Temperature selection drives microbial adaptation and succession during repeated back-slopping of spontaneous sourdough and modulates bread quality

Fermentation temperature acts as a key environmental selective factor driving microbial adaptation and succession during spontaneous sourdough back-slopping; however, its role in sourdough microecosystem stability and bread quality remains unclear. In this study, spontaneous sourdoughs were subjected to repeated back-slopping at different temperatures, and temperature-mediated microbial succession and its effects on bread properties were investigated. Sub-low temperature (8 °C) delayed sourdough maturation but promoted the establishment of temperature-specific microbial communities. After repeated back-slopping, Latilactobacillus replaced Pediococcus as the dominant bacterial genus and Wickerhamomyces was enriched in 8 °C-adapted sourdough, whereas Pediococcus remained dominant in 15 °C- and 25 °C-adapted sourdough. Bread incorporating 8 °C-adapted sourdough (bread T8 group) exhibited improved gluten network structure, the highest specific volume (4.45 mL/g), and sensory score (88.71). Conversely, bread T15 group optimized protein hydrolysis, showing the highest in vitro protein digestibility (85.39%) and total free amino acids (561.07 mg/kg). GC-MS identified 48 volatile compounds, and odor activity value analysis revealed that bread T8 group specifically accumulated key aroma-active esters and aldehydes ((E)-2-nonenal, methyl laurate, and ethyl dodecanoate), which positively correlated with Latilactobacillus and Wickerhamomyces. Overall, repeated temperature selection shaped microbial adaptation and succession, which correlated with differences in sourdough functionality and bread quality.