Concentration and selective separation of bioactive peptides from an alfalfa white protein hydrolysate by electrodialysis with ultrafiltration membranes

We investigated the fractionation of an alfalfa white protein concentrate (AWPC) hydrolysate by electrodialysis with ultrafiltration membranes (EDUF), a novel membrane technology. The latter, based on the separation mechanisms of conventional membrane filtration (size) and electrophoresis (electrical charge), is suitable for the large scale fractionation of valuable molecules from complex feedstocks. Two ultrafiltration membranes were stacked in an electrodialysis cell to allow a configuration with two recovery compartments (KCl 1 and 2). The effect of pH (3 and 9) on the migration of basic/cationic and acid/anionic peptides was studied in these conditions. It was established that EDUF allows the simultaneous separation and concentration of charged peptides with a transport rate up to 7.3 g/(m2 h). Amongst a total of 70 peptides contained in the AWPC hydrolysate, only 8 peptides were found in the separated adjacent recovery solutions (KCl 1 and 2). Amongst these eight migrating peptides, four significant peptides were recovered in the basic KCl 1 and one antihypertensive peptide identified as VW was recovered in KCl 2. The maximum transmission rate recorded for a peptide was 18.23%. Furthermore, apart from the selective separation, our results showed that EDUF could overcome some of the fouling problems in the conventional pressure-driven processes.