Autochthonous yeasts: Role in vinification and aging of Cabernet-Sauvignon

Wine is a product of series of biochemical transformations, which begins during the ripening of grapes, throughout alcoholic fermentation and aging (Romano et al., 2003).Wine composition is determined by the grape variety, geographical and viticultural conditions of grape cultivation, microbial ecology and winemaking practices (Nardi, 2006; Robinson et al., 2011). 

Yeasts are the heart of biochemical interaction with the must. The diversity of native yeast strains, in the spontaneous fermentation of grape must, can produce wines with different qualities and peculiar flavours. Therefore, production of wine using the selected yeast culture is the common enological practice followed, to produce wine with desirable organoleptic properties and assure the homogeneity of successive vintages (Nardi, 2006).

 The most preferred species for global wine production is Saccharomyces cerevisiae. Recently, there has been an increase in the use of autochthonous yeasts for fermentation. Autochthonous yeasts are inferred to be more competitive as they are better acclimated to the environmental conditions and dominate the fermentation process. Selection of the appropriate autochthonous yeasts assures the maintenance of the unique enological characteristics, which could be considered representative of an enological region (Nardi, 2006; Aponte & Blaiotta,2016; Tristezza et al., 2012). 

Wine style is determined by the relative concentrations of volatile and non-volatile compounds extracted from grapes, transformed during fermentation and maturation, and synthesized de-novo by yeast and bacteria during fermentation. The choice of yeast strain represents a low-cost opportunity, amongst the myriad of grape and wine processing options, to broaden the spectrum of wine flavour profiles. Therefore, the choice of yeast strain for red wine fermentation requires consideration of relative impacts on volatile and non-volatile wine components (Holt et al., 2013). 

Thus, evaluation of the influence of autochthonous yeast on vinification is crucial, to know the potential differences in enological characters of yeast and produce desirable wine. However, limited literature is available on enological properties of Indian yeast isolates and its role in aging of wine. Therefore, the present study was aimed to evaluate, the impact of yeasts of the Indian Geographical origin on fermentation of Cabernet Sauvignon, so as to select the yeast strain, which assures the maintenance of unique properties of wine, which could be considered representative of Indian geographical region. 

Aging of wine increases the complexity of wine aroma as a consequence of processes involved in its maturation(Pereira et al., 2010). The development of post-fermentative flavour during the aging of wine in glass bottles was studied with respect to the variation in the aromatic and phenolic profile of wine.