A novel method for screening high glycerol- and ester-producing brewing yeasts (Saccharomyces cerevisiae) by heat shock treatment

Influence of heat shock-treated cells on the production of glycerol and other metabolites in alcoholic fermentation

“…However, the fact that heat-shocked cultures typically recovered and attained a faster fermentation rate than the controls, implies an enduring consequence of heat treatment, as has been shown previously. 1,2 In our experiment, increases in the glycerol production after the heat shock were reported only when using yeast strain L2056 in the case of the direct inoculation (Table 2), whereas in the case of intermediate growth on plates, production remained the same as the unheated control (data not shown). Experiments conducted with yeast strain QA23 did not present the same behavior, and net difference in the glycerol yield was independent of the inoculation of the medium when conducted directly after the heat shock (Table 2) or after growth on plates (data not shown).…”

“…[1][2][3][4] The purpose of this research is to investigate the possibility of applying prefermentation heat shock not only to achieve increased glycerol production but also to prevent the loss of cell viability, so as not to cause problems in fermentation kinetics and the commencement/completion of the alcoholic fermentation. Furthermore, this research aimed to evaluate the impact of the heat shock on the production of secondary metabolites.…”

“…The heat treatments applied are near lethal for yeast, unlike with previous research conducted by other authors, where the heat treatment was moderate. [1][2][3][4] Regardless of the physiological basis, the production of higher alcohols, ethyl esters, and glycerol could have important implications for beverage fermentations and could be a tool for winemakers and brewers in achieving improved quality.…”

“…2,27 Gas chromatography mass spectrometry analysis was required to more completely evaluate chemical differences among strains and heat treatments. The chemical compounds selected for detection were chosen according to their sensory importance and available methods for quantitation.…”

“…Among other compounds, glycerol has been reported to be produced in increased amounts following heat shock treatment. [1][2][3][4] In wines, glycerol has the potential to influence sensory properties; however, it is not tasted until present in excess of 5.2 g/L, and increases in viscosity are not apparent below 25 g/L. 5,6 Apart from glycerol, no other compounds of sensory importance have been reported to be produced after heat shock application.…”