Peptidic hydrolysates with different degrees of hydrolysis (3,15 and 23%) has been obtained by hydrolysis of bovine haemoglobin by pepsin. RP-HPLC analysis of these hydrolysates coupled with mass spectroscopy has given information about the retention time and the peptidic size distribution. Pendant-drop tensiometry of aqueous-buffer solutions versus concentration points out differences in the curves superficial tension versus concentration between starting haemoglobin and hydrolysates. The weight percentage of hydrolysates in the bulk C-B(max) for which stable foam can be obtained has been determined. Foam fractionation was studied by a bubbling-draining method. Collected top foam was analyzed by RP-HPLC and compared to the initial hydrolysate. No stable foam has been obtained with hydrolysate (DH = 23%) and no interesting fractionation can be obtained with hydrolysate (DH = 15%). However, a peptidic fraction (3500-7000 Da), having an antimicrobial activity, with a 5% extraction yield can be separated from hydrolysate (DH = 3%), using a forced draining volume of 100 or 150 mL. (C) 2008 Elsevier B.V. All rights reserved.