Abstract:

A strain of Hanseniaspora uvarum with high activity β-glucosidase has been isolated in our previous study. In this
work we conducted a kinetic study on alcohol fermentation by mixed cultures of the isolate and Saccharomyces cerevisiae
with the aim to find out the theoretical basis and technical support for the application of the strain of Hanseniaspora uvarum
in winemaking for aroma enhancement. Ecolly grapes in Yangling, Shaanxi were used as raw materials for winemaking.
Two treatments, inoculation of the isolate 48 h earlier than S. cerevisiae and simultaneous inoculation, were designed. The
inoculation amount of the isolate was 1.0 × 106 CFU/mL. The fermentation of these two treatments with YPD liquid medium
as grape juice model system was also performed. The fermentation with S. cerevisiae alone was set as the control. During
fermentation, the amount of different yeast strains, alcohol production and residual sugar were recorded. Then the kinetic
equations were built. Results showed that, in the asynchronous inoculation treatment, the live isolate subsisted for a longer
time and its amount was higher than that in the other treatment and the control. In the logarithmic period of the isolate,
alcohol production and sugar consumption were both lower than those in the other treatment and the control. In addition, its
alcohol fermentation was normal and the final alcohol production was the same as that in two other treatments. It could be
concluded that inoculation of the isolate 48 h earlier than S. cerevisiae could show better hydrolysis of aroma precursors by
β-glucosidase during winemaking, and it will have promising applications in winemaking for aroma enhancement.

Key words: Hanseniaspora uvarum, β-glucosidase, Saccharomyces cerevisiae, mixed culture fermentation, kinetics