Effect of Saccharomyces species interaction on alcoholic fermentation behaviour and aromatic profile of Sauvignon blanc wine

Abstract

Enhancing the sensory profile of wine by the use of different microorganism has been always a challenge in winemaking. The aim of our work was to evaluate the impact of different fermentation schemes by using mixed and pure cultures of different Saccharomyces species to Sauvignon blanc wine chemical composition and sensory profile. Sauvignon blanc must has been inoculated with mixed and pure cultures of S. pastorianus and S. cerevisiae. For the mixed fermentation schemes, one strain of S. pastorianus has been inoculated under different frequencies (99%, 95% , 90%, 80% and 70%) with two strains of S. cerevisiae. Totally 13 fermentations trials, 3 monocultures and 10 mixed cultures, were realised in triplicate. The fermentation kinetics has been controlled by density measurement and classic oenological analysis (residual sugars, total acidity, volatile acidity, malic acid degradation, glycerol production etc) were performed based on OIV protocols.The population dynamics was conducted by the specific interdelta PCR reaction of the Saccharomyces species in the beginning and in the end of the fermentation process. Volatile aromatic compounds such as esters, superior alcohols and thiols were evaluated by GC/MS analysis. Sensory assesement was carried out for all wines by trained panel. All fermentation trials lead to dryness and the fermentation lasted from 9 days to 13 days. The population dynamics analysis revealed that the S. cerevisiae strain was the most predominant in the end of the fermentation process in any inoculation ratio tested. The wines fermented with S. pastorianus, either in pure or mixed cultures, were characterised by significant lower acetic acid production and greater malic acid degradation compared to the wines fermented with S. cerevisiae strains. The aromatic profile of the produced wines was highly affected from the inoculation ratio while the effect of the S. cerevisiae used strain was less important. Our study based on different fermentation frequencies of mixed cultures of S. pastorianus and S. cerevisiae strains, revealed the impact of the inoculation ratio on the 30 tested volatiles compounds, correlated to Sauvignon blanc aromatic profile. The species of S. pastorianus starts to become an interesting candidate for co-inoculation with S. cerevisae strains, able to boost varietal aromas intensity.