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International audience; Dietary diversification, which starts between 4 and 6 months, is a pivotal period in the infant development. After this diversification, complementary foods such as infant flours are therefore widely consumed throughout the world, particularly in southern countries. However, infant flours have often an unbalanced lipid profile in favor of omega 6 and overages in certain vitamins content (especially A and E). The aim of this study was to optimize the formulation of enriched infant flour in order to improve its nutritional profile and oxidative stability. For this purpose, the nutritional values and ingredient lists of 96 infant flours were analyzed to formulate model flours representative of the marketed products. The lipid profile of these model flours was then optimized by including flours with balanced omega 6/omega 3 ratios, i.e. teff and cowpea flours, and/or by adding long-chain polyunsaturated fatty acid (LC-PUFA) powder (DHA and ARA). After 3 months of storage, the optimized flour showed a quite good resistance to oxidation with a low evolution of peroxide values and a low tocopherols degradation. However, the inclusion of LC-PUFA significantly increased the oxidation sensitivity of the flours. In order to counteract this phenomenon, phenolic compounds were added via the addition of brown rice bran which did not seem to have a positive effect on stabilization regardless the particle size. Nevertheless, optimized omega 3 enriched and fortified infant flours could be proposed with fair stability over 3 months of storage.

International audience; Infancy period is a key window of development during which the requirements in lipids and more particularly in long-chain polyunsaturated fatty acids are specific. In order to abide by the recommendations, European regulation now requires a fortification of infant follow-on formulas (IFF) with docosahexaenoic acid (C22:6, DHA) which strongly impacts their oxidative stability. The aim of this study was to optimize the structure and formulation of DHA-enriched IFF in order to improve their lipid profile and oxidative stability. To do so, a model IFF representative of marketed products was formulated and declined by varying the saturated fatty acids sources (refined (POM) or unrefined (RPOM) palm oil, coconut oil (COM), and dairy fat (DFOM)), the emulsifiers (soy lecithin or dairy phospholipids (DPL)) and the structure (droplet size). These model IFF were submitted to an accelerated storage test of 20 days at 40°C during which peroxide values (PV), tocopherols, vitamin A, and fatty acids profiles were monitored. Despite the addition of DHA, all model IFF had quite good oxidative stability with PV lower than 10 meqO2/kg of lipids until 9 days of storage. DFOM and POM had equivalent kinetics of PV increase and tocopherols degradation. Moreover, no significant differences were observed between these two IFF regardless of droplet size (0.4 or 0.7 µm). RPOM was more stable than POM, very likely due to its higher carotenoids content. Regarding emulsifiers, DFOM-DPL (stabilized with DPL) had a PV twice lower than POM (stabilized with lecithin) at 20 days and a tocopherols degradation of 67.5% vs 88.8% for POM. This result translates a more important resistance to oxidative degradation of DFOM-DPL. This favorable effect was even reinforced for smaller droplet sizes. The introduction of dairy lipids but also of carotenoids in DHA-enriched IFF composition are interesting levers of stabilization. Moreover, dairy lipids lead to a more complex lipid profile and a higher content of short and medium-chain saturated fatty acids which is beneficial for infant nutrition.

