Sourdough lactic acid bacteria – from food industry by-products and alternative food stock valorization to neurotransmitters production

Sourdough is a complex ecosystem, where lactic acid bacteria (LAB) and yeasts are dominant organisms. LAB isolated from sourdough can be employed as a biotechnological starters to improve the safety and functionality of food and feed, to provide added value and to increase safety of food industry by-products, to design synthesis of functional molecules in fermentable substrates, and to moderate the technologies for safer alternative stock (e.g., insect flour) incorporation to the main food (e.g., bread) formulas. Sourdough contains a wide range of LAB, which metabolic activity strongly affects the characteristics of the fermentable substrates. The addition of starter cultures under controlled conditions is a highly prospective technology for sustainable feed preparation. Metabolites of the LAB as well as viable LAB cells in fermented feed material leads to desirable changes in animal microbiota, better health and production quality. Additionally, the high-functionality fermented feed can be produced by applying sourdough LAB for the food industry by-product valorisation. Also, fermentation with sourdough LAB greatly contribute not only to the flavour, aroma, and texture of the final product but also to functional molecules synthesis, e.g., galactooligosaccharides can be synthesized from the dairy industry by-products containing lactose; gamma-aminobutyric acid can be produced from the substrates containing L-glutamic acid (e.g., Spirulina). This type of bioconversion is a very promising technology for food and nutraceutical production. Finally, our works showed, that sourdough LAB application in industry is extremely broad: from food industry by-products and alternative food stock valorisation to neurotransmitter production.