Increasing Higher Alcohols and Acetates in Low-Alcohol Beer by Proteases

Area of Science:

• Food Science and Technology
• Fermentation Science
• Biotechnology

Background:

• The non-alcoholic and low-alcohol beer market is expanding due to health-conscious consumer trends.
• Current production methods often result in undesirable off-flavors, such as aldehydes, and reduced desirable aroma compounds.
• Non-conventional yeasts show potential in mitigating these production challenges.

Purpose of the Study:

• To investigate the use of proteases to optimize wort amino acid profiles for improved aroma production during fermentation.
• To enhance the production of specific aroma compounds, such as 3-methylbutan-1-ol and 3-methylbutyl acetate (banana-like aromas), using leucine enrichment.
• To evaluate the yeast-dependent impact of optimized wort composition on the final aroma profile of low-alcohol beer.

Main Methods:

• Applied design of experiments to optimize protease treatment for increasing leucine concentration in wort.
• Fermented treated wort using different non-conventional yeasts, specifically *Saccharomycodes ludwigii* and *Pichia kluyveri*.
• Quantified key aroma compounds, including higher alcohols and esters, and aldehyde intermediates post-fermentation.

Main Results:

• Protease treatment successfully increased leucine molar fraction in wort from 7% to 11%.
• Fermentation with *Saccharomycodes ludwigii* resulted in significant increases in 3-methylbutan-1-ol (87%) and 3-methylbutyl acetate (64%).
• Fermentation with *Pichia kluyveri* led to increased levels of valine and isoleucine-derived compounds, while 3-methylbutan-1-ol decreased by 58%.

Conclusions:

• Wort amino acid optimization using proteases can enhance specific aroma compound production in low-alcohol beer.
• The final aroma profile is highly dependent on the yeast strain employed during fermentation.
• Further sensory analysis is required to determine the perceptual impact of these aroma and off-flavor changes in low-alcohol beer.