Ability of Saccharomyces cerevisiae strains to modulate the aroma of albariño wines

Abstract

The objective of the present work is to evaluate the impact of three S. cerevisiae strains on the comprehensive aroma profile of Albariño wine along its shelf life.

The strains Lalvin QA23TM, Lalvin SauvyTM and Affinity ECA5TM (Lallemand Bio) fermented a model must containing precursors of polyfunctional mercaptans (PFMs) and a polyphenolic and aroma precursor fraction1 extracted from Albariño grapes. Wines were submitted to accelerated anoxic aging at 50 ºC during 1, 2, 5, 8 weeks and at 75 ºC during 12, 24, 48, 72h of aging, respectively. Fermentative aroma compounds, SO2, Strecker aldehydes, and varietal aroma compounds were determined by GC, using six different analytical methods.

The aroma profiles of the Albariño wines obtained are characterized by low amounts of volatile phenols, vanillin derivatives and TDN precursors and by medium to high levels of linalool, β-damascenone, rose oxide, γ-nona and γ-decalactones, which explain the typical and subtle floral aroma notes associated with Albariño wines2. Levels of linalool faded during aging, but floral notes may be partially compensated by increasing levels of ethyl cinnamate.

The ability of the strains assayed to modulate levels of terpenes and lactones was limited citronellol and rose oxide. They were able to influence slightly but significantly levels of β-damascenone and ethyl cinnamate in aged wines. This suggests that the influence of the strains on floral notes is significant, but not dominant3. In clear contrast, the strains introduced a great variability in the levels of PFMs which mostly remained all along wine shelf life.

Even if aging was carried out under strict anoxic conditions, levels of Strecker aldehydes increased, isobutanal and 2-methylbutanal in a strain-dependent way, suggesting that Strecker degradation of amino acids took place with already present wine α-dicarbonyls. Levels of diacetyl and isovaleric acid increased during aging, in spite of the fact that aging conditions were not adequate for microbial development.

Regarding fermentative compounds, levels of higher alcohols and their acetates, straight and branched chain fatty acids and their ethyl esters as well as Strecker aldehydes were strongly strain-dependent. Except for acetates, differences were maintained during aging or even intensified in the cases of aldehydes and ethyl esters of branched acids.

Finally, aging at 50 and 75 ºC were in general very well correlated, suggesting that aging at 75ºC can satisfactorily predict evolution during aging of many wine components. aging at 75ºC can satisfactorily predict evolution during aging of many wine components, except PFMs and Strecker aldehydes.

S. cerevisiae strains can be used to produce Albariño wines with completely different sensory profiles and different sensory evolutions during aging. While the effects on varietal floral and sweet aroma compounds was just moderate, effects on PFMs and fermentative aroma compounds, including Strecker aldehydes were very large.