International audience; Pancreatic lipase related-protein 2 (PLRP2) exhibits remarkable galactolipase and phospholipase A1 activities, which depends greatly on the supramolecular organization of the substrates and the presence of surfactant molecules such as bile salts. It is responsible for the effective hydrolysis of the main lipids composing plant photosynthetic membranes, which represent an excellent source of omega-3 for human nutrition. The objective of the study was to understand the modulation of the adsorption mechanisms and enzymatic activity of Guinea pig PLRP2 (gPLRP2), by the physical environment of the enzyme and physical state of its substrate at the nanoscopic and microscopic scales. Langmuir monolayers were used to reproduce homogeneous and heterogeneous photosynthetic model membranes containing galactolipid, and/or phospholipid, and/or phytosterol, presenting uncharged or charged interfaces. The same lipid mixtures were also used to form micrometric liposomes, and their digestion kinetics by gPLRP2 were investigated in the presence or absence of bile salts (NaTDC) during static in vitro, so called “bulk”, digestion. The enzymatic activity of gPLRP2 onto mixed monolayer of galactolipids and/or phospholipids, and/or phytosterols was characterized with an optimum activity at 15 mN/m, in the absence of bile salts. Additionally, gPLRP2 showed enhanced adsorption onto biomimetic model monolayer containing negatively charged lipids, but the compositional complexity in these systems induced a lag phase before the initiation of lipolysis, and a slowdown in enzymatic activity. In bulk, no enzymatic activity could be demonstrated on GL-based liposomes in the absence of bile salts, probably due to the high lateral pressure of the lipid bilayers. In the presence of NaTDC (4 mM), however, gPLRP2 showed both high galactolipase and moderate phospholipase A1 activities on liposomes, probably due to a decrease in packing and lateral pressure upon NaTDC adsorption, and subsequent disruption of liposomes. The understanding of PLRP2 enzymatic activity at the level of natural plant-based assemblies open the way to new strategies to vectorize bioaccessible omega-3 and rebalance human and animal diets.; La lipase pancréatique apparentée à la protéine 2 (PLRP2) présente des activités galactolipase et phospholipase A1 remarquables, qui dépendent fortement de l'organisation supramoléculaire des substrats et de la présence de molécules tensioactives telles que les sels biliaires. Elle est responsable de l'hydrolyse efficace des principaux lipides composant les membranes photosynthétiques des plantes, qui représentent une excellente source d'oméga-3 pour la nutrition humaine. L'objectif de l'étude était de comprendre la modulation des mécanismes d'adsorption et de l'activité enzymatique de la PLRP2 de cobaye (gPLRP2), par l'environnement physique de l'enzyme et l'état physique de son substrat à l'échelle nanoscopique et microscopique. Des monocouches de Langmuir ont été utilisées pour reproduire des membranes modèles photosynthétiques homogènes et hétérogènes contenant des galactolipides, et/ou des phospholipides, et/ou des phytostérols, présentant des interfaces chargées ou non. Les mêmes mélanges lipidiques ont également été utilisés pour former des liposomes micrométriques, et leur cinétique de digestion par la gPLRP2 a été étudiée en présence ou en absence de sels biliaires (NaTDC) au cours d'une digestion statique in vitro, dite "bulk". L'activité enzymatique de la gPLRP2 sur une monocouche mixte de galactolipides et/ou phospholipides, et/ou phytostérols a été caractérisée avec une activité optimale à 15 mN/m, en l'absence de sels biliaires. De plus, la gPLRP2 a montré une meilleure adsorption sur des monocouches modèles biomimétiques contenant des lipides chargés négativement, mais la complexité de la composition de ces systèmes a induit une phase de latence avant l'initiation de la lipolyse, et un ralentissement de l'activité enzymatique. En bulk, aucune activité enzymatique n'a pu être démontrée sur les liposomes à base de GL en l'absence de sels biliaires, probablement en raison de la pression latérale élevée des bicouches lipidiques. En présence de NaTDC (4 mM), cependant, la gPLRP2 a montré des activités galactolipase élevées et phospholipase A1 modérées sur les liposomes, probablement en raison d'une diminution du packing et de la pression latérale lors de l'adsorption du NaTDC, et de la rupture ultérieure des liposomes. La compréhension de l'activité enzymatique de la PLRP2 au niveau des assemblages naturels à base de plantes ouvre la voie à de nouvelles stratégies pour vectoriser des oméga-3 bioaccessibles et rééquilibrer les régimes alimentaires humains et animaux.

