Removal of phenylalanine from egg white powder: Two-step enzymatic method combined with activated carbon adsorption

Abstract

Individuals suffering from phenylketonuria require foods containing low levels of phenylalanine (Phe). In this research, we therefore developed a two-step enzymatic hydrolysis method followed by activated carbon treatment to remove Phe from egg white powder (EWP). Nine proteases were tested for their ability to expose or release Phe residues from the egg proteins, while nine kinds of activated carbon were tested as an adsorptive medium for removing Phe residues. Our results showed that trypsin combined with flavourzyme released the most Phe residues, and No.4 activated carbon was most effective at removing Phe residues. The percentage of Phe removal varied from 91.71–97.78% and the final mass yield from 230.08–342.45 g low Phe peptide (LPP) / Kg of EWP. The LPP mixtures obtained mainly containing amino acids and oligopeptides (< 600 Da). The EWP-LPP mixture obtained therefore has the potential to prepare medical foods for patients with phenylketonuria.