INSIGHTS ON THE ROLE OF GENES ON AROMA FORMATION OF WINES

The well-known antifungal and antibiotic molecule, eugenol, is widely spread in various plants including clove, basil and bay. It is also abundant in the hybrid grapevine cultivar (cv) Baco blanc (Vitis vi-nifera x Vitis riparia x Vitis labrusca), created by François Baco (19th century) in the Armagnac region. This study confirmed this cv as highly resistant to Botrytis cinerea by comparing fruit rot incidence and severity with two Vitis vinifera cultivars: Folle Blanche and Ugni Blanc. We have demonstrated the efficiency of eugenol in vitro, by further investigating the effect of small concentrations of eugenol, 3 to 4 ppm (corresponding to IC10), on B. cinerea. By comparing the two major modes of action (direct or volatile antibiosis), the vapour inhibiting effect of eugenol was more powerful. In the skin of Baco blanc berry, the total eugenol concentration reached a maximum at veraison, i.e. 1118 to 1478 μg/kg.

The synthetic herbicide glyphosate has been used extensively in viticulture over many decades to combat weeds. Despite this, the possible influence of residual glyphosate on both the alcoholic fermentation of grape juice and the subsequent metabolite profile of wines has not been investigated. In this study, Pinot noir juice supplemented with different concentrations of glyphosate (0 µg L-1, 10 µg L-1 and 1000 µg L-1) was fermented with commercial Saccharomyces cerevisiae yeast strains. Using a combination of analytical methods, 80 metabolites were quantified in the resulting wines.

Marselan wines have an unusual high proportion of seed derived tannins from grapes having high proportions of skins, which are rich in tannins. But the causes behind this characteristic have not yet been identified. In vintage 2023 wines were made at experimental scale (9 kg by experimental unit) from Arinarnoa, Marselan and Tannat Vitis vinifera grape cultivars by traditional maceration, and by techniques aimed to increase the wine content in skin derived tannin: addition of extraction enzymes, addition at vatting of grape-skin enological tannins, or by extended maceration, known to increase the seed derived tannin contents of wines. Macerations were of 7 days, except in the extended macerations that were of 15 days.

The sensory characteristics of wine are a topic studied by several researchers over time, but it continues to be a current and challenging subject. These characteristics are fundamental for the consumer acceptability, which has increasingly aroused their interest to modulate them in line with current market trends and innovation demands. The wine physical-chemical and sensory properties depend on a wide set of factors: they begin to be designed in the vineyard and are later constructed during the various stages of winemaking. Afterwards, the wine is placed in bottles and stored or commercialized.

Post-harvest grape berries dehydration/withering are worldwide applied to produce high-quality sweet and dry wines (e.i., Vin Santo, Tokaji, Amarone della Valpolicella). Temperature and water loss impact grape metabolism [1] and are key variables in modulating the production of grape compounds of oenological interest, such as Volatile Organic Compounds (VOCs), secondary metabolites responsible for the aroma of the final wine.
The aim of this research was to assess the impact of post-harvest dehydration on free and glycosylated VOCs of two Italian red wine grapes, namely Nebbiolo and Aleatico, dehydrated in tunnel under controlled condition (varied temperature and weight-loss, at constant humidity and air flow). From these grapes Sforzato di Valtellina Passito DOCG and Elba Aleatico Passito DOCG, respectively.