49F-27 |
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V.-D. TRUONG1, R. L. Thompson1, R. F. McFeeters1, and M. M. Lanier2. (1) USDA-ARS-South Atlantic Area-Food Science Research Unit, North Carolina State Univ., Dept. of Food Science, Box 7624, Raleigh, NC 27695-7624, (2) Dept. of Animal Science, Box 7621, North Carolina State Univ., Raleigh, NC 27695-7621 Recent literature indicates that phenolic compounds in various fruits and vegetables may play an important role in health-promoting functions and prevention of chronic diseases. Few studies of the phenolic components of sweetpotatoes have been carried out. Information on these bioactive compounds will enhance the consumers' awareness of the nutritional value of sweetpotatoes. Objectives of this study were to 1) determine the types and distribution of phenolic compounds in different tissues in the roots of the major U.S. commercial sweetpotato cultivars and 2) measure the antioxidant activity of phenolic extracts. The outer layers (0.5 cm), including the skin and cortex of the roots were separated from the inner tissue. Samples were homogenized with 80% boiling ethanol and centrifuged. Supernatants were analyzed for total phenolics by the Folin-Ciocalteau method. Phenolic profiles were determined by UV-HPLC. Antioxidant activity (Trolox equivalent mg/g fresh weight) was evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radicals. Total phenolic content ranged from 0.72- 1.75 and 0.50-0.70 mg chlorogenic acid equivalent g-1 fresh weight for outer layers and inner tissue, respectively. There were significant differences (p>0.05) among the cultivars. Caffeic acid, chlorogenic acid, and four isochlorogenic acid derivatives were the main phenolic components present. DPPH and ABTS antioxidant capacity of outer layers were 0.65-3.22 and 0.35-1.39, respectively, and 0.23-0.62 and 0.37-0.50 for the inner tissue. Total phenolics were highly correlated with DPPH (r=0.94) and ABTS (r=0.98) antioxidant capacity. Cultivars and tissue zones of sweetpotato roots had different phenolic contents and antioxidant capacity. Appropriate cultivar selection and utilization of the whole roots in processed products would increase the availability of phenolic compounds from sweetpotatoes.
Session 49F, Fruit & Vegetable Products: Fresh vegetables
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