Redundancy analysis for determination of the main physicochemical characteristics of filtration membranes explaining their fouling by peptides

Peptide fouling is a technological drawback in filtration membrane processes. The impact of membrane characteristics on fouling by peptides from a complex whey protein hydrolysate (WPH) fouling was assessed based on advanced statistical redundancy analysis. Six membranes were characterized and tested: PES, PVDF, CF55, S11, S11(+) and S11(-). Among the eight physicochemical characteristics analyzed, zeta-potential (ZP) and roughness (Rz) were highly correlated with total fouling quantity (TFQ), suggesting that peptide fouling was mainly due to electrostatic interactions over wider surfaces. Concerning peptide sequences, redundancy analysis indicated that at least one characteristic among ZP, Rz, contact angle and thickness contributed significantly to the fouling of ALMPHIR, LIVTQTMK, TKIPAVFK, VLVLDTDYK, TPEVDDEALEK, TPEVDDEALEFDK or SLAMAASDISLLDAQS-APLR. It appeared that membranes with hydrophilic surfaces were more likely to be fouled by WPH regardless the peptide hydrophilicity. Besides, wider surface would enable more contact area for peptides, increasing consequently fouling. The TFQ was described by a statistical predictive model using the combined effect of ZP and Rz, of the form: ln(TFQ) = 8.64 + 0.072.X-Rz + 0.088.X-ZP (R-2 = 0.9098). Moreover, statistical models were also established for each peptide, enabling to predict their specific fouling on a variety of membranes with different physicochemical characteristics.