Impact of minerals on the microbial species diversity and metabolite dynamics during spontaneous backslopped wheat sourdough productions.

Abstract

Sourdough production represents a dynamic fermentation process, involving complex interactions between microorganisms and the flour-water matrix. The quality of mature sourdoughs depends on factors such as the type of inoculum (spontaneous or starter culture-initiated), process parameters (temperature, pH, and dough yield), and ingredient variations (constituents of flour and water). Concerning the latter, the mineral availability may influence the microbial diversity and metabolite kinetics during sourdough production. Hence, in the present study, 10-day laboratory backslopped wheat sourdough productions were carried out, differing in mineral contents of the water phase, based on the screening of mineral compositions of different flours and waters collected from three Belgian bakery companies. The minerals added as chloride salts were calcium, magnesium, manganese, or sodium. A polyphasic approach, encompassing microbiological analysis (both culture-dependent and culture-independent) and metabolite target analysis, was employed. Although influences of calcium (positive) and manganese (negative) on yeast growth and of calcium (negative) on acetic acid bacteria (AAB) growth were found, no clear-cut trend concerning the lactic acid bacteria (LAB) diversity was found, except for the occurrence of a three-phase LAB evolution. Among 17 typical LAB sourdough species retrieved, Lactiplantibacillus plantarum/paraplantarum, Levilactobacillus brevis, and Limosilactobacillus fermentum prevailed toward the end of the backslopping cycles in all cases. Regarding the yeast species diversity, wheat sourdoughs supplemented with calcium chloride harbored only Saccharomyces paradoxus, whereas Maudiozyma saulgeensis and Naumovozyma castellii were only found in sourdoughs supplemented with sodium chloride. Metabolite target analysis revealed higher ethanol and glycerol concentrations in sourdoughs produced in the presence of calcium chloride and magnesium chloride compared to the others