Influence of salt-in-moisture on proteolysis in Cheddar-type cheese

Cheddar cheese curd was divided into portions after manufacture and salted at different levels (0 to 3.3%, w/w), yielding salt-in-moisture (S/M) values of 0.37 to 5.41 % (w/w). Water-soluble N was produced more slowly in cheeses with high S/M values, but high S/M cheeses generally contained higher levels of amino acid N soluble in 5% (w/v) phosphotungstic acid. Ureapolyacrylamide gel electrophoresis showed that S/M influenced the rates of hydrolysis of the caseins, particularly β-casein. Cleavage of the bonds Leu₁₉₂-Tyr₁₉₃ in β-casein and Leu₁₀₁-Lys₁₀₂ in α_s1-casein by the coagulant appeared to be particularly sensitive to NaCl concentration. Reverse-phase high performance liquid chromatography showed greater production of short peptides (particularly β-CN f193-209) in cheeses with low S/M levels. Cheeses with lower or higher than normal S/M values for Cheddar (∼4%) were downgraded on the basis of flavour and body.