Angiotensin converting enzyme-inhibitory activity in Cheddar cheeses made with the addition of probioticLactobacillus caseisp.

The aim of the study was to examine the release of ACE-inhibitory peptides in Cheddar cheeses made with starter lactococci and Lactobacillus casei 279 or Lb. casei LAFTI® L26 during ripening and to isolate, purify and identify such peptides. Addition of probiotic organisms increased the ACE-inhibitory activity of the cheeses during ripening at 4°C possibly due to the increased proteolysis. The IC50 (concentrations of ACE needed to inhibit 50% of ACE activity) was the lowest after 24 weeks of ripening in the probiotic cheeses (0.23-0.25 mg·mL-1) compared to 36 weeks for cheeses without any probiotic (0.28 mg·mL-1). Water-soluble extracts of each cheese were subjected to several stages of chromatography fractionation, Inhibitory activity found in the crude fractions ranged from 0.1 to 2.0 mg·mL-1. The fraction with the highest activity was purified using a second stage chromatography. Various ACE-inhibitory peptides corresponding to the αs1-casein N-terminal peptides [(f 1-6), (f 1-7), (f 1-9), (f 24-32) and (f 102-110)] and β-casein N-terminal peptides [(f 47-52) and (f 193-209)] were found, Our results suggested that ACE inhibition in Cheddar cheeses was dependent on proteolysis to a certain extent. Probiotic organisms used in this study can be added successfully in Cheddar cheeses in order to provide health benefits while simultaneously producing bioactive peptides for additional health attributes.