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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

Steam-jet granulation process consists in agglomeration mechanisms promoted by the wetting of fine particles and colliding them to generates the agglomerates, and in consolidation mechanisms of the agglomerates by drying stage. The aim of the present study was to evaluate the influence of the drying step on the properties of the agglomerates. Experiments were conducted using an original pilot system with different drying conditions (time and temperature). We demonstrated that the mechanisms induced by drying stage contribute to the final structure and characteristics of the agglomerates. On the other hand, the changes in drying temperature (70, 90, or 110 °C) did not significantly impact the structural properties. The rehydration properties of the agglomerates were found to depend on the changes in water content. During the first minutes of drying, a rapid decrease of the wetting time of the agglomerates was observed and associated with rapid lactose crystallization. For long drying times, the large decrease in water content induced a considerable increase in the glass transition temperature, leading to a delay in the plasticization effect of the water during rehydration. The drying stage is a key factor to control the stability and functional properties of agglomerates.

International audience; The world dairy sector is undergoing sustained developments due to the increasing dairy needs of a growing population and a gradual change in diets. This article evaluates the position of West African countries amid the "dairy planet". The analysis uses FAO statistical data over a long period (1961 to 2017) and customs statistics from 2000 to 2018 for global data ("BACI" database) and from 2000 to 2019 for European data ("COMEXT" database). Although per capita consumption of dairy products per year is still low in many West African countries compared with industrialised countries, overall requirements for dairy products are increasing rapidly as a result of population growth. Due to numerous difficulties (climate, soil quality, low animal productivity, lack of investment... ), the development of milk production in West Africa (5.8 billion litres in 2017 for sixteen countries, the equivalent to the production of Brittany) is not sufficient to meet local needs. A little over two thirds of the dairy products imported into this zone come from the EU, whose exports have increased sharply over the past ten years (end of milk quotas). Around 40% of these imports are skimmed milk and vegetable fat powder blends (based on palm oil), a product that benefits from a competitive price and which is only very slightly taxed on entry into West African countries.; Le secteur laitier mondial connaît un développement soutenu en raison de l’augmentation des besoins en produits laitiers d’une population en croissance et d’un changement progressif des régimes alimentaires. Cet article s’intéresse à la place des pays de l’Afrique de l’Ouest dans la « planète laitière ». L’analyse mobilise pour ce faire, d’une part, les données statistiques de la FAO sur une longue période (1961 à 2017) et, d’autre part, les statistiques des douanes de 2000 à 2018 pour les données mondiales (base de données « BACI ») et de 2000 à 2019 pour les données européennes (base de données « COMEXT »). Si la consommation de produits laitiers par habitant et par an est encore faible dans de nombreux pays de l’Afrique de l’Ouest, comparativement aux pays industrialisés, les besoins globaux en produits laitiers augmentent rapidement sous l’effet de la croissance démographique. En raison de nombreuses difficultés (climat, qualité des sols, faible productivité des animaux, manque d’investissement...), le développement de la production laitière en Afrique de l’Ouest (5,8 milliards de litres en 2017 pour seize pays, soit l’équivalent de la production de la Bretagne) n’est pas suffisant pour faire face aux besoins locaux. Les importations de cette zone en produits laitiers se font pour un peu plus des deux tiers en provenance de l’UE, dont les exportations ont fortement augmenté depuis une dizaine d’années (fin des quotas de production). Ces importations concernent à 40 % des mélanges de lait écrémé et de matière grasse végétale en poudre (à base d’huile de palme), un produit qui bénéficie d’un prix compétitif et qui n’est que très faiblement taxé à l’entrée dans les pays de l’Afrique de l’Ouest.

Fat-filled spray-dried dairy powders have achieved great economic, nutritional and functional importance. This includes a wide range of products such as whole milk powder, cream powder, whey derivatives, infant milk formula and dairy ingredients enriched with either milk fat or with vegetable oils.

