Egg white gel structure determines biochemical digestion with consequences on softening and mechanical disintegration during in vitro gastric digestion

Abstract

The aim of this work was to investigate the role of biochemical digestion on softening and disintegration kinetics of pH 5 and pH 9 egg white gel (EWGs) during in vitro gastric digestion. EWG samples (5 mm length cubes) underwent in vitro digestion by incubation in simulated gastric fluid at different time intervals for up to 240 min. The hardness was measured using a Texture Analyser; softening kinetics was fit to the Weibull model. Results revealed that pH 9 EWG had the highest softening halftime (458 ± 86 min), indicating the slowest softening, whereas pH 5 EWG had the lowest softening halftime (197 ± 12 min), indicating the quickest softening. The digested samples were immediately exposed to mechanical forces generated by the human gastric simulator (HGS) for 10 min to investigate the influence of gastric juice on the breakdown behaviour of EWG cubes. The breakdown behaviour of the disintegrated samples was characterized by fitting the cumulative distributions of particle surface areas to a mixed Weibull function (R 2 > 0.99). The weight of fine particles (α) showed that regardless of gastric juice diffusion, the pH 5 EWG (α = 0.22 ± 0.03) disintegrated into more fine particles than those resulting from pH 9 EWG disintegration (α = 0.07 ± 0.02). As expected, the diffusion of gastric juice enhanced erosion of the EWG particles into fine particles. Result obtained from the particle surface area distribution is in good agreement with the softening kinetics of EWGs during simulated in vitro gastric phase.

Impact of Cooking Preparation on In Vitro Digestion of Eggs Simulating Some Gastrointestinal Alterations in Elders

“…The literature reports the impact of the egg protein structure on proteolysis in model systems consisting in white gels. Studies performed at static 19−21 and dynamic in vitro systems 21,22 clearly evidencing the role of the matrix structure. However, information related to the modulation of egg protein digestibility neither by cooking nor under elderly GI conditions has been previously reported in real foods.…”

Evaluation of the performance of the human gastric simulator using durum wheat-based foods of contrasting food structure

“…Particles <4 mm 2 that resulted from chipping and surface erosion of pasta in the HGS were hypothesized to constitute the solid fraction of emptied pasta digesta. 57,58…”