Postbiotics produced at laboratory and industrial level as potential functional food ingredients with the capacity to protect mice against Salmonella infection

Aim To determine the protective capacity against Salmonella infection in mice of the cell-free fraction (postbiotic) of fermented milk, produced at laboratory and industrial level. Methods and Results The proteolytic activity (PA) of 5 commercial cultures and 11 autochthonous Lactobacillus strains was evaluated. The DSM-100H culture displayed the highest PA and it was selected for further studies. The capacity of the postbiotics produced by pH-controlled fermentation to stimulate the production of secretory IgA in faeces and to protect mice against Salmonella infection was evaluated. A significant increase in secretory IgA in faeces of mice fed 14 days the postbiotic obtained at the laboratory (F36) was detected compared to control animals. A significantly higher survival was observed in mice fed the F36 and the FiSD (industrial product) compared to controls. Conclusion The postbiotics obtained showed immunomodulatory and protective capacity against Salmonella infection in mice. Significance and Impact of the Study The pH-controlled milk fermentation by the proteolytic DSM-100H culture could be a suitable strategy to obtain a food ingredient to be added to a given food matrix, not adequate to host viable cells of probiotics, to confer it enhanced functionality and thus expand the functional food market.