EUGENOL AS QUALITY MARKER OF WINES AND SPIRITS FROM HYBRID VINES: IMPACT OF DIFFERENT WINEMAKING AND DISTILLATION PROCESSES

Abstract

Eugenol, widely spread in various plants notably cloves, basil and bay, was identified too in wines from hybrid grapes without contact with oak wood. This aromatic molecule presents a strong spicy note of clove and also antifongic properties. Eugenol was described as an endogenous compound of Baco blanc, from the grapes to the spirits of Armagnac area. Moreover, this compound is a chemical marker of Baco blanc products quality.
Influences of harvest time and different winemaking processes (settling, use of enzymatic preparations, lees content and stock time before distillation) on Baco blanc wine eugenol contents were explored using a two-levels full factorial Design of Experiments (DoEs). Each modality was twice-distilled at the same ABV (Alcohol By Volume) to produce white spirits. Quantified by HS-SPME-GC/MS with a proven methodology, eugenol is particularly concentrated in wines (median content 43 μg/L) and white spirits (me-dian content 124 μg/L) made with Baco blanc cultivar. Eugenol content in wines and spirits were mainly determined (66%) by harvest time: the earlier the harvest date, the higher eugenol concentration in wines (variation from 28 to 126 μg/L) and spirits (variation from 57 to 317 μg/L). This observation was confirmed by measuring the concentration of eugenol in Baco blanc berries during their development. Our results also highlight the fact that the use of β-glucosidase enzymatic preparation after alcoholic fermentation (21% of determination) permits to enhance eugenol levels. At the evidence a bound fraction of eugenol in Baco blanc wines exists. The perspective of identification and evaluation of the eugenol precursor have been operated to improve quality of Baco blanc products. First approaches trends to identify a majority precursor (80% of the bound eugenol). Moreover the use of a full factorial DoE highlighted the key steps of winemaking process that most influence the concentrations of the different forms of eugenol. Sensory analyses carried out with a panel of professionals trends to show that eugenol is involved in perceptual interactions at the heart of Baco blanc spirits quality. Finally, the different forms of eugenol are not only a subject of study for Armagnac spirits, but of wider interest in the composition of hybrid and resistant vines and in the characterisation of the organoleptic quality of wine spirits.