Seasonal variations and climate interactions with phenolic extractability of Pinot noir across the whole winemaking process

Abstract

Context and Purpose of the Study. A deeper understanding of the relationship between weather conditions and wine quality is essential for assessing the impact of climate change and developing effective adaptation strategies. This study introduces a novel approach, utilizing data from a single vineyard under controlled conditions to analyze phenolic extraction. Results on berry phenolics were combined with a micro-scale winemaking technique to produce wines under consistent conditions for each vintage over 11 years (Blank et al., 2019). The aim of this second part of the study was to deepen insights into the climatic influence on phenolic extractability by incorporating data from pomace and lees to perform a component allocation mass balance analysis.

Material and methods. Grapes of Vitis vinifera L. cv. Pinot Noir, grafted onto rootstock SO4 and cultivated in a vineyard at Hochschule Geisenheim University (Germany), were studied over the 2005–2015 period. The phenolic composition was analyzed across four field replicates of Pinot Noir, both before and after fermentation, in various co-products (berries, wines, pomace, and lees).

Results. Only 9% of tannins present in the grapes were extracted into the wine, while 56% remained in the pomace and 13% bound to the lees. Using a component allocation method, phenolic profiles were successfully linked to seasonal climatic conditions. Warmer temperatures, particularly before véraison, combined with low precipitation, were associated with increased tannin accumulation in fruit and wine, with a stronger accumulation in skins compared to seeds. Heat accumulation between flowering and veraison ([ΣGDD10°C]) increased the proportion of seed-derived tannins in the wine. However, higher temperatures during this period negatively affected tannin extraction efficiency, resulting in a larger proportion of tannins being “”unaccounted for.””

Conclusion. This study presents the first comprehensive component allocation approach for tannins throughout the entire winemaking process, correlating phenolic profiles to seasonal climatic variations, allowing for adaptation strategies to mitigate the impacts of climate change on wine quality.