Microbiological non-GMO approaches for the reduction of ethanol in wines

Identificador:  TDX:3277

Handle: https://hdl.handle.net/20.500.11797/TDX3277

Autors:  Zhu, Xiaolin

Resum:
As the increase in ethanol content in wine has attracted much attention, the pursuit of health and low-alcohol wine has urged researchers to find ways to reduce the ethanol content in wine. The aim of this work is the selection and application of non-Saccharomyces yeast species to reduce ethanol content. This general goal can be divided into the following three specific objectives: A rapid method to screen non-Saccharomyces yeast species with a low ethanol yield. This study was to propose a rapid method to screen yeasts with a low ethanol yield from 45 non-Saccharomyces yeast strains, belonging to 19 species. This method included two steps and was complete in 5 days to obtain the selected yeasts. The effect of a non-Saccharomyces multistarter on ethanol reduction and yeast population dynamics, using different inoculation ratios and strategies. As a single starter, all three strains (from M. pulcherrima, T.delbrueckii and Z.baili species) can reduce ethanol content in wine. In order to achieve the appropriate inoculation strategy, the three strains were used as a multistarter in co-inoculated or sequential fermentations with S. cerevisiae at different inoculum ratios. The ethanol reduction by selected non-Saccharomyces yeast species and evolved Saccharomyces cerevisiae. Two selected non-Saccharomyces yeast strains from M. pulcherrima and L. thermotolerans species and three selected evolved S. cerevisiae strains (evolved on iso-butanol or high sugar conditions), were used in simultaneous and sequential inoculated fermentations to evaluate their ability to reduce the alcohol content. Conclusions Strains from M. pulcherrima, T. delbrueckii and Z. bailii species achieved higher ethanol yield reductions (1.39, 0.84 and 1.02% (v/v), respectively) when used in fermentation with S. cerevisiae, being M. pulcherrima the species with the highest ethanol reduction (1.44% (v/v)) obtained in all tested conditions.