Hard Pressed to Find A Difference: Evaluating the total tannin content of Cabernet franc L cv. wines, made using pre- and post-fermentation pressing treatments

Abstract

Total tannin concentrations were monitored in Cabernet franc grapes in 2018 and 2019 from two vineyard areas in the Niagara Peninsula, Ontario. Total tannins were measured using the methyl cellulose precipitation (MCP) assay. In 2018, post-fermentation pressing treatments of 100kPA, 150kPA and 200kPA were applied with a control (no press treatment). In 2019, pre-fermentation pressing treatments in combination with juice removal (saignée) were applied with a control (no pre-fermentation treatment). Free sorting and consumer preference testing of the 2018 wines were evaluated using trained panellists and a consumer panel. Pre- and post-fermentation press treatments had little impact on the tannin concentrations in wines post fermentation. Observed trends over time suggest treatments have an influence in the behavior of tannin polymerization and stability, but these results are specific to vineyard site. This suggests that Cabernet franc varietal wines can be produced using low press-treatments without compromising the concentration of total tannins which may contribute to improved wine quality.