The amount of pH 4.6-soluble peptides increased in the samples with 1 pkat mL−1, 10 pkat mL−1 and 100 pkat mL−1 to 6.49 ± 0.11 mm, 16.05 ± 0.45 mm and 29.68 ± 0.52 mm serine equivalents, respectively. No increase in sedimented protein was observed in the milk samples containing enzyme activities of 0.1 pkat mL−1 and 0 pkat mL−1 (control) during the four weeks of storage.