2024 Survey of Phenolic Compounds in Virginia Cabernet Franc Wines

Muheng Li, Alicia Surrat, Joy Ting, Dennis Cladis

The WRE, in collaboration with Virginia Tech presents:

An introductory foray into categorizing phenolics in Virginia red wines

Summary

Phenolic compounds are one of the hallmarks of quality in red wines. In 2024 the WRE partnered with Dr Dennis Cladis from the Virginia Tech Department of Food Science & Technology to survey phenolic content in Virginia Cabernet Franc wines. The purpose of this Virginia Wine Board funded study was to:

build the capacity to measure wine phenolic compounds in Dr. Cladis’ lab
identify average and range for phenolic compounds in Virginia Cabernet Franc wines and
compare the average and range of phenolic compounds in Virginia Cabernet Franc based on vintage year and growth region.

For this study, 79 samples of bottled wine from the 2019-2023 vintages were collected from vineyards in 5 regions of Virginia: Northern (33), Central (31), the Shenandoah Valley (10), Southwest (3) and Eastern (2), as well as samples from outside Virginia (7) to use as comparators. Wines were analyzed for total phenolic content, monomeric anthocyanins, polymeric anthocyanins and condensed tannin. LC/MS-MS was used for quantification of individual compounds.

Wines from Virginia contained similar total phenolic content, condensed tannin, monomeric and polymeric anthocyanins as the non-Virginia wines tested. There were also no significant differences in any of the phenolic measures based on regions within Virginia.

Wines from the 2019 and 2023 vintages had significantly higher average total phenolic content while wines from 2020 and 2022 had significantly lower average total phenolic content. Higher phenolic content in 2023 was likely driven by significantly higher monomeric anthocyanins (it was the youngest wine in the dataset). Wines from 2019 also had significantly higher condensed tannins, possibly due to excellent growing conditions of 2019 leading to increased extractability of tannins in fully mature grapes. Pending LCMS-MS data may shed additional light on the impact of oak barrels (ellagic acid), contribution of seed and skin tannins (catechin, epicatechin vs. gallocatechin, epigallocatechin), and susceptibility for Brett spoilage (ferulic acid, p-coumaric acid).

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