Amino acid, mineral, vitamin B contents and bioactivities of extracts of yeasts isolated from sourdough

Bread is one of the most consumed major leavened foods all around the world. Yeasts are responsible for leavening the bread dough. However, bread dough contains high amounts of yeast biomass that have the potential to contribute to the bioavailability of the bread. This study aims to find out the potential effects of yeast biomass on bread bioavailability. For this purpose, yeast extracts were produced from three Saccharomyces cerevisiae, two Kazachstania humilis and one Torulaspora delbrueckii strains by autolysis and subsequently the nutritional compositions, phenolic compound profiles, antioxidant activities and immune modulation properties of the yeast extracts were determined. Among yeast samples, S. cerevisiae PFC401 showed high protein, essential amino acids, vitamin B7, total phenolic content and immune modulation property. However, K. humilis PFC393 stood out in terms of DPPH radical scavenging activity, and T. delbrueckii PFC394 in terms of major and minor minerals. These results indicated that the bioactive properties of yeast extracts vary depending on the yeast strain. In conclusion, results showed that yeasts not only leaven the bread dough but also contribute to the bioavailability of bread due to their rich nutritional compositions and bioactive properties.