International audience; Nowadays, malnutrition (i.e. over and undernutrition) is a major public health issue. This reflects energy and macro and micronutrient imbalances. Among strategies to fight malnutrition, governmental food programs, fortification and nutritional optimization of staple food can be alternatively or concomitantly adopted. Pasta is one of the most popular staple foods. Traditionally made from wheat, its formulation has been improved by including legumes beside wheat. The next effort for improving its formulation would be to use raw materials from climate-smart crops. Our study takes place in the European H2020 Innofood Africa project federating European and African countries on the development of climate-smart crops and their use in the context of a balanced diet. It aims to develop new nutritionally optimized pasta made from gluten free African raw materials adapted to the climate transition e.g. drought resistance, low input requirement. Raw materials are cowpea, faba bean and bambara legume flours; teff, finger millet and amaranth cereal grain flours and additional nutritious raw materials such as orange fleshed sweet potato and amaranth leave flours. Nutritional and antinutritional composition of all flours were determined (protein, amino acids content, starch, sugar, fibres, vitamins, minerals, phytic acids, trypsin inhibitor). This constituted a data base for nutritional optimization of pasta by mathematical programming. In order to cover adults needs, the following criteria were selected: an amino acid chemical score above 110 taking into account process and cooking losses, an omega 6/omega 3 ratio closest to 5, a fiber quantity for 100g of pasta less than 25g, quantities of iron, zinc, B9 vitamin and beta carotene at less equal to recommendations and minimization of anti-nutritional factors. The best formulations covering the nutritional requirements, mainly based on cowpea, teff, amaranth leaves flours, have been selected. They were processed by a classical low temperature extrusion followed by a low temperature drying preserving their nutritional qualities. They have been characterized and compared with classical 100% durum wheat semolina pasta for their textural and culinary properties and their nutritional composition. The in vitro protein and starch digestibility was carried out to determine the impact of formulations on the nutritional potential of pasta.

National audience; La période postnatale est caractérisée par une croissance et un développement rapide. Les lipides et plus particulièrement les acides gras polyinsaturés à longues chaînes (AGPI-LC) tels que les acides docosahexaénoïque (DHA) et arachidonique (ARA) jouent un rôle essentiel durant cette période. L’objectif principal des formules infantiles est d’être biomimétique de « l’étalon d’or » : le lait maternel, aussi bien en termes de composition que de structure, pour ainsi offrir la meilleure alternative possible à l’allaitement lorsqu’il a échoué et/ou n’est pas possible. Dans ce contexte, la réglementation européenne a évolué pour encourager une optimisation de la composition des préparations infantiles. Ainsi, depuis février 2020 la supplémentation des formules en DHA a été rendue obligatoire. Ces formules sont également fortifiées en ARA, autre AGPI indispensable pour le développement de l’enfant, bien qu’aucune obligation ne soit établie quant à sa teneur minimale. Leur important degré d’insaturation rend ces acides gras particulièrement sensibles à l'oxydation lipidique, complexifiant ainsi leur introduction dans les formules infantiles. Les lipides laitiers du fait de leur haute teneur en certains acides gras saturés constituent donc un atout pour la stabilisation contre l’oxydation. De plus, d’un point de vue structurel, des différences persistent entre le lait maternel et les formules infantiles ce qui a un fort impact sur les cinétiques de digestion et donc d’absorption des nutriments. Une fois de plus, les lipides laitiers (polaires ou apolaires) du fait de leur structure et composition complexe, présentent un intérêt particulier pour le développement de l’enfant notamment en modulant la digestion des protéines, le développement intestinal et en contribuant à l’éducation immunitaire et à celle du microbiote. L’objectif de cet exposé est de mettre en évidence, à travers une étude de stockage, l’intérêt technologique et nutritionnel de la réintroduction des lipides laitiers dans la composition des préparations de suite afin de les stabiliser contre l’oxydation.

National audience; The lipid fraction of infant follow-on formulas is mainly composed by a mixture of oils mainly of vegetable origin with palm oil as the main source of saturated fatty acids and are enriched in long-chain polyunsaturated fatty acids to support the infant development. However, these oil blends are not optimal for nutritional needs of infants and are particularly sensitive to lipid oxidation. This study aimed to substitute palm oil with other sources of saturated fatty acids in order to ensure a more suitable nutritional profile for infant without impacting or improving stability against lipid oxidation. A panel of model IFF representative of marketed products was formulated depending on the lipid sources including refined or unrefined palm oil, coconut oil and dairy fat. After an accelerated storage to follow their oxidative stability, the results show that the inclusion of carotenoids and dairy lipids in the composition of the oil phase improved the stability against lipid oxidation and provides bioactive compounds that are involve in the infant development. This study has thus highlighted the importance of the balance between nutritional profile and oxidation stability.

