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International audience; Introduction et but de l’étudeLa formulation des préparations pour nourrissons (PPN) est très réglementée et doit mimer au mieux l’aminogramme du lait humain (LH), premier élément essentiel de la qualité nutritionnelle des protéines. Peu d’études in vivo se sont intéressées à la digestibilité des acides aminés (AA) du LH et des PPNs, permettant d’estimer leur biodisponibilité, autre indicateur important de la qualité nutritionnelle des protéines. L’objectif de cette étude était de mesurer la digestibilité iléale vraie (DIV) des protéines du LH et d’une PPN, afin de calculer leur DIAAS (Digestible Indispensable Amino Acid Score ; FAO, 2013). Un modèle mini-porcelet a été utilisé comme modèle du nourrisson.Matériel et MéthodesDes porcelets âgés de 19 jours ont reçu pendant 6 jours du LH (n=7) ou une PPN (n=9). Un troisième groupe de porcelets a reçu un régime sans protéines (n=6), permettant d’évaluer les pertes en protéines endogènes. Les trois régimes contenaient du Cobalt-EDTA comme marqueur de transit. Le dernier jour, les repas ont été distribués toutes les heures pendant six heures avant sacrifice des animaux et récupération des contenus iléaux pour mesurer la digestibilité vraie de l’azote total et des AA. Le DIAAS a été calculé à partir des digestibilités et des teneurs en AA des aliments au regard du profil de référence, correspondant au profil en AA du LH (FAO, 2007). Des hydrolyses de durées multiples (0 à 120 h) des échantillons ont été réalisées afin d’évaluer les pertes en AA au cours de cette étape et corriger les valeurs classiquement obtenues à 24 h d’hydrolyse acide ou 16 h d’hydrolyse basique pour le tryptophane. Une ANOVA multifactorielle a permis l’analyse et la comparaison des données.Résultats et Analyses statistiquesLes hydrolyses multiples ont permis de corriger les teneurs en AA des aliments et des digestas, en particulier pour la tyrosine et la valine (+10% de la valeur mesurée à 24 h d’hydrolyse). Les profils en AA du LH étaient en accord avec la méta-analyse de Zhang et al. (2003). La DIV de l’azote aminé n’était pas significativement différente (LM : 96,7 ± 1,0 % et PPN : 98,0 ± 0,7 for IF, p > 0,05) tandis que la DIV de l’azote total était significativement plus faible pour le LH (91,3 ± 1,2 %) que pour la PPN (98,0 ± 0,9 %). Cette différence s’expliquait par la plus forte proportion d’azote non protéique dans le LH (LH : 31,0 ± 0,7 % et PPN :4,4 ± 0,2 % de l’azote total), partiellement non digestible et non-absorbable. Quelques AA présentaient des différences de digestibilité. Ainsi, la lysine était significativement plus digestible dans le LH que dans la PPN (98,4 ± 0,7 % vs. 96,0 ± 0,5 %), probablement lié à l’absence de glycation des protéines (réaction de Maillard) dans le LH. A l’inverse, les DIVs de la phénylalanine, la thréonine, la valine, l’alanine, la proline et la sérine, étaient significativement légèrement plus faibles dans le LH que dans la PPN (-2,6 à -7,3 points). La DIV moyenne dutryptophane était proche entre le LH et la PPN (96,8 ± 0,5 %, p = 0,079). Le DIAAS était plus élevé pour le LH que pour la PPN (+10%) et était, pour les deux aliments, liés à une teneur en AA aromatiques (phénylalanine + tyrosine) plus basse que celle du profil de référence.ConclusionCette étude a démontré que le LH, comparé à la PPN, avait une DIV plus faible uniquement pour l’azote total et non pas pour l’azote aminé. Ceci suggère qu’une fraction d’azote non protéique du LH est sous forme non digestible et non absorbable, tel que l’urée, et est donc transférée vers le colon. Cette fraction azotée, bien que peu considérée dans la formulation des PPNs, peut cependant avoir un rôle sur la composition du microbiote. Par ailleurs, la digestibilité plus élevée de la lysine dans le LH que la PPN, est certainement dû à l’absence de réaction de Maillard dans le LH contrairement aux PPNs, qui reçoivent de nombreux traitements thermiques

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.

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.

Whey protein microparticles are of great potential in diverse applications such as fat replacement, emulsification, cargo delivery and formulation of high-protein beverages. We developed a method by which the major whey protein, β-lactoglobulin, (β-lg) is at first encapsulated through a facile procedure within CaCO3 micro-templates, followed by enzymatic crosslinking of the protein and succeeding removal of the template to form protein microparticles. Protein encapsulation increased the colloidal stability and influenced the micro-morphology of CaCO3 microparticles. Dynamic light scattering and ζ-potential measurements, supported by gel electrophoresis indicated that β-lg was entrapped in monomeric form. Heating of the protein-loaded CaCO3 microparticles to gel protein as an alternative to enzymatic crosslinking, was not feasible because pH reduction to 7.0 before heating caused considerable agglomeration and deformation of the carbonate particles. In subsequent to enzymatic crosslinking and template dissolution, confocal laser scanning microscopy illustrated that the resulting protein particles were spherical, micron sized (≈3μ) and structurally homogenous. It was found based on Fourier transform infra-red spectroscopy that enzymatic crosslinking twisted the β-sheet structures of β-lg. Gel electrophoresis and intrinsic fluorescence measurement showed that in addition to the enzymatic polymerization, thiol-disulfide exchange reactions contributed in protein particles formation. It was also concluded based on intrinsic fluorescence measurement that tryptophan microenvironment was not influenced by the enzymatic crosslinking. The fabricated β-lg particles did not undergo significant denaturation by subsequent heating. This may open a route to deliver near-native whey protein microparticles to final consumers.

Improving the nutritional and health properties of food products, e.g. infant milk formula, by the addition of functional ingredients is of primary importance. This study focused on bioactive milk polar lipids (PLs) recovered from dietary sources that are of increasing interest. The chemical compositions of buttermilks and butter serums were determined and the modulation of the fatty acid composition of milk PLs was investigated. Butter serums contain a higher amount of milk PLs than buttermilks (88 vs. 13-18g/kg dry matter), with a higher proportion of sphingomyelin (34 vs. 19% of PLs, respectively) interestingly close to human milk PL profile. Butter serums are also interesting sources of choline, an important nutrient for infant brain development. We demonstrated that the unsaturated fatty acid content of milk PLs recovered in the buttermilks and the butter serums, mainly the amount of C18:3n-3 and C22:6n-3 (DHA) that are of nutritional interest, can be increased by dietary strategies. This work opens perspectives for a better valorization of milk PLs in human nutrition (both infants and adults) to benefit their functional, nutritional and health properties.

Unravelling the mechanisms of food digestion to improve our knowledge of the effect of food on human health. 4. Simposio de Alimentos e Nutriçao

Infant formulas (IF) are the key nutritional source for infants who cannot be breastfed. There is currently a growing interest for these sensitive products, in order to control their quality and to design their composition with regard to nutritional balance and sustainable development concerns.This work aimed to study how plant proteins influence the digestibility of IF.Five infant formulas were developed with identical composition except that the protein source were whey proteins in the “reference IF”, pea, faba bean, rice or potato proteins in the four “plant IF” tested. The five IF were first evaluated using an in vitro static gastrointestinal model simulating infant conditions. Protein hydrolysis rate (PHR) and amino acid bioaccessibility (AAB) were measured using free amino group and free amino acid analyses, respectively. The pea and faba bean IF were then submitted to an in vitro dynamic digestion model closer to the physiological conditions, and compared to the reference IF. Protein digestibility (PHR and AAB) as well as the digesta microstructure were followed.Results showed that both PHR and AAB were very similar between the reference IF and pea and faba bean IF, but significantly lower for rice and potato IF. In dynamic conditions, the structure disintegration and the PHR showed differences among the reference, pea and faba bean IF. These differences were more pronounced during the gastric phase compared to the end of the intestinal digestion. This could result from the structure of proteins obtained from the processing steps that is known to influence the protein hydrolysis.This study provides new insights on the impact of protein source on the digestibility of IF. It especially showed that some plant proteins could be appropriate candidates for the composition of IF from a nutritional point of view.

