Proceedings of IVAS 2022

Among the many compounds in wine, condensed tannins play an important role in the organoleptic properties of the products; they are partly responsible for astringency, bitterness and also contribute to the color. This research work aims to study the oxidation state of these bio-heteropolymers which is an important lock in the analysis of processed products in order to better control their quality. Indeed, their identification remains at present a challenge because of the large heterogeneity of their degrees of polymerization (DP) based on 4 monomers (epicatechin, catechin, epigallocatechin, epicatechin-3-O-gallate) thus multiplying the number of oxidation products.

Volatile phenols namely 4-ethylphenol and 4-ethylguaiacol are formed by enzymatic decarboxylation of hydroxycinnamic acids by Brettanomyces yeasts to give vinylphenols and subsequent reduction of the vinyl group to form the correspondent ethylphenols. The presence of these compounds in wine affects negatively its aromatic quality, conferring unpleasant animal and phenolic odor when present in quantities above the olfactory detection threshold [1]. Several methods have been described to remove these undesirable compounds from wines, including the use laccase enzymes [2, 3]. Due to this, the aim of this work was to evaluate the effect of several natural redox mediators on the activity of Botrytis cinerea laccase against these volatile phenols.

Varietal flavor is commonly known as the aromatic character of a wine in which the aroma of a particular grape variety predominates. However, not all varieties present particularly pronounced aromas. Therefore, different methods are constantly sought to enhance the aroma of wines with neutral aromatic characteristics, such as the use of glycosidases (1), certain yeast strains (2) or maceration with different agricultural products. In this work, aiming to improve the sensory profile together with the diversification of this product, white wines, derived from a neutral grape variety, were elaborated with the addition of mango peel by-products.

The protein haze formation in white and rosé wines during storage, shipping and commercialization has always been an important issue for winemakers. Among the various solutions industrially proposed, the use of bentonite is certainly the most widespread. However, the harmful effects of this treatment are known either in terms of wine volume loss and wine flavour and aroma.