Study on Kinetics of Trans-Resveratrol, Total Phenolic Content, and Antioxidant Activity Increase in Vine Waste during Post-Pruning Storage

There is increasing evidence surrounding the health benefits of E-resveratrol; this has triggered interest in stilbenoids in grapes, wine, and by-products. On the one hand, there is an enormous amount of underutilized vine waste, rich in bioactive substances during wine production. On the other hand, there is a growing demand for promising phytochemicals, for dietary and pharmaceutical purposes. Vine shoots are promising sources of stilbenoids; they have economic potential because they are sources of high-value phytochemicals. Recent studies have shown that, due to biosynthesis pathway genes, especially STS (forming trans-resveratrol), which is abundant during storage periods of vine shoots—trans-resveratrol accumulates up to 40-fold. The objective of this research was to determine the most economical part of vine waste to be exploited, and to study the kinetics of resveratrol increase in a 90-day period, to determine the optimal storage period to reach a maximum trans-resveratrol content. Total phenolic content (TPC) and antioxidant activity (AA) were studied to determine possible correlations. In Fetească Neagră vine shoot varieties stored at laboratory temperatures, trans-resveratrol content increased to a maximum (2712.86 mg/kg D.W.) at day 70, and then slightly decreased until day 90. TPC remained constant and there was a slight increase in AA. Vine shoots contained the largest amounts of trans-resveratrol (1658.22 mg/kg D.W.), followed by tendrils (169.92 mg/kg D.W.), and leaves (43.54 mg/kg D.W.).