Monitoring small-scale alcoholic fermentations using a portable FTIR-ATR spectrometer and multivariate analysis

La caratterizzazione della frazione volatile aromatica dei vini attraverso l’analisi quali­quantitativa dei diversi composti, ha portato corne primo risultato la netta differenziazione delle annate in prova.

Spatial variability of vine productivity in winegrapes is important to characterise as both yield and quality are relevant for the production of different wine styles and products. The objectives were to understand how patterns of variability of Cabernet Sauvignon fruit composition changed over time and space, how these patterns could be characterised with indirect measurements, and how spatial patterns of the variation in fruit compositional attributes can aid in improving management. Prior to the 2017 vintage, 125 data vines were distributed across each of four vineyards in the Lodi American Viticultural Area (AVA) of California. Each data vine was sampled at commercial harvest in 2017, 2018, and 2019. Yield components and fruit composition were measured at harvest for each data vine, and maps of yield and fruit composition were produced for eight ‘objective measures of fruit quality’: total anthocyanins, polymeric tannins, quercetin glycosides, malic acid, yeast assimilable nitrogen, β-damascenone, C6 alcohols and aldehydes, and 3-isobutyl-2-methoxypyrazine. Patterns of variation in anthocyanins and phenolic compounds were found to be most stable over time. Given this relative stability, management decisions focused on fruit quality could be based on zonal descriptions of anthocyanins or phenolics to increase profitability in some vineyards. In each vineyard, dormant season pruning weights and soil cores were collected at each location, elevation and soil apparent electrical conductivity surveys were completed, and remotely sensed imagery was captured by fixed wing aircraft and two satellite platforms at major phenological stages. The data collected were used to develop relationships among biophysical data, soil, imagery, and fruit composition. The standardised and aggregated samples from four vineyards over three seasons were included in the estimation of ‘common variograms’ to assess how this technique could aid growers in producing geostatistically rigorous maps of fruit composition variability without cumbersome, single season sampling efforts.

In the Champagne’s region, a complete press cycle is a series of pressure increases (squeezes) and decreases (returns). After alcoholic fermentation, the two wines (the “cuvee” and the “tailles”) obtained from grape juice fractions exhibit strong differences for numerous characteristics. Nevertheless, there is no study of the impact of the press cycle, followed after each pressure increase (22-28 steps), on wine colour, current analyses and phenolic composition. So, the aim of this study (vintage 2020) was to investigate the composition changes of Pinot noir and Pinot meunier wines, produced from 22-28 grape juices isolated for each complete pressing cycle.

The market trend heads to food products with less chemical inputs, including in oenology. During the winemaking process, sulfites are commonly use to avoid microbiological contamination and stabilization of the wine thanks to its antimicrobial and antioxidant activities. Nevertheless, this use is not without consequences on human health and environment, leading for example to allergic reaction and pollution. A biological alternative to these sulfites has emerges: the bioprotection.

Toasted pruning vine-shoots represent a promising new enological tool for developing wines with chemical and organoleptic high quality, allowing that the resources of the vineyard to be returned to the wine through a “circular process”.