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

Abstract

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.

Keywords: Salmonella; fermented milk; functional food ingredient; postbiotics; proteolytic activity.