This study aimed at investigating the chemical composition and microstructure of spray dried camel and cow milk powders' surfaces with two different milk-fat contents (1 and 20g 100 g−1). The SEM (Scanning Electron Microscopy) micrographs showed that spherical particles with a ‘brain’-type surface for both milk powders were produced. The surface roughness (Ra) of whole (WDMP) and skimmed (SDMP) camel milk powders (Ra = 7.6 ± 0.4 nm and 5.6 ± 0.7 nm, respectively) were significantly lower as compared with the partially skimmed (PSCMP) and skimmed (SCMP) cow milk powders. The XPS (X-ray Photoelectron Spectroscopy) analysis highlighted that the surface of skimmed camel milk powders contained twice the lactose amount (17.7 ± 0.8%) as compared to cow milk powders (8.7 ± 0.4%). Furthermore, both milk powders showed the overexposure of proteins and fats at their surfaces regardless of the fat content. The CLSM (Confocal Laser Scattering Microscopy) micrographs highlighted that most of the camel milk fat globules were encapsulated by the proteins near the powder surface. Camel milk fat behavior during particle formation was attributed to their lower size distribution and their higher crystallization temperature.

Bovine milk fat is an important dairy component which is consumed by human infants and adults via various dairy products such as milk, milk powder, cream, cheeses, and butter. Apart from the major physiological role of milk fat in delivering human nutrition and providing health benefits, milk fat also plays as a pivotal func-tionality controlling role in many dairy products. The biological membrane sur-rounding milk fat globules has been found to have interesting applications in food formulation innovations, human nutrition, and paediatrics. Therefore, understand-ing the fundamental science and technology of milk fat is of great importance not only from a scientific point of view but also with regard to the economic impact of milk fat, especially in fat-rich products. The intention of this book is to provide readers with recent and outstanding literature in important areas of dairy fat contain-ing products and functionality. This book represents a valuable source of informa-tion for students, academics, and industry personnel who work in the fields of dairy lipids and dairy fat products.In this book, 24 chapters have been organised into three main themes: (1) dairy fat chemistry and nutrition, (2) dairy fat physics and materials science, and (3) dairy fat processes and products. In the first theme, fascinating insights into milk fat glob-ule membrane such as structure, lipidomic characterisation, and applications are presented. Physiochemical characterisation, lipase action, adulteration, and digest-ibility of milk lipids are also covered. The second theme provides excellent funda-mentals in physical properties of milk fat such as crystallisation, rheology, and microstructure aspects. It also highlights relatively new research areas driven by material science approach in dairy fats, where innovative dairy products and the new generation of dairy ingredients can be tailor-made. Cutting-edge topics on tri-bology of dairy fat products, oil structuring in dairy fat products, manipulation of differentiated-sized milk fat globules, and production of human milk fat substitutes from dairy fats are featured in dedicated chapters. The third theme presents compre-hensive reviews on the relationship among processes—structure—functionality in dairy fat products towards new developments in manufacturing processes and health-promoting dairy products. The last theme also focuses on the importance of vimilk fat as a key quality controlling factor in the manufacturing of butter, ghee, dairy cream, dairy powder, cheeses, and aerated products.The expert contributions of 43 authors from 10 countries are greatly acknowl-edged with gratitude. Special acknowledgements are also extended to Springer for their support during the course of this book project.

National audience

International audience; The production of milk powders is a strategic sector of the dairy industry. Due to its complex macromolecular composition, shedding light on the mechanisms governing milk drying constitutes a main industrial concern and a scientific challenge at the same time. In this study, we used the single droplet[1] and the directional drying[2] approaches to investigate the evaporation of colloidal mixes of the two major milk proteins (whey protein isolates and native phosphocaseinates). Notably, we observed the crack development in the samples to evaluate the competitive impact of the physico-chemical properties of whey proteins (rigid globular shape) and casein micelles (deformable sponge-like structure) on the drying process. Our outcomes are potentially useful to better control the functional properties of milk powders. Furthermore, they contribute to improve the understanding of the drying mechanisms in binary colloidal systems, which are still far from being fully elucidated.

