Usefulness of Potentially Probiotic L. lactis Isolates from Polish Fermented Cow Milk for the Production of Cottage Cheese

Lactococcus lactis bacteria are used as starter cultures in cottage cheese and fermented milk production due to their acidification and contribution in the creation of the characteristic sensory features. The aim of the research was to carry out isolation, genetic identification, and verification of the probiotic properties of selected Lactococcus lactis isolates obtained from Polish fermented cow milk and apply the best strains to produce cottage cheese with good rheological and sensory characteristics. The isolates obtained were identified morphologically, biochemically, and with the use of 16S rRNA gene sequencing. After pre-screening two of the tested Lactococcus lactis strains, A13 and A14 were observed to be most tolerant to high NaCl concentrations and bile salts and to acidify milk the most. We confirmed the activity of A13 and A14 against such pathogenic strains as Escherichia coli, Salmonella enterica ssp. enterica, Salmonella enterica ssp. enterica sv. anatum, Staphylococcus aureus, and Enterococcus faecalis. As a potential industrial starter culture with probiotic potential, the selected Lactococcus lactis A13 and A14 strains produced cottage cheese quickly with good sensory (colour, smell, taste, texture) and rheological (viscosity, elasticity) properties.

Automated summary

The aim of this study was to isolate and identify Lactococcus lactis strains from Polish fermented cow milk, and verify their probiotic properties. Two strains, A13 and A14, were found to be the most tolerant to high NaCl concentrations and bile salts, and showed strong acidification of milk. They also exhibited activity against pathogenic strains. These selected strains have potential as industrial starter cultures for producing cottage cheese with good sensory and rheological properties.