EFFECT OF DIFFERENT VITICULTURAL AND ENOLOGICAL PRACTICES ON THE PHENOLIC COMPOSITION OF RED WINES
Global climate change is exerting a notable influence on viticulture sector and grape composition. The increase in temperature and the changes in rainfall pattern are causing a gap between phenolic and technological grape maturities . As a result, the composition of grapes at harvest time and, consequently, that of wines are being affected, especially with regards to phenolic composition. Hence, wine quality is decreasing due to changes in the organoleptic properties, such as color and astringency, making necessary to implement new adaptive technologies in wineries to modulate these properties in order to improve wine quality.
The aim of this work is to study the effect of different viticultural practices, such as traditional cultivation, organic cultivation and the use of natural fertilizer on the phenolic composition of grapes. In addition, the effect on wine phenolic composition of using tanks made of different materials (stainless steel tanks, oak wood barrels/tanks or earthenware vats) at different stages of winemaking and aging was evaluated over three vintages. The detailed phenolic composition of grapes and wines was determined by HPLC-DAD-MS .
Results obtained showed that the use of natural fertilizer did not cause significant differences in the pigment composition of grapes. However, a combination of organic cultivation with natural fertilizer significantly increased the total content of pigments and flavanols when compared to traditional cultivation with no fertilization. Regarding wines, higher levels of total flavanols and anthocyanins were observed when alcoholic fermentation (AF) was carried out in stainless steel tanks than when wines were fermented in earthenware vats. In the first ones (AF in stainless steel tanks), the type of container (oak barrels or earthenware) employed for the subsequent malolactic fermentation (MLF) did not have a significant influence in their phenolic composition. However, higher levels of phenolic compounds were observed in wines with AF made in stainless steel tanks and MLF in earthenware vats than in wines in which both fermentation processes occurred in earthenware vats. The obtained results showed that the type of tank as well as the stage at which it is used might have a significant influence on the phenolic composition of the wines. This could allow envisaging the most adequate tanks for each step of winemaking and aging in order to obtain wines with an adequate phenolic composition.
Issue: OENO Macrowine 2023
1. Grupo de Investigación en Polifenoles, Facultad de Farmacia, Universidad de Salamanca, Salamanca, E37007, Spain
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red wine, phenolic compounds, earthenware vats, HPLC-DAD-MS