NativIF: Conception of an infant formula by filtration : nutritional ,physiological and sensory impacts. STLOpendays

Comprendre la digestion du lait maternel pour concevoir les formules infantiles de demain. Les rencontres 2019 de l'institut Carnot Qualiment - 7ème édition

International audience; Infant formulas (IF) are the only source of nutrition for infants who cannot be breastfed from their mothers. There is currently a growing interest for these sensitive products, in order to control more carefully their quality and design their composition with regard to sustainable development concern. The aim of this work was to study how a partial substitution of dairy proteins by plant proteins influenced the functionality and the digestibility of IF. Three IF were developed with identical composition, except that 50% of the proteins were whey proteins in the “reference IF”, and pea or faba bean proteins in the “plant IF”. Homogenization and drying steps parameters were investigated at a semi-industrial scale (IF flow rate around 100 kg.h-1). The process influence was assessed through the IF microstructure using confocal microscopy, and the protein digestibility using a dynamic in vitro digestion model. The results showed that the emulsion structure differed depending on the protein type source that did not lead to the same stabilization of the fat droplets. It simultaneously affected the viscosity of the IF and consequently the drying parameters. Last, differences in terms of protein hydrolysis rate were observed mainly during the gastric phase compared to the end of the digestion. This study provides new insights on the impact of the substitution of protein source in IF. It showed that plant protein sources could be good candidates for dairy proteins substitution in IF, both from a processing and nutritional point of view.

The standard tool for emulsification during formulation trials is a homogenizer, which unfortunately requires too much raw material and is time consuming. A lab-scale process using a rotor-stator shearing step followed by ultrasound treatment was designed, both with lecithin and whey protein, for emulsification as efficient as in pilot-plant trials. Ranges for the lab-scale process were defined (rotor-stator: 5 min, 5000–10000 rpm; sonication time: 2–10 min). Process conditions were identified to obtain both emulsions with the same structure at lab and pilot scales: for lecithin, respectively shearing at 10000 rpm/10 min sonication and high pressure for both pilot stages. However, due to protein denaturation, some conditions differed for whey proteins: shearing at 5000 rpm instead of 10000 rpm (all the other parameters being unchanged). Finally, recommendations concerning the position of the ultrasound probe and temperature control are provided to insure good reproducibility.

Lait infantile, comment formuler "biomimétique"

International audience; In 2018, about 60% of world’s newborns received cow milk-based infant formulas (IF) instead of human milk (UNICEF). The process of manufacturing IF involves heat treatments altering the physicochemical properties of milk components, especially whey proteins (WP). The objective of the study was to investigate the impacts of thermal treatments on the denaturation of WP of IF, particularly for those mimicking the protein profile of human milk, and to characterize the heat-induced protein structures. Methods: Three model IF were produced with a caseins:WP ratio of 40:60 at 1.3% and 5.5% of total proteins, differing in the quality of WP. The kinetic of heat-induced denaturation of each WP was investigated between 67.5°C and 80°C by quantification of the residual native proteins by RP-HPLC. The heat-induced protein structures were studied by dynamic light scattering, electrophoresis and asymmetric flow field flow fractionation coupled with MALLS. Results: The quantification of native WP fractions revealed an enhanced denaturation of α-lactalbumin in presence of both β-lactoglobulin and lactoferrin, an increased denaturation of β-lactoglobulin in presence of lactoferrin, and an increased denaturation lactoferrin in presence of β-lactoglobulin. At similar rate of total WP denaturation at 67.5°C and 80°C, the protein composition of the heat-induced aggregates changed between formulas, protein concentrations and heating temperatures but disulfide bonds were the main intermolecular links. The aggregates were larger and of fractal shape (apparent fractal dimension dfapp = 2.1) in formulas at 5.5% proteins whereas they were of spherical shape (dfapp = 2.9) in formulas at 1.3% proteins. Discussion: Effets of heat treatment on the denaturation of α-lactalbumin, β-lactoglobulin and lactoferrin and the protein structure are influenced by the WP quality of IF. These results will give to industrials reliable data on the protein structures formed during the heat treatments of IF. The impact on digestibility will be subsequently investigated

Infant milk formulas: effect of heat treatments on the protein physicochemical properties and the nutritional quality. STLOpendays

National audience; Introduction et but de l’étude : Rapprocher les préparations pour nourrissons (PPN) du lait maternel, d’un point de vue fonctionnel, constitue un enjeu majeur pour optimiser la santé des nourrissons qui ne sont pas allaités par leur mère. La structure et la composition très particulières de la matrice lipidique du lait maternel et la présence d’un microbiote laitier pourraient en partie expliquer les différences physiologiques et métaboliques observées entre enfants allaités au sein et ceux recevant des PPN. L’objectif de cette étude était d’évaluer les effets de l’ajout dans les PPN de matière grasse laitière (MGL) bovine associée ou non à une souche probiotique (L. fermentum CECT5716, Lf) sur la digestion, le microbiote et la fonction barrière de l’intestin du nourrisson à l’issue de la période d’allaitement.Matériel et méthodes : Vingt-six miniporcs Yucatan ont été allaités avec une PPN classique à base de matières grasses végétales (MGV), ou une PPN à base d’un mélange de MGV et de MGL supplémentée ou non en Lf (MGL et MGL+Lf respectivement). La digestion des PPN (protéolyse, lipolyse), la composition et l’activité du microbiote rectal et la fonction barrière de l’intestin ont été évaluées à l’âge de 28 jours.Résultats et Analyse statistique :L’ajout de MGL associée ou non au probiotique Lf a induit une protéolyse gastrique plus importante et a augmenté la diversité de peptides bioactifs et potentiellement antimicrobiens présents dans l’iléon et le côlon. Une lipolyse intestinale plus importante a également été observée avec la MGL. L’association de la MGL et de Lf a de plus renforcé les défenses intestinales non spécifiques de l’hôte, via une augmentation de la densité des cellules à mucus dans le jéjunum, ainsi qu’une plus forte expression des ARN codant les protéines des jonctions serrées (ZO-1 et occludine) et une diminution de la perméabilité transcellulaire dans le côlon. Ces effets pourraient en partie être médiés par la modulation de la composition et du métabolisme du microbiote intestinal observée dans le groupe MLG+Lf avec notamment une sur-abondance de genres bactériens tels que Lachnospiraceae UCG-001 et Coprococcus 3,et une augmentation de la production de métabolites bactériens tels que le butyrate, l’isobutyrate et le glutamate.Conclusion : La MGL et le probiotique Lf ont modifié la digestion des PPN, l’implantation du microbiote et la fonction barrière intestinale du nourrisson. Ces résultats soulignent l’importance de la composition des FI sur la santé digestive du nourrisson. Une étude à plus long terme nous a permis de mettre en évidence des conséquences bénéfiques de ces modifications précoces sur la physiologie intestinale du jeune adulte.Conflits d’intérêts :M. Lemaire a reçu une subvention/soutien de Lactalis, est employé(e) de Lactalis, G. Boudry: Aucun conflit à déclarer, O. Ménard: Aucun conflit à déclarer, P. Le Ruyet est employé(e) de Lactalis, C. Baudry est employé(e) de Lactalis, P. Gérard: Aucun conflit à déclarer, D. Dupont: Aucun conflit à déclarer, A. Deglaire: Aucun conflit à déclarer, I. Le Huërou-Luron a reçu une subvention/soutien de Lactalis, S. Blat a reçu une subvention/soutien de Lactalis

Introduction et but de l’étudeL’encapsulation de nutriments et de bioactifs pour la formulation d’aliments fonctionnels représente une voie à fort potentiel pour l’industrie agro-alimentaire. La coacervation complexe, séparation de phase liquide-liquide obtenue par mélange de protéines et de polysaccharides de charges opposées, est un procédé doux et adéquat pour l’encapsulation. Nous démontrons que les coacervats exclusivement de protéines (coacervats hétéroprotéiques) présentent la même efficacité en tant que vecteur d’encapsulation.Matériel et méthodes : La lactoferrine et la ß-lactoglobuline, deux protéines laitières, ont été utilisées pour former les coacervats hétéroprotéiques. La capacité et l’efficacité de ces coacervats à encapsuler la vitamine B9, nutriment modèle, ont été étudié en conditions optimales de pH et de force ionique, en faisant varier les concentrations en protéines et en B9. Le pouvoir protecteur des coacervats vis-à-vis de la dégradation de B9 par différents traitements utilisés lors de la transformation et du stockage des aliments a été déterminé. La biodisponibilité de B9 ainsi encapsulée a été évaluée in vivo par une étude pharmacocinétique après administration orale chez le rat. Le dosage de la vitamine B9 par ELISA, garantissant la détection exclusive de la forme native, a été effectué sur des prélèvements sanguins réalisés jusqu’à 10h post administration.Résultats et Analyse statistique :Nous avons établi la preuve de concept de la formation des coacervats de protéines en présence de B9. Des hauts rendements à la fois de coacervation et d’encapsulation de B9 ont pu être obtenus. Ainsi, en conditions optimales, nous obtenions l’encapsulation de 4 mg de B9/g de protéines. Par ailleurs, comparativement à la B9 seule en solution,la B9 encapsulée est plus résistante aux traitements physiques ou chimiques tels que la lumière, la lyophilisation ou encore lors d’une oxydation accélérée en présence d’H2O2 . Outre la protection, le principal objectif de l'encapsulation est de favoriser la libération contrôlée de la molécule encapsulée. L’étude harmacocinétique chez le rat met en évidence une concentration plasmatique supérieure en B9 lorsque celle-ci est administrée sous forme de coacervats, en comparaison à l'administration de B9 seule ou simplement complexée à une des deux protéines [1]. La biodisponibilité améliorée par les coacervats est attribuée à leur effet protecteur améliorant ainsi la solubilité de la vitamine lors du transit gastro-intestinal.Conclusion : Ce travail constitue une première preuve de concept prometteusepour l’utilisation potentielle des coacervats de protéines pour l’encapsulation de bioactifs. Leur usage pour formuler des produits sans additifs est une des applications. Des études sur la stabilité de la vitamine B9 dans une matrice alimentaire ainsi que sur le devenir de la vitamine et des protéines des coacervats après traitement physique (thermique) ou biologique (digestion) sont en cours. L'usage des coacervats hétéroprotéiques pour l'encapsulation de molécules d'intérêt pour d'autres secteurs est également envisagé.

