Fruit quality, nutraceutical and antimicrobial properties of 58 muscadine grape varieties (Vitis rotundifolia Michx.) grown in United States

Fifty-eight muscadine grape varieties were evaluated for their fruit quality, nutraceutical, and antimicrobial properties during two growing seasons (2012 vs. 2013). Fruit quality was significantly different among muscadine grape varieties, with weight ranged from 2.93 to 22.32 g, pH from 3.01 to 3.84, titratable acidity from 0.27% to 0.83%, and Brix from 10.92 to 23.91. Total phenols for different muscadine juices varied from 0.26 to 1.28 mg GA/mL, skins from 10.13 to 30.02 mg GA/g DM, and seeds from 22.47 to 72.01 mg GA/g DM. Accordingly, the antioxidant activity of grape juices varied from 0.97 to 6.78 mmol Trolox/mL, skins from 83.59 to 221.20 mu mol Trolox/g DM, and seeds from 178.22 to 619.73 mu mol Trolox/g DM. Study demonstratedgrape seed polyphenols (MIC 54.8-60.1 mu g/ml) showed stronger antimicrobial activity against S. aureus than skin polyphenols (MIC 70.7-80.2 mu g/ml). This information could be a valuable asset in the research and extension of muscadine grapes. (C) 2016 Elsevier Ltd. All rights reserved.