Electrochemical modification of dairy-based functional peptides by means of cross-flow electro membrane filtration

Abstract

The stability of functional peptides against electrochemical modification during their selective fractionation via cross-flow electro membrane filtration is a prerequisite for their successful application in food products to ensure the bio-functionality, emulsification, foam formation, or stabilizing properties. This study investigated the impact of electrical fields applied to cross-flow membrane filtration on electrolysis and the associated electrochemical modification of functional dairy-based peptides to calculate the electrical load of target analytes during the process. Firstly, electrolysis and the hypochlorite-induced oxidation of the model peptide β-CN f(108–113) and lactose at different hypochlorite concentrations were studied under well-controlled laboratory conditions, followed by the electrochemical modification of functional peptides during cross-flow electro membrane filtration. At laboratory conditions, a chemical modification of the model peptide β-CN f(108–113) below a value of 3 mol.L−1 hypochlorite was not observed, while lactose was modified at minimal hypochlorite concentrations and, thus, acted as a protection group for peptides. The electrochemical modification of functional peptides was only observed for voltages ≥10 V in cross-flow electro membrane filtration experiments. In addition, results indicate that a further increase in electrical voltage (>5 V) does not result in a significant improvement of peptide electrophoresis, and thus, there is no higher fractionation of functional peptides. These experiments show that under optimal conditions of filtration with a superimposed electrical field, no chemical modification of functional peptides takes place that indicates an advantage compared to conventional filtration processes by significantly increasing the fractionation efficiency at voltages between 5 and 7 V.