Potential of Lactobacillus strains for health-promotion and flavouring of fermented dairy foods

Ninety-eight Lactobacillus (Lb.) strains were tested for safety traits, health-promoting properties, and sensory characteristics for the strains to be used in the manufacture of fermented dairy products. First, a screening based on the production of biogenic amines was performed, and the potential amine-producing strains were discarded. The remaining 62 strains were analysed for antibiotic resistance, the presence of antibiotic resistance and amino acid decarboxylase genes, and virulence factors (haemolytic, DNAse, and coagulase activity). Principal component analysis of the safety results allowed to select 39 strains. Antimicrobial activity was used to select 13 of them, which were further analysed for sensory characteristics, several interesting enzymatic activities and for γ-aminobutyric acid (GABA), ornithine, and tryptophan production. All these strains produced fermented milks without sensory defects, as well as pleasant sensory properties. Among them, the strains Lb24 and Lb86 highlighted by their β-galactosidase activity; the strain Lb47 was able to hydrolyse bile salts; the strains Lb86 and Lb93 produced high concentrations of both GABA and tryptophan, and the strain Lb111 produced the highest concentrations of ornithine. In consequence, these five strains (Lb24, Lb86, Lb47, Lb93 and Lb111) were selected and could be used in the manufacture of a variety of fermented dairy products.