International audience; Spray drying is a well-established process, but the phenomena ruling droplet-to-particle transition remain black box, resulting in variable powder properties and drying performances. Therefore, understanding precisely how the particle is formed and how to control its properties remain a major challenge. This work aims to breakdown the complexity of the drying phenomena using an exploratory multi-scale approach. Particle formation of different milk proteins (whey proteins and casein micelles) was investigated using different experimental systems (single pendant droplet, mono-dispersed droplets and spraying cone droplets) in controlled drying environments. The results showed that the drying of a single protein droplet included three distinct stages highlighting the occurrence of specific morphological events (constant rate shrinkage, buckling instability, vacuole nucleation). According to the type of proteins, these stages differed in drying kinetics and droplet dynamics, leading to characteristic and reproducible particle shapes irrespective of the droplet configuration and the drying conditions. These different drying behaviors were related to specific skin formation mechanisms at droplet air-liquid interface and consequent responses of the protein material to internal stresses. In this work, we aimed at understanding how the different physico-chemical properties of whey proteins (rigid globular shape) and casein micelles (deformable sponge-like structure) affect the mechanisms of formation of such a skin, and from this the particle final shape. However, the full understanding of the drying process of biocolloids is far to be achieved and, notably, the impact of solute properties on the morphological characteristics of the evaporating droplets, such as colloid segregation, skin formation and crack pattern development is not elucidated yet. To this aim, the use of model colloidal solutions, whose rheological behavior is more easily deducible, could represent a significant boost. Consequently, we compared the drying of droplets of whey proteins and casein micelles to that of dispersions of silica particles and polymer-coated silica particles, respectively. The mechanical behavior of such biological colloids and model silica dispersions was investigated through the analysis of crack formation, and the measurements of their mechanical properties using indentation testing. The study reveals numerous analogies between dairy and corresponding model systems, thus confirming these latter as powerful tools to highlight the signature of the matter on the drying process and at the molecular scale. The outcomes presented in this work represent a first step to shed light on the physics of drying dairy droplets; they open the road to further investigation about mixes of milk proteins. Moreover, the observation of mixtures of dairy colloids would contribute to improve the knowledge about the evaporation of colloidal polydisperse systems, which represents a current scientific challenge.

The production of dairy powders, involving high added value products such as high protein powders and infant milk formulas, has nowadays become strategic for the dairy industry. Due to their complex composition in terms of proteins and macromolecules, shedding light on the underlying mechanisms governing the evaporation of such dairy products constitutes a main industrial concern and a scientific challenge at the same time. In this study, we used the single droplet approach to investigate the evaporation of dairy solutions consisting of the two major milk protein components (whey proteins and native micellar caseins), alone or in mixes with different whey protein to casein ratio. In the works performed in our group in the last decade[1-3], we demonstrated that studying the drying of such biocolloidal systems at the single droplet stage is consistent to predict the behavior at larger industrial drying scale. We observed that the droplet-to-particle transition that characterizes the evaporation of dairy mixes consists of three main phases: pure shrinkage, skin formation and buckling, and finally end of the process. Here, we mainly focused on the gradual development of the droplet gelled skin due to the continuous sol-gel transition at the air-liquid interface (buckling stage). In particular, we aimed at understanding how the different physico-chemical properties of whey proteins (rigid globular shape) and casein micelles (deformable sponge-like structure) affect the mechanisms of formation of such a skin and therefore the particle final shape. To this end, we estimated in real-time the internal flows in drying droplets of whey protein and casein mixes by optical microscopy (particle tracking and particle image velocimetry). Simultaneously, the development of the skin due to the continuous solute migration was visualized by both optical and confocal microscopy. In addition, an elemental analysis by scanning electron microscopy was realized on the dried particle skin of the different mixes to extract further information about the specific deposition of the two colloidal components during the desiccation process. Our outcomes highlight the strong impact of both chemical composition and physical structure of whey proteins and casein micelles on the duration and the intensity of the internal flows during the drying of mixes, as well as on the mechanisms of organization of the external skin throughout the evaporation process. These results represent a promising progress in order to improve the control of the functional properties of milk powders. Furthermore, they contribute to improve the understanding of the drying mechanisms in binary colloidal systems, which are still far from being fully elucidated.