The main objective of follow-on formulas is to mimic as closely as possible the composition and structure of mature breast milk. In order to optimize the formulas, important regulatory changes have taken place, including the obligation to supplement the formulas with DHA. The oil phase is therefore formulated from a mixture of oils mainly of vegetable origin with palm oil as the main source of saturated fatty acids and enriched in long-chain polyunsaturated fatty acids. However, these oil blends are not optimal for nutritional needs of infants and are particularly sensitive to lipid oxidation. The aim of this study was to substitute palm oil with other sources of saturated fatty acids in order to ensure a more suitable nutritional profile for infant without impacting or improving stability against lipid oxidation. To reach this objective a model system representative of marketed follow-on formulas was formulated and declined into a panel of model systems depending on the source of saturated fatty acids used. The results showed that depending on the composition of the oil phase the stability against lipid oxidation could be improved. This study has thus highlighted the importance of the balance between nutritional profile and oxidation stability. (Texte intégral)

Oil bodies (OB) are the natural form of energy storage in oilseeds. They consist of a triacylglyceride core stabilized by proteins (mainly oleosins) embedded in a phospholipid membrane. In some tree nut species, OB contain an important amount of polyunsaturated fatty acids that make them interesting food ingredients but prone to oxidation. Due to the growing interest in minimally processed nut-based beverages, the understanding and the preservation of the physico-chemical properties of these lipoprotein assemblies are of great interest. In this context, previous inte rfacial studies have led to the proposition of a new model of adsorption for minimally processed OB that is useful to design functional emulsion or foam in which OB act as emulsifiers. The objective of the present study was to determine the impact of processing and fat content on the physico-chemical behavior of tree nut-based matrixes. The interfacial and oxidative behaviors of minimally processed isolated OB were compared with processed complex nut-based matrixes (i.e., beverages) of different fat content. Processing operations (heat-treatment, homogenization) affected OB interfacial properties and oxidative stability but fat content had even stronger impact on this last parameter, with more concentrated systems more stable to oxidation. The results underline the good physico-chemical stability of tree nut OB and raise the interest of their use in the minimally processed form to fully exploit their beneficial properties. (Texte integral)

Lipid oxidation is a major cause of quality deterioration in food or cosmetic products. In these matrices, lipids are often present in a bulk or in emulsified forms. In both systems, the rate, extent, and pathway of oxidation are highly dependent on the presence of colloidal structures and interfaces because these are the locations where oxidation normally occurs. In bulk oils, reverse micelles (association colloids) are present and are believed to play a crucial role on lipid oxidation. Conversely, in emulsions, surfactant micelles are present that also play a major role in lipid oxidation pathways. This review discusses the current understanding of the influence of micellar structures on lipid oxidation. In particular, is discussed the major impact of the presence of micelles in emulsions, or reverse micelles (association colloids) in bulk oil on the oxidative stability of both systems. Indeed, both micelles in emulsions and associate colloids in bulk oil are discussed as nanoscale structures that can serve as reservoirs of antioxidants and pro-oxidants and are involved in their transport within the concerned system. Their role as nanoreactors where lipid oxidation reactions occur is also commented. The results underline the importance of a better understanding of the role of micelles in the control of lipid oxidation in food or cosmetic products. (Texte intégral)

Langmuir films and their analysis by tensiometry, ellipsometry and Langmuir–Blodgett transfer coupled to atomic force microscopy are suitable tools to study the interactions of various lipases with model membranes. The objective of our study was to characterize the adsorption and lipolysis behavior of different gastrointestinal enzymes onto biomimetic vegetal membranes. An heterogenous monolayer based on a mixture of unsaturated galactolipids (MGDG, DGDG), saturated phospholipids (DPPC), and phytosterols was used. Four enzymes were studied, (i) gastric lipase (GL), which has no lipolytic activity on polar lipids but whose adsorption may modulate the subsequent adsorption and activity of other lipases, and three pancreatic enzymes: (ii) pancreatic lipase 2 (PLRP2) presenting both galactolipase and phospholipase A1 activities, (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 at both the expanded lipid phase and at the boundary phase were observed, in line with previous results obtained with biomimetic milk fat globule mem- brane. With PLRP2, changes in surface pressure indicated a lipolytic activity in addition to lipase adsorption, with a higher rate at surface pressure below 15 mN/m. A drastic decrease in film thickness was also observed by ellipsometry, suggesting the removal of some lipolysis products. Such variation was not observed upon PTL/coPTL adsorption and may be related to the absence of activity of PTL on polar lipids. Finally, the evolution of adsorption kinetic after injection of sPLA2-IB did not indicate a clear trend of lipolysis on the lipid film. However, a change in the morphology of condensed domains was observed by AFM, suggesting a phase separation of lipids induced by binding of sPLA2-IB. This study is a step forward in the understanding of interaction of gastrointestinal lipases with plant lipid membranes, an overlooked aspect of lipid digestion. (Texte intégral)

