Unveiling the impact of traditional sourdough propagation methods on the microbiological, biochemical, sensory, and technological properties of sourdough and bread: a comprehensive first study

In the last thirty years, the factors driving the establishment and composition of the sourdough biota have been deeply studied. Nevertheless, to date, no study has ever evaluated the biochemical and microbial dynamics of sourdoughs propagated using the different traditional methods integrated into procedural back-slopping practices worldwide. A mature type I sourdough was propagated for 10 days according to four managing conditions (Milanese, In Water, Free and Piedmontese) entailing incubations in a jute sack, submerged in water, in a jar or a combination of them. Sourdoughs obtained under the different conditions (and corresponding breads) were extensively characterized. When processing parameters modified the sourdough environment, the microbial community changed. In the first days of propagation Fructilactobacillus sanfranciscensis was the main dominant species regardless of the type of propagation, remaining present in all sourdoughs, especially those maintained in a jar. Differences among the propagation methods emerged from the biochemical analysis. Sourdoughs propagated in water exhibited higher titratable acidity, mainly due to the acetic acid produced, and were characterized by a more complex aromatic profile which differentiated them from the others. Biochemical features of breads mainly reflected those of the corresponding sourdough, whereas nutritional (protein digestibility and glycemic index) and technological (texture profile, colorimetric coordinates) features were hardly affected by the propagation method. Thus, investigation on the effect of the variation of the ecological determinants within the same propagation methods and their role in the definition of sourdough potential could be the subject of further studies.