Impact of organic inputs on soil biodiversity in vineyard systems. A monitoring approach during 20 years

In this work, these four red varieties were characterized in terms of phenolic composition. Thus, the anthocyanin accumulation and the extractability evolution during ripening were compared.

Hydroxytyrosol (HT) is well known for its potent antioxidant activity and anticarcinogenic, antimicrobial, cardioprotective and neuroprotective properties. One possible explanation to its origin in wines is the synthesis from tyrosol, which in turn is produced from the Ehrlich pathway by yeasts. This work aims to explore the factors that could increase the final content as the initial concentration of yeast assimilable nitrogen (YAN) and sugar. Two different concentrations of YAN were proved between 210mg/L and 300 mg/L. Additionally, two different concentrations of sugar were used: 100g/L and 240 g/L. Alcoholic fermentations in synthetic must were performed with the strain QA23.

Over the last decade, the use of non-Saccharomyces yeasts in the winemaking process has been re-assessed and accepted by winemakers. These yeasts can be used to achieve specific objectives such as lowering the ethanol content, preventing wine spoilage and increasing the production of specific aroma compounds. Since these species are unable to complete alcoholic fermentation, strategies of co- and sequential inoculation of non-Saccharomyces and Saccharomyces cerevisiae have been developed. However, when mixed starter cultures are used, several parameters (e.g. strain yeast, inoculation timing and nutrient competitions) impact the growth of the individual yeasts, the fermentation kinetics and the metabolites/aroma production. In particular, competition for nitrogen compounds could have a major impact, potentially leading to sluggish fermentation when the yeast assimilable nitrogen (YAN) availability is low. Moreover, many aroma compounds produced by the yeasts are directly produced and influenced by nitrogen metabolism such as higher alcohols, acetate esters and ethyl esters which participate in the organoleptic complexity of wine.

Oxidative stability is a critical factor in wine shelf-life. SO₂ is commonly added to wine due to its strong antioxidant activity, although there is a general push to reduce SO₂ use in vinification.

Au Brésil, 80 % du vignoble national et 90 % du vignoble de l’État du Rio Grande do Sul (principale région productrice de vins dans le pays) sont plantés avec des cépages issus de vitis labrusca ou de cépages hybrides (DEBASTIANI, 2015). Une partie de cette production est utilisée pour la préparation de jus de raisin et de concentrés de moût ou de pulpe de raisin. Le restant est consacré à