Coming of age: do old vines actually produce berries with higher enological potential than young vines? A case study on the Riesling cultivar

Abstract

Consumers and the wine industry tend to agree on the ability of old vines to produce fruit that allows the production of wine of superior character. However, despite past and ongoing research, objective evidence of this point of view is still debated and studies on robust, specifically dedicated plots are scarce.

Thus the impact of grapevine age on berry oenological potential and wine quality remains an open question. To try to objectively address the issue, a unique vineyard was established at Geisenheim University, Germany. It was planted in 1971 with cv. Riesling grafted on 5C Teleki. In 1995 and 2012, several rows were uprooted and replanted with the same rootstock/scion combination, resulting in a vineyard with alternate rows of identical plant material, but with different planting dates. The parameters of technical maturity and grape composition at harvest were analyzed during seasons 2014, 2015, 2016 and 2017 combining HPLC and enzymatic methods. Separate micro-vinifications were made for each age group and wine composition was analyzed by a combination of 1H-NMR and SPE-GC-MS.

The results showed that technical maturity parameters (TSS, TA, must pH) were not significantly different across the three grapevine age groups. Berry composition showed little differences in quality-relevant metabolite contents, with the noticeable exceptions of α-amino acid, skin flavonols, free and bound monoterpene and norisoprenoid amounts that were significantly higher in vines planted in 2012 compared to older vines, but only in seasons 2014 and 2015 where soil management practices of the young vines differed. Berries from vines planted in 1971 and 1995 did not exhibit significant differences in berry composition, throughout the four seasons. Wine chemical analysis complemented and confirmed results obtained in berry composition. Wine made from grapes produced by vines planted in 2012 had higher terpene and norisoprenoid amounts, compared to wines made with grapes from the two other vines groups, but only for the 2014 and 2015 vintages. Wines from grapes produced by vines planted in 1971 and 1995 did not exhibit significant differences in composition throughout the four seasons.

conclusion:

In conclusion, even though vines planted in 2012 exhibits significant differences in berry and wine composition for their two first vintages compared to older ones, these differences appeared to vanished once the vines were fully established and soil management practices became uniform.

Acknowledgments:

This work was supported by a PhD grant to K. Bou Nader from the Forschungsring Deutscher Weinbau.