Accurate Quantification of Quality Compounds and Varietal Classification from Grape Extracts using the Absorbance-Transmittance Fluorescence Excitation Emission Matrix (A-TEEM) Method and Machine Learning

Wine lees are the second most important wine by-product in terms of quantity after grape stalk and marc. During aging on lees, it is well known that wine lees yield compounds that act as antioxydant. However the chemical nature of the compounds involved in this behavior (except polyphenols and glutathione) has not yet been totally elucidated. The scarce knowledge of wine lees composition and their potential exploitation make them a promising candidate to obtain new antioxidant products to be used in winemaking. In this study, an eco-sustainable approach to obtain lees extracts exhibiting antioxidant capacity is proposed. Such extracts could be used in a global enological strategy of sulfites level reduction.

Proanthocyanidins are important phenolic fraction for wine quality, contributing to astringency, bitterness and color. Their metabolism begins in the mouth and continues throughout the gastrointestinal tract; however, most of them are accumulated in the colon where are metabolized by the intestinal microbiota, giving rise to a whole series of phenolic acids that may have greater activity at physiological level than the precursors[1]. This study aimed to evaluate in vitro the bioaccessibility of proanthocyanidins in a red wine developed by Bodegas Pradorey, as well as to evaluate the potential effect of intestinal microbiota on polyphenols metabolism identifying and quantifying secondary metabolites.

The historian starts from a scientific, rigorous and recent definition of the wine-growing region. “A viticultural terroir is made up of several homogeneous units: geological and pedological elements (texture,
grain size, thickness, mineralogical nature, chemical components), geomorphological (altitude, slope, exposure), climatological (rainfall, temperature, insolation)”. Absent from this definition, the man is fortunately reintroduced a little further. By associating viticulture and winemaking, it forms a “couple” with the terroir and this couple.

This study evaluates the effect of microwave treatment in grape maceration on the content of free and glycosidically bound varietal compounds) of must and wine and on the overall aroma of wines produced in the presence and absence of SO2.

Global warming is accelerating grape ripening, leading to unbalanced wines from fruit with high sugar content but poor aroma and colour development. Reducing the size of the photosynthetic apparatus after veraison has been shown to delay technological ripeness in cool climates, but methods have not been tested in areas with high irradiance and temperature where fruit exposure could have disastrous effects on berry composition. In this Cabernet-Sauvignon trial, we compared the application of an antitranspirant (pinolene), to severe canopy topping and above bunch zone leaf removal, all performed at mid-ripening, with an untouched control. We monitored the vines weekly by measuring stem water potential, gas exchange, fruit zone light exposure. We sampled berries to measure berry weight, total soluble solids, pH, titratable acidity, and the anthocyanin profile. At harvest, we assessed yield components, measured carbon isotope discrimination, rated sunburn on clusters, and produced experimental wines. We submitted harvest samples to metabolomic profiling through PFP-Q Exactive MS/MS and wines to sensory analysis. Application of the antitranspirant significantly reduced stomatal conductance and assimilation rate but did not affect the stem water potential. Inversely, leaf removal and topping increased water potential but did not affect leaf gas exchange. The late topping was the only treatment able to decrease sugar content (up to 2Bx), increase titratable acidity and pH, and improve anthocyanin content because of lower degradation of di-hydroxylated forms. Late leaf removal above the bunch zone increased lightning conditions in the canopy and produced the most significant damage on fruits. Yield components were not affected. This work suggests that late-season canopy management can effectively control ripening speeds and improve grapes and wines. Still, the effect on grape exposure in a critical time must be well balanced to avoid problems with the appropriate technique.