Technological role and metabolic profile of two probiotic EPS-producing strains with potential application in yoghurt: Impact on rheology and release of bioactive peptides

Limosilactobacillus fermentum Lf2 (Lf2) and Bifidobacterium animalis INL1 (INL1) are two autochthonous probiotic strains that produce exopolysaccharides (EPS), and some of these molecules were associated with health-promoting properties. In the present work, stirred yoghurts supplemented with these bacteria (added before or after fermentation) were made, in parallel with yoghurt with purified EPS from Lf2. The rheological properties, water holding capacity, microstructure, metabolic activity (aminopeptidase activity, sugar and organic acid metabolism), and production of bioactive peptides (before and after in vitro digestion) were assessed, as well as the activities of six peptidases for each strain, the latter clearly showing different patterns. Yoghurts made with starter culture and Lf2 exhibited a major impact on the previously mentioned parameters. In conclusion, both EPS-producing microorganisms increased the release of bioactive metabolites in yoghurt; they also impacted on levels of organic acids and carbohydrates, rheological properties, and microstructure.