Diverse Sourdough Starter Microbiomes Produce Unique Metabolomic Profiles with Antioxidant Capacity: Functional Outlooks for Baked Goods

Sourdough fermentation is an ancient processing technology which, with the help of modern analytical techniques, can be harnessed to address some of the major threats to the food system such as overproduction of unstable products and consumers becoming increasingly vulnerable to chronic diseases. Recent studies by our research group have demonstrated that the unique fungal and bacterial populations of sourdough starter cultures influence the physical and chemical properties of the dough and bread they are used to produce. The objective of this study was to characterize the influence of starter culture microbiome on the metabolomic profile of sourdough bread and determine whether these differences in metabolomic profile translate to differences in antioxidant functionality within the context of food preservation and health. Sourdough bread was produced using 20 sourdough starters with distinct microbial profiles based on 16S and ITS rRNA sequencing. Non-targeted LC-MS/MS was used to characterize the small molecular composition of the bread based on standardized methods developed by the Periodic Table of Food Initiative. Hierarchical clustering of nutrient and metabolite data revealed 3 distinct groups of breads, suggesting an influence of microbiome composition on metabolite composition. Further analysis revealed that these differences were driven largely by compounds with antioxidant properties, which we hypothesized would contribute to differences in the oxidative stability and potential health benefits of the breads. The antioxidant capacity of each bread was measured using DPPH/ORAC/FRAP assays, and the effect of fermentation-derived antioxidants on the oxidative stability was determined by measuring peroxide value and TBARS; this revealed significant differences between the sourdough breads, demonstrating the influence of starter microbiome on food stability. The potential GI-protective effects of these fermentation-derived antioxidants were evaluated using an in vitro model of obesity-associated inflammation. These findings present a foundation for the identification of novel natural antioxidants for bakery applications and beyond.