Le secteur laitier mondial connait un développement soutenu en raison de l’augmentation des besoins en produits laitiers d’une population en croissance et d’un changement progressif des régimes alimentaires. Si les pays asiatiques sont depuis longtemps placés au coeur de cette dynamique, ce qui stimule le développement des exportations dans trois grandes zones géographiques (l’Union européenne, la Nouvelle-Zélande et les Etats-Unis), la place qu’occupe l’Afrique dans la « planète laitière » est étudiée ici de façon spécifique. Moyennant une focalisation sur le cas des pays de l’Afrique de l’Ouest, cette communication aborde successivement la consommation de produits laitiers, la production de lait et les échanges de produits laitiers. Pour ce faire, cette analyse mobilise, d’une part, les données statistiques de la FAO sur une longue période (1961 à 2017) et, d’autre part, les statistiques des douanes sur la période 2000 à 2017 (pour la base de données BACI) ou 2018 (COMEXT). Une attention est portée à la question des importations de ces pays, notamment en mélanges de lait écrémé et de matière grasse végétale en poudre en provenance de l’Union Européenne (UE). Compte tenu de la faiblesse des droits de douane appliqués aux frontières et du caractère hautement compétitif de ces produits, un débat est engagé autour du devenir de la production laitière locale et de la stratégie déployée par les autorités européennes pour soutenir ou non, au travers de sa politique agricole, le développement de l’agriculture africaine., The global dairy sector is growing steadily due to the increased dairy requirements of a growing population and a gradual shift in diets. While Asian countries are, since a long time, at the heart of this dynamic, which stimulates the development of exports in three main geographical areas (European Union, New Zealand and the United States), the place occupied by Africa is studied here specifically. With a focus on the countries of West Africa, this paper successively discusses the consumption of dairy products, the production of milk and the exchange of dairy products. This analysis uses long-term statistics from FAO (1961 to 2017) and customs statistics from 2000 to 2017 (for the database BACI) or 2018 (COMEXT). An attention is paid to the question of imports of these countries, particularly of “fat filled milk powder” (a product that corresponds to a mixture of vegetable fat and milk powder) from the European Union (EU). Given the low tariffs applied at the borders and the highly competitive nature of these products, there is a debate about the future of local milk production and the strategy deployed by the European authorities to support or not, through its agricultural policy, the African agriculture’s development.

Mécanismes de formation de l’interface au cours du procédé de séchage : approche multiéchelles appliquée aux poudres laitières. journée scientifique "science des aliments et valorisation des bio-produits"

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

When dairy powders are produced, the mineral fraction undergoes strong modifications during the vacuum concentration step, leading to the fouling of falling film evaporators. The objective of this study was to determine the nature of the deposits formed during the vacuum concentration of two fouling and highly mineralized products: hydrochloric acid whey and lactic acid whey. These products mainly differ in terms of their mineral composition: lactic acid whey contains a high level of lactic acid and traces of citrate, whereas hydrochloric acid whey contains citrate and no lactic acid. Concentrates at different concentration factors were produced using a pilot-scale falling film evaporator. The compositions of the fouling deposits as well as the precipitates present in the concentrates were deduced from the analytical determination of the composition of the concentrates and their respective diffusible phases. The behavior of the mineral fraction of both acid wheys during concentration was shown to be very different. In the case of hydrochloric acid whey, experimental results suggested a deposition of calcium and citrate ions in the evaporator as well as their precipitation in the highly concentrated products. On the contrary, neither mineral deposition nor precipitation occurred during the concentration of lactic acid whey. This study underlined the key role of citrate ions in the fouling of evaporators during the concentration of hydrochloric acid wheys.