Introduction et but de l’étude Les protéines généralement utilisées dans les formules infantiles proviennent du lait de vache et sont majoritairement des protéines de lactosérum afin de se rapprocher de la composition du lait maternel. Cependant, certaines protéines végétales offrent également de bonnes propriétés nutritionnelles et pourraient constituer d’intéressants substituts dans un contexte de compétition d’usage des protéines de lactosérum. Le but de cette étude était de comprendre l’impact de la substitution des protéines de lactosérum par des protéines végétales sur le degré d’hydrolyse et sur la bioaccessibilité des acides aminés. Matériels et Méthode Quatre protéines végétales ont été sélectionnées (PV1 à PV4) en raison de leur composition en acides aminés essentiels adaptée aux besoins du nourrisson. Elles ont été utilisées pour développer des formules infantiles de composition identique à la référence (R), à ceci près que les protéines de lactosérum étaient remplacées par une des quatre protéines végétales. Les cinq formules infantiles ont ensuite été soumises à un modèle de digestion in vitro gastro-intestinale en conditions statiques (Ménard et al. 2018). Le degré d’hydrolyse des protéines était mesuré par la méthode OPA (O-phtaldialdehyde). Les acides aminés libres ont été quantifiés par chromatographie échangeuse de cations. Résultats Tableau 1. Teneur en acides aminés libres et degré d’hydrolyse en point final de digestion de cinq formules infantiles Formules infantiles Thréonine (%) Isoleucine (%) Leucine(%) Lysine (%) AAS (%) AAA (%) Degré d’hydrolyse (%) R 12,6±0,7 19,1±0,6 47,9±2,9 71,1±3,2 23,6 ±2,6 79,6 ±3,7 53,0±6,1 PV1 5,8±0,1*** 1,9±0,2*** 12,1±0,7*** 16,9±0,9*** 9,1 ±1,2*** 21,1±0,9*** 29,0±4,1*** PV2 15,7±1,2* 20,9±0,7 51,4±1,6 72,6±1,1 22,0 ±2,3 74,8 ±5,2 65,6±1,2 PV3 14,9±4,0 17,2±1,1 49,7±4,9 73,1±4,4 24,1 ±4,8 75,5 ±5,3 45,4±4,4 PV4 11,8±2,3 16,4±2,8* 45,6±5,1* 68,7±6,6 25,8 ±6,8 71,1 ±8,2 40,2±2,7* Les différences entre les valeurs moyennes des formules PV1 à 4 par rapport à R sont considérées significatives lorsque p < 0.05 (t-Test : *0,05 ; **0,01 ; ***0,001). AAS (acides aminés soufrés) ; AAA (acides aminés aromatiques) Les formules PV2 et PV3 libèrent autant d’acides aminés que la référence (R) et présentent un degré d’hydrolyse équivalent (p>0.05). En revanche, la formule PV4 se distingue de R par une moindre libération d’isoleucine et de leucine et présente également un degré d’hydrolyse plus faible. Enfin, la formule PV1 conduit à des valeurs très inférieures à celles obtenues avec R pour toutes les variables étudiées. Conclusion Il est établi que la cinétique de digestion des protéines dans une matrice et par conséquence, la libération des acides aminés et leur absorption peuvent être influencées notamment par sa composition en protéines (Le Feunteun et al., 2014). De manière concordante, nous montrons ici que la nature des protéines des formules infantiles aurait un effet sur la protéolyse. Ainsi, parmi les quatre formules « végétalisées » testées, seules PV2 et PV3 sembleraient être nutritionnellement comparables à la référence. Des digestions in vitro en conditions dynamiques (plus proches des conditions physiologiques) seront réalisées prochainement afin de compléter ces résultats quant à la qualité nutritionnelle de ces formules infantiles innovantes.

Les recommandations de l’OMS pour l’alimentation du nourrisson et du jeune enfant sont un allaitement exclusif jusqu’à l’âge de 6 mois, puis un allaitement partiel jusqu’à l’âge de 2 ans. Le taux et la durée de l’allaitement maternel en France restent cependant plus bas que les autres pays d’Europe. En 2017 en France, seulement 38% des enfants sont allaités jusqu’à l’âge de 6 mois (WHO/UNICEF, 2017). Lorsque l’allaitement maternel n’est pas possible ou non souhaité pour diverses raisons culturelles, économiques ou personnelles, les formules infantiles restent l’alternative la plus adaptée à la nutrition du nourrisson si leurs compositions respectent les besoins nutritionnels du jeune enfant. Ces formules doivent participer au développement optimale du nourrisson tout en respectant ses contraintes physiologiques, liées notamment à une immaturité digestive et rénale. Les formules infantiles doivent donc se rapprocher le plus possible du lait maternel. Leur composition nutritionnelle est globalement très proche, mais la composition fine et la structure diffèrent de par l’organisation des gouttelettes lipidiques et de la nature des protéines. En terme de digestion, étant donné l’immaturité du tube digestif à la naissance, des conditions de spécificités digestives adaptées aux nourrissons sont à prendre en considération afin de mettre en place des modèles de digestion in vitro pertinents (Bourlieu et al., 2014). Ces modèles sont utilisés aujourd’hui pour des raisons éthique, économique et de praticité pour les études de digestibilité. L’amélioration des formules infantiles, via la recherche et l’innovation, permet de répondre aux besoins nutritionnels et aux enjeux économiques. Des formules infantiles ont été développées pour répondre aux difficultés telles que les allergies, les intolérances, les problèmes de régurgitation, les troubles digestifs ou encore une production plus respectueuse de l’environnement. L’incorporation de probiotiques pour reproduire une partie du microbiote du lait maternel fait également partie de ces nouvelles générations de formules infantiles, mais également des formules infantiles de structures lipidiques et de composition en protéines plus proche du lait maternel ont été mises au point. De nouvelles perspectives visent à rechercher des protéines alternatives aux protéines de lactosérum du lait de vache via l’introduction de nouvelles sources de protéines d’origines végétales. L’objectif est de rechercher et d’étudier l’apport de nouvelles sources protéiques et d’aller jusqu’à la faisabilité technologique et la mesure de digestibilité en vue de s’assurer de la valeur nutritionnelle de ces nouvelles sources protéiques.

La composition chimique des formules infantiles a été optimisée, mais pas leurstructure qui reste souvent basée sur des gouttelettes lipidiques submicroniques (0,5 m) avecdes interfaces néoformées, différent des globules gras laitiers (4 m). Or, il a été récemmentdémontré que la structure des lipides dans le lait maternel module les cinétiques de digestion etparticiperait à la préprogrammation métabolique. La différence de structure initiale entre laitmaternel et formules se maintient pendant toute la phase gastrique. La taille des gouttelettesest le paramètre clé pour contrôler les lipolyses gastrique et intestinale, moduler la vitessede vidange gastrique néonatale et les cinétiques de protéolyse. Ces différences de structureimpacteraient chez l’animal le développement des systèmes digestif et immunitaire, du micro-biote et la préprogrammation des tissus adipeux à l’âge adulte. La réintroduction d’extraitsmembranaires et de triacylglycérols de lait bovin dans les formules ainsi que les dernièrestendances de développement de formules biomimétiques sont ici discutées.© 2017 Publi´e par Elsevier Masson SAS au nom de Soci´et´e franc¸aise de nutrition.

