DETERMINATION OF MINERAL COMPOSITION IN CV. TERAN (VITIS VINIFERA L.) RED WINE AFFECTED BY PRE-FERMENTATIVE MASH COOLING, HEATING, SAIGNÉE TECHNIQUE AND PROLONGED POST-FERMENTATIVE MACERATIONS

Quercetin (Q) is present in grape in form of glycosides and as aglycone. These compounds are extracted from grape skins during winemaking. In wines, following the hydrolysis reactions, the amount of quercetin aglycon can exceed its solubility value. Unfortunately, a threshold solubility concentration for quercetin in wine is not easy to determine because it depends on wine matrix (Gambuti et al., 2020).

Oenococcus oeni is the main Lactic Acid Bacteria responsible for malolactic fermentation, converting malic acid into lactic acid and carbon dioxide in wines. Following the alcoholic fermentation, this second fermentation ensures a deacidification and remains essential for the release of aromatic notes and the improvement of microbial stability in many wines. Nevertheless, wine is a harsh environment for microbial growth, especially because of its low pH (between 2.9 and 3.6 depending on the type of wine) and nutrient deficiency. In order to maintain homeostasis and ensure viability, O. oeni possesses different cellular mechanisms including organic acid metabolisms which represent also the major pathway to synthetize energy in wine.

Botrytis cinerea Pers., the causal agent of grey mould disease, is responsible for substantial economic losses, as it causes reduction of grape and wine quality and quantity. Exploitation of antagonistic yeasts is a promising strategy for controlling grey mould incidence and limiting the usage of synthetic fungicides. In our previous studies, 119 different indigenous yeasts were screened for putative multidimensional modes of action against filamentous fungus B. cinerea [1]. The most promissing biocontrol yeast was Pichia guilliermondii ZIM624, which exhibited several anatagonistic traits (production of cell wall degrading enzymes, chitinase and β-1,3-glucanase; demonstration of in vitro inhibitory effect on B. cinerea mycelia radial growth; production of antifungal volatiles, assimilation of a broad diversity of carbon sources, contributing to its competitivnes in inhabiting grapes in nature).

The use of toasted vine-shoots (SEGs) as an enological tool is a new practice that seeks to improve wines, differentiating them and encouraging sustainable wine production. The micro-oxygenation (MOX) technique is normally combined with alternative oak products with the aim to simulate the oxygen transmission rate that takes place during the traditional barrel aging. Such new use for SEGs implies a reduction in color due to the absorption by the wood of the responsible compounds, therefore, given the known effect that MOX has shown to have on the modification of wine color, its use together with the SEGs could result in an interesting implementation with the aim to obtain final wines with more stable color over time.

Ultra-premium champagne wines are characterized by a long stay on laths. The goal of the winemaker is to use all possible oenological techniques to keep the aromatic freshness of the future products. To that purpose, some champagne base wines can be aged on lees in oak barrels. However, if it is now acknowledged that such ageing practices contribute to the oxidative stability of dry white wines, no study has been done on Chardonnay champagne base wines designed for a long ageing on laths [1].