Functional and health-promoting properties of acid-tolerant yeasts from sourdough-based and other agro-food products

The gut microbiota affect overall health and the immune system, and disruptions can lead to various health disorders. Altering the gut microbial composition through dietary interventions, including fermented products and functional foods, can positively impact health. Functional foods have essential nutritional value and show positive health effects such as hypoglycemic, anti-hypertensive, and immunomodulatory. Conventional fermented foods, nutraceuticals, probiotics, prebiotics, and symbiotics are the major types of functional foods. Yeasts have diverse applications in food fermentation, enhancing nutritional features, improving flavor and aroma, and reducing anti-nutritional factors and toxins. Yeasts are used in the production of a wide range of fermented foods, including cereal-based leavened products, milk products, fermented meat and fish products, and condiments. The bioactive metabolites accounting for health benefits in yeast-fermented foods are either generated by the yeast itself or formed by the modifications in the product components mediated by the enzymes generated by the related yeast species. Fermentation is an effective way to preserve foods, improve agricultural crops' functional and nutritional properties, and increase food storage and safety by outcompeting pathogenic and spoilage microorganisms. Fermented foods and beverages have been consumed for more than 14, 000 years, and there are currently more than 5000 types available globally, showing their importance in the human diet. Consuming diets rich in fermented foods can lower disease risk, increase longevity, and improve life quality. This chapter aims to give detailed literature on the functional and health-promoting properties of acid-tolerant yeasts from sourdough-based and other agri-food products.