Relationship between proteolysis and angiotensin-I-converting enzyme inhibition in different cheeses

The inhibition of angiotensin-l-converting enzyme (ACE) by the ethanol (70%)-soluble fraction (ESF) from different cheeses was analysed with an extract from rabbit lung acetone powder as enzyme source and 2-furanacryloyl-l-phenylalanylglycylglycine (FAPGG) as substrate. Proteolysis was assessed by a spectroscopic o-phthaldialdehyde (OPA) assay of the pH 4.6-soluble fraction and ESF. Peptides in the ESF were separated by reverse phase-HPLC. The traditional Norwegian cheese Gamalost had per unit cheese weight higher ACE inhibition potential than Brie, Roquefort and Gouda-type cheese, likely due to the combination of highest protein content and most extensive proteolysis providing a high content of ACE inhibitory peptides. However, ACE-inhibition expressed as IC50 per unit peptide concentration from ESF assessed by the OPA-assay was highest for Kesam, a Quark-type cheese with a low degree of proteolysis. (c) 2005 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.