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International audience; Gastrointestinal lipases are crucial for lipid hydrolysis and must get adsorbed onto the substrate interface prior lipolysis. Such adsorption had not been deeply investigated on biomimetic vegetal membranes. Our objective was thus to characterize such adsorption and lipolysis using complementary biophysical tools (tensiometry, ellipsometry, atomic force microscopy) and in vitro digestion.Heterogenous monolayers based on galactolipids, phospholipids, and phytosterols were used. Four lipases were studied: i) gastric lipase (GL), ii) pancreatic lipase 2 (PLRP2), (iii) pancreatic triacylglycerol lipase and its cofactor, colipase (PTL/coPTL), and (iv) pancreatic secreted phospholipase A2 (sPLA2-IB).A strong surfactant property of GL and its preferential adsorption onto expanded lipid phase and at the phase boundary were observed, in line with previous results on milk fat globule membrane. With PLRP2, changes in surface pressure indicated a lipolytic activity. Such variation was not observed upon PTL/coPTL adsorption, and may be related to the absence of activity of PTL on polar lipids. The injection of sPLA2-IB did not indicate a clear trend of lipolysis on the lipid film but changed the morphology of condensed domains.This study is a step forward to understand the interactions of gastrointestinal lipases with plant lipid membranes, an overlooked aspect of lipid digestion

Caatinga is a Brazilian semi-arid ecosystem that stands out for presenting unique environmental characteristics with a dry, spiny and deciduous shrub/forest vegetation with several species that can be renewable oil sources with potential applicability in oleochemical and nutrition. Caatinga oilseeds have a high content of unsaturated fatty acids, phytosterols and sterols, and this composition is related to its nutritional potential. The present review summarizes the knowledge on the oil contents and fatty acid profiles of seeds from six representatives caatinga species. It was observed that plants species like Caju (Anacardium occidentale L.), Favela (Cnidoscolus quercifolius Pohl), Licuri (Syagrus coronata (Mart.) Becc.), Pinhao-bravo (Jatropha mollissima Pohl Baill), Pequi (Caryocar brasiliense Camb) and Oiticica (Licania rigida Benth) contains approximately 33.1, 33.5, 49.2, 18.3, 70.16 and 57.0% w/w of oil, respectively, on a dry weight basis. Their fatty acid profiles are mostly saturated for Licuri oil, with a high content of lauric acid (up to 40%) and unsaturated for Favela, Pinhao-bravo, Cashew nut, Pequi and Oiticica oils. Oiticica oil shows a high concentration of unusual conjugated polyunsaturated fatty acids, like α-Eleostearic and Licanic acid with 16.90 and 43.20% w/w, respectively.

International audience; In their native state, milk lipids are present in the form of dispersed droplets called Milk Fat Globules (MFG, average diameter of 4 µm in human and bovine milks) that have been recently pointed out as key elements of early nutritional programming. The native MFG is a unique biophysical element differing from other lipoproteic objects by its external trilayered membrane inherited from its secretory past. To play its major biological function, i.e. deliver energy to the mammal newborn, the MFG has to be hydrolyzed in the gastro-intestinal tract by lipases. This hydrolysis is typically a heterogeneous phase reaction, in which the lipase has to diffuse and get adsorbed onto the lipid phase before the formation of the enzyme-substrate complex, and the onset of the proper catalytic action. Very few techniques allow assessing the mechanism involved in the enzymatic hydrolysis of complex supramolecular substrates such as milk fat globules in emulsion. To get a better insight of this mechanism, 4-D imaging of gastric and pancreatic lipases enzymes using synchrotron SOLEIL UV fluorescence microscopy was applied. This methodology allowed mapping the adsorption and diffusion of lipases onto/within human or bovine MFG or biomimetic droplets devoid of membrane proteins. These data were completed with simultaneous transmission light imaging of MFG disintegration during hydrolysis. The high sensitivity of the DISCO beamline allowed detecting the auto-fluorescence of the digestive lipases, is a unique tool to unravel their mechanisms of adsorption onto complex substrate using free-label imaging and has generated useful data for infant formula optimization.

