Influence of vineyard location on the quality parameters and phenolics of must and wine from two white grape varieties

Introduction: Nowadays, native grape varieties are considered important for their regions of origin, since they respond less to global warming compared to international varieties, increasing the suitability of winemaking regions, which are likely to decrease in the future. The aim of this study was to monitor the adaptation of two white wine grapes to different environments of the Drama PGI (Protected Geographical Indication) region and evaluate their impact on the qualitative characteristics and phenolic content of must and wine.

Methods: Two white varieties, one international (Sauvignon blanc, SB) and one native Greek (Assyrtiko, AS), grown in different locations (7 and 2, respectively) of the Drama PGI region during 2023 were used. Parameters such as harvest date and 100-berry weight were determined immediately after harvesting. Properly mature intact berries were removed from stems and crushed (25 kg batch-scale), and the juice was fermented (Saccharomyces cerevisiae 0.25 g/L) in 30 L vessels. The same winemaking procedure was applied to all grape samples. The parameters pH, titratable acidity, sugars, and total phenolic content, flavonoids, and anthocyanins (TPC, TFC, TA) were measured in must and the respective wines.

Results: The weight of 100 berries and the harvesting date of SB varied among locations (96-176 g, 233-283 days). Assyrtiko had heavier berries (>325 g) than SB and is a late-maturing variety (> 261 days). At higher altitudes (820m), SB grape maturation was delayed by 40 days. The must and respective wines differed regarding the quality attributes measured among the regions. Vineyard altitude correlated positively with must acidity (0.581, p<0.5) and negatively with wine pH (-0.548, p<0.05).

Conclusions: Although there exists a variation in the quality parameters of must and wines among the locations, in general, for the vintage 2023, the two varieties differ only on the acidity, TPC, and TFC values of wine. Moreover, the native Greek variety showed lower acidity and total phenolic content but higher flavonoid content than the Sauvignon blanc.