Proteolysis in Cheddar-type cheese made from goat's milk

Three batches of cheese were manufactured from pasteurised goat's milk usin g 3 levels of rennet, but otherwise following a standard recipe for Cheddar cheese. Composition was found generally to be in the normal range for Ched dar cheese (pH 4.9-5.0; 35.8-38.3% moisture; 1.0-1.2% NaCl; 49.8-54.8% fat- in-dry-matter; 21.3-21.9% protein). The levels of pH 4.6-soluble nitrogen a s % of total nitrogen and free amino acids increased throughout ripening an d were generally proportional to rennet levels. Urea-PAGE analysis of the p H 4.6-insoluble fraction of the cheese showed more degradation of alpha (s) - than beta -caseins throughout ripening, with proteolysis of the former pr otein being correlated with rennet level. Analysis of the 70% (v/v) ethanol -insoluble fraction by reversed-phase HPLC showed that higher levels of ren net produced the highest levels of peptides. However, as ripening progresse d, fewer differences in peptide patterns were apparent, confirming the impo rtance of the coagulant as an agent for primary proteolysis in cheese.