pharmacological applications. High retention of antioxidant activity in processed products implies the sorghums are valuable food ingredients.
"Major Subject: Food Science and Technology".
Issued also on microfiche from University Microfilm Inc.
Includes bibliographical references (leaves 103-114).