International audience

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

Les microalgues sont des organismes unicellulaires photosynthétiques riches en nutriments constituant une biomasse à fort potentiel pour des applications alimentaires. Leur production est énergivore avec un fort risque d'altération au cours du procédé de récolte et de conservation. La fermentation, procédé ancestral de conservation, offre une alternative aux procédés actuels en limitant le développement des flores d'altération. La capacité des Bactéries Lactiques (BL) à fermenter les microalgues n'a été jusqu'à présent que très peu explorée1,2.Dans cette étude, nous avons criblé la capacité de 89 souches (10 espèces) de BL à fermenter Chlorella vulgaris, une des deux microalgues autorisées en alimentation humaine3. Pour cela nous avons suivi au cours du temps une suspension de biomasse lyophilisée de C. vulgaris resolubilisée (50mg/mL) inoculée par les BL en mesurant le pH et en dénombrant les flores bactériennes présentes. En parallèle, nous avons évalué la capacité fermentaire des 89 souches à métaboliser huit sucres. Pour les trois souches présentant la meilleure aptitude à fermenter C. vulgaris, nous avons testé l'effet de l'ajout de différentes concentrations de glucose et d'extrait de levure sur la baisse de pH.Les résultats obtenus montrent que 72% des souches acidifient la biomasse microalgale selon 3 profils d’acidification : A - acidification rapide en moins de 12h (60 % des souches) ; B - vitesse d'acidification intermédiaire nécessitant 36h de fermentation pour avoir une baisse significative du pH (12%) ; C - absence d'acidification au bout de 36h. Les souches sont réparties indépendamment de l'espèce dans les trois profils. Les espèces les plus acidifiantes sont L. lactis, L. plantarum, L. pentosus avec un pH moyen de 4.86 à 36h. Aucun lien n’a pu être observé entre la capacité fermentaire des 89 souches pour les huit sucres testés et leur capacité à fermenter les microalgues. Pour les trois souches les plus acidifiantes (CIRM-BIA2469, CIRM-BIA2211 et CIRM-BIA2178), seul l’ajout de 1g/L de glucose a eu pour effet d'améliorer l'acidification. Une flore contaminante (identifiée par séquençage ADNr16S comme Bacillus sp.), présente à 3.103 UFC/mL dans les lots de C. vulgaris testés croit jusqu'à 108 UFC/mL en l’absence de BL. Elle est en revanche systématiquement inhibée lors de la fermentation par les BL.Nos travaux montrent que les BL sont capables de fermenter la microalgue C. vulgaris et d'inhiber le développement de la flore contaminante. C'est à notre connaissance la première étude de fermentation de microalgues portant sur une aussi grande diversité de BL.

International audience; Mettre en évidence les propriétés physicochimiques de divers OB  Développer et évaluer le nouveau schéma de raffinerie verte pour l'extraction et la valorisation des OB Objectifs Contexte Les graines oléo-protéagineuses et les grains de céréales renferment de nombreux nutriments et micronutriments minéraux et organiques. In planta, ces nutriments se retrouvent sous forme d'assemblages naturels tels que les oléosomes (OB), qui présentent des propriétés intéressantes (tailles microniques, activité de surface, grande stabilité physico-chimique, ...). Ces assemblages sont généralement extraits par des procédés qui endommagent leurs structures, et de ce fait certaines fonctionnalités. Exploiter la biodiversité des assemblages naturels pour répondre à la demande sociétale d'une alimentation plus naturelle et peu transformée (Green Label), apparaît nécessaire. Le projet du consortium OBTAIN** se propose d'évaluer les potentialités d'un nouveau schéma de raffinerie verte (sans solvant, moins dénaturant).

International audience