Effect of wort biological acidification by Limosilactobacillus fermentum isolated from malt on sour craft beer quality in Mexico

Abstract

The aim of this study was to evaluate the effect of biologicalacidification using Sauergut produced by lactic acid bacteriaisolated from malt grain, on the physicochemical andsensory properties of sour craft beer. Three isolates wereobtained and characterized as Gram-positive, catalasenegative,and heterofermentative. Two strains (3-Lac and19-Lac), identified as Limosilactobacillus fermentum, wereselected based on their acidification performance. Both isolatesreached the maximum lactic acid production at 9 days(1.16 % and 1.24 %, respectively) and rapidly reduced pH to2.119 and 1.915 within 24 h at 48 °C. Lactic acid productionand pH were significantly affected by strain and wort type(p < 0.05). Fermentation also influenced color parameters,increasing lightness (L*) and decreasing saturation (C*), witha positive correlation between lactic acid production and L*values. Sensory analysis revealed desirable aroma and flavorattributes, with higher intensities observed for 3-Lac. Theseresults demonstrate that biological acidification using Limosilactobacillusfermentum improves both physicochemicaland sensory quality of wort, highlighting its potential forcontrolled sour beer production.