Abstract
In the past decades, studies on the physiology and biochemistry of sourdough lactic acid bacteria provided insight into the microbial ecology of sourdough as well as the effect of the metabolic activity of lactic acid bacteria on flavor, texture, shelf life, and nutritional properties of leavened baked goods. Lactic acid bacteria are the dominant microorganisms of sourdough. Their metabolic versatility favors adaptation to the various processing conditions and the metabolic interactions with autochthonous yeasts determine mechanisms of proto-cooperation during sourdough fermentation (Gobbetti et al. Trends Food Sci Technol 16:57–69, 2005; De Vuyst and Neysens. Trends Food Sci Technol 16:43–56, 2005; Gänzle. Food Microbiol 37:2–10, 2014; Gänzle and Zheng. Int J Food Microbiol 302:15–23, 2019; Gänzle. Curr Opin Food Sci 2:106–117, 2015). Species of genera in the Lactobacillaceae species are most frequently found in sourdough fermentations although species belonging to the genera Enterococcus and Lactococcus were also occasionally identified (Gänzle and Zheng. Int J Food Microbiol 302:15–23, 2019; Hammes and Gänzle. Microbiol Fermented Foods 199–216, 1998; Vogel et al. Antonie van Leeuwenhoek Int J Gen Mol Microbiol 76:403–411, 1999; De Vuyst et al. Food Microbiol 37:11–29, 2014; see Chap. 6). A large number of species in the Lactobacillaceae were first identified from sourdoughs or fermentation processes of cereals (Vogel et al. Antonie van Leeuwenhoek, Int J Gen Mol Microbiol 76:403–411, 1999; Zheng et al. Int J Syst Evol Microbiol 70:2782–2858, 2020). This chapter gives an overview of the general growth and stress parameters, carbohydrate and amino acid metabolism, synthesis of exopolysaccharides and antimicrobial compounds, and the conversion of phenolic compounds and lipids of lactic acid bacteria during sourdough fermentation.