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

National audience

The global market for dairy powders has undergone two major transitions over the past four decades, firstly by integrating scientific and technological knowledge, and secondly due to the growing demand from the emerging markets. The use of separation techniques such as membrane filtration (e.g., microfiltration and ultrafiltration) allowed access to a new range of dry products with higher added value, including concentrates and isolates of specific whey protein fractions (Schuck, 2002). By the production of the latter, the dairy sector turned toward the nutritional control of these powders as well as their technological functionalities. Whey protein powders are widely used as dry food ingredients due to their high nutritional values and are producedon a large scale. Whey proteins now appear to be the one of the most valuable components of bovine milk. Besides their nutritional aspects, they possess interesting functional properties such as solubility, emulsification, foaming, and gelling. Milk goes through a number of processing steps including preheating, evaporation, and filtration before drying to obtain whey protein powders of specific characteristics (e.g., composition). These steps involve high temperature, shear, and removal of water from wheysolids, which may cause physicochemical changes in whey components such as protein, lactose, minerals, and fat (Fox, 2003). The quality of fresh whey protein powders can be evaluated through their solubility at pH 4.6, which is a method of quantification of the native whey proteins (nondenatured) content. It gives an indirect indication of the extent of whey proteins denaturation and aggregation as well as the severity of heat treatments that have been used during whey protein powder production. This constitutes an important parameter as whey protein functional properties are dependent on the production history.

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

A composite face-centered experimental design was used to investigate the influence of spray drying conditions on the physicochemical characteristics of camel and cow milk powders. Response surface methodology (RSM) was deployed to appraise the effects of these processing parameters (the outlet drying temperature and the milk fat content) on water activity (aw), glass transition temperature (Tg), bulk density, and free fat quantity. Accordingto RSM analysis, it was noticed that the aw and the Tg were primarily influenced by the outlet drying temperature instead of by milk fat content. Our results highlighted the negative effects of milk fat content and of the outlet drying temperature on the bulk density as well as on the free fat quantity of camel milk powder. Likewise, our findings underlined the negative effect of the outlet drying temperature on the bulk density of cow milk powder.However, the increase of fat content has led to the overexposure of fat at the free surface of the cow milk powder. Our results suggested a marked similarity of the overall thermodynamic behavior of both milks, during drying. Nevertheless, some differences were highlighted regarding the structuring of the particles of camel milk powder.

Les poudres laitières sont obtenues par concentration du produit liquide (membranes, évaporation sous vide) puis séchage du concentré. Contrairement au séchage par atomisation, peu de travaux ont été menés sur la concentration par évaporation sous vide. Pourtant, la maîtrise du schéma global de production des poudres gagnerait en une meilleure compréhension de cette opération réalisée dans des évaporateurs à flot tombant. Le présent travail vise à étudier comment améliorer les performances des évaporateurs ; il s’appuie sur deux facteurs limitants de l’opération : l’encrassement des surfaces d’échange et la viscosité maximale en sortie des évaporateurs. La contribution des différents constituants des produits à l’encrassement a été étudiée grâce à une méthodologie développée sur un évaporateur pilote. Les résultats obtenus ont permis d’identifier les éléments minéraux qui contribuent à l’encrassement lors de la concentration de microfiltrat et d’ultrafiltrat de lait, de lactosérums acides chlorhydrique et lactique. Afin de dépasser l’extrait sec maximal en sortie des évaporateurs à flot tombant, deux évaporateurs rotatifs à couche mince, de conceptions différentes, ont été testés à l’échelle pilote. Les études de faisabilité ont été menées jusqu’à la poudre. Le potentiel des équipements a été évalué suivant les propriétés fonctionnelles des poudres et le coût énergétique d’élimination de l’eau. Dans l’un des cas, le remplacement de la tour de séchage par deux évaporateurs rotatifs en série constitue une rupture technologique pour la production de poudres de perméat et diminue significativement les coûts énergétiques associés.

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.

