The structural properties of egg white gels impact the extent of in vitro protein digestion and the nature of peptides generated

The impact of egg white gel (EWG) structure on the process of digestionwas investigated using an in vitrodigestion model and a multi-scale characterization of the EWG structure. Four different structures ofEWG were prepared combining various pH and ionic strength conditions before heating. The extent ofdigestion, estimated by the appearance of soluble peptides, was greater for the particulate gel comprisingspherical aggregates as compared to the filamentous gel comprising linear aggregates. This result may beexplained by an alteration of enzyme diffusion due to the microstructural characteristics of the gel, or analteration of digestive enzyme adsorption or catalytic activity due to local differences in pH within the gelmatrices. Peptide identification using LC-MS/MS highlighted that the aggregate morphology modulatedovotransferrin hydrolysis which resulted in the release of specific peptides depending on the EWGstructure. This work illustrates the links existing between two multi-step processes, protein structurationinto gel matrices and matrix destructuration by digestive enzymes. Such quantitative and qualitativedifferences reinforce the importance of the food matrix on the digestibility of food and its subsequentnutritional quality