Comprehensive exploration of wine aroma-related compounds as promoted by alternative vinification procedures in case of Zelen (Vitis vinifera L.) grapes processing

There is a growing interest in the exploitation of vine-shoots waste, since they are often left or burned. Sánchez-Gómez et al. [1] have shown that vines-shoots aqueous extracts have significant contents of bioactive compounds, among which several polyphenols and volatiles are highlighted. Recent studied had demonstrated that the chemical composition of vine-shoots is enhanced when vine-shoots are toasted
[2,3]. The application of vegetable products in the vineyards has led to significant changes towards a more “Sustainable Viticulture”. An innovative foliar application for Airén vine-shoot extracts have been carried out to the vineyard. It has been shown that they act as grape biostimulants, improving certain wine quality characteristics [4].

País grape has been estimated to arrive to Chile almost 500 years ago, being the first strain grown in this country. Traditionally, this grape has been used to mix with other varieties, to produce poor quality wines, but today is beginning to be used in the production of high quality wines. However, very little is known about the chemical characteristics of this variety. The aroma is one of the most important quality attributes of wine. Volatile compounds of this beverage may come from the grape (varietal aromas), from the fermentation process, from the ageing. The aromatic compounds are found in the grape in two forms: as free volatile compounds and as non-volatile compounds. The last ones, are aroma precursors present mainly as glycoconjugates formed by a sugar and an aglycone…

Tannin and polysaccharide concentration and composition is important in defining the texture of red wines, but can vary due to factors such as cultivar, region, grape ripeness, viticultural practices and winemaking techniques. However, the concentration and composition of these macromolecules is dependent not only on grape tannin and polysaccharide concentration and composition, but also their extractability and, in the case of polysaccharides, their formation by yeast. Through studies into the influence of grape maturity, winemaking and sensory impacts of red grape polysaccharides, seed and skin tannins, recent research in our laboratory has shown that the processes involved in the extraction of these macromolecules from grapes and their retention in wine are very complex.

The occurrence of faults and taints in wine, such as those caused by microbial spoilage or various taints, have resulted in significant financial losses to wine producers. The wine industry commits significant financial resources towards fining and taint removal processes each year. Fining involves the addition of one or more adsorptive substrates to juice or wine to bind certain components, thus reducing their concentration [1]. However, these processes are often not selective and can also remove desirable flavour and aroma compounds.

Initiatives have been ongoing in recent years to safeguard biodiversity in the oenological sector via a process of enhancement of ancient varieties, under a pressure of a market strongly oriented towards production deriving from native vines of specific geographical zones. In that sense, Aosta Valley
(Italy) has raised the need to preserve and characterize its minority vine varieties which have the potentiality to give varietal wines. Fumin represents the 7% of the production of the region with 16 hectares of vineyards and 753 hectolitres of derived wine. Due to its large phenolic potential, strong astringency and deep colour, it has long been, and is still today, assembled or blended with other varieties as occurs, for example, for the Torrette.