15E-15 |
Polyphenolics and antioxidant capacity of muscadine grape cultivars grown in South Georgia |
C. C. AKOH and E. Pastrana-Bonilla. Food Science, University of Georgia, Athens, GA 30602-7610 Muscadine grape (Vitis rotundifolia) is an important food crop indigenous to the southeastern United States. As member of the Vitis family, it shares with other grapes a high content of phenolic compounds which have received increased attention because of their potential antioxidant activities and positive health effects on humans. The objectives of the study were to determine the major phenolic compounds found in muscadines such as total anthocyanins and total phenolics content, and to assess the antioxidant capacity of the grapes as well as their parts. Ten cultivars of muscadine grapes (five bronze-skin and five purple-skin) were separated into skin, seed and pulp, and each fruit part was extracted as aglycones and analyzed by HPLC for major phenolics. Total phenolics were determined colorimetrically, using Folin-Ciocalteu reagent. Total anthocyanins were determined by a pH-differential method, using UV-visible spectrophotometer. Antioxidant capacity was determined by the TEAC (trolox equivalent antioxidant capacity) assay. Gallic acid, (+)catechin and epicatechin were the major phenolics in seeds with average values of 6.56, 789 and 1234 mg/100g fresh weight, respectively. In muscadine skins ellagic acid, myricetin, quercetin, kaempferol and trans-resveratrol were the major phenolics with respective average values of 16.5, 8.34, 1.74, 0.64 and 0.14 mg/100g. Average total phenolics were 21.78, 3.75 and 0.24 mg/g gallic acid equivalent in seed, skin and pulp, respectively. Total anthocyanins contents were 1.34 and 118 mg/100g, in skins of bronze and purple grapes, respectively; 4.4 and 1.0 mg/100g in seeds and pulps, in that order. Antioxidant capacity values were 1.0, 11.4 and 285 mM TEAC for pulps, skins and seeds, respectively. The results show that muscadines are good sources of phenolic compounds, especially catechin, epicatechin and ellagic acid, and they may be considered as functional foods. Seeds were high in phenolic content and antioxidant capacity.
Session 15E, Nutraceuticals & Functional Foods I
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