To improve our understanding of gastrointestinal digestion of solid foods, spatially resolved insights into disintegration mechanisms at the particle level are needed. Magnetic resonance imaging (MRI), despite its noninvasive and multiscale capabilities, remains underexploited for such purposes. This study pursued two objectives: (1) to develop an MRI-compatible miniaturized setup for static in vitro oral-gastric-intestinal digestion, and (2) to apply this system to investigate online the digestion of a bread piece measuring a few millimetres using MRI (UTE 3D morphometric imaging and T2 mapping), supplemented by chemical analyses of starch and protein hydrolysis. The setup comprises a circulation loop of the digestion fluid, linking an MRI-compatible digestion cell to a remote pH-stat system, which enables real-time control of temperature, pH, enzyme addition, and sampling. MRI results correlated well with peptide and polysaccharide release kinetics in the digestion fluid. UTE 3D imaging showed stable bread volume during gastric digestion, followed by volume loss, surface roughening, and fluid ingress into pores during intestinal digestion, consistently with gluten hydrolysis. T2 analysis distinguished more mobile water in the pores and less mobiles ones in bread. An increase in the amount of more mobile protons suggested erosion-driven exposure and internal enzymatic attack. The release of starch hydrolysis products was shown to be independent on the breakdown of the gluten network and could be monitored with T2 in the digestion fluid. In conclusion, this MRI-compatible setup enables time-lapse, submillimetric resolution monitoring, offering valuable insights into bread piece digestion, and could be adapted to various solid food matrices.

Protein digestibility can be determined in vitro from the digesta bioaccessible fraction. Different fractionation methods were compared on casein, ovalbumin, gelatin, lupin and pea globulins digested at high (INFOGEST protocol) or low extent (enzyme reduced 10×). Digesta were centrifuged, alone or after trichloroacetic acid (TCA, 3 or 8.5%), sulfosalicylic acid (SSA, 1.5 or 4.5%) or methanol (80%) precipitation. The supernatants were analyzed by size exclusion chromatography. Real in vitro digestibility values of 15N-labelled casein were compared with those obtained in vivo. Only the chemical agents, offering similar efficiency except methanol and 1.5% SSA somehow differing, allowed large peptide (>10 kDa) depletion. The effectiveness of chemical agents depended both on the protein source and their digestion extent. The real digestibility of casein could be determined appropriately in vitro using 4.5% SSA or methanol, with values similar to that measured previously in humans, at the ileal level, on the same protein source.

Understanding lipid digestion is crucial for promoting human health. Traditional methods for studying lipolysis face challenges in sample representativeness and pre-treatment, and cannot measure real-time lipolysis in vivo. Thus, non-invasive techniques like magnetic resonance imaging (MRI) need to be developed. This study assessed the MRI water-fat separation method for monitoring in vitro intestinal digestion of dairy cream, supported by high-performance thin-layer chromatography (HP-TLC) and time-domain nuclear magnetic resonance (TD-NMR). A clear distinction was found between the T-2 of undigested lipids (similar to 120 ms) and lipolytic products (0.1-15 ms). The short T-2 of lipolytic products likely results from semi-crystalline structures formed with bile salts. While MRI methods cannot detect such fast-relaxing protons, it effectively quantified lipolysis by tracking the residual undigested lipids, showing high correlation with HP-TLC results (R-2 = 0.93 and 0.95 for 13-s and 6-min MRI methods, respectively). The rapid 13-s MRI method offers strong potential for future in vivo applications.

Physiologically relevant gastrointestinal digestion models for infants, adults, and the elderly are commonly used to explore the fate of food in vitro. However, no consensus protocol exists to simulate the specific conditions observed in the stomach of people using oral proton pump inhibitors (PPIs), a class of widely prescribed medications that reduce gastric acid secretion and may alter food digestion and nutrient absorption. The first objective of this study was to propose an in vitro gastric digestion protocol adapted to model PPI use. This protocol is an extension of the semi-dynamic INFOGEST protocol previously developed to mimic the digestion of an adult human (referred to hereinafter as "Standard"), with two modifications based on reported clinical effects of PPIs: (i) a final gastric pH of 4.2 and (ii) a 50 % reduction in simulated gastric acid fluid volume. The second objective was to compare the release kinetics of peptides, soluble carbohydrates, lipids, and minerals during simulated gastric digestion of a mixed meal (bread, cheese, and tomato) with both standard and PPI versions of the protocol. Results demonstrated that the release of peptides, arabinose, and minerals, including calcium, magnesium, and phosphorus, was significantly (p < 0.05) reduced in the PPI model, while the hydrolyses of starch and lipids, assessed through maltose release and triacylglycerol disappearance, respectively, were not significantly affected. These findings are in agreement with the expected effects of reduced gastric acidity on pepsin activity and mineral solubility. These findings are also consistent with known or presumed side effects of PPIs such as an increased risk of hypomagnesemia, fractures, skeletal muscle loss, and vitamin B12 deficiency. In conclusion, this modified INFOGEST protocol appears to serve as a valuable tool to study the side effects of PPI use on food digestion and related nutrient bioaccessibility.

The increasing demand for food and especially proteins leads to the search for alternative protein sources. Meat co-products, which are available but little used in human food, provide a potential solution to this challenge. The present study aimed to evaluate the nutritional quality of two beef protein ingredients (greasy greaves recovered proteins (GGRP) and water recovered proteins (WRP)), both co-products of the fat rendering process. Their true ileal digestibility (TID), digestible indispensable amino acid score (DIAAS) and kinetics of plasma amino acids (AA) were measured in ten growing pigs, each fed the two co-products and a protein-free diet. Titanium dioxide was used as an indigestible marker. Digesta samples were collected for 9 h after meal ingestion, and blood samples were collected at ten time points during the same period. Total nitrogen (N) and AA contents were determined. Data were statistically analysed using linear mixed models. The TID of total N was not different between WRP and GGRP (81-84 %, P > 0·05). The first-limiting AA was Trp for both ingredients, with a DIAAS much higher for GGRP than for WRP (74 and 10 % for adults, respectively; P < 0·001). Postprandial plasma AA concentration peaked earlier for WRP (3 h) than for GGRP (5 h). Plasma concentrations of total and essential AA were higher (P < 0·001) with GGRP diet than WRP diet. Overall, GGRP has a nutritional quality suitable to meet the needs of adults for AA, while WRP needs to be supplemented with other protein sources to fulfil the dietary requirements.

The study aimed to assess the extent to which protein aggregation, and even the modality of aggregation, can affect gastric digestion, down to the nature of the hydrolyzed peptide bonds. By controlling pH and ionic strength during heating, linear or spherical ovalbumin (OVA) aggregates were prepared, then digested with pepsin. Statistical analysis characterized the peptide bonds specifically hydrolyzed versus those not hydrolyzed for a given condition, based on a detailed description of all these bonds. Aggregation limits pepsin access to buried regions of native OVA, but some cleavage sites specific to aggregates reflect specific hydrolysis pathways due to the denaturation-aggregation process. Cleavage sites specific to linear aggregates indicate greater denaturation compared to spherical aggregates, consistent with theoretical models of heat-induced aggregation of OVA. Thus, the peptides released during the gastric phase may vary depending on the aggregation modality. Precisely tuned aggregation may therefore allow subtle control of the digestion process.

The valorization of co-products may be a promising way to meet the dual challenge of increasing global food resources and sustainability of food systems. In particular, meat co-products may be nutritionally interesting protein resources, if they offer functional properties in accordance with food applications. In that aim, two bovine co-products, resulting from the fat rendering process, have been characterized, regarding the protein solubility, gelling, and emulsifying properties. The effect of protein concentration, pH variation and NaCl addition on these properties was tested. Despite an effect of the ionic strength on the protein solubility of the two ingredients, a little or no significant impact was observed on the functionalities. Similarly, the functional properties were scarcely affected by pH. In the end, the protein concentration has proven to be the only important parameter, which points to an easy utilization of these ingredients in many food conditions.

Meat co-products are a promising alternative for meeting the increasing demand for protein, especially for the formulation of meat products. The present study aims to determine the optimal conditions under which two innovative bovine co-products, resulting from the fat rendering process, can mimic the gelling and emulsifying properties of commercial gelatines and sodium caseinate (NaCas), respectively, using Response Surface Methodology (RSM). The desirability function was used to determine the values for protein concentration, pH and NaCl content that enable the two co-products to effectively mimic gelatine and NaCas. The co-product obtained from water recovered during the fat rendering process proved to be the most suitable to mimic commercial gelatines. Very high desirability scores were obtained with this ingredient on 4 criteria out of 7, and a high overall score as well, provided 90 g/L protein was used to mimic a 50 g/L gelatine 150 Bloom. Both co-products appeared as effective alternatives to NaCas as emulsifiers, especially regarding their capacity in stabilizing emulsions. The co-product made of greasy greaves can be even regarded as more effective than NaCas, as less proteins are needed to obtain the same performances (110 g/L vs 125 g/L, respectively).

L'oeuf : un aliment aux qualités nutritionnelles avéréesAliment peu coûteux, l'oeuf est une source de protéines de très bonne qualité, de lipides pour les deux tiers insaturés, de minéraux et vitamines, ainsi que de caroténoïdes d'intérêt pour lutter contre certaines pathologies de l'oeil.L'absence de lien, chez les sujets en bonne santé, entre une consommation modérée d'oeuf, le niveau de cholestérol sanguin et le risque de maladies cardiovasculaires fait aujourd'hui consensus.Mais l'oeuf est aussi un allergène majeur chez le jeune enfant.Eggs: a food with proven nutritional qualities .An inexpensive foodstuff, eggs are a source of high-quality proteins, lipids (two-thirds of which are unsaturated), minerals and vitamins, as well as carotenoids of interest in the fight against certain eye diseases.Today, the consensus is that there is no link, in healthy subjects, between moderate egg consumption, blood cholesterol levels and the risk of cardiovascular disease.But eggs are also a major allergen in young children.

The monitoring of food degradation during gastrointestinal digestion is essential in understanding food structure impacts on the bioaccessibility and bioavailability of nutrients. Magnetic Resonance Imaging (MRI) has the unique ability to access information on changes in multi-scale structural features of foods in a spatially resolved and non-destructive way. Our objective was to exploit various opportunities offered by MRI for monitoring starch, lipid and protein hydrolysis, as well as food particle breakdown during the semi-dynamic in vitro gastrointestinal digestion of complex foods combined in a meal. The meal consisted of French bread, hard cheese and water (drink), with a realistic distribution of bolus particle sizes. The MRI approach was reinforced by parallel chemical analysis of all macronutrients in the supernatant. By combining different imaging protocols, quantitative MRI provided insights into a number of phenomena at the level of the cheese and bread particles and within the liquid phase that are hard to access through conventional approaches. MRI thus revealed the progressive ingress of fluids into the bread crust and the release of the gas trapped in the crumb, the erosion of cheese particles, the creaming of fat, the disappearance of small food particles and changes in liquid phase composition. Excellent agreement was obtained between the quantitative parameters extracted from the MRI images and the results of the chemical analysis, demonstrating the strong potential of MRI for the monitoring of in vitro gastrointestinal digestion. The present study proposes further improvements to fully exploit the capabilities of MRI and constitutes an important step towards the extension of quantitative MRI to in vivo studies.

Studying the mechanisms of food disintegration in the gastrointestinal tract should provide a better understanding of the effect of food on human health. Numerous studies have reported the behaviour of purified compounds (macro or micronutrients) under digestive conditions. However, micro and macronutrients are rarely consumed in the form of pure compounds but most of the time integrated into food matrices. The structure of food products is now considered to be a key parameter that strongly influences the release of nutrients in the gastrointestinal tract and their bioavailability in the bloodstream. This article will therefore focus on how the structure of foods and food constituents affects digestion. It will show that depending on the scale considered (molecular, micro or macroscopic) to follow the disintegration of foods, the data obtained can vary considerably. Finally, it will demonstrate that the structure of foods can be a lever for optimizing the delivery of micronutrients. (c) 2021 Soci & eacute;t & eacute; fran & ccedil;aise de nutrition. Published by Elsevier Masson SAS. All rights reserved.

Pepsin diffusion in food particles during gastric digestion is one of the main factors limiting proteolysis kinetics. Diffusion coefficients of pepsin are needed as input parameters for in silico models of digestion, but no values are currently available in real foods. The challenge of this study was to apply the Fluorescent Recovery After Photobleaching (FRAP) technique to determine diffusion coefficients of fluorescently labeled (FITC)-pepsin in four realistic food matrices with complex and heterogeneous structures (Custard, Pudding, Sponge cake and Biscuit), but an identical composition on a dry matter basis. The effective diffusion coefficients determined for FITC-pepsin at 37 ? ranged from 48 +/- 14 to 2 +/- 1 mu m(2). s(-1) for Custard and Biscuit, respectively. A modelling approach based on the stretched exponential equation generated a very good fit of the experimental dataset as a function of dry matter content of the matrix.