Production of sourdough steamed bread by liquid sponge fermentation and parameters optimization

To investigate the production of sourdough steamed bread by liquid sponge fermentation, solid sourdough was converted into liquid sour, and sourdough steamed bread was prepared using the liquid sponge fermentation. The optimal maturation time range and continuous propagation process were determined by analyzing changes in the viable cell counts of lactobacilli and yeast strains in liquid sour and sponge, as well as pH and TTA. Based on these findings, the effects of four single factors sponge fermentation time, liquid sour maturation time, flour dosage in liquid sponge, and liquid sour dosage on the quality of steamed bread were investigated. Using sensory scores as the response variable, the process parameters for producing sourdough steamed bread were optimized through response surface methodology. The quality of steamed bread prepared by different methods, including the yeast rapid method, retarding sponge-dough method, and liquid sponge method, was finally compared.The results revealed that the optimal maturation time for liquid sour ranged from 9 h to 21 h. After 4 days of continuous replenishment, the viable cell counts of lactobacilli and yeast strains and pH and TTA in liquid sour became stable. The optimal process parameters for producing sourdough steamed bread were as follows: sponge fermentation time, 7 h; liquid sour maturation time, 15 h; flour dosage in liquid sponge, 25%; and liquid sour dosage, 40%. Steamed bread produced under these conditions exhibited a larger volume, improved texture, and enhanced flavor. Liquid sponge fermentation can produce high quality sourdough steamed bread, due to the pumpable nature of liquid sour and sponge, this method is highly suitable for the industrialization and large-scale production of steamed bread made with traditional fermenting agents.