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Kirje Acid composition of wines depending on grapevine (Vitis spp.) cultivars grown in Estonia(Estonian University of Life Sciences, 2025) Rätsep, Reelika; Maante-Kuljus, Mariana; Karp, Kadri; Seeme, Kersti; Moor, Ulvi; Estonian University of Life Sciences. Institute of Agricultural and Environmental Sciences. Chair of Horticulture; Estonian University of Life Sciences. Institute of Veterinary Medicine and Animal Sciences. Chair of Food Science and TechnologyIn Estonia’s very cool climate, excessive acid content in grapes can be a challenge due to delayed ripening. This study aimed to compare the acid profiles of commercial single-cultivar wines produced by Estonian winemakers, and assess the influence of grapevine cultivar. The wines were made from grapes of five different cultivars: ‘Solaris’, ‘Regent’, ‘Leon Millot’, ‘Cabernet Cortis’, and ‘Marquette’. The results revealed significant variation in malic, tartaric, citric, and lactic acid concentrations among the wines. Marquette exhibited the lowest malic acid content (0.3 g L⁻¹), while Leon Millot had the highest (4.4 g L⁻¹). Tartaric acid levels in wines ranged from 2.2 g L⁻¹ in Leon Millot to 4.1 g L⁻¹ in Regent. Citric acid levels varied considerably, with Solaris containing the highest concentration (1.44 g L⁻¹). Marquette had the highest lactic acid content (2.27 g L⁻¹), contributing to its smooth character. Total acid content in wines ranged from 6.9 g L⁻¹ in Marquette to 9.4 g L⁻¹ in Leon Millot, while pH values varied between 2.9 and 3.3. These findings indicate that grape cultivar significantly influences wine acid composition. Contrary to the hypothesis, excessive acid content was not a major issue in commercial wines; however, grape-growing conditions, such as high plastic tunnels, could alter this outcome. This study provides valuable insights for winemakers seeking to optimize acid balance and enhance wine quality in cool-climate viticulture.Kirje Maturity parameters of grapevine (Vitis sp) yield(Eesti Maaülikool, 2021) Maante-Kuljus, Mariana; Karp, Kadri (advisor); Mainla, Leila (advisor); Vool, Ele (advisor); Kampuss, Kaspars (opponent)The biochemical composition of table and wine grapes is affected by the cultivar properties, vintage and viticultural practices. Most of the research has been done with different grapevine (Vitis vinifera) cultivars. There is a little information about interspecific hybrid grapevine cultivars yield in cool climate conditions. The aim of the thesis was to find out the effect of vintage, cultivar, and viticultural practises on maturity parameters of interspecific hybrid grapevine cultivars. Table grape experiment showed that it is recommended to cultivate 'Osella', 'Somerset Seedless', 'Kosmonavt', and 'Arkadia' in tunnel. Technological maturity parameters of wine grapes were not at the desirable level every year. 10-year-long data assessment showed that there was a problem with low sugars and high organic acids contents. Tartaric acid content was at the desirable level but there was a problem with higher malic acid content, which gives sharp-sour taste to wine. Analyse of phenolic maturity showed that anthocyanins content could reduce in tunnel conditions. In addition, there were significant differences in anthocyanins profiles. In cooler years, wine colour could be reddish because dominant monoanthocyanins were peonidin- and cyanidin-3-O-glycosides, and in warmer years (also in tunnel), it could be purplish because delphinidin- and malvidin-3-O-glycosides were dominant. In addition, results showed that the ripening of wine grapes significantly varies from year to year, which in turn affects the choice of vinification technology. According to Heliothermal Index Rõhu experimental area situates in a very cool viticultural zone. Early cultivars can be cultivated in the field (e.g. 'Hasansky Sladky'), but later ripening ones are recommended to be cultivated in the tunnel (e.g. 'Rondo'). In cool years, it is advisable to make wines with lower alcohol content: white, rose or sparkling. Also mixing cultivars can be recommended. For example, 'Hasansky Sladky' had high sugar but low anthocyanins content. But in 'Rondo' these parameters were reversed. By mixing the yield of these two cultivars, a better quality raw material for the red wine can be obtained.Kirje Polyphenols and resveratrol from discarded leaf biomass of grapevine (Vitis sp.): Effect of cultivar and viticultural practices in Estonia(MDPI, 2020) Rätsep, Reelika; Karp, Kadri; Maante-Kuljus, Mariana; Aluvee, Alar; Bhat, Rajeev; ERA Chair for Food (By-) Products Valorisation Technologies (Valortech). Estonian University of Life Sciences; Institute of Agricultural and Environmental Sciences. Polli Horticultural Research Centre; Institute of Agricultural and Environmental Sciences. Estonian University of Life SciencesGrapevine 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.Kirje Polyphenols and resveratrol from discarded leaf biomass of grapevine (Vitis sp.): Effect of cultivar and viticultural practices in Estonia : [data](Estonian University of Life Sciences, 2020) Rätsep, Reelika; Karp, Kadri; Maante-Kuljus, Mariana; Aluvee, Alar; Bhat, RajeevGrapevine 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.Kirje Recovery of polyphenols from vineyard pruning wastes - shoots and cane of hybrid grapevine (Vitis sp.) cultivars(MDPI, 2021) Rätsep, Reelika; Karp, Kadri; Maante-Kuljus, Mariana; Aluvee, Alar; Kaldmäe, Hedi; Bhat, Rajeev; ERA-Chair for Food (By-) Products Valorisation Technologies (VALORTECH). Estonian University of Life Sciences; Polli Horticultural Research Centre. Institute of Agricultural and Environmental Sciences; Institute of Agricultural and Environmental Sciences. Estonian University of Life SciencesGrapevine 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.Kirje Recovery of polyphenols from vineyard pruning wastes - shoots and cane of hybrid grapevine (Vitis sp.) cultivars : [data](Estonian University of Life Sciences, 2021) Rätsep, Reelika; Karp, Kadri; Maante-Kuljus, Mariana; Aluvee, Alar; Kaldmäe, Hedi; Baht, RajeevGrapevine 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.