Study of some Saccharomyces cerevisiae strains for winemaking after preadaptation at low temperatures

Low-temperature fermentations (13 degrees C) are considered to improve wine aromatic profiles. However, because the risk of stuck and sluggish fermentations is high, these fermentations are not common. The aim of this paper was to analyze the effect of different preadaptation protocols in two commercial wine strains on the fermentation and some wine parameters. Preadaptation is understood to be the process between the rehydration of active dry yeast and the inoculation. In this study, it consisted of preparing a fermentation starter (addition of yeast grown at 25 degrees C) or inocula preadapted at low temperatures (as before, but grown at a fermentation temperature of 13 or 17 degrees C). These results were compared with those of rehydrated active dry yeast, and a commercial "cryotolerant" yeast was used as a reference. General fermentation kinetic parameters, yeast imposition, nitrogen consumption, and main wine products were analyzed. The results showed that the preadaptation of a yeast could improve the fermentation performance, although this improvement was strain-dependent. Low-temperature fermentations also had some general effects: reduction of acetic acid and fusel alcohol production and increased concentrations of glycerol. When the yeast performed better in fermentation because of preadaptation, nitrogen consumption was faster and the wine's "negative" attributes (acetic acid, fusel alcohols) were significantly reduced. Thus, in some strains, preadaptation could be an effective mechanism for improving low-temperature fermentation, which also significantly reduces detrimental wine attributes.