Influence of Commercial Yeast Strains and Fermentation Temperature on Alcohol Content and Aroma Profile in Low-Alcohol Beer Production

The production of low-alcohol beer with acceptable sensory quality remains a technological challenge because limiting ethanol formation may affect fermentation performance and aroma development. This study evaluated the combined effects of yeast strain and fermentation temperature on fermentation performance, physicochemical properties, volatile compounds, and sensory characteristics of low-alcohol beers. Two conventional brewing strains (Saccharomyces cerevisiae US-05 and Saccharomyces pastorianus W-34/70) were compared with the dedicated low-alcohol strain LA-01. Wort was fermented at 5, 10, and 15 °C, while LA-01 was fermented at its recommended temperature of 15 °C. Alcohol content, apparent degree of fermentation, residual sugars, pH, free amino nitrogen, volatile compounds, odor activity values, GC-O aroma intensity, and sensory attributes were determined. Fermentation temperature strongly affected yeast activity, sugar utilization, ethanol production, and volatile compound formation. US-05 fermented at 5 °C produced beer containing 0.33% alcohol by volume (ABV), compared with 2.53% ABV at 15 °C. W-34/70 produced 1.02–2.31% ABV, whereas LA-01 produced 0.54% ABV at 15 °C. Increasing fermentation temperature generally increased attenuation, ethanol production, and the formation of higher alcohols and esters, although the response was compound- and strain-dependent. Several esters and higher alcohols exceeded their odor thresholds, indicating their potential contribution to beer aroma. The results demonstrate that the combination of an appropriate conventional brewing yeast and low-temperature fermentation provides an effective strategy for producing non-alcoholic and low-alcohol beers while achieving a favorable balance between low final alcohol content and aroma development. Controlled low-temperature fermentation with a conventional brewing strain may therefore provide an alternative approach to limiting ethanol formation while maintaining a diverse aroma profile.