Changes in Phenols, Color, and Sensory Characteristics of Muscadine Wines by Pre- and Post-Fermentation Additions of PVPP, Casein, and Gelatin

White muscadine wine (Vitis rotundifolia, cv. Welder) was treated before or after fermentation with polyvinylpolypyrrolidone (PVPP, 0.5 and 1 g/L), casein (Kolorfine, 0.5 and 1 g/L), and gelatin (0.3 and 0.6 g/L) and compared to a control (non-treated). Red muscadine wine (cv. Noble) was treated with the same fining agents after fermentation. PVPP and casein added pre- or post-fermentation reduced total and flavonoid phenols, lightened the color, and improved resistance to browning in the white wine. PVPP was more effective than casein, and there was little difference between the pre- and post-fermentation additions of fining agents on color or phenols in the white wine. Gelatin had little effect on the color, but reduced phenols in the white wine, and both pre- and post-fermentation additions of gelatin changed the sensory characteristics of the white wine as compared to a control in triangle tests. Post-fermentation additions of PVPP also altered the sensory characteristics of the white wine, but casein did not. Post-fermentation addition of casein and especially PVPP reduced total and polymeric phenols, and lightened the color of the red wine. PVPP also reduced the brown color in the red wine. Gelatin had little effect on the phenols, color or sensory characteristics of the red wine. Only PVPP significantly altered the sensory characteristics of the red wine.