Search results

Grapevine leaves are a major by-product of viticulture practices derived from the leaf-removal from the fruit cluster zone in all vine growing regions. These leaves can be a valuable source of antioxidants to be used in pharmaceuticals or other health-related products. In this study, the leaves of grapevine cultivars were analysed by ultra-high performance liquid chromatograph-diode array detector () for the total polyphenols (TPC) and resveratrol a ected by cultivar, leaf-removal time and viticultural practice. The e ect of cultivar varied yearly, European grapevine cv. 'Regent' had increased TPC and resveratrol in comparison to 'Boskoop's Glory', 'Rondo' and 'Solaris' in 2017, but 'Solaris' in 2018. TPC (1213–1841 mg 100 g-1) and resveratrol (1.061 mg 100 g-1) were higher in leaves of interspecific hybrid cvs. 'Zilga' and 'Hasansky Sladky' during full fruit ripeness. Cv. 'Rondo' grown under the polytunnel had decreased TPC in leaves. In conclusion, cultivar selection, viticultural practice and leaf-removal time contribute significantly to the accumulation of total polyphenols and resveratrol. Results of this study will contribute to better utilization of biomass produced in the vineyards, help to decrease the negative environmental impacts, and provide an overview on various factors a ecting the biochemical constituents, especially in leaves. ; This research is funded by VALORTECH project, which has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 810630. ; This research is funded by VALORTECH project, which has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 810630.

Grapevine shoots and canes represent a significant amount of biomass, considered as a waste in viticulture. In cooler climates, grapevines are pruned in the autumn (October) and spring (March) due to harsh winter conditions (e.g., snow, low temperatures), and large amounts of biomass are produced at these different pruning times. This work was undertaken in order to investigate the potential of vineyard pruning waste for recovery of polyphenolic compounds for biomass valorization. Qualitative and quantitative analyses of grapevine shoot and cane polyphenols, including flavonoids and stilbenoids were performed using UHPLC MS/MS method. The results revealed the flavonols (quercetin) to be the most abundant compounds in shoots among all the three cultivars screened (Zilga, Hasansky Sladky, Rondo). Stilbenoids (ε-viniferin) dominated in the canes, while increased level of flavonols with lower contents of stilbenoids was detected in the endodormant canes, and higher amounts of flavanols and stilbenoids were recorded in eco-dormant canes. In conclusion, the content of polyphenols in grapevine shoots and canes differed among the cultivars and dormancy phases. The results generated from the present study contribute to the sustainable and environmentally friendly viticulture practice via valorization of vineyard pruning wastes. ; This research received funding from the ongoing project—Valortech, which has received funding from the European Union's Horizon 2020 research and innovation program under a grant agreement No 810630. Funding received from Mobilitas Pluss ERA-Chair support (Grant no. MOBEC006 ERA Chair for Food (By-) Products Valorisation Technologies of the Estonian University of Life Sciences) is acknowledged.