Protection of candidate probiotic lactobacilli by Cheddar cheese matrix during simulated gastrointestinal digestion

Previously, Lacticaseibacillus rhamnosus DPC7102 and Lacticaseibacillus paracasei DPC7150 isolated from com-mercial Irish Cheddar cheeses were shown to exhibit probiotic traits in vitro. The objective of this study was to investigate how these strains survive in cheese and to explore whether a cheese or fermented milk matrix pro-vided protection during simulated digestion using the INFOGEST 2.0 static digestion model. Manufacture of Cheddar cheese and fermented milks using these strains did not significantly impact cheese composition or ripening parameters. The Cheddar cheese matrix provided significantly more protection to non-starter lactic acid bacteria than the fermented milk. Pulsed-field gel patterns of isolates surviving simulated digestion confirmed the presence of the strains of interest. These data indicate that these two Lacticaseibacillus strains successfully persist in the cheese matrix during cheese ripening following which they are capable of surviving simulated digestion. This supports their potential for further development as candidate food-delivered probiotics.