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 (D eff = 44.2 ± 6.1 μm 2 s −1), compared to the pH5-EWG (D eff = 52.5 ± 5.3 μm 2 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.
This study investigated the feasibility of using hyperspectral imaging (HSI) to characterize the diffusion of acid and water within food structures during gastric digestion. Two different sweet potatoes (steamed and fried) and egg white gel (pH5 and pH9 EWGs) structures were exposed to in vitro gastric digestion before scanning by HSI. Afterward, the moisture or acid present in the digested sample was analyzed for calibration purposes. Calibration models were subsequently built using partial least-squares (PLS). The PLS models indicated that the full-wavelength spectral range (550−1700 nm) had a good ability to predict the spatial distribution of acid (R cal 2 > 0.82) and moisture (R cal 2 > 0.88). The spatiotemporal distributions of moisture and acid were mapped across the digested food, and they were shown to depend on the food composition and structure. The kinetic data revealed that the acid and moisture uptakes are governed by Fickian diffusion or by both diffusion and erosion-controlled mechanisms. Article pubs.acs.org/JAFC Cite This: J. Agric. Food Chem. XXXX, XXX, XXX−XXX
Innovations in the plant protein space have made significant strides in the past few years. A substantial body of work is to replace animal protein-based products with plant protein ingredients. Pulse proteins are receiving utmost attention among these plant proteins due to their nutritional and functional properties. This article critically evaluates the food and non-food applications of pulse protein and intends to present the most current knowledge with interest to stimulate further research to optimize pulse protein utilization. With the increased attention on plant-based foods, many novel applications and products such as infant formulas, meat analogues, milk alternatives, bean curd, bakery products, extruded products, pastes, food decorations, animal and fish feed, protein supplementations, microencapsulation carrier matrixes, biopolymer-based edible packaging, and cosmetic application are explored. Although pulse protein has limited non-food applications, there is considerable potential in nutraceutical, pharmaceutical, and cosmeceutical applications. Thus, further research is crucial for both food and non-food applications of pulse protein for broader market integration.
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.
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