Wholemeal wheat flours drive the microbiome and functional features of wheat sourdoughs

This study aimed to evaluate the effect of soft (Triticum aestivum) and durum (Triticum durum) wheat flours at different extraction rate (type 00, 0, 1 and 2) and wholemeal flours on the microbial composition and functionality of type I sourdough. Enterobacteriaceae constituted the main component of the microbiome of refined soft and durum wheat flours. On the contrary, wholemeal durum wheat flour harboured mainly Xanthomonadaceae. Differences were also found between the soft and durum wheat flours. After 8 h of fermentation (1 day), a different behaviour of the microbiome components was observed. All the mature sourdoughs harboured a core microbiome constituted by 4 species (Pediococcus pentosaceus, Lactobacillus brantae, Pediococcus argentinicus and Weissella cibaria). Based on the type of flour, the relative abundance of each core species differed among sourdoughs. In addition, other dominant lactic acid bacteria species were variously detected in sourdoughs. Mature sourdoughs showed marked variations for the concentrations of glucose, fructose, maltose, lactic and acetic acids, ethanol and free amino acids (FAA). Specific correlations (r > 0.7; FDR < 0.05) were found between the microbiome and total phenols, fibres and metabolome of mature sourdoughs. Breads made by using wholemeal soft wheat or durum wheat doughs started by wholemeal wheat flour-based sourdoughs were characterized by the highest total amount of free cations (Ca²⁺, Zn²⁺, Fe²⁺, Mg²⁺), antioxidant activity and improved sensory traits.