Influence of the type of tanks employed for winemaking on red wine phenolic composition

Abstract

The grape maturation process is being affected by the consequences of global climate change and, as a result, there is a gap at harvest time between the technological maturity of grapes (mostly the concentration of sugar and acids) and its phenolic quality. Due to this gap, the wines elaborated using those grapes show a non-adequate phenolic composition, which results in defects on its color and astringency characteristics. Astringency is mainly related to the salivary protein precipitation because of the interaction not only with wine flavanols but also with other wine phenolics, such as flavonols or different pigments. Moreover, the different flavanol structures (catechins, gallocatechins, galloylated derivatives) show different abilities for interacting with salivary proteins and, therefore, they show different astringent characteristics (Ferrer-Gallego et al, 2015). Likewise, color is mainly related to anthocyanin composition of wines but the presence or other phenolic compounds, namely flavonols, flavanols or phenolic acids, which can act as copigments, also exert an important influence on that organoleptic property. Thus, different strategies, both viticultural and oenological, could be addressed looking for the modulation of phenolic composition and, consequently, the improvement of the organoleptic properties of wine, such as the modulation of astringency and the stabilization of wine color (García-Estévez et al., 2017).This work evaluates the influence of different type of tanks built with different materials, i.e. stainless steel tanks, oak wood barrels or earthenware vats, on the phenolic composition of wines at different times of winemaking and wine maturation. To do this, the alcoholic fermentation was performed using stainless steel tanks or earthenware vats, whereas the malolactic fermentation was carried out using oak wood barrels of different sizes or earthenware vats. The detailed anthocyanic, flavanolic and flavonolic composition of wines were determined after both fermentation steps by using HPLC-DAD-MS. Results show that wines that performed the alcoholic fermentation in stainless steel tanks have higher levels of flavanols and anthocyanins but lower levels of flavonols than those wines fermented in earthenware vats. Moreover, wines elaborate in stainless steel tanks that performed the malolactic fermentation in oak barrels or in earthenware vats do not show significant differences on their phenolic composition excepting for the prodelphinidins proportion in their flavanol composition. However, when earthenware vats were used just for malolactic fermentation, after alcoholic fermentation in stainless steel tanks, wines showed higher levels of phenolic compounds than when both fermentation processes are carried out in the earthenware vats, thus pointing out that boththe type of tank and the time when it is employed are important for the phenolic composition of wines.

References

Ferrer-Gallego et al., 2015. Chem Senses, 40, 381-390.
García-Estévez et al., 2017. OENO One, 51, 237-249.