Effect of drying methods on the phenolic content and antioxidant capacity of Brazilian winemaking byproducts and their stability over storage.

This work aimed to study the antioxidant capacity by different methods, the total content of polyphenols and the stability over time of dried byproducts from Brazilian hybrids and Vitis vinifera varieties. Oven-dried at 50 °C and spray-dried samples were monitored for 90 days of storage. Under testing conditions, BRS Violeta grapes showed the greatest stability and initial high levels of total phenolics and anthocyanins remained almost unchanged until the end of storage period. The same behavior was observed in BRS Violeta freeze-dried skins, seeds and lees (8557, 9520 and 4261 mg GAE/100 g DM, respectively, and 829 and 257 mg mv-3-glc/100 g DM in skin and lees, respectively). In all methodologies tested, BRS Violeta also showed higher values for antioxidant capacity. These results suggest that dried winemaking byproducts can be used as rich sources of polyphenol compounds for industrial extractions with high stability and antioxidant capacity.