Comparative application of pressure- and electrically-driven membrane processes for isolation of bioactive peptides from soy protein hydrolysate

Nanofiltration (NF) (pressure-driven process) and electrodialysis with ultrafiltration membrane (EDUF) (electrically-driven process) were compared in terms of mass flux and mass balance. Molecular weight profile and protein, peptide and amino acids contents of the fractions obtained were also analysed. The two processes lead to different results since NF was more efficient in terms of mass flux than EDUF when compared on a same basis (membrane area, process duration), while EDUF recovered larger range of peptide molecular weights and amount of polar amino acids. The antioxidant capacity of the fractions was analysed and the more relevant fractions were tested for their potential neurone cells protection against reactive oxygen species (ROS). The peptides isolated by EDUF in the anionic recovery compartments at pH 3 and 6 showed an increase of the antioxidant capacities for the ORAC assay as well as for the H2O2 degradation assay. The anionic recovery compartment at pH 9 and the permeate from NF at pH 6 also showed a significant increase in antioxidant capacity only for the H2O2 degradation assay. These results, of the first study in the literature on the comparison of pressure-driven and electrically-driven processes for the fractionation of bioactive peptide fractions, showed that coupling NF and EDUF in a same process line would optimize their own separation performances and allow the production of more specific peptide fractions than alone.