45F-6 |
Ellagitannin content and antioxidant capacity of muscadine grapes as affected by cultivar and maturity |
J. LEE and S. T. Talcott. Dept. of Food Science & Human Nutrition, Univ. of Florida, 359 FSHN Bldg., Newell Dr., PO Box 110370, Gainesville, FL 32611-0370 Muscadine grapes are an important fruit crop in the southern United States with a unique phytochemical composition due to their ellagic acid and ellagitannin composition. These compounds have been related to potential health-promoting benefits and exhibit good antioxidant properties. Limited data exists on ellagic acid and ellagitannin composition of muscadine grapes and their resultant antioxidant capacity (AOX). These attributes were examined in 8 grape cultivars as influenced by two maturity levels and their location within the fruit (skin, pulp and juice). Ellagic acid and ellagitannins were partitioned into ethyl acetate from hot-pressed juice and from extracts of skin and pulp. Solvent was evaporated and re-dissolved in citric acid buffer. Novel chromatographic conditions were developed to characterize and quantify free ellagic acid, two ellagitannins, and total ellagic acid (following acid hydrolysis) by HPLC. AOX was determined on these same isolates using the oxygen radical absorbance capacity assay. Generally, both ellagic acid and ellagitannins increased as fruit ripened, with highest concentrations located in the skins. Free ellagic acid ranged from 40-811 and 3-122 mg/kg while total ellagitannins ranged from 134-1,040 and 0-94 mg/kg in the skin and pulp of mature grapes, respectively. Total ellagic acid varied from 586-1,890 mg/kg in skin and 4-383 mg/kg in pulp of mature grapes. Hot-pressed juice contained considerably less of each compound and yielded only 8, 9 and 34% of free ellagic acid, total ellagitannins and total ellagic acid, respectively. AOX varied with cultivar and maturity and showed higher correlations to the amounts of ellagic acid species in immature grapes compared to mature grapes. These differences were potentially due to the development of additional polyphenolics during fruit ripening. Results show the diversity of ellagic acid and ellagitannins in muscadine grape varieties and related changes associated with maturity and location within the fruit.
Session 45F, Fruit & Vegetable Products: Fruits (Fresh)
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