Introduction et but de l’etude Le vieillissement est associe a une baisse de la qualite de vie, notamment a cause du developpement de pathologies comme la sarcopenie. Plusieurs strategies nutritionnelles sont possibles pour retarder son apparition. Elles sont basees sur l’augmentation de la consommation d’aliments riches en proteines, comme les produits laitiers. De plus, les proteines du lactoserum sont reconnues pour leur richesse en leucine, et leur digestion rapide, qui favorise la synthese musculaire. L’objectif de cette etude est d’evaluer les performances nutritionnelles, en condition de digestion in vitro, de produits fromagers riches en proteines du lactoserum et de les comparer a celle d’un fromage traditionnel riche en caseines. Nous cherchons a determiner comment la source proteique, la structure des matrices laitieres et le niveau de denaturation des proteines influencent la bioaccessibilite des acides amines. Materiel et methodes Trois produits fromagers a base de proteines du lactoserum, de composition identique mais de texture variable (gels plus ou moins fermes), ont ete obtenus en modulant le traitement thermique. Ils etaient compares a deux temoins : un fromage du commerce a base de caseines et une matrice liquide (avant thermocoagulation des gels). La macrostructure des produits a ete evaluee grâce a un test de compression, et leur microstructure en microscopie confocale. Le taux de denaturation des proteines a ete quantifie par dosage de l’azote soluble a pH 4,4 et total. Les digestions ont ete realisees selon le protocole de digestion in vitro INFOGEST. Les cinetiques de digestion des proteines et de liberation des acides amines ont ete caracterisees par analyse biochimique des digestas : cinetiques d’hydrolyse par SDS-Page, liberations des peptides par la methode OPA et des acides amines par chromatographie ionique. Resultats et analyse statistique Les resultats montrent que le fromage a base de caseines presente le degre d’hydrolyse le plus eleve en phase intestinale (39 % au temps final), en comparaison aux autres matrices. Concernant les matrices riches en proteines du lactoserum, les degres d’hydrolyse obtenus en phase intestinale avec les gels sont superieurs (19 a 28 % au temps final) a celui obtenu avec la matrice liquide non traitee thermiquement (16 %). Bien que les produits a base de proteines du lactoserum contiennent 30 % de plus de leucine que le fromage du commerce, la liberation de leucine mesuree en fin de digestion est plus elevee pour le fromage du commerce (29 %), que pour les gels de proteines du lactoserum (17 %) et la matrice liquide (9 %) Conclusion Dans les produits gelifies, la denaturation des proteines du lactoserum due au traitement thermique, facilite l’hydrolyse de ces proteines par les enzymes pancreatiques, ameliorant ainsi la bioaccessibilite des acides amines par rapport au produit liquide ou les proteines sont natives. La bioaccessibilite des acides amines est superieure pour les fromages du commerce par rapport a celle des produits composes de proteines du lactoserum. Ceci s’explique par une hydrolyse plus elevee des caseines par la pepsine en phase gastrique, par rapport aux proteines du lactoserum.

Impact des procédés de transformation sur la digestion du lait maternel et des formules infantiles chez le nouveau-né. CIAG : Carrefour de l'innovation agronomique- alimentation 2018

Advances in neonatal nutrition: a step forward infant formula biomimetic of human milk structure and digestive behaviour. Conférence PPGAN UNIRIO

The biological membrane surrounding fat globules in milk, the MFGM, is poorly known despite its importance in the functional properties of many dairy products and in the mechanisms of milk lipids digestion occurring in the gastrointestinal tract of mammal newborns. Studies recently revealed the formation of lipid domains in the MFGM that have been interpreted as the lateral segregation of high phase transition temperature (Tm) lipids, mainly milk sphingomyelin (MSM; Tm 34°C) [1]. The role played by these MSM-rich domains in the MFGM is currently unknown and needs further investigation. In this context, the aim of this study was to investigate the role of temperature and cholesterol in the morphology and nanomechanical properties of the MFGM. Accessing the biophysical properties of biological membranes at nanoscale is possible using Atomic Force Microscopy (AFM). In the complex biomimetic membranes formed using a MFGM lipid extract, topographical AFM images revealed for T < 35°C the formation of µm-large domains that protruded above the continuous phase by ~1 nm [2]. The resistance of the MSM-rich gel phase domains to rupture was significantly higher than that of the liquid disordered continuous phase, i.e. breakthrough force FB of 23 nN vs. 6 nN at 25°C, respectively. The key role played by cholesterol in the lateral segregation of high Tm lipids, by decreasing the size of the lipid domains, their height and by fluidizing the MFGM has been demonstrated [3]. Such work on the heterogeneous distribution of polar lipids in the MFGM may open perspectives in dairy technology and infant nutrition, e.g. optimisation of the interface of processed lipid droplets in infant milk formulas to mimick the biological MFGM in breast milk.

Whey proteins present in milk are widely used in the food industry for their nutritional and functional properties. Many studies have been undertaken on the improvement of functional properties of these proteins, mainly by heat-induced denaturation/aggregation in the liquid state. Depending on the heating conditions, a large variety of aggregates having different structures and different physicochemical properties, and remarkable techno-functional properties, such as gelling, foaming or emulsification are produced [1]. While many works have been dedicated to whey proteins heat-treated in a solution, less studies considered heat as applied in a solid or a dry state. Whey protein solutions at pH 9.5 are freeze-dried or spray-dried. Then, whey protein powders are conditioned at a water activity of 0.24 and dry heated at 100°C. The color of powders and the presence of particles were followed during the dry heating time.Uncommon large stable particles are formed by this dry heat treatment. The lactose content is a critical factor for the kinetics of particle formation, via glycation and the Maillard reaction. The kinetics of particle formation is studied as a function of the lactose content in powders. Functional properties of particles are also studied such as their water entrapment and flow properties. Dry heat-induced particles retain a huge amount of water, and are able to bring large viscosity values.These particles could be used in food formulation to replace undesirable food additives.

Food structure affects the kinetics of food digestion and the bioavailability of nutrients. Rencontre Université de Suzhou et industriels chinois COFCO

Lipids of human milk or infant formula convey most of the energy necessary to support the newborn growth. Until recently, infant formula chemical composition had been optimized but not their structure. And yet, more and more proofs of evidence have shown that lipids structure in human milk modulates digestion kinetics and is involved in metabolic programming. Indeed there is a striking difference of structure between human milk which is an emulsion based on dispersed milk fat globules (4 µm) secreted by the mammary gland and the submicronic neoformed lipid droplets (0.5 µm) found in infant formula. These droplets result from a series of operation units. This difference of structure modifies digestion kinetics and emulsion disintegration in the intestinal tract of the newborn. This difference persists along gastric phase which is mainly dominated by acid and enzyme-induced aggregation. Lipid droplets size is thus the key parameter to control gastric lipolysis, gastric emptying and intestinal lipolysis. This parameter also controls proteolysis since adsorbed proteins are more rapidly hydrolyzed than when in solution. In animal models, these differences of lipid structure would also impact digestive and immune systems’ maturation and microbiota. Lipid structure during neonatal period would also be involved in the early programming of adipose tissues and metabolism. The supplementation of infant formulas with bovine milk fractions (milk fat globule membrane extracts, triacylglycerol) or recent development of large droplets infant formula biomimetic of human milk lipid structure, along with new fields of innovation in neonatal nutrition, will be reviewed. Despite these recent innovations, more data on the structure of human milk throughout lactation and on the digestive behaviour of specific fractions of human milk lipids are still needed to build a sound basis for the optimization of infant formula. A better understanding of fractions that escape enzymatic digestion in the upper tract, and serve as substrates for microbiota, may help controlling microbiota shifts that exist between breast-fed and formula-fed infants. Combinations of factors (synbiotics and lipid structure) and more staging, seem important levers to further improve infant formula but their efficacy and safety still have to be assessed in clinical trials.

Studying food digestion in humans through clinical trials is difficult for economical, ethical and technical reasons. In vitro alternatives are thus used for screening different foods and for a better understanding of the mechanisms of the digestive process. To date, there are only few models for simulating infant digestion and most of them lack of physiological relevance. Thanks to an extensive literature review of the in vivo infant digestive conditions, a gastrointestinal static in vitro model was developed for infants born at term and aged of 28 days. The oral phase was omitted due to the liquid nature of infant formula but also because carbohydrate digestion was not monitored here. The following parameters were determined: pH, ratio of meal to secretions, enzyme units of pepsin and gastric lipase (added as rabbit gastric extract) and of pancreatin (porcine source), and biliary salt molarity. Gastric and intestinal phases lasted 60 min each. The model was applied to the digestion of a commercial infant formula. Kinetics of digestion and end-points were compared with those obtained while submitting the same formula to the adult standardised protocol of in vitro static digestion1.Gastric and intestinal digesta were sampled regularly. Proteolysis kinetics were followed by SDS-PAGE and NMR and lipolysis kinetics by thin layer and gas chromatography. The structure evolution during the gastric phase was evaluated by confocal laser scanning microscopy and laser light scattering. As a result, the kinetics of proteolysis and lipolysis differed according to the physiological stage likely due to the reduced level of enzymes in the infant model and the higher gastric pH at the infant stage. This model is of interest for scientists or companies studying the digestion of infant food.

