The structural properties of egg white gels impact the extent of in vitro protein digestion and the nature of peptides generated
Résumé
The impact of egg white gel (EWG) structure on the process of digestionwas investigated using an in vitro
digestion model and a multi-scale characterization of the EWG structure. Four different structures of
EWG were prepared combining various pH and ionic strength conditions before heating. The extent of
digestion, estimated by the appearance of soluble peptides, was greater for the particulate gel comprising
spherical aggregates as compared to the filamentous gel comprising linear aggregates. This result may be
explained by an alteration of enzyme diffusion due to the microstructural characteristics of the gel, or an
alteration of digestive enzyme adsorption or catalytic activity due to local differences in pH within the gel
matrices. Peptide identification using LC-MS/MS highlighted that the aggregate morphology modulated
ovotransferrin hydrolysis which resulted in the release of specific peptides depending on the EWG
structure. This work illustrates the links existing between two multi-step processes, protein structuration
into gel matrices and matrix destructuration by digestive enzymes. Such quantitative and qualitative
differences reinforce the importance of the food matrix on the digestibility of food and its subsequent
nutritional quality.