A Rapid Method for Selecting Non-Saccharomyces Strains with a Low Ethanol Yield

Area of Science:

• Enology
• Microbiology
• Fermentation Science

Background:

• Rising alcohol content in wine is a growing concern.
• Certain non-Saccharomyces yeasts show potential for reducing ethanol during fermentation.

Purpose of the Study:

• To develop a rapid screening method for identifying non-Saccharomyces yeast strains with low ethanol yield.
• To evaluate the ethanol-reducing capacity of selected non-Saccharomyces strains.

Main Methods:

• Screening of 45 non-Saccharomyces yeast strains from 18 species using single fermentations.
• Sequential fermentations in synthetic and natural must with selected strains.
• Comparison of ethanol reduction with Saccharomyces cerevisiae.

Main Results:

• Ten non-Saccharomyces strains demonstrated the ability to reduce ethanol content.
• Ethanol reduction ranged from 0.29% to 1.39% (v/v) compared to S. cerevisiae.
• Specific strains like Metschnikowia pulcherrima and Torulaspora delbrueckii showed significant ethanol reduction (up to 1.39% v/v).

Conclusions:

• A rapid screening method for low-ethanol-yield non-Saccharomyces yeasts was successfully established.
• Several non-Saccharomyces yeast strains can effectively reduce wine alcohol content.
• These findings offer potential strategies for managing alcohol levels in winemaking.