Immobilization of trypsin on resin-carriers: A novel strategy to realize controlled hydrolysis and enhance the foaming properties of pasteurized and frozen-thawed egg white.

Through mechanistic analyses of protein structure and interfacial properties, this study revealed that both pasteurization and freeze-thaw treatments decreased the foaming capacity (FC) of egg white to 265 % and 95 %, respectively, by inducing protein aggregation due to thermal or ice crystal damage. To address this, trypsin and papain hydrolysis were employed to depolymerize pasteurized egg white (PEW) and five freeze-thaw cycles treated egg white (FT-5). The maximum FC (403 %) achieved with a 60-min trypsin treatment. Subsequently, trypsin was immobilized on three resins (D1, D2, E1) to enable controlled hydrolysis. The D1-trypsin bound via ion exchange displayed the highest loading capacity (122.6 mg/g), enzymatic activity (3455 U/g) and FC (447 %), whereas the covalently conjugated E1-trypsin demonstrated superior stability and reusability. Enzymatic and adsorption kinetics were also evaluated. These findings insights into the potential applications of controlled hydrolysis using immobilized enzymes to enhance the functional properties of egg white.