International audience; Postnatal nutrition has long-lasting impacts on adult metabolism and gut physiology. Gut microbiota has been identified as a key actor of this nutritional imprinting. We hypothesized that improving infant formulas (IF) to mimic the composition of human milk could provide short- and long-term health benefits. We therefore investigated the short- and long-term effects of addition of dairy lipids (DL) and probiotic Lactobacillus fermentum CECT 5716 (Lf) in IF on gut microbiota and physiology in a Yucatan minipig model.Forty-eight piglets received a formula containing only plant lipids (PL), a half-half mixture of PL and DL (DL), or a half-half mixture of PL and DL supplemented with Lf (DL+Lf) from postnatal day (PND) 2 to 28. Twenty-two piglets were euthanized at PND28 whereas twenty-six pigs were weaned on a standard diet for 1 month, then challenged with a hyperenergetic diet for 3 months and euthanized at PND140. At PND28, DL±Lf piglets displayed higher gastric protein hydrolysis and higher proximal jejunal and ileal diglycerides and cholesterol contents compared to PL. In addition to changes in intestinal permeability and density of goblet cells, faecal metabolome and microbiota composition were modified by the IF composition. At family level, operational taxonomic units (OTUs) belonging to Ruminococcaceae and Prevotellaceae were higher in DL±Lf compared to PL whereas those of Bacteroidales S24-7 group were lower compared to PL.At PND140, OTUs belonging to Ruminococcaceae and Prevotellaceae families were increased in DL compared to PL while OTUs belonging to Lachnospiraceae family were increased in DL±Lf compared to PL. Ileal trans- and paracellular permeabilities were higher in DL±Lf compared to PL, while jejunal LPS passage and ileal explant LPS-induced pro-inflammatory cytokine (TNFα and IL-8) secretions were decreased.This study demonstrates IF composition-induced changes in neonate gut physiology with a long-term programming effect involving gut microbiota

The process of manufacturing infant milk formulas (IMFs) involves heat treatments that can lead to whey protein denaturation. The objective of the study was to determine how protein composition affects the denaturation kinetics of the whey proteins within IMFs. Three model IMFs (1.3% of cow’s milk protein) were produced with a caseins: whey proteins ratio of 40:60, differing only by the whey protein composition. The kinetics of heat-induced denaturation of α-lactalbumin, β-lactoglobulin and lactoferrin were investigated between 67.5 °C and 80 °C by chromatographic quantification of the residual native proteins. Results showed that the heat-denaturation of α-lactalbumin was reduced when β-lactoglobulin was absent. The heat-denaturation of lactoferrin was not affected by the composition of the IMFs but its presence enhanced the heat-denaturation of β-lactoglobulin. This study revealed that, for higher heat treatments (90 °C/15 s, 75 °C/15 min), IMF containing α-lactalbumin and lactoferrin preserved a higher proportion of native whey proteins than IMFs containing β-lactoglobulin.

Lipids of human milk or infant formula convey most of the energy necessary to support thenewborn growth. Until recently, infant formula chemical composition had been optimized but not theirstructure. And yet, more and more proofs of evidence have shown that lipids structure in human milkmodulates digestion kinetics and is involved in metabolic programming. Indeed there is a striking differenceof structure between human milk which is an emulsion based on dispersed milk fat globules (4 mm) secretedby the mammary gland and submicronic neoformed lipid droplets (0.5mm) found in infant formula. Thesedroplets result from a series of operation units. This difference of structure modifies digestion kinetics andemulsion disintegration in the intestinal tract of the newborn. This difference persists along gastric phasewhich is mainly dominated by acid and enzyme-induced aggregation. Lipid droplets size is thus the keyparameter to control gastric lipolysis and emptying and intestinal lipolysis. This parameter also controlsproteolysis since adsorbed proteins are more rapidly hydrolyzed than when in solution. In animal models,these differences of lipid structure would also impact digestive and immune systems’ maturation andmicrobiota. Lipid structure during neonatal period would also be involved in the early programming ofadipose tissues and metabolism. The supplementation of infant formulas with bovine milk fractions (milk fatglobule membrane extracts, triacylglycerol) or recent development of large droplets infant formula, alongwith new fields of innovation in neonatal nutrition, are here reviewed.; Vers des formules infantiles mimant la structure et le profil de digestion du lait maternel.Les lipides laitiers du lait maternel ou de formules infantiles fournissent la plupart de l’énergie disponiblepour la croissance du nouveau-né. Jusqu’alors, la composition chimique des formules infantiles a étéoptimisée mais pas leur structure. Or il est de plus en plus démontré que la structure des lipides dans le laitmaternel module les cinétiques de digestion et participe à la pré-programmation métabolique. Il existe eneffet une différence majeure entre les émulsions natives de globules gras laitiers (4mm) sécrétées par laglande mammaire et la structure des lipides dans les formules infantiles qui résultent d’une successiond’opérations unitaires de transformation et sont constituées de gouttelettes submicroniques (0.5 mm) avecdes interfaces néoformées. Cette différence de structure modifie les cinétiques de digestion et dedéstructuration des émulsions dans le tractus digestif des nouveau-nés. De façon générale, la différence destructure initiale entre lait maternel et formules infantiles se maintient pendant toute la phase gastrique, quiest surtout dominée par des mécanismes d’agrégation acide et enzymatique. La taille des gouttelettes est leparamètre clé pour contrôler les lipolyses gastrique et intestinale et module également la vitesse de vidangegastrique néonatale. Ce paramètre contrôle également les cinétiques de protéolyse puisque les protéinesadsorbées sont hydrolysées plus rapidement que les protéines solubilisées. Ces différences de structureimpacteraient également chez l’animal le développement des systèmes digestif, immunitaire et la mise enplace du microbiote. La structure des lipides ingérés pendant la période néonatale pourrait également participer à la pré-programmation des tissus adipeux et du métabolisme chez l’adulte. La réintroductiond’extraits membranaires et de triacylglycérols issus de lait bovin dans les formules, le développement deformules nouvelles basées sur des émulsions moins fines ainsi que les dernières tendances de développement de formules infantiles biomimétiques sont reportées et discutées dans cette synthèse.

The potentiality of heteroprotein complex coacervates as biocarrier for a bioactive was investigated. Vitamin B9 (B9), also known as folic acid, was encapsulated by complex coacervation of two whey proteins (WP), β-lactoglobulin and lactoferrin. The stability and bioavailability of formed B9-WP coacervates was then characterized. Under degradative conditions in vitro (UV light irradiation, and oxidation by H2O2), WP coacervates protected the vitamin against chemical degradation. B9-WP coacervates also showed considerable physical stability over time when incorporated in real food matrices. Compared to unencapsulated B9, oral administration of B9-WP coacervates to healthy rats enhanced the plasma level of the vitamin. This improved bioavailability can be ascribed to the improvement in the solubility of B9 throughout the gastro-intestinal tract. We thus demonstrate the efficiency of WP coacervates as biocarrier for the protection and delivery of small bioactive molecules.

Notre connaissance scientifique actuelle démontre que, l’allaitement maternel reste la meilleure solution pour un nourrisson prématuré. En effet le lait maternel contient des hormones qui favorisent le développement des cellules intestinales. Mais il est très difficile pour les mères de respecter cet engagement. Pour répondre aux besoins nutritionnels spécifiques des nouveau-nés prématurés, des formules infantiles existent mais ne contiennent pas ces hormones. Dans ce présent travail, nous nous intéressons au lait de vache où l’Insulin-like Growth Factor (IGF2) a été retrouvée. Afin de déterminer si l’hormone bovine pourrait assurer le même rôle que l’hormone humaine nous allons nous intéresser à l’interaction de cette hormone avec son récepteur spécifique chez l’Homme. Pour mettre en évidence l’interaction entre l’IGF2 bovine et le récepteur IGF2R Humain nous avons modélisé l’hormone avec I-TASSER. Puis nous avons utilisé une approche de docking semi-flexible en utilisant le logiciel HADDOCK. Le complexe fournit par ce logiciel a révélé qu’une interaction du ligand est possible sur le domaine 11 du récepteur IGF2R humain. Nous avons également spécifiquement mis en évidence au cours de ce travail que les propriétés de surface électrostatique entre nos deux protéines jouent un rôle important dans l’interaction., Our current scientific knowledge demonstrates that breastfeeding remains the best solution for a premature infant. Indeed, breast milk contains hormones that promote the intestinal cells development. Nevertheless, it is very difficult for mothers to fulfill this commitment. To respond to the specific nutritional needs of preterm infants, infant formulas exist but do not contain these hormones. In this work, we are interested in cow's milk where the Insulin-like Growth Factor (IGF2) has been found. In order to determine whether the bovine hormone could perform the same role as the human hormone we are interested in the interaction of this hormone with its specific receptor in humans.To demonstrate the interaction between bovine IGF2 and the human IGF2R receptor, we have modeled the hormone with I-TASSER. Then we used a semi-flexible docking approach using the HADDOCK software. The complex provided by this software revealed that an interaction of the ligand is possible on domain 11 of the human IGF2R receptor. We have also specifically highlighted in this work that the electrostatic surface properties between our 2 proteins play an important role in the interaction.

