Yeasts in foods and beverages: In vitro characterisation of probiotic traits

The possible beneficial properties of food and associated microorganisms for both human and animal health are increasingly investigated. While many bacteria have been characterised as probiotics, only one yeast variety, Saccharomyces cerevisiae var. boulardii, has been recognised to be part of this group, regardless of the importance of yeasts in the food industry. In this work, we have studied the probiotic or health-beneficial potential of 130 yeast strains isolated from food belonging to the collection of the Institute of Food Science Research CIAL (CSIC-UAM). To that end, the response of these yeasts to physiological conditions during consumption has been assessed through measuring their capacity to grow at 37 °C and to survive the gastrointestinal transit conditions. Almost 50% of the yeast analysed could thrive at the host intestine temperature, and of these, almost 37% had growth kinetic parameters higher at 37 °C than at 25 °C. In addition, about 95% of the strains could survive the exposition to conditions simulating the gastrointestinal transit. The yeast strains were also analysed for exhibiting auto-aggregation phenotype, antioxidant activity and the production of killer peptides, this only found in 8.5% of the strains analysed. These properties could be regarded as additional interesting features for selecting new probiotic strains.