Advancement of foam separation of bioactive peptides using an aeration column with a bubbling-draining method

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 CBmax 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.