Similarity in the drying behavior between biological colloids and model colloidal dispersions . Première réunion plénière du GDR SLAMM (Solliciter LA Matière Molle)

Inlactis es el Simposio Internacional en Ciencia y Tecnología de Lácteos que se organiza de forma interinstitucional desde Uruguay.; Dairy Ingredients Interactions process / product: Effect on dairy powder quality. Inlactis

Drying is ubiquitous in industry and our everyday life. It is a priori a complex process involving coupled vapor diffusion and liquid transport through a complex, multi-scale, soft or solid, porous structure. Despite this complexity, many recent researches now provide insight in, and rationalization of, the physical processes at work in drying of soils, building materials, colloids, gels, model porous systems, etc. The aim of this meeting, within the frame of the Chair Innovating solutions for sustainable housing (Saint-Gobain –Ecole des Ponts ), is to gather experts and review significant improvements in our understanding in this scientific field.

Milk is extremely perishable, and yet it has to be preserved for later consumption. In this view, membrane filtration, vacuum concentration lactose crystallization, homogenization and spray drying dehydration are valuable techniques to stabilize most dairy ingredients. Considering the increasing development of dairy trade, there is a need for the dairy industry to improve its understanding of how these concentration and spray drying processes affect the quality of the resulting dairy powders, so to control it. However, the residence time of the droplet and the powder in the spray dryer is so short that it is very difficult to implement studies on the mechanisms of the structural changes in the protein without fundamental research into the process/product interactions. Moreover, several authors have reported the crucial and specific role of dairy components in the mechanisms of water transfer during drying and rehydration. The aim of this paper is to review the present and recent advances in knowledge and innovations, on the properties of spray-dried dairy products, on the modelling and simulation of water transfer processes (drying and rehydration) and on spray drying equipment and energy consumption.

Innovations and eco-friendly processes in dairy powders. Green Food Tech 2018

National audience; Hypothesis: The effective contribution of interfacial properties to the rheology of foams is a source of many open questions. Film dynamics during topological T1 changes in foams, essentially studied for low molecular weight surfactants, and scarcely for proteins, could connect interfacial properties to protein foam rheology. Experiments: We modified whey protein isolate (WPI), and its purified major protein b-lactoglobulin (b-lg) by powder pre-conditioning and dry-heating in order to obtain a broad variety of interfacial properties. We measured interfacial properties, film relaxation duration after a T1 event and bulk foam rheology. Findings: We found that, for b-lg, considered as a model protein, the higher the interfacial elastic modulus, the longer the duration of topological T1 changes and the greater the foam storage and loss moduli and the yield stress. However, in the case of the more complex WPI, these correlations were less clear. We propose that the presence in WPI of other proteins, lactose and minerals modify the impact of pre-conditioning and dry-heating on proteins and thereby, their behaviour at the interface and inside the liquid film.

