Sensory profiles and European Consumer Preference related to Aroma and Phenolic Composition of Wines made from Fungus Resistant Grape Varieties

Abstract

New grape varieties with several resistance loci towards powdery and downy mildew allows to significantly reduce the use of fungicides. These fungus resistant grape varieties (PIWI from the German Pilzwiderstandsfähig) play a crucial role to reach the goal to lower pesticide use by 50% as requested by the European Green Deal for 2030. However, wine growers are reluctant to plant them due to a lack of experience in vinification and uncertainty how consumer perceive and purchase wines of these completely unknown varieties.
The objective of this study within the VITIFIT research consortium was to vinify different wine styles in two vintages from grapes of four white and three red PIWI. Most of them came from the same experimental site, where four classic varieties were planted as well. We regressed data obtained by descriptive analysis with hedonic ratings from German, French, Italian, Danish and Dutch consumers. Several consumer segments appeared having different drivers of preference, however all consumers disliked sour, astringent and green wines with less fruit and color. Wine professionals scored the same wines and judged the wines very similar to the consumers: 9% of PIWI wines were rated significantly better, 9% significantly inferior and in 82%, no difference occurred.
To unravel the molecular base we analysed aroma compounds in a non-targeted way as well as by targeted analysis by SIDA-GC-MS or LC-MS for monoterpenes, C13-norisoprenoids and polyfunctional thiols. Analysis of phenolic compounds covered indirect measurements such as Folin-C or Harbertson-Adams-Assay as well as targeted analysis by LC-MS or LC-DAD. In case of the Muscaris (PIWI) versus Muskateller comparison Muscaris wines were richer in cis-roseoxide, while linalool and α-terpineol were higher in Muskateller wines. A sensory napping analysis however, could not distinguish wines of both varieties. So far, no specific off-flavors could be detected in the new PIWIs as they are reported for old hybrid varieties. Although fungus resistance may relate to increased polyphenols in the grape skin, red wines made from PIWI did not show higher concentrations in general across the different winemaking styles.
Overall, making wines from grapes from the same or very similar vineyards, PIWIs delivered from a sensory and hedonic point of view equivalent or even superior wines. Using different winemaking styles allow fulfilling specific and varying sensory demands of European consumers. Combining these findings with the elsewhere reported improved sustainability in growing PIWIs, should convince a rising number of conventional and organic vintners to plant more PIWIs in the near future.

References

sensory evaluation, fungus resistant grape varieties, consumer, aroma compounds, polyphenols