Résumé
Bread is an important staple food, that plays an important role in many cultures. There are two primary ways of making bread, either using commercial yeast or using sourdough, a mixture of flour and water naturally fermented by yeasts and bacteria. While commercial yeasts have been consciously selected for bread making and sold all over the world, sourdough microbial communities are propagated by local bakers through the addition of flour and water. Previous studies revealed the role of the house microbiota on sourdough microbial species diversity. The role of grain milling has been less explored. Using a participatory research approach, we tested the effect of milling technics on the dynamic of microbial community during the establishment of new sourdoughs in four bakeries. A strong parallelism of the dynamic of bacteria and yeast installation was found. Interestingly, LAB and yeast colonization reached rapidly their carrying capacity with bacteria being faster. Each bakery was associated to a specific sourdough microbial community whatever the milling practice. Bread aroma compounds were mostly impacted by the microbial community composition while the bread protein content was also partly impacted by the milling technic. These results highlighted the importance of local food chain in the conservation of microbial species diversity.