SENSORY PROFILES AND EUROPEAN CONSUMER PREFERENCE RELATED TOAROMA AND PHENOLIC COMPOSITION OF WINES MADE FROM FUNGUSRESISTANT GRAPE VARIETIES (PIWI)

Abstract

Planting grape varieties with several resistance loci towards powdery and downy mildew reduces the use of fungicides significantly. These fungus resistant or PIWI varieties (acronym of German Pilzwiderstandsfähig) contribute significantly to the 50% pesticide reduction goal, set by the European Green Deal for 2030. However, wine growers hesitate to plant PIWIs as they lack experience in vinification and are uncertain, how consumer accept and buy wines from these yet mostly unknown varieties.

Grapes from four white and three red PIWI varieties were vinified in three vintages to obtain four different white and red wine styles, respectively plus one rosé. PIWI varieties as well as four reference Vitis vinifera varieties were planted in the same site. For each vintage, more than 70 winemakers compared the different PIWI styles with the Vitis vinifera reference wines. 70% of the comparisons yielded no significant differences, in 20% PIWI wines were superior and in 10% the reference wines. Regressing intensity ratings obtained by descriptive analysis with hedonic ratings from German, French, Italian, Danish and Dutch consumers, we could deduce drivers of liking in respect to the different cultural back ground. All consumers disliked sour, astringent and green expressions in wines while fruit and colour remained low. Floral and yellow fruits were preferred by French and German consumers, Danish liked thiol-derived flavours.

To unravel the molecular base aroma compounds were analysed non-targeted as well as targeted for monoterpenes, C13-norisoprenoids and polyfunctional thiols applying SIDA-GC-MS or LC-MS. Analysis of phenolic compounds was done by indirect methods such as Folin-C or Harbertson-Adams-Assay as well as targeted analysis by LC-MS or LC-DAD. Comparing Muscaris (PIWI) versus Muskateller Muscaris wines were richer in cis-rose oxide, while linalool and α-terpineol were higher in Muskateller wines. So far, no specific off-flavour could be detected in wines from PIWI varieties as it was the case for old hybrid varieties. Although fungus resistance may be related to grape skin polyphenols, in general neither white nor red PIWI wines revealed higher polyphenol concentrations, except for Muscaris and Cabernet Cortis. A fact which needs to be addressed in winemaking.

In conclusion, applying targeted winemaking allows to produce PIWI wines, which meets the expectations of European consumers in sensory terms, but also in respect to improved sustainability.