UNTARGETED METABOLOMICS ANALYSES TO IDENTIFY A NEW SWEET COMPOUND RELEASED DURING POST-FERMENTATION MACERATION OF WINE

Canopy-management practices are applied in viticulture to improve berries composition and quality, having a great impact on primary and secondary grape metabolism. Among these techniques, cluster zone leaf removal (defoliation) is widely used to manage air circulation, temperature and light radiation of grape bunches and close environment. Since volatiles are quantitatively and qualitatively influenced by the degree of fruit ripeness, the level of solar exposure, and the thermal environment in which grapes ripen, leaf removal has been shown to affect volatile composition of grape berries [1].

In recent years, vineyards in Australia, the US, Canada, Chile, South Africa and Europe have been exposed to smoke from wildfires. Wines made from smoke-affected grapes often exhibit unpleasant smoky, ashy characters, attributed to the presence of smoke-derived volatile compounds, including volatile phenols (which occur in free and glycosylated forms). Various strategies for remediation of smoke tainted wine have been evaluated. The most effective strategies involve the removal of smoke taint compounds via the addition of adsorbent materials such as activated carbon, which can either be added directly or used in combination with nanofiltration. However, these treatments often simultaneously remove wine constituents responsible for desirable aroma, flavour and colour attributes.

Lambrusco is a commercially successful sparkling red and rosé wine. With 13.06 million litres sold in 2021 was the second best-selling Italian wine after Chianti. According to National Catalogue of Vine Varieties there are thirteen Lambrusco Varieties with which to date are produced seven PDO wines. Among these, “Lambrusco Salamino di Santa Croce”, “Lambrusco Grasparossa di Castelvetro” and “Lambrusco di Sorbara” are the only ones that can be considered mono-varietal appellations, all located in Modena area. The PDOs contemplate the possibility of producing wines by secondary fermentation either in tank (Charmat method), or in bottle (Classico method). Sur lie is a third method commonly employed for Lambrusco, similar to the Classico method, from which differs for the absence of disgorgement.

Young white wines are typically released to the market a few months after harvest, to be consumed within a year, when their fresh fruity aromas are still dominant and appealing to modern consumers. Esters, particularly higher alcohol acetates (HAAs) and ethyl esters of fatty acids (EEFAs), play a central role in the fruity expression of young white wines [1]. However, these esters are known to undergo significant hydrolysis during the first months of aging [1, 2].

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.