Selective adsorption of egg white hydrolysates onto activated carbon: Establishment of physicochemical mechanisms for removing phenylalanine

Previously, it was shown that activated carbon can remove phenylalanine from egg white hydrolysates to produce a low phenylalanine peptide ingredient that can be used by individuals suffering from phenylketonuria. However, the factors impacting the selective adsorption of phenylalanine and peptides to activated carbon is not fully understood, which is holding back the optimization of this process. In this research, two activated carbons with different morphologies and electrical characteristics were used to adsorb egg white hydrolysates with different degrees of hydrolysis. The selective adsorption behavior of the different constituents within the hydrolysates was studied to identify the nature of the adsorption mechanisms involved. The results showed that aromatic amino acids and components with higher molecular weight were preferentially adsorbed. Moreover, the main driving force for adsorption was hydrophobic attraction, followed by hydrogen bonding and electrostatic interactions. These results could facilitate the preparation of medical foods for patients with phenylketonuria.