IntroductionThe biological membrane surrounding fat globules in milk, i.e. the milk fat globule membrane (MFGM), is a trilayer assembly of polar lipids including 25-40% of sphingomyelin (SM) and glycerophospholipids. It is involved in the mechanical stability of fat globules, in the mechanisms of their digestion, and in physiological functions that need to be further understood. Increasing knowledge about the MFGM is therefore of primary importance both for dairy technology and nutrition. AimThe objectives of this study were to explore the dynamics of the MFGM polar lipids in situ in milk and to describe the biophysical properties of milk polar lipids assemblies as a function of temperature and composition, e.g. presence of cholesterol. MethodsThe biophysical properties and organization of polar lipids in the MFGM were investigated by the combination of techniques: DSC, synchrotron radiation XRD, CLSM, electron microscopy, AFM imaging and force spectroscopy. ResultsThe MFGM is a dynamic patchwork exhibiting phase separation of the high melting temperature (Tm) polar lipids, mainly SM, to form domains in ordered phase dispersed in a continuous fluid phase composed of the unsaturated polar lipids. In absence of cholesterol, the SM-rich domains are formed for T < 35°C and can melt upon heating. These domains protrude by 1 nm and have a higher resistance to rupture than the fluid phase composed of the unsaturated polar lipids. When present, cholesterol exhibits attractive interactions with SM with a condensing effect, and affects the topography of the membrane with a fluidizing effect. ConclusionWe propose an updated model for the heterogeneous organization of polar lipids in the MFGM, highlighting the dynamic changes in the topography and nanomechanical properties that are governed by the temperature and the presence of cholesterol. These recent findings on the assemblies of polar lipids in the MFGM and specific biophysical properties of SM in interaction with cholesterol will undoubtedly contribute in the development of smart biomimetic fat globules, e.g. in infant milk formulas.

Milk proteins are natural surfactants used to emulsify and to stabilize dairy emulsions. However, in numerous cases, they do not sufficiently stabilize emulsions against flocculation, coalescence, aggregation or gelation during processing such as heat treatments. By analogy to Pickering stabilization mechanism, it is suggested that whey protein aggregates could be more efficient than native whey proteins to stabilize emulsions. To confirm this hypothesis we investigated the stability of dairy emulsions reconstituted with 30% milk fat and 3 to 6% whey protein (commercial WPI) solutions unheated or heated prior to homogenization. Heating WPI solutions under specific physicochemical conditions prior to homogenization allowed the production of 2 types of heat-induced protein aggregates exhibiting differences in size and morphology. Emulsions stability was determined by visual observation, granulometry and confocal laser scanning microscopy (CLSM) after heating the samples at 120°C up to 30 min. Emulsions prepared with unheated WPI did not show any sign of macroscopic instabilities up to 30 min of heating at 120°C at low protein concentration (3%) but a gradual decrease of heat stability when protein concentration increased. Instability at high protein concentration is mainly due to protein aggregation or gelation in the aqueous phase entrapping the fat globules. In the opposite, emulsions formed with whey protein aggregates are destabilized as soon as 5 min of heating at 120°C for low protein concentration (3%) but are more stable at higher concentration. The stability of the emulsions at protein concentration higher than 4% is correlated to the stability of the aggregates in the aqueous phase. In conclusion, it is possible to form stable whey protein emulsions in a large protein concentration scale by a proper structuration of the proteins before emulsification even if a Pickering stabilization mechanism is excluded. It undoubtedly opens interesting perspectives in the formulation of dairy emulsions without additives.

absent

Sphingomyelin-rich microdomains have been observed in the biological membrane surrounding milk fat globules (MFGM). The role played by cholesterol in these domains and in the physical properties and functions of the MFGM remains poorly understood. The objective of this work was therefore to investigate the phase state, topography, and mechanical properties of MFGM polar lipid bilayers as a function of cholesterol concentration, by combining X-ray diffraction, atomic force microscopy imaging, and force spectroscopy. At room temperature, i.e. below the phase transition temperature of the MFGM polar lipids, the bilayers showed the formation of sphingomyelin-rich domains in the solid ordered (so) phase that protruded about 1 nm above the liquid disordered (ld) phase. These so phase domains have a higher mechanical resistance to rupture than the ld phase (30 nN versus 15 nN). Addition of cholesterol in the MFGM polar lipid bilayers (i) induced the formation of liquid ordered (lo) phase for up to 27 mol % in the bilayers, (ii) decreased the height difference between the thicker ordered domains and the surrounding ld phase, (iii) promoted the formation of small sized domains, and (iv) decreased the mechanical resistance to rupture of the sphingomyelin-rich domains down to ∼5 nN. The biological and functional relevance of the lo phase cholesterol/sphingomyelin-rich domains in the membrane surrounding fat globules in milk remains to be elucidated. This study brought new insight about the functional role of cholesterol in milk polar lipid ingredients, which can be used in the preparation of food emulsions, e.g. infant milk formulas.

Valorisation de matières premières locales pour l’alimentation des poulets en agriculture biologique

Introduction et But de l’étude Une meilleure compréhension de la digestion du lait maternel chez le nouveau-né est nécessaire pour améliorer les formules infantiles et les rendre plus biomimétiques. Pour des raisons éthiques, il est difficile de conduire de telles études chez le nouveau-né. Il est donc nécessaire de développer des modèles pertinents de digestion in vitro. L’objectif de notre étude était de comparer un modèle de digestion dynamique in vitro avec des données obtenues chez le nouveau-né.Matériel et Méthodes Un digesteur in vitro dynamique (i.e. avec, en continu, une régulation du pH, une sécrétion enzymatique et une vidange) comportant une phase gastrique et une phase intestinale (DIDGI®, INRA) a été utiliséa. Les paramètres du modèle de digestion au stade nouveau-né prématuré ont été fixés grâce à une revue exhaustive de la littératureb en termes de types et quantités d’enzymes, de flux de sécrétions, de descente en pH et de vitesse de vidange. Un pool de lait maternel cru ou pasteurisé (62,5°C, 30 min) issu de mères d’enfants prématurés (n = 5) a été digéré in vitro. Les digestas gastriques étaient prélevés à intervalle régulier. En parallèle, la digestion de lait maternel cru ou pasteurisé a été suivie chez des nouveau-nés prématurés au Centre Hospitalo-Universitaire de Rennes (NCT02112331, n=12). Des prélèvements postprandiaux étaient réalisés à 35, 60 ou 90 minutes après le début du repas par la sonde d’alimentation de ces enfants. La structure des digestas (in vitro et in vivo) a été analysée par granulométrie laser et microscopie confocale, la protéolyse par électrophorèse (SDS-PAGE) et la lipolyse par chromatographies en couche mince et gazeuse. Le pH et les volumes des digestas étaient également suivis.Résultats et Analyse statistique Au cours des digestions in vitro et in vivo, une hydrolyse rapide des caséines et une résistance de l’alpha-lactalbumine ont été observées. Un faible degré de lipolyse gastrique (7-19% à 90 min) a été confirmé in vitro et in vivo. Dans les deux types de digestion, la pasteurisation n’affectait pas les cinétiques ni le degré final de lipolyse et protéolyse, mais impactait l’évolution structurale des digestas, en particulier la désintégration de l’émulsion et l’agrégation protéique. Les données de descente en pH et de vidange gastrique paramétrées dans le digesteur sont à améliorer pour s’approcher au mieux de la physiologie du nouveau-né prématuré.ConclusionNotre étude a permis de mettre en évidence des conclusions similaires in vitro et in vivo quant à l’impact de la pasteurisation sur la digestion du lait maternel, en termes d’hydrolyse digestive mais aussi en termes d’évolution structurale. Les données in vivo vont permettre d’ajuster au plus près les paramétrages concernant la descente en pH et la vidange gastrique. Notre modèle sera utile à la fois pour la communauté scientifique et pour les industriels qui s’intéressent à la digestion néonatale et l’optimisation de formules infantiles.Références:a Bourlieu C., et al. (2015). Crit Rev Food Sci Nutr, 54(11), 1427-57.b Ménard O., et al. (2014). Food Chem, 145, 1039-45.

