Modulating the bioactive peptides content in Swiss cheeses by combinations of thermophilic Lactobacilli strains and species

Peptides within the sequence of milk proteins can be released during food processing such as cheese making.Depending on their amino acid sequence, these peptides may exert a number of activities in vivo, affectingcardiovascular, endocrine, immune and nervous systems. Bioactive peptides have been described in cheeses, but theirquantification and the way to produce them in situ are far from being well controlled. In this work, we demonstrate thatthe amount of antihypertensive peptides in cheese can be modulated by combinations of lactobacilli starters.Selected strains of the three starter species encountered in Swiss-type cheeses were used in various combinations:Streptococcus thermophilus (ST, 2 levels of the same strain), Lactobacillus helveticus (LH, 2 strains H1 and H2 and noneH0), Lactobacillus delbrueckii (LD, 2 strains D1 and D2 and none D0). 18 model cheeses were then manufacturedunder identical controlled conditions. Microbial and physico-chemical analyses were performed on cheeses at differenttimes of process and ripening.Cheese aqueous extracts exhibited various in vitro anti-hypertensive activities, expressed as concentration that inhibits50 % of angiotensin I converting enzyme activity, i.e. IC50. Levels and dynamics of this anti-hypertensive activity variedaccording to the combination of lactobacilli strains used, up to 6 fold at the end of the ripening time. The combinationH2D2 led to the lowest IC50, i.e. the highest antihypertensive activity.Twenty-one peptides with potential anti-hypertensive activity were identified by tandem mass spectrometry: 15from β-casein, four from αs1- and two from αs2-caseins. Two particular anti-hypertensive peptides, VPP and IPP, werespecifically quantified by mass spectrometry showing a strong correlation between their content and the IC50. Strainbiodiversity and starter combinations are powerful tools to modulate bioactive peptides content in cheese.