Dynamic interactions of lactic acid bacteria in Korean sourdough during back-slopping process

This study aimed to clarify the cause of quality reduction in Korean sourdough after successive back-slopping.

We investigated the dynamic changes in lactic acid bacteria during the back-slopping process using genetic fingerprinting techniques. During the initial propagation phases, the dominant lactic acid bacteria were Fructilactobacillus sanfranciscensis (<5 log CFU per g sourdough), Latilactobacillus curvatus (9·5 log CFU per g sourdough) and Levilactobacillus brevis (6·5 log CFU per g sourdough). However, after the 11th propagation, F. sanfranciscensis became more prominent (>9·0 log CFU per g sourdough), whereas L. curvatus and L. brevis rapidly decreased. Monitoring these bacteria in the co-culture system revealed that acid-tolerant F. sanfranciscensis rapidly utilized maltose (1·65 g l^-1  h^-1 ) and produced large amounts of lactic acid, whereas L. brevis and L. curvatus consumed maltose slowly and L. curvatus was poorly tolerant to lactic acid.

The results indicate that competition exists between the lactic acid bacteria in sourdough during the back-slopping process, and microbial succession by acid-tolerant species results in quality reduction of sourdough.

This study uncovered the cause of microbial changes during the propagation of Korean sourdough and proposed a strategy to develop starters to produce high-quality bakery products.