Reference Number: 421
Sourdough starters are naturally occurring microbial communities in which the environment, ingredients, and bakers are potential sources of microorganisms. The relative importance of these pools remains unknown. Here, bakers from two continents used a standardized recipe and ingredients to make starters that were then baked into breads. We characterized the fungi and bacteria associated with the starters, bakers’ hands, and ingredients using 16S and internal transcribed spacer (ITS) rRNA gene amplicon sequencing and then measured dough acidity and bread flavour. Starter communities were much less uniform than expected, and this variation manifested in the flavour of the bread. Starter communities were most similar to those found in flour but shared some species with the bakers’ skin. While humans likely contribute microorganisms to the starters, the reverse also appears to be true. This bidirectional exchange of microorganisms between starters and bakers highlights the importance of microbial diversity on bodies and in our environments as it relates to foods.
IMPORTANCE Sourdough starters are complex communities of yeast and bacteria which confer characteristic flavour and texture to sourdough bread. The microbes present in starters can be sourced from ingredients or the baking environment and are typically consistent over time. Herein, we show that even when the recipe and ingredients for starter and bread are identical, different bakers around the globe produce highly diverse starters which then alter bread acidity and flavour. Much of the starter microbial community comes from bread flour, but the diversity is also associated with differences in the microbial community on the hands of bakers. These results indicate that bakers may be a source for yeast and bacteria in their breads and/or that bakers’ jobs are reflected in their skin microbiome.
Significance of this study: This study integrates into our philosophy here at the Sourdough School and Club. Not only may a fermented sourdough bake boost your health, but also the making of the sourdough with your own hands, helps your own personal digestion, benefiting your overall health and wellbeing. The impact of simply using your own hands means that you are making the connection with your bread, personalising it and adding variety, ultimately helping your gut heath as well as improving your mindfulness and joy in baking!
Watch a discussion referring to this paper in Professor Rob Dunn’s webinar with Vanessa Kimbell