This study focused on improving the efficiency of sour beer production through mixed fermentations of Lachancea thermotolerans and Kveik yeast strains, aiming to reduce fermentation time while preserving the sour profile characteristic of L. thermotolerans. While in earlier trials, mixed fermentations with S. cerevisiae (US-05) achieved low pH values (~3.65), they did not achieve the best sensory profiles at elevated temperatures. Kveik yeast strains were selected as an alternative due to their high-temperature tolerance and rapid fermentation kinetics.

Fermentations were conducted at 25 °C using Kveik yeast and L. thermotolerans at ratios of 1:10, 1:20, and 1:30 (Kveik to L. thermotolerans). All fermentations were completed in under 10 days, confirming Kveik’s ability to significantly accelerate fermentation. However, final pH values remained relatively high (~3.8) compared to previous US-05 L. thermotolerans mixed cultures.

To enhance acidification, additional fermentations were carried out with glucose supplementation, based on prior findings that glucose increases L. thermotolerans's acidifying ability. Glucose-supplemented mixed fermentation trials using both Kveik (at 25 °C, 1:30 and 1:40) and US-05 (at 20 °C, 1:10 and 1:30) led to lower final pH values while maintaining clean sensory profiles and short fermentation times.

Across all trials, pH and extract (ºPlato) were monitored daily. Final beers were analyzed for alcohol content, total acidity, FAN, and underwent sensory evaluation. These findings suggest that mixed fermentations with L. thermotolerans and Kveik yeast (particularly with glucose addition) are an effective strategy for producing sour beers efficiently, without compromising flavor balance or sour character.