Lactic acid bacteria and yeast consortia as sourdough starter cultures: volatile compound profile, bacterial community composition, and dough rheology

Abstract

Growing public awareness of healthy nutrition is pushing the baking industry to replace synthetic improvers with natural ones, and sourdough starter cultures are among the most promising candidates for this role. Using autochthonous strains isolated from Kazakhstani raw materials (wheat flour, kumis, and spontaneous sourdoughs), two three-strain consortia of lactic acid bacteria (LAB) and yeast were assembled, with their components selected for biocompatibility during co-cultivation. The consortia were characterised within a single experimental framework covering aroma formation, antimicrobial activity, bacterial community structure (16S rRNA gene amplicon sequencing), and dough rheology. The consortia inhibited the principal agents of bread spoilage, producing growth-inhibition zones of up to 27–30 mm against Penicillium notatum and 18–19 mm against Aspergillus flavus. Their volatile profile combined LAB-derived organic acids and carbonyl compounds (acetic acid, up to 72%; diacetyl, about 32% in one of the consortia) with yeast-derived higher alcohols and esters, broadening the aroma-forming potential relative to monocultures. In the inoculated sourdoughs, the introduced genus Lacticaseibacillus dominated the bacterial community from as early as 18 h (68–82%), in contrast to the spontaneously fermented sourdough, in which Enterobacteriaceae prevailed (Pantoea, up to 91%). When added at 10%, the sourdoughs softened the dough, reducing deformation energy (W) by approximately 38–39% and shifting the rheological parameters toward more balanced values. Taken together, the results characterise the developed autochthonous consortia as candidate sourdough starter cultures.