L’utilisation des lipides connait un engouement depuis quelques années dans les secteurs de la cosmétique, agro-alimentaire, chimie, santé. Selon ces secteurs, des méthodologies différentes sont développées pour être plus performantes, innovantes et peu couteuses. Les lipases sont un outil majeur pour répondre aux besoins industriels. Leur coût et leur capacité d’intervenir dans des procédés industriels sont des enjeux pour la production de lipides. Le contexte économique et écologique nécessite une réflexion collective pour aller vers de nouveaux défis. Cela passe par une bonne maitrise et une bonne connaissance des procédés enzymatiques impliqués. Ce colloque a pour but de rassembler les laboratoires de recherche performants, les producteurs et utilisateurs industriels de ces lipides d’avenir qu’ils soient d’origine microbienne, végétale, algale ou animale. Pour répondre à des coûts économiques valables et au développement durable, des nouvelles sources de lipides apparaissent, tels que les co-produits ou insectes, nécessitant de nouveaux procédés industriels.L’utilisation des lipides connait un engouement depuis quelques années dans les secteurs de la cosmétique, agro-alimentaire, chimie, santé. Selon ces secteurs, des méthodologies différentes sont développées pour être plus performantes, innovantes et peu couteuses.Les lipases sont un outil majeur pour répondre aux besoins industriels. Leur coût et leur capacité d’intervenir dans des procédés industriels sont des enjeux pour la production de lipides.Le contexte économique et écologique nécessite une réflexion collective pour aller vers de nouveaux défis. Cela passe par une bonne maitrise et une bonne connaissance des procédés enzymatiques impliqués.Ce colloque a pour but de rassembler les laboratoires de recherche performants, les producteurs et utilisateurs industriels de ces lipides d’avenir qu’ils soient d’origine microbienne, végétale, algale ou animale. Pour répondre à des coûts économiques valables et au développement durable, des nouvelles sources de lipides apparaissent, tels que les co-produits ou insectes, nécessitant de nouveaux procédés industriels.; International audience; La membrane du globule gras laitier conditionne sa réactivité chimique et sa susceptibilité enzymatique. L’utilisation d’extraits membranaires bovins pour formuler des laits infantiles plus biomimétiques du lait humain a été proposée récemment1,2. Une comparaison du comportement physico-chimique des extraits membranaires humains et bovins et de leurs interactions avec la lipase gastrique humaine n’a jamais été réalisée pour déterminer si leur comportement interfacial est vraiment similaire. Cette comparaison est ici entreprise en utilisant des outils biophysiques complémentaires : tensiométrie, ellipsométrie, microscopie à angle de Brewster et de force atomique en présence ou en absence de lipase. Des extraits membranaires comprenant environ 70 % de lipides polaires (30 % triglycérides résiduels) ont été obtenus par extraction Folch puis acétonique à partir d’un pool de lait humain mature (n=5) ou de babeurre bovin. Des films de Langmuir et isothermes de compression (0 to 50 mN/m, 20°C) ont été réalisés à partir des deux extraits. Les films ont été transféré sur mica en présence ou en absence de lipase gastrique dans la sous-phase (pH 5, tampon d’acétate de sodium).L’extrait membranaire humain présentait une plus grande compressibilité avec une cohésion latérale moindre que l’extrait bovin. Des domaines condensés (LC) étaient visibles dans l’extrait humain dès 10 mN/m tandis que des domaines plus petits étaient observés dans l’extrait bovin. En compression, ces domaines LC devenaient plus nombreux mais restaient individualisés tandis qu’ils avaient tendance à fusionner dès 20 mN/m dans l’extrait bovin. En présence de lipase gastrique, la coexistence de phase liquide-liquide a impacté la distribution latérale de la lipase de façon similaire à ce qui avait été observé pour l’extrait bovin3: la lipase gastrique s’adsorbe dans la phase liquide expansée (LE) et à plusieurs niveaux de hauteurs indiquant différents mécanismes d’interaction avec la membrane. Les extraits membranaires humains et bovins partagent certaines propriétés physico-chimiques et présentent une réactivité interfaciale proche en conditions gastriques. L’approche biophysique proposée dans ce projet est intéressante pour caractériser les intéractions ‘lipase-lipides complexes’ et pourrait être appliquée à d’autres sources de lipides membranaires laitiers (e.g. equidae) ou végétaux.

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.

