Bulk samples of caprine milk were characterized for chemical composition, enzyme activities and rheological properties: plasmin, elastase. and cathepsin D concentrations were measured as 3.22 +/- 0.18, 1.14 +/- 0.05, and 1.81 +/- 0.06 mg L-1, respectively. Pasteurized caprine milk was incubated with aprotinin, pepstatin, or a mix of these inhibitors at 37 degrees C for 7 days. Hydrolysis of alpha- and beta-caseins was influenced by the presence of inhibitors: overall serine proteases, i.e., plasmin and possibly elastase mainly contributed to the hydrolysis of caseins whereas the limited proteolysis observed in milk incubated with aprotinin suggested a marginal role for cathepsin D. Pasteurized milk displayed a greater number of peptides than milk incubated with pepstatin, whereas no peptides were detected in samples incubated with aprotinin or a mix of aprotinin and pepstatin. Several unreported peptides were identified by mass spectrometry in caprine milk, many of which showed sequences previously described as bioactive in bovine and caprine milk. (C) 2009 Elsevier Ltd. All rights reserved.