Screening of Superior Non-Saccharomyces Yeast and Its Esterase Activity Changes during Fermentation

In order to explore the growth characteristics of non-Saccharomyces yeasts and the evolution of their flavor enzyme activity during alcohol fermentation, autochthonous strains with high esterase and alcohol acyltransferase production were isolated from spontaneous fermentation of wine grapes in Hexi Corridor region of Gansu Province. The selected non-Saccharomyces yeast strains were inoculated into simulated grape juice and the growth kinetics, fermentation kinetics and flavor enzyme activity of these strains were dynamically monitored in the process of fermentation. Results showed that autochthonous HX-6 and HX-7 strains had higher total C2-C6 esterase activity (102.69, 102.51 U/mL), while HX-6 strain had the highest alcohol acyltransferase activity (3.46 U/mL). These two strains were identified as Torulaspora delbrueckii through sequence analysis of the D1/D2 domain of 26S rDNA. The result of fermentation kinetics and biomass analysis for autochthonous HX-6, HX-7 strains and commercial strains TD-n confirmed that all three strains could not independently complete alcohol fermentation. Dynamic detection of enzyme activity showed that the cumulative activities of C2-C6 esterase (143.74, 121.85 mU/mL) and alcohol acyltransferase (15.75, 12.74 U/mL) were the highest during simulated wine fermentation triggered by HX-6 strain. The cumulative activity of C6 esterase (86.63 mU/mL) of HX-7 strain was high in the process of simulated red wine fermentation. Based on comprehensive analysis, the selected non-Saccharomyces yeasts autochthonous strains have application potential for wine aroma enhancement. © 2024 Chinese Institute of Food Science and Technology. All rights reserved.