Characterization of egg white gel microstructure and its relationship with pepsin diffusivity
Résumé
Understanding the diffusion of digestive enzymes, particularly pepsin, in different food structures, is a key factor
to better control protein digestion and absorption. This study aimed to investigate how protein-based food
microstructure impacts pepsin diffusion. Two egg white gels (EWGs) of identical protein concentration (10%)
but different structures were used as food models. The two different gel structures were prepared by heating
liquid egg white at pH5 and pH9, respectively. Results showed that egg white proteins formed a compact and
microstructurally homogeneous gel at pH9 (mean particle size of 0.32 ± 0.02 μm, with a mean interparticle
distance of 0.76 ± 0.07 μm), which leads to a lower FITC-pepsin diffusion coefficient
(Deff=44.2 ± 6.1 μm2 s−1), compared to the pH5-EWG (Deff=52.5 ± 5.3 μm2 s−1). The microstructure of
the pH5-EWG was characterised by a spatially heterogeneous loose protein matrix made of larger aggregate
particles (mean particle size of 0.76 ± 0.07 μm, with a mean interparticle distance of 1.79 ± 0.57 μm). In
addition to the effects of the EWG microstructure, the environmental pH also affects the FITC-pepsin diffusion,
likely because of the impact on electrostatic interactions between pepsin and the egg white proteins.
Origine : Accord explicite pour ce dépôt
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