Materials
2.1.1. Grape materials
Fully ripened Muscadine grape (Vitis rotundifolia Michx.) cv. Noble (red) and cv. Carlos (bronze) were harvested from the Center for Viticulture and Small Fruit Research (latitude 30.65 N, longitude 84.60 W) at Florida A&M University on September 2, 2011. The collected samples were shipped to the University of Florida on the same day and stored in a cold room (4°C). Grape skins and seeds were separated manually from berries and freeze-dried in a freeze drier (Advantage, The Virtis Company, NY, USA) within the following three days. The freeze-dried samples were stored in vacuum-packaged polyethylene pouches at −20°C until analysis.