The influence of different lactic acid bacteria on sourdough flavor and a deep insight into sourdough fermentation through RNA sequencing. (1st March 2020) - Liu, Tongjie
Highlights: Main volatiles of different type of LAB showed differences in carbon chain length. L. sanfranciscensis showed a unique volatile profile without distinctive compounds. Ethyl acetate and ethyl lactate differed in generation mode in L. sanfranciscensis . L. sanfranciscensis upregulated genes for carbohydrates metabolism at 12 h vs . 6 h. Abstract: Ten lactic acid bacteria (LAB) strains of different species isolated from Chinese traditional sourdough were investigated on their volatile compounds in sourdough fermentation. Sourdoughs fermented with different LAB species were analyzed by principal component analysis (PCA) based on their volatiles. Furthermore, the in situ gene expressions of Lactobacillus sanfranciscensis during sourdough fermentation were investigated by using RNA sequencing for the first time. PCA could discriminate between the sourdoughs fermented by homofermentative and heterofermentative LAB, the former containing more aldehydes and ketones with more than 6 carbon atoms, while the latter featuring ethanol and esters. The Lactobacillus plantarum -fermented sourdough was characterized by high C4–C6 volatiles content, while L. sanfranciscensis showed a unique volatile profile without explicit explanatory compounds. The RNA sequencing suggested that, compared to the sourdough fermented for 6 h, L. sanfranciscensis enhanced carbohydrate metabolism and self-protection activities, but decreased cell proliferation in sourdough at 12 h.