Fractionation of dairy based functional peptides using ion-exchange membrane adsorption chromatography and cross-flow electro membrane filtration

Two food grade fractionation processes using ion-exchange membrane adsorption chromatography (IE-MAC) and cross-flow electro membrane filtration (CFEMF) were successfully developed for the fractionation of complex peptide mixtures. Feed solutions for the fractionation steps were generated by tryptic hydrolysis of aqueous solutions of β-lactoglobulin (β-Lg) and micellar casein (MCN). The fractionation efficiency of both processes, to separate bioactive peptides was determined by analysing the yield of angiotensin-I-converting enzyme (ACE)-inhibitory peptides in the obtained fractions and by measuring their ACE-inhibitory activities in vitro. Both techniques were successfully applied for the fractionation of complex hydrolysates and the ACE-inhibitory peptides were enriched in individual fractions, resulting in yields of 52% for β-Lg(9–14) by IE-MAC and 25% for β-casein f(108–113) by CFEMF. Additionally, the ACE-inhibitory activity of the fractions was determined to be 3- to 6-fold higher compared with the hydrolysates.