Master; Depuis plus d’une centaine d’années, le séchage du lait de vache permet d’améliorer la conservation, le transport et le stockage. Ainsi il favorise les exportations qui sont en fortes croissances vers les pays tiers. De bonnes propriétés de réhydratation des poudres de lait obtenues sont nécessaires à leur utilisation, c’est pourquoi la poudre de lait peut être agglomérée par le procédé de granulation. Ce procédé consiste à assembler des particules fines afin d’assurer la formation de nouvelles structures, appelées granulés, aux propriétés d’utilisation améliorées. En effet, les granulés formés présentent une structure poreuse et ouverte, favorisant la pénétration de l’eau par capillarité et son immersion lors du processus de réhydratation. L’entreprise Régilait, partenaire du projet de recherche, est un des leaders mondiaux dans la production de poudre de lait granulé écrémé. Cependant, le procédé de granulation est difficile à contrôler et 6% de ses productions sont non conformes. Se pose alors la question : quels facteurs de contrôle du procédé influencent les propriétés des granulés de lait écrémé? Le présent rapport contribue à l’approche expérimentale visant à comprendre et expliquer les relations matière première-procédé-produit dans la granulation du lait en poudre. Il s’inscrit dans le cadre de la thèse CIFRE en collaboration avec Régilait et l’UMR STLO menée par Mathieu Person. Au cours de ce projet de recherche, un équipement pilote a été mis au point afin de tester les différents facteurs de contrôle du procédé d’agglomération. Des poudres de lait ont alors été agglomérées à l’aide de cet équipement pilote, puis les granulés obtenus ont été caractérisés afin d’observer l’influence des facteurs de contrôle. Les propriétés structurelles ont été étudiées en analysant le diamètre de Féret, la circularité et les masses volumiques des granulés. L’état physico-chimique des granulés a également été étudié par analyse de leur teneur en eau et de leur activité de l’eau. Les propriétés fonctionnelles (résistance mécanique et mouillabilité) des granulés ont également été mesurées. Au cours des essais menés sur le pilote, l’ensemble des facteurs de contrôles testés ont montré une influence importante sur les propriétés des granulés. Les conditions de séchage des granulés engendrent des modifications importantes de l’état du lactose (cristallisation, transitions vitreuse), qui modifient alors les propriétés de réhydratation des granulés. La taille et l’humidité des particules de matière première ont montré un impact important sur la structure des granulés formés. L’obtention d’une structure plus compacte est néfaste pour la réhydratation des granulés, car cela réduit alors la capacité d’absorption de l’eau par capillarité des granulés. L’état physico-chimique de la matière première a également montré une influence importante sur les propriétés de collage et donc sur la structure des granulés. Enfin, l’état dénaturé des protéines a montré un effet néfaste considérable sur la mouillabilité des granulés.

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

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.

Whey proteins are derived from milk and are widely used in the food industry for their nutritional and functional properties. Many studies have been undertaken on the improvement of the functional properties of these proteins, mainly by their heat-induced denaturation/aggregation. Depending on the heating conditions, it is possible to obtain a variety of aggregates that have different structures and different physicochemical properties, leading to remarkable techno-functional properties, such as gelling, foaming or emulsification (Nicolai et al., 2011). While many works has been dedicated to heat treatments of whey proteins as present in a solution, very few studies considered heat as applied in a dry state, say by applying heat on powder. This heating pathway was reported to strongly affect the heat-induced gelling properties of whey proteins (Gulzar et al., 2012). The purpose of this study was to produce particles having high functional properties by dry heating of a whey protein isolate powder. Power composition effects were investigated on the formation and the structure of particles. Moreover, special attention was paid to the role of lactose in the formation of these uncommon particles.

International audience

O interesse por produtos lactose-hidrolisados é crescente no mercado. A hidrólise causa adesão, empedramento e diminuição da produção durante a secagem, mas as condições de operação podem minimizar estes efeitos. Os grandes volumes e energia necessários nos testes industriais em spray dryer são limitantes ao desenvolvimento destes produtos. Buscam-se mecanismos de triagem (plantas piloto, simulações em software, técnicas analíticas) que permitam selecionar as melhores condições de secagem a serem testadas nas industrias. Objetivou-se avaliar em planta piloto semi-industrial se o índice Stickiness and caking sensitivity index (SCSI) permite prever o comportamento de produtos lácteos lactose-hidrolisados durante a secagem. A adesão e o empedramento previstos pelo SCSI foram fielmente observados nos ensaios para os produtos lactose-hidrolisados leite, soro e mistura de ambos. O SCSI mostrou-se eficaz para a previsão da adesão e do empedramento, e potencial ferramenta de triagem para o desenvolvimento de produtos e a pesquisa aplicada.

Produtos sem lactose são um grande nicho de mercado atualmente, contudo as dificuldades para a secagem em spray dryer (adesão e empedramento) são um limitante a produção de lácteos desidratados lactose-hidrolisados. As condições de operação do spray dryer (vazão de alimentação, temperaturas de entrada e saída do ar e controle da umidade absoluta do ar) impactam diretamente sobre as propriedades dos produtos. Objetivou-se avaliar em dois tipos de spray dryers o efeito de quatro diferentes condições de secagem sobre a formação de depósitos na torre (Stickiness) