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International audience; Infant formula (IF) is the adequate Human milk (HM) substitute despite of still remaining differences in fine composition and structure.✓ HM and IF are assumed to have different digestion kinetics although they are rarely directly compared either in vivo or in vitro.➔ The present study aimed to evaluate the digestion kinetics and the structure evolution using the DIDGI® dynamic digestion system at the infant stage

International audience; Infant formula (IF) is a complex matrix requiring numerous ingredients and processing steps. The objective was to understand how the quality of protein ingredients impacts IF structure and, in turn, their kinetics of digestion. Four powdered IFs (A/B/C/D), based on commercial whey protein (WP) ingredients, with different protein denaturation levels and composition (A/B/C), and on caseins with different supramolecular organisations (C/D), were produced at a semi-industrial level after homogenization and spray-drying. Once reconstituted in water (13 %, wt/wt), the IF microstructure was analysed with asymmetrical flow field-flow fractionation coupled with multi-angle light scattering and differential refractometer, transmission electron microscopy and electrophoresis. The rehydrated IFs were subjected to simulated infant in vitro dynamic digestion (DIDGI®). Digesta were regularly sampled to follow structural changes (confocal microscopy, laser-light scattering) and proteolysis (OPA, SDS-PAGE, LC-MS/MS, cation-exchange chromatography). Before digestion, different microstructures were observed among IFs. IF-A, characterized by more denatured WPs, presented star-shaped mixed aggregates, with protein aggregates bounded to casein micelles, themselves adsorbed at the fat droplet interface. Non-micellar caseins, brought by non-micellar casein powder (IF-D) underwent rearrangement and aggregation at the interface of flocculated fat droplets, leading to a largely different microstructure of IF emulsion, with large aggregates of lipids and proteins. During digestion, IF-A more digested (degree of proteolysis + 16 %) at 180 min of intestinal phase than IF-C/D. The modification of the supramolecular organisation of caseins implied different kinetics of peptide release derived from caseins during the gastric phase (more abundant at G80 for IF-D). Bioactive peptide release kinetics were also different during digestion with IF-C presenting a maximal abundance for a large proportion of them. Overall, the present study highlights the importance of the structure and composition of the protein ingredients (WPs and caseins) selected for IF formulation on the final IF structure and, in turn, on proteolysis. Whether it has some physiological consequences remains to be investigated.

International audience; Exclusive breastfeeding in the first months of life has protective effects on infant health compared to formula-fed infants including a lower risk of gastrointestinal and respiratory infections and of metabolic and immune disorders. These observable differences in 'health effect' are likely due to differences in composition between breast milk and infant formula. In particular, breast milk contains a wide variety of bacterial species that are present at low dose. This microbial counterpart contributes to the development of the newborn's gut microbiota after digestion of milk matrix. It was also suggested to influence more largely intestinal homeostasis, acting on the gut immunity and intestinal barrier, and thus to contribute to breastmilk health promoting effects [1]. Several studies have investigated the impact of commensal bacteria on gut homeostasis. However, they generally do not include the different phases of digestion, like gastric (G) or intestinal (I) phases, which could have an impact on the physiological state and properties of the bacteria. The aim of this study was to evaluate the impact of newborn digestion on the physiology of breastmilk bacteria and on their mmunomodulatory potential. For this study, six strains representative of the prevalent bacteria in breast milk were selected. The strains were digested in a static in vitro model of digestion, at full-term infant stage, in a milk matrix. Following the G and I phases, bacterial cultivability was measured and the immunomodulation properties were determined through the quantification of IL-10 and TNF-α released by macrophages (THP-1 line: human monocytic cell line differentiated into macrophages). The impact of the G and I digestion phases on both viability and immunomodulation properties was strain-dependent, pointing out the interest to consider these steps for the determination of ingested bacteria properties.This study is part of the PROLIFIC project and was financially supported by the Régions Bretagne and Pays de Loire and the Milkvalley-BBA consortium.

International audience; Introduction et but de l’étudeLes préparations pour nourrissons (PPN), seuls substituts adéquats au lait maternel (LM), sont des matrices complexes qui nécessitent de nombreux ingrédients et étapes de transformation. L'objectif de ces essais était de comprendre comment la structure et la composition protéiques des préparations pour nourrissons modulent leur cinétique de digestion et d’absorption en utilisant des modèles de digestion in vitro et in vivo.Matériel et MéthodesQuatre PPNs contenant des protéines de lactosérum avec différents taux de dénaturation (A/B/C) ou des caséines de structures micellaires différentes (C/D) ont été fabriquées. Leur profil protéique variait légèrement mais leur composition nutritionnelle et leur taux d'azote aminé étaient similaires. Elles ont été digérées (1) à l'aide d'un modèle de digestion in vitro dynamique (DIDGI) pour suivre la structure des digestas (microscopie), la protéolyse globale (OPA) et la cinétique d'apparition des peptides (LC-MS/MS) au cours de la digestion et (2) par des mini-porcelets Yucatan (n=10, 12-27 jours de vie) afin de suivre la cinétique postprandiale (4h) d'apparition plasmatique des acides aminés (AA). Les données ont été analysées par un modèle linéaire mixte pour données répétées.Résultats et Analyses statistiquesAvant digestion, les structures lipoprotéiques étaient différentes entre les PPNs. La PPN A présentait des structures lipoprotéiques étoilées avec la présence d'agrégats de protéines du lactosérum à la surface des caséines pour un taux de dénaturation global des protéines du lactosérum de 44%. Les PPNs B et C ne présentaient pas de structures particulières et avaient des taux de dénaturation respectifs de 36 et 31%. La PPN D contenant des caséines non micellaires présentait de grandes structures avec de nombreuses structures caséiques à l'interface de gouttelettes lipidiques partiellement floculées. Son taux de dénaturation des PS était de 29%. La PPN A, caractérisée par des taux de protéines du lactosérum glyquées et dénaturées plus élevés, avait un degré de protéolyse significativement plus élevé à 180 min de phase gastrique que la PPN D et en phase intestinale que les PPNs C et D. Les peptides (en particulier ceux issus des caséines) apparaissaient plus tôt en phase gastrique pour la PPN D (à 80 mincontre 180 min pour les PPNs A et B). La PPN C présentait une abondance maximale pour près de la moitié des peptides bioactifs. Chez le porcelet, les PPNs A et B présentaient des concentrations plasmatiques en AA totaux et essentiels significativement plus élevées que les PPNs C et D. La dénaturation des protéines du lactosérum (PPN A) ou la modification structurelle des caséines (PPN D) semblerait induire une diminution du catabolisme oxydatif des acides aminés.ConclusionLes approches complémentaires in vitro et in vivo ont permis de mettre en évidence l'influence de la structure des PPNs sur la digestion des protéines et l'absorption des acides aminés. La structure micellaire de l'ingrédient caséique avait un impact majeur sur la structure protéique des PPNs, leur cinétique de protéolyse avec une libération plus précoce et plus abondante de peptides pour les structures caséiques modifiées ainsi que sur l'oxydation des acides aminés plasmatiques. La structure de la fraction protéique du lactosérum a induit des différences de cinétiques de protéolyse in vitro et in vivo, avec une augmentation de la protéolyse pour les protéines du lactosérum les plus dénaturées induisant des concentrations en acides aminés plasmatiques postprandiales plus importantes. Au vue de la littérature, la digestion de la PPN C (présentant une faible dénaturation,des caséines micellaires et induisant des cinétiques postprandiales plus faibles pour de nombreux acides aminés comparés aux PPNs A et B) se rapprocherait davantage de celle du lait maternel. L'impact physiologique de ces PPNs sera évalué au cours d'une prochaine étude sur le porcelet Yucatan

Le réseau GALACTINNOV vient structurer une collaboration fructueuse entre un ensemble de dix unités de recherche sous tutelle des établissements français partenaires, et de quatre universités québécoises, regroupées au sein du regroupement « Op+lait ».; International audience; Les préparations pour nourrissons (PPNs) sont des matrices complexes, issues de nombreuses étapes de transformation, qui peuvent potentiellement altérer la structure et la composition des protéines qu’elles contiennent. L’objectif était de comprendre comment la structure et la composition des ingrédients protéiques laitiers impactaient la structure des PPNs et leurs cinétiques de digestion. Quatre PPNs ont été formulées à partir d’ingrédients commerciaux dont la structure protéique variait selon leur origine et leurs procédés d’obtention, avec des protéines du lactosérum (PS) de degrés de dénaturation et glycation différents (PPNs-A/B/C) et des caséines ayant une organisation supramoléculaire différente (PPNs-C/D). La structure des PPNs a été étudiée à différentes échelles avant et pendant la digestion ainsi que leur protéolyse en conditions in vitro dynamiques.Les structures lipoprotéiques des PPNs avant digestion étaient différentes, avec la PPN-A qui présentait des structures lipoprotéiques étoilées et la PPN-D de larges structures composées de caséines agrégées et de matière grasse floculée. A l’issye de chacune des phases de digestion (gastrique et intestinale), le degré d’hydrolyse de la PPN-A était plus élevé que celui des PPNs-C/D. La cinétique de relargage des peptides issus de caséines était également différente, en particulier pour la PPN-D, dont l’organisation supramoléculaires des caséines étaient modifiée avant digestion, par comparaison aux autres PPNs.Ces résultats soulignent que la qualité initiale des ingrédients protéiques laitiers, dépendante de leur origine et de leur transformation, influe sur la structure finale des PPNs et sur leur protéolyse. Des études in vivo complémentaires ont été réalisées et permettront d’évaluer l’impact physiologique de ces différences.

This conference is a major event in the field of Food, Nutrition and Health. It is organized in the frame of the INFOGEST research network(www.cost-infogest.eu) whose objective is to “improve the health properties of food by sharing our knowledge on the digestive process”. INFOGESTis a global network of approximately 582 research scientists (academic and food companies) from 150 institutions across 46 countries.; International audience; Infant formulas (IFs), the only adequate substitute to breastmilk, are complex matrices that require numerous ingredients and processing steps. The objective was to understand how protein structure within IFs modulates their digestive kinetics. Four IFs (A/B/C/D), containing whey protein (WP) ingredients with different denaturation and glycation levels (A/B/C) and caseins with different structures (C/D), were subjected to infantin vitro dynamic digestion (DIDGI®). Digesta were regularly sampled to follow structural changes (A4F, microscopy), proteolysis (OPA, LC-MS-MS) and lipolysis (GC-MS). Data were analysed using repeated measures ANOVA. Before digestion, lipoprotein structures were different among IFs. IF-A, characterized by higher glycated and denatured WP rates, tended to be more digested at 180min of intestinal phase than IF-C/D (degree of proteolysis +16% and lipolysis +5.2%). Peptides (protein-origin independent) appeared sooner into the gastric phase for IF-D (at 80 min vs. 180 min for IF-A/B), suggesting that the initial bigger lipoprotein structures in the matrix were less dense and more accessible to pepsin. Different bioactive peptides kinetics were also observed among IFs during digestion. Overall, it highlights the importance of the structure of protein ingredients (WPs and caseins)selected for IFs. Further investigation will be conducted in vivo (mini-piglets) to complete these data.

International audience; Les préparations pour nourrisson (PPNs) sont des matrices complexes. L’objectif était de comprendre comment la structure des ingrédients protéiques impactait la structure des PPNs et leur cinétique de digestion. Quatre PPNs, formulées à partir de protéines sériques (PS) présentant des degrés de dénaturation et de glycation différents (A/B/C) et de caséines avec une organisation supramoléculaire différente (C/D), ont été digérées à l’aide d’un modèle in vitro dynamique (DIDGI®) au stade infantile. Les digestas ont été échantillonnés à intervalle régulier afin de suivre les modifications structurales, la protéolyse (OPA, SDS-PAGE, LC-MS/MS) et la lipolyse (GC-MS). Les données ont été analysées par ANOVA pour mesures répétées. Avant digestion, les structures lipoprotéiques des PPNs étaient différentes. La PPN-A, caractérisée par des taux élevés de glycation et de dénaturation de ses PS, tendait à être davantage digérée à 180min de la phase intestinale que les PPNs-C/D (augmentation du degré de protéolyse et lipolyse : +16% et + 5%). Les peptides apparaissaient plus rapidement en phase gastrique pour la PPN-D (dès 80min vs. 180min pour les PPN-A/B), suggérant que les grosses structures lipoprotéiques initialement présentes dans la matrice étaient moins denses et donc plus accessibles par la pepsine. Ces résultats soulignent l’importance de la structure des ingrédients protéiques sur la structure des PPNs et leur digestion. Une étude in vivo complémentaire est en cours.

This conference is a major event in the field of Food, Nutrition and Health. It is organized in the frame of the INFOGEST research network(www.cost-infogest.eu) whose objective is to “improve the health properties of food by sharing our knowledge on the digestive process”. INFOGESTis a global network of approximately 582 research scientists (academic and food companies) from 150 institutions across 46 countries.; International audience; Background. Docosahexaenoic acid (DHA) is an essential polyunsaturated fatty acid (FA) mainly involved in cognitive and cardiac functions. Nutritional intake is nevertheless globally insufficient in many countries. Food fortification alternatives should be developed to meet nutritional needs, while avoiding lipid oxidation. Methods. Pickering emulsion was prepared with heat-denatured whey protein particles to encapsulate DHA oil composed of DHA-enriched triacylglycerols. Then omelets were cooked with either non-encapsulated or encapsulated DHA oil. Each food matrix was digested according to the INFOGEST in vitro static model and tested in vivo on a rat model as food supplementation. The effect of encapsulation was investigated on bioaccessibility, bioavailability, tissue accretion and metabolism of DHA. Results. In vitro, DHA oil was not hydrolyzed during the gastric phase, on the contrary to the other triacylglycerols from eggs. In the intestinal phase, encapsulation of DHA oil promoted DHA release from triacylglycerols as free FA (52% vs 40% of total DHA). In vivo, encapsulation increased rat growth by enhancing food consumption, without globallymodulate the tissue FA profile. In contrast, it drastically impacted profiles of oxidized derivatives of FA in plasma, heart and even brain.Conclusion. The intake form of DHA oil greatly influenced DHA metabolism in tissues.

International audience; Human milk (HM) and Infant formula (IF) are assumed to present different digestion kinetics, while rarely directly compared. The study aimed to address this question using a dynamic digestion model (DIDGI®) at the infant stage.Fresh HM (pool from 50 mothers) and standard IF with similar total nitrogen content were digested in triplicate. Digesta were sampled regularly in gastric and intestinal phase from 0 to 180 min to evaluate structural changes (confocal microscopy and laser light scattering), proteolysis (SDS-PAGE and densitometry, OPA), and nitrogen digestibility (µ-Kjeldahl). Differences between groups were assessed using a two-way repeated measures ANOVA.The microstructure of the digesta differed between HM and IF along the gastric digestion. Proteolysis of the common HM and IF proteins, caseins and α-lactalbumin, was significantly slower for HM than for IF. The intestinal degree of proteolysis was lower for HM than IF, at least during the first two hours. Total N digestibility was lower with HM, such as observed in vivo. Peptidomic and lipolysis data will complete the dataset.Despite nutritional similarity, this study highlights the influence of the matrix on the digestion kinetics and gives some further understanding to the global value of digestibility, such as determined in vivo.

The FAO recommends the digestible indispensable amino acid score (DIAAS) as the measure for protein quality, for which the true ileal digestibility needs to be assessed in humans or pigs. However, due to high costs and ethical concerns, the FAO strongly encourages as well the development of validated in vitro methods, which complement the in vivo experiments. Method: Recently, an in vitro workflow, based on the validated static INFOGEST protocol, was developed and compared towards in vivo data. In parallel to the validation with in vivo data, the repeatability and reproducibility of the in vitro protocol were tested in an international ring trial (RT) with the aim to establish an international ISO standard method within the International Dairy Federation (IDF). Five different dairy products (skim milk powder, whole milk powder, whey protein isolate, yoghurt, and cheese) were analyzed in 32 different laboratories from 18 different countries, across 4 continents. Results: in vitro protein digestibilities based on Nitrogen, free R-NH2, and total amino acids as well as DIAAS values were calculated and compared to in vivo data, where available. Conclusion: The in vitro method is suited for quantification of digestibility and will be further implemented to other food matrices.

International audience

International audience; Protein digestibility, a key indicator of dietary protein quality, can be estimated in vitro. The objectivewasto determinethe contribution of endogenous N, released by the enzyme autolysis, to in vitro protein digestibilityusing 15N-labelled proteins. Methods:15N-labelled gluten and caseins (4, 8 and 16% of the meal) were digested using the INFOGEST static in vitromodel.The endogenous N was measured after centrifugation and 10-kDa ultrafiltration, allowing the true N digestibilitydetermination. The proteolysis degree, based on the primary amine content, was determined. Results: Alarge proportion (93±11%) of the endogenous N < 10 kDa within digesta was present before digestion, with somecontribution, although limited(20-30%),of the enzyme autolysis. For both proteins, true N digestibility was not significantly different between 30and120 min of intestinal digestion,but significantly higher for the lowest protein content (4%). The proteolysis degree was more correlated to theapparentdigestibility, i.e.withno endogenous N correction, than to the true digestibility, showing that further endogenous correction is needed for more accuracy.Conclusion: In vitro protein digestibility, as well as proteolysis degree, needs to be corrected for the endogenous N contribution, although to a different extent.