Lactic acid bacteria can produce lactic acid, acetic acid, propionic acid and other organic acids during the fermentation process. They can reduce the pH value of bread, facilitate the degradation of gluten and promote the production of gluten, thereby significantly changing the rheological properties of the dough, increasing the viscosity of the dough, and improving the texture of the bread . Lactic acid bacteria can also produce some hydrophilic colloids during the fermentation process, which can improve the mechanical processing properties of the dough, the specific volume, texture structure and shelf life of the bread.

(2) Improve the flavor of bread

The organic acid produced by the fermentation of lactic acid bacteria can interact with the alcohol, aldehyde, ketone and other substances produced in the fermentation to form a variety of new taste substances, thereby improving the flavor of bread. In addition, the molar ratio between lactic acid and acetic acid is considered to be an important factor affecting the flavor of sourdough products, and the optimal ratio is 2.0-2.7.

(3) Extend the shelf life of bread

　　 Research has found that the sourdough bread made by Lactobacillus, especially the sourdough fermented by Lactobacillus fermentum, is an effective anti-mold dough. Because lactic acid bacteria produce some natural antibacterial components during the fermentation process, they can effectively inhibit food-borne pathogens and food spoilage bacteria, including Listeria, Bacillus subtilis and Staphylococcus aureus. Use this strain Yeast dough can reduce the use of chemical preservatives in pasta products.

(4) Anti-aging ability

　　 The acidic environment formed by the fermentation of lactic acid bacteria in the dough, the protease produced by lactic acid bacteria, and the metabolites such as polysaccharides produced by the lactic acid bacteria are all conducive to reducing the aging of bread. On the one hand, the acid and polysaccharides produced by lactic acid bacteria can change the structure of the dough, which can improve the water retention capacity of the dough to a certain extent. On the other hand, the starch molecules are affected by the enzymes produced by the lactic acid bacteria, and the starch regenerating ability changes, which slows down the aging of the bread. speed.