This work was integrated in the COST action FA1005 INFOGEST, and the researchers associated are acknowledged for contribution to the discussion. The authors warmly thank the volunteer mothers and the colleagues from the bank milk of the Rennes University Hospital Center. The author SCDO acknowledges the PhD scholarship from CNPq BrazilThis work was integrated in the COST action FA1005 INFOGEST, and theresearchers associated are acknowledged for contribution to the discussion. The authors warmly thankthe volunteer mothers and the colleagues from the bank milk of the Rennes University HospitalCenter. The author SCDO acknowledges the PhD scholarship from CNPq Brazil; Understanding the behavior of human milk in the newborn gastrointestinal tract is a key step in developing substitutes with optimized health benefits. However, ethical and technical reasons limit the possibility of in vivo trials. Consequently, it is important to develop relevant in vitro models. The aim of this work was to compare a dynamic in vitro digestion system developed by the French National Institute for Agricultural Research1 against in vivo data from raw or pasteurized human milk gastric digestion.Supported by an exhaustive literature review2, the dynamic digester parameters were set in terms of types and amounts of enzymes, secretions, pH decrease and emptying rate to mimic as closely as possible the gastric digestive conditions of preterm newborns. Raw or pasteurized (62.5°C, 30 min) pooled preterm human milks (n=5 donors) were digested in triplicate3. In parallel, in vivo study was conducted on hospitalized preterm newborns at Rennes Hospital (NCT02112331, n=12)4. Gastric digesta were sampled regularly. Structural changes were evaluated by confocal microscopy and laser light scattering. Lipolysis and proteolysis kinetics were monitored by SDS-Page, thin-layer and gas chromatography methods. Likewise, gastric volume, pH and emptying rates were compared. During both in vitro and in vivo gastric digestions, pasteurization did not affect the kinetics and final degree of lipolysis and proteolysis, but impacted on emulsion disintegration, protein aggregation and the persistence of native fat globule structure. Results showed the rapid hydrolysis of caseins and a resistance of alpha-lactalbumin in vitro and in vivo. The relatively limited extent of lipolysis by the gastric lipase was confirmed in vitro and in vivo, with a lipolysis degree ranging from 7 to 19% at 90 min.Although curves of pH decrease and emptying rates can be improved to adjust closer to in vivo data, kinetics of hydrolysis and disintegration of human milk showed that thedynamic system of in vitro newborn digestion proposed here is a relevant tool to study gastric digestive kinetics. Our model will be useful to the scientist community and food manufacturers who focus on neonatal gastric digestion and infant formulas optimization.

Human milk is the ideal food for infant nutrition and optimal growth. When breastfeeding is not available, infant formulas are often administrated. The chemical composition of infant formulas has been optimized but human milk structure and bioactive compounds contents are not mimicked1. These initial differences may modulate the kinetics of digestion and of disintegration of the emulsion in the digestive tract of the newborns. To check this hypothesis, the digestive behaviors of a commercial infant formula (IF) and raw human milk (HM) were compared using a dynamic in vitro digestion system (DIDGI®)2. Supported by an exhaustive literature review3, the dynamic digester was set to mimic as closely as possible the digestive conditions of term newborns. Pooled term HM (n=5 donors)4 and a liquid commercially available IF were digested in triplicate. Samples werecollected from the gastric and intestinal compartments throughout digestion. Initial emulsions and digesta were characterized. Lipolysis and proteolysis kinetics were monitored by SDSPage, thin-layer and gas chromatography methods. Structural changes were evaluated by confocal microscopy and laser light scattering.The initial differences in structure, composition and pre-hydrolysis state of the two emulsions strongly impacted digestion kinetics and deconstruction. Lipolysis levels were higher in HM than in IF before digestion and during gastric phase. This order was reversed at the beginning of the intestinal phase. Gastric proteolysis of caseins was accelerated in IF compared to HM. As observed by confocal microscopy and in coherence with previous results on model infant emulsions5, the differences in initial structure of the emulsions were maintained during the gastric phase of digestion: presence of native human milk fat globule in HM (5.1 ± 0.2 μm) and submicronic lipid droplets in IF (0.2 ± 0.0 μm). HM presented a structural destabilization from 60 min of gastric digestion, with a bimodal distribution of the particles size (mode 1 = 76.5 μm, mode 2 = 6.5 μm). IF gastric digestion was marked by average mode diameter changing drastically from 90 min (16.6 ± 2.2 μm). A progressive disruption of these aggregates was observed in the intestinal phase for both HM and IF. Despite in constant evolution, infant formulas are not yet biomimetic of human milk digestive behavior. These differences may have important physiological implications and underline the need for developing soft processes with minimal impact on milk native emulsion structure in the near future.

International audience; Human milk is the ideal food for infant nutrition and optimal growth. When breastfeeding isnot available, infant formulas are often administrated. The chemical composition of infant formulashas been optimized but human milk structure and bioactive compounds are not mimicked1. Theseinitial differences may modulate the kinetics of digestion and of disintegration of the emulsion inthe digestive tract of the newborns. To check this hypothesis, the digestive behaviors of acommercial infant formula (IF) and raw human milk (HM) were compared using a dynamic in vitrodigestion system (DIDGI®)2.Supported by an exhaustive literature review3, the dynamic digester was set to mimic asclosely as possible the digestive conditions of term newborns. Pooled term HM (n=5 donors)4 anda liquid commercially available IF were digested in triplicate. Samples were collected from thegastric and intestinal compartments throughout digestion. Initial emulsions and digesta werecharacterized. Lipolysis and proteolysis kinetics were monitored by SDS-Page, thin-layer and gaschromatography methods. Structural changes were evaluated by confocal microscopy and laserlight scattering.Our findings indicated that the initial differences in structure, composition and prehydrolysisstate of the two emulsions strongly impacted digestion kinetics and deconstruction.Lipolysis levels were higher in HM than in IF before digestion, during gastric phase and this orderwas reversed at the beginning of the intestinal phase. Gastric proteolysis of caseins wasaccelerated in IF compared to HM, probably in link with their partition at the interface of thesubmicronic droplets. As observed by confocal microscopy and in coherence with previous resultson model infant emulsions5, the differences in initial structure of the emulsions were maintainedduring the gastric phase of the digestion: the presence of native human milk fat globule in HM (5.1± 0.2 μm) and of submicronic lipid droplets in IF (0.2 ± 0.0 μm). HM presented a structuraldestabilization from 60 min of gastric digestion, with a bimodal distribution of the particles size(mode 1 = 76.5 μm, mode 2 = 6.5 μm). IF gastric digestion was marked by average modediameter changing drastically from 90 min (16.6 ± 2.2 μm). A progressive disruption of theseaggregates was observed in the intestinal phase for both HM and IF.Despite in constant evolution, infant formulas are not yet biomimetic of human milkdigestive behavior. These differences may have important physiological implications andunderline the need for developing soft processes with minimal impact on milk native emulsionstructure in the near future.

International audience; Milk fat globule membrane conditions the reactivity and enzymatic susceptibility of milk fat. The use of bovine membrane extracts to formulate infant formulas more biomimetic of human milk has been suggested in the recent literature 1,2 . A comparison of the physico-chemical behavior of human (HMM) and bovine (BMM) milk membrane extracts and their interaction with gastric lipase is lacking to assess whether their interfacial behavior is similar. This comparison is undertaken in the present project using complementary biophysical tools based on Langmuir film characterization as tensiometry, ellipsometry, Brewster angle (BAM) and atomic force (AFM) microscopies in the presence or in absence of gastric lipase. Milk membrane extracts were obtained from either a pool of mature human milk (n=5) or bovine butterserum and were analyzed using GC and HPLC.Compression isotherms indicated a higher compressibility of HMM than BMM. However, both extracts presented close collapse pressures (~45 mN/m). Despite the presence of liquid condensed (LC) domains (AFM and BAM) from low to highest surface pressure in the two extracts, their morphological aspect and growth differed strongly in relation with their specific lipid composition (GC and HPLC). As reported for BMM 3 , the gastric lipase got adsorbed toward liquid expanded phase (LE) and at several height levels in HMM. However its insertion did not impact on LC domain morphology as observed in BMM. Despite differences in their physico-chemical properties, both extracts present close interfacial reactivity in gastric conditions. Such biophysical Investigation of ‘lipase-complex lipid’ interactions will be broaden to other milk membrane extracts (equidae) interesting for human milk substitution

Menard O., Cattenoz T., Guillemin H., Souchon I., Deglaire A., Dupont D., Picque D. (2014). Validation of a new in vitro dynamic system to simulate infant digestion. Food Chemistry 145, 1039-1045.; The prediction of the digestion kinetics of infant formulas depending on their lipid and protein composition would be of great interest (i) to limit time-consuming and costly in vitro or in vivo experiments, (ii) to optimize their digestibility and (iii) to predict the fate of newly developed formulas in the gastrointestinal tract.This study aimed to establish a mechanistic model of the kinetics of proteolysis and lipolysis during the gastric and intestinal digestion of two different infant formulas using an in vitro dynamic simulator with two-compartments: stomach and small intestine1. Experimental data were available from a previous study2.The model approach was based on mass and volume balance equations on the different proteins ( -lactalbulmin, -lactoglobulin and caseins), triacylglycerides (TAG) and digestive enzymes (pepsin, lipase and pancreatin), assuming the stomach and small intestine as two perfectly stirred reactors displayed in series and at steady state. For each infant formula, a system of 11 differential equations with 6 unknown parameters was implemented in Matlab® software for resolution. These unknown parameters, which correspond to the enzymatic reaction rates, were estimated by finding the minimum of constrained nonlinear multivariable function between the solutions of the mathematical model and experimental data with the fmincon function.The mathematical model will be extended to four other experimental data sets of in vitro digestions of infant formulas presenting various fat and protein compositions and different rheological properties, in order to test its ability to predict their kinetics of digestion. A proper modelling of dynamic in vitro digestion phenomena occurring in the gastrointestinal tract is a challenging task, but could be of great help to better understand the key factors involved in the final nutritional quality of infant milk constituants.

