Abstract: This study attempted to investigate the effects of reducing sodium content and adding Lactobacillus paracasei M3, with high angiotensin-converting enzyme (ACE) inhibitory activity in skimmed milk, as an adjunct starter culture on the physicochemical properties and in vitro antihypertensive potential of Cheddar cheese. One control group (100% NaCl) and three experimental groups, 50% NaCl + 50% KCl, 100% NaCl + 0.5% L. paracasei M3, and 50% NaCl + 50% KCl + 0.5% L. paracasei M3 were set up. The major chemical components, microbial load, proteolysis, texture, flavor and ACE inhibitory activity of these four groups were evaluated. The results showed that there was no significant difference in the principal chemical components among the four groups (P > 0.05). The number of lactic acid bacteria, pH 4.6 soluble nitrogen and total free amino acid content were significantly higher in the experimental groups than the control?group (P < 0.05), while hardness and pH were lower in the experimental groups (P < 0.05) and bitterness was higher. The inhibition percentages of the three experimental groups toward ACE were 65.2%, 74.3% and 78.7% after six months of ripening, which were 19.6%, 36.2% and 44.4% higher than that of the control group, respectively. We concluded that potassium salt substitution and use of L. paracasei could contribute to the production of ACE inhibitory peptides with antihypertensive potential in cheese, but further research is needed to understand their effect on the flavor of cheese.

Key words: potassium salt substitution; adjunct starter culture; Cheddar cheese; angiotensin-converting enzyme inhibition percentage; flavor