Production of aroma compounds by cryotolerantSaccharomycesspecies and hybrids at low and moderate fermentation temperatures

Abstract

Aim: Among the most important factors influencing wine quality are yeast strains and fermentation temperature. Fermentation at low temperature is presently used in winemaking to improve both aroma formation and retention. In this study, we have analysed the oenological characteristics of Tempranillo wines produced at 12 and 28°C by different Saccharomyces species and hybrids. Methods and Results: Low temperature had a strong influence on yeasts fermentation kinetics, increasing fermentation times to more than 2 weeks. In some strains, glycerol production seemed to be positively influenced by low fermentation temperature. Analysis of the aroma composition of wines produced by different Saccharomyces species and hybrids revealed large differences depending on fermentation temperature. Conclusions: Higher alcohols production seemed to be dependent on the strain. Production of acetate esters seemed to be favoured at 28°C, whereas production of ethyl esters was apparently preferred at low fermentation temperatures. The best aroma producers at 28°C were Saccharomyces cerevisiae strains, whereas Saccharomyces uvarum and some hybrids excelled at 12°C. Significance and Impact of the Study: Our results suggest that fermentation temperature and yeast species are of crucial importance for production of metabolites influencing wine aroma.

Environmental Stress and Aroma Production During Wine Fermentation

“…In contrast to our studies, for which a transient temperature decrease was applied, other studies have compared the impact of yeast fermentation temperature at 25 to 28°C and 12 to 15°C on the levels of volatile aroma compounds (Molina et al, 2007;Beltran et al, 2008;Gamero et al, 2013). The reduction in the yeast fermentation temperature had a major impact on the levels of volatile aroma compounds produced, and the levels produced varied between yeast strains.…”

“…Fermentation at higher temperature (28°C) is reported to yield greater concentrations of higher alcohols that give flowery aromas to wine (Molina et al, 2007). On the other hand, Gamero et al (2013) found that the higher alcohol concentrations produced by 13 wine yeasts after fermentation at 28° compared to 12°C varied considerably between strains, pointing to an inconsistent response pattern to increased temperature.…”

“…However, the temperature stress was applied within the first 30 h of fermentation, whereas in our study the stress was only applied on day two or day eight of the fermentation, suggesting that the timing of stress application may play a role in glycerol production. When glycerol production by 13 wine yeast strains at 12° and 28°C was compared, no consistent effect of fermentation temperature on production could be established (Gamero et al, 2013). Other researchers have found the impact of reduced temperature fermentation on acetic acid levels to have variable results, pointing to an effect of strains and fermentation conditions.…”

“…However, a comparison of levels of aroma compounds produced by 13 commercial wine yeast strains at fermentation temperatures of 12 and 28°C showed wide ranges (Gamero et al, 2013), pointing to a strain-specific response to reduced temperature.…”

Yeast Hybrids in Winemaking

“…The spectrum of compounds produced was shown to be temperature dependent 25 , such that non-hybrid strains were thought to have a more appealing aroma profile at higher temperatures. Analysis of regulation of aroma production indicated that the hybrids have unique regulatory mechanisms for aroma production not easily predicted from the parental strains 26 .…”