The microstructure of milk fat in processed dairy products is poorly known despite its importance in their functional, sensorial and nutritional properties. However, for the last 10 years, several research groups including our laboratory have significantly contributed to increasing knowledge on the organization of lipids in situ in dairy products. This paper provides an overview of recent advances on the organization of lipids in the milk fat globule membrane using microscopy techniques (mainly confocal microscopy and atomic force microscopy). Also, this overview brings structural information about the organization of lipids in situ in commercialized milks, infant milk formulas and various dairy products (cream, butter, buttermilk, butter serum and cheeses). The main mechanical treatment used in the dairy industry, homogenization, decreases the size of milk fat globules, changes the architecture (composition and organization) of the fat/water interface and affects the interactions between lipid droplets and the protein network (concept of inert vs active fillers). The potential impacts of the organization of lipids and of the alteration of the milk fat globule membrane are discussed, and technological strategies are proposed, in priority to design biomimetic lipid droplets in infant milk formulas.

In the study presented here, we investigated the interaction at pH 5.5 between folic acid (FA) and lactoferrin (LF), a positively charged protein. We found a binding constant Ka of 10(5) M(-1) and a high stoichiometry of 10 mol of FA/mol of LF. The size and charge of the complexes formed evolved during titration experiments. Increasing the ionic strength to 50 mM completely abolished the isothermal titration calorimetry (ITC) signal, suggesting the predominance of electrostatic interactions in the exothermic binding obtained. We developed a theoretical model that explains the complex triphasic ITC profile. Our results revealed a two-step mechanism: FA/LF interaction followed by self-association of the complexes thus formed. We suggest that 10 FA molecules bind to LF to form saturated reactive complexes (FA10/LF) that further self-associate into aggregates with a finite size of around 15 nm. There is thus a critical saturation degree of the protein, above which the self-association can take place. We present here the first results that provide comprehensive details of the thermodynamics of FA/LF complexation-association. Given the high stoichiometry, allowing a load of 55 mg of FA/g of LF, we suggest that FA/LF aggregates would be an effective vehicle for FA in fortified drinks.

International audience; Twenty-four raw materials, harvested or produced in 2013 and commonly used in animal feed, were used to measure their hydration capacities through both water-holding capacity (WHC, g H2O/g DM after 24h of water addition) and swelling capacity (SC, mL H2O/g DM during 60 min after water addition, every 5 min during the first 30 min and then every 10 min). The raw materials were provided in the form of whole seeds (F1 class; n=8), flour/mash/hulls (F2 class, n=8) or pellets (F3 class, n=9). Hydration capacities were measured for unprocessed material and also after grinding of whole seeds (1, 3, 5 or 8 mm grid). The raw materials were analysed for fibre content to study the relation with WHC and SC. Moreover, WHC and SC were measured on twenty-eight compound pelleted feeds containing some of the raw materials studied in the present experiment, harvested or produced in the same year (i.e. 2013; Experimental feeds; n=8) or in an earlier year (i.e. 15%), especially when measured WHC was high. In conclusion, hydration capacity could be considered as additive, however, the theoretical values of pelleted compound feeds should be supported by real measurements.

Milk lipids supply most of the calories necessary for newborn growth in maternal milk or infant formulas. The chemical composition of infant formulas has been optimized but not the structure of the emulsion. There is still a major difference between the native emulsions of milk fat globules and processed submicronic emulsions in infant formulas. This difference may modify the kinetics of digestion of emulsions in newborns and influence lipid metabolism. To check this, semi-dynamic gastric in vitro digestions were conducted on three matrices: a standardized milk emulsion containing native milk fat globules referred to as minimally-processed emulsion and two processed model infant formulas (homogenized or homogenized/pasteurized). Gastric conditions mimicked those reported in newborns. The minimally-processed emulsion was lipolyzed and proteolyzed slower than processed formulas. The difference in initial structure persisted during digestion. The surface of the droplets was the key parameter to control gastric lipolysis kinetics, the pattern of released fatty acids and proteolysis by faster hydrolysis of adsorbed proteins.

Le lait maternel est l’aliment idéal pour le nouveau-né (OMS). Quand l’allaitement n’est pas possible ou souhaité, des formules infantiles peuvent être administrées. Alors que la composition nutritionnelle des formules infantiles a été optimisée, peu de travaux se sont intéressés à la structure de ces formules.[br/]Quel est l’impact de la structure des émulsions (formules infantiles, lait maternel) sur leurs cinétiques de digestion (lipolyse et protéolyse) et de déstructuration?[br/]Quels sont les paramètres clés affectant la digestion gastrique chez le nouveau-né ?[br/][br/]Les traitements technologiques modifient la structure des émulsions laitières (agrégation protéique, surface spécifique des gouttelettes). Cette structure influe sur la déstructuration de ces matrices et sur les cinétiques de lipolyse et protéolyse au cours de la digestion gastrique. La modulation des cinétiques d’hydrolyse en phase gastrique peut impacter sur les vitesses d’absorption des nutriments et ainsi moduler les réponses métaboliques. Il serait nécessaire de développer des traitements technologiques doux pour la fabrication des formules infantiles, avec un impact minimum sur le globule gras, pour mimer au mieux la déstructuration et l’hydrolyse des matrices natives.

Milk lipids supply most of the calories necessary for newborn growth in maternal milk or infant formulas. The chemical composition of infant formulas has been optimized but not the structure of the emulsion. There is still a major difference between native emulsions of milk fat globules (4 μm) and processed submicron emulsions with neoformed interface (0.5 μm) in infant formulas. This structural difference may modify the kinetics of digestion and disintegration of the emulsion in the digestive tract of the newborns. To check this hypothesis, several model infant formulas representative of native, homogenized, homogenized/pasteurized milk emulsions, commercial infant formula or Human milk were subjected to semi-dynamic or dynamic in vitro digestion mimicking the conditions reported in newborns [1,2]. In the gastric phase, native emulsions were lipolyzed and proteolyzed slower than processed model or commercial infant formulas. The difference in initial structure was maintained during the gastric phase of digestion which was dominated by acid aggregation. Our findings indicate that the surface of the droplets in the infant formula is the key parameter to control gastric lipolysis kinetics, the degree of gastric lipolysis and also the pattern of released fatty acids. This parameteralso indirectly controls gastric proteolysis kinetics since adsorbed proteins are hydrolyzed faster than solubilized proteins. These differences in gastric digestion may have important physiological implications and provide important new data to review and partly explain the difference in gastric emptying between human milk and infant formulas. The results of this study will be useful to food scientists and infant food manufacturersas they provide evidence for the direct influence of the structure of the emulsion in neonatal gastric digestion and underline the need for developing soft processes with minimal impact on milk emulsion structure in the near future.

Spray drying is a well-established technique to convert a liquid solution into individual and solid particles which is widely used in food industry especially in the dairy sector. This process allows formation of a large range of particle morphology all distinct from each other by their physical characteristics (distribution of the particle size, particle shape and particle density) providing to particles a typical aerodynamic behaviour and determining their final functionality (flowability, dispersibility, wettability, etc.). In dairy industries, controlling physical properties of powder represent a key issue to facilitate the industrial hand-use and optimize the rehydration. Therefore, understanding how the final shape of the particle is formed has recently become a huge scientific concern. So far, much attention has been paid to the so called process – product relationships, most often considering theoretical models based on drying kinetics to predict the shell formation and the morphology of dairy powders. However, the way the protein kind influence the particle morphology remains a hot topic. In this study we focused on the drying behaviour of two major milk protein concentrates: whey protein isolate and native micellar caseins. To acquire a better understanding on the role of each protein in the particle forming mechanisms, seven mixtures containing different ratios of caseins and whey proteins were investigated. A micro-fluidic-jet-spray-dryer (MFJSD) was used to produce uniform particles by drying monodisperse droplets in a hot and dry air flow. Powders were characterized with regard to their physical characteristics and their rehydration properties. Besides, characterisation of particle size and shape was ensured by means of a dynamic image analysis system. It is shown that particle morphology is mainly governed by the protein material type, almost regardless of the drying kinetics; controlling the product formulation thus represents a potential means to tune particle morphology, and therefore powder functional properties