How peptide physicochemical and structural characteristics affect anion-exchange membranes fouling by a tryptic whey protein hydrolysate

Peptide adsorption on ion-exchange membranes (IEM) affects negatively the electrodialysis efficiency. Hence, the peptide species and nature of peptide/anion-exchange membranes (AEMs) interactions involved in fouling were explored at different pH. It appeared that fouling was severe at pH10, twice lower at pH6 and absent at pH2. Based on HPLC-MS results, the three main fouling peptides were VLVLDTDYK, TPEVDDEALEK and IDALNENK representing 86% of the total fouling. Since these peptides carried negative net charges on their C-terminal, D and E residues at pH6 and 10, interactions are of electrostatic nature and mostly happened between the negative peptide charges (COO-) and the positive charges of AEM groups (N+CH3)(3)). In addition, TPEVDDEALEK interacted more intensively than VLVLDTDYK at pH6. This was explained by charges distribution at the surface of the macromolecular structures. Interestingly, working at acidic pH would completely prevent the fouling on AEMs due to repulsion between peptides and AEMs groups. To the best of our knowledge, it is the first time that an in-depth analysis with peptides from a complex protein hydrolysate was carried out to demonstrate the impact of peptide physicochemical and structural characteristics as well as the mechanisms involved in anion-exchange membranes fouling. (C) 2016 Elsevier B.V. All rights reserved.