Lipolysis of complex lipoproteic assemblies such as milk fat globules is particularly frequent during neonatal digestion1. Such lipolysis proceeds at acid pH and requires a rapid adsorption of the enzyme onto the external membrane enveloping the substrate before the onset of catalytic activity2. The interactions governing this adsorption are not fully elucidated. Our objective was thus to unravel the involved interactions and precise gastric lipase lateral distribution in model membranes of milk fat globules presenting liquid phase separation. Recombinant dog gastric lipase (rDGL) was used as model of the human gastric lipase. Ellipsometry, tensiometry and atomic force microscopy were used to get an insight on the ability of rDGL to get inserted into the lipid membrane3. Lipid Langmuir films were used to mimic the outer leaflet of the external membrane of the milk fat globule. Different lipid mixtures and natural extracts of cow’s buttermilk with variable physical phases, surface charge and lateral packing were tailored to identify the nature of the enzyme/membrane interactions.We showed that: 1.rDGL is characterized by a high affinity for the lipid/liquid interface as revealed by adsorption equilibrium coefficients. Nevertheless, a large amount of molecules is located close to the interface but a limited number is inserted; 2. rDGL partitions toward liquid expansed phase and at phase boundaries, gets adsorbed at three levels of insertion (h1~5.5 nm, h2

Human milk is the ideal food for infant nutrition and optimal growth. This is especially true for preterm neonates that are preferentially fed pasteurized donor milk when their own mother milk is not available. In vitro studies have shown that pasteurization had structural and biochemical consequences on human milk digestion among which a lipolysis reduction1,2. Homogenization reduces the milk fat globule size and may restore digestive hydrolysis by increasing the surface available for enzyme adsorption. The impact of pasteurization and homogenization on the gastric digestion of human milk has never been investigated in vivo. Our study (ClinicalTrials.gov Identifier: NCT02112331) aimed at filling this gap. It was conducted on hospitalized preterm newborns (n = 11) fed by a feeding nasogastric tube. Different matrices were compared within two independent groups: 1) raw versus pasteurized human milk; 2) pasteurized versus pasteurized/homogenized human milk. Gastric digesta were collected at 35, 60 and 90 min after meal. Gastric volume, pH and emptying rates were determined. Structural changes were evaluated by confocal microscopy and laser light scattering. Lipolysis and proteolysis kinetics were followed by SDS-Page, thin-layer and gas chromatography methods. The study evidenced that gastric pH for raw milk was significantly lower than that for pasteurized milk at 35 min while milk homogenization did not affect postprandial gastric pH. Within the two groups, gastric emptying was strongly affected by treatments at 35 min. Although lipolysis and proteolysis presented high inter and intra-individual variabilities, they were still affected by treatments. More specifically, lipolysis at 35 and 60 min tended to be higher in homogenized/pasteurized versus pasteurized milk and proteolysis at 60 min was higher in raw compared to pasteurized milk.This study presents a unique set of data illustrating the impact of food structure on its gastric digestion and disintegration in preterm infant newborns. These data will be useful to validate in vitro and in silico digestion models. They will improve the understanding of the human milk digestive behaviour and should help optimizing technological treatments of human milk.

Plusieurs équipes de recherche rennaises utilisent des expériences aux interfaces fluides planes pour connaître et comprendre les propriétés de biomolécules variées. Lors d’une journée d’échanges, des scientifiques de l'UMR STLO et d’autres équipes contribueront à dresser le panorama des thématiques concernées et montrer le potentiel de ces expériences. Une journée d'échanges scientifiques est organisée par l'Institut de Physique de Rennes, le 22 janvier 2015. Elle vise à illustrer le potentiel et à construire une vision d'ensemble des expériences aux interfaces planes, dans des domaines scientifiques aussi variés que la physique des mousses et émulsions, les technologies de transformation des aliments, la digestion néonatale des lipides laitiers ou l'interaction de protéines avec les membranes biologiques. L'opportunité de montrer que les expériences aux interfaces planes livrent des informations abondantes et pertinentes.Plusieurs équipes de recherche rennaises utilisent des expériences aux interfaces fluides planes pour connaître et comprendre les propriétés de biomolécules variées. Lors d’une journée d’échanges, des scientifiques de l'UMR STLO et d’autres équipes contribueront à dresser le panorama des thématiques concernées et montrer le potentiel de ces expériences.Une journée d'échanges scientifiques est organisée par l'Institut de Physique de Rennes, le 22 janvier 2015. Elle vise à illustrer le potentiel et à construire une vision d'ensemble des expériences aux interfaces planes, dans des domaines scientifiques aussi variés que la physique des mousses et émulsions, les technologies de transformation des aliments, la digestion néonatale des lipides laitiers ou l'interaction de protéines avec les membranes biologiques. L'opportunité de montrer que les expériences aux interfaces planes livrent des informations abondantes et pertinentes.; National audience; La lipolyse d’assemblages lipoprotéiques complexes tels que le globule gras laitier est très fréquente notamment durant la phase néonatale1. Cette lipolyse est initiée dans l’estomac par la lipase gastrique humaine qui agit à pH acide et possède des propriétés biochimiques et biophysiques uniques lui permettant d’initier l’attaque du globule gras, ce qui favorise ensuite l’action de la lipase pancréatique. La lipolyse est une réaction interfaciale qui nécessite avant la phase catalytique stricte une étape d’adsorption de la lipase gastrique sur cette interface2. Les interactions qui gouvernent l’adsorption de la lipase gastrique sur la membrane du globule gras ne sont pas totalement élucidées. L’objectif de ce travail était donc d’élucider ces interactions ainsi que la distribution latérale de la lipase gastrique dans des membranes modèles présentant une coexistence de phases identique à celle observée dans la membrane du globule gras. Une lipase gastrique recombinante de chien (rDGL) a été utilisée comme modèle à la lipase gastrique humaine. Une combinaison d’outils biophysiques de la plateforme BioMIF (ellipsométrie, tensiométrie et microscopie de force atomique) a été mise en œuvre pour caractériser l’adsorption de la rDGL dans les membranes modèles3. Des films de Langmuir ont été utilisés pour imiter le feuillet extérieur de la membrane du globule gras. Des mélanges de glycérophospholipides et extraits de babeurre présentant différentes phases physiques, charges de surface et densités moléculaires ont permis d’identifier les interactions enzyme/membrane gouvernant l’adsorption. Nous avons montré que: 1.La rDGL présente une forte affinité pour les interfaces lipide/liquide. Néanmoins, si une grande partie des molécules est proche de l’interface un nombre restreint de molécules s’insère à l’interface. 2. La rDGL s’adsorbe préférentiellement dans la phase liquide expansée et aux frontières des deux phases, l’adsorption se fait à trois niveaux de profondeur dans la membrane (h1~5.5 nm, h2

International audience; Part of medium chain fatty acids (MCFAs) coming from dietary triglycerides (TGs) can be directly absorbed through the gastric mucosa after the action of preduodenal lipase (lingual lipase in the rat). MCFA gastric absorption, particularly that of octanoic acid (C8:0), may have a physiological importance in the octanoylation of ghrelin, the orexigenic gastric peptide acting as an endogenous ligand of the hypothalamic growth hormone secretagogue receptor 1a (GHSR-1a). However, the amount of C8:0 absorbed in the stomach and its metabolic fate still haven't been clearly characterized. The purpose of the present study was to further characterize and quantify the importance of preduodenal lipase activity on the release and gastric absorption of dietary C8:0 and on the subsequent ghrelin octanoylation in the stomach mucosa. Fifteen days old rats received fat emulsions containing triolein or [1,1,1-13C]-Tri-C8:0 and a specific inhibitor of preduodenal lipase, 5-(2-(benzyloxy)ethoxy)-3-(3-phenoxyphenyl)-1,3,4-oxadiazol-2(3H)-one or BemPPOX. The fate of the 13C-C8:0 was followed in rat tissues after 30 and 120 min of digestion and octanoylated ghrelin was measured in the plasma. This work (1) demonstrates that part of C8:0 coming from Tri-C8:0 is directly absorbed at the gastric level, (2) allows the estimation of C8:0 gastric absorption level (1.3% of the 13C-C8:0 in sn-3 position after 30 min of digestion), as well as (3) the contribution of rat lingual lipase to total lipolysis and to duodenal absorption of dietary FAs (at least 30%), (4) shows no short-term effect of dietary Tri-C8:0 consumption and subsequent increase of C8:0 gastric tissue content on plasma octanoylated ghrelin concentration.

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.

Human milk is the ideal food for infant nutrition and optimal growth. This is especially truefor preterm neonates that are preferentially fed donor milk when their own mother milk is notavailable. For sanitary reasons, donor milk is pasteurized. This may have structural andbiochemical consequences on the maternal milk emulsion and affect kinetics of digestion anddisintegration of the emulsion in the digestive tract of the newborns. This has been rarelyinvestigated, thus that was the aim of our study.An in vitro dynamic system was used to simulate the gastric digestion phase of a 1-month oldnewborn [1,2]. A pool of mature human milk (n = 5 donors) was digested as raw orpasteurised (holder pasteurisation: 62.5°C, 30 min), triplicate digestions. Structural changes ofdigested samples were evaluated by confocal microscopy and laser light scattering. Lipolysisand proteolysis were monitored over 120 min. Hydrolysis kinetics were followed by SDSPage,thin-layer and gas chromatography methods, followed by densitometry for semiquantitativeestimations.Pasteurization impacted the emulsion structure by increasing the protein susceptibility to acidaggregation especially on the milk fat globule membrane. Structure of fat globule wasmaintained during gastric digestion mainly in pasteurised human milk. Lipids were digestedfaster in raw than in pasteurised milk. In the end of the gastric phase, less triglycerids andmore free fatty acids were observed for raw milk (p

Human milk is the ideal food for infant nutrition and optimal growth. This is especially true for preterm neonates that are preferentially fed donor milk when their own mother milk is not available. For sanitary reasons, donor milk is pasteurized. This may have structural and biochemical consequences on the maternal milk emulsion and affect digestive kinetics. This has been rarely investigated. Thus that was the aim of our study. Mature human milk was collected over 2 days and stored at +4°C. Half of it was digested as is (fresh milk). The other half was frozen (-20°C, 5 weeks) and pasteurized (62.5°C, 30 min) prior digestion. An in vitro dynamic system was used to simulate the gastric and intestinal digestion phases of a 1-month old newborn. Structural changes of digested samples were evaluated by confocal microscopy and laser light scattering. Proteolysis and lipolysis were monitored over 180 min. Hydrolysis kinetics were followed by SDS-PAGE and Thin-Layer Chromatography methods, followed by densitometry for semi-quantitative estimations. Pasteurization impacted the emulsion structure by increasing the protein susceptibility to acid aggregation especially on the milk fat globule membrane (Fig. 1). In the gastric compartment, we observed a faster hydrolysis of caseins (κ, β) and lactoferrin in pasteurized milk than in fresh milk (X 2 at 30 min). At 120 min, virtually all proteins were digested in pasteurized milk, whereas approximately 55% of proteins were undigested in fresh milk. In the intestinal phase, most proteins were digested during the first 30 min. Lactoferrin was more resistant in fresh milk than in pasteurized milk. Similarly, lipids were digested faster in pasteurized than in fresh milk, but to a lesser extent than proteins. These results demonstrate that pasteurization increases the rate of proteolysis and lipolysis. The physiologic and metabolic impacts remain unknown, especially in newborns exclusively fed pasteurized milk

Milk lipids supply 50-60 % of the calories necessary for newborn growth under the form of maternal milk or infant formulas. Infant formulas have been optimized in terms of chemical composition but not with regards to the structure of the emulsion. An important difference remains between the native emulsions of milk fat globules (4 µm) as opposed to the processed submicronic emulsions (0.5 µm) of infant formulas. This structural difference may modify the kinetics of digestion and disintegration of the emulsion in the digestive tract of the newborns. Indeed the native emulsions develop an interfacial surface of 1.8 m2/g of lipid stabilized by a natural trilayered membrane based of phospholipids and proteins, whereas infant formulas present a much higher neoformed interfacial surface (30 m2/g of lipid) stabilized by dairy proteins. This higher interfacial surface is supposed to increase infant formula susceptibility to lipolysis but also to proteolysis through the higher accessibility of proteases to adsorbed proteins. To check this hypothesis, 3 matrices were formulated: M1 containing raw bovine milk fat globules dispersed in an infant formula-type serum phase, M2 similar to M1 with an additional high pressure homogenization treatment and M3 similar to M2 with the addition of a pasteurization treatment. The matrices were subjected to the semi-dynamic gastric phase of an in vitro digestion mimicking the conditions reported in newborns. The disintegration and the kinetics of lipolysis and proteolysis were monitored during the 180 minutes of digestion. The initial structure affected both the kinetics of the hydrolysis and the disintegration of the matrices. The initial rate of lipolysis of M1 was ~ 55 times lower than for M2 or M3 which was partially explained by its lower specific surface. Total proteolysis of caseins was observed at 30 minutes on M3 whereas it only occurred after 120 minutes for M1. The initial structure impacted the gastric destabilization with the formation of larger aggregates for M1 (mode at 190 µm at 30 min) than on the two other matrices. Since the free fatty acids and amino acids liberated in the gastric phase can act as second messenger and modulate the gastric emptying, this effect of structure may have important physiologic consequences. The gastric in vitro semi-dynamic model allowed rapid screening of matrices and limitations of consumption of digestive enzymes. In the future, it will be employed on maternal milk to determine the additional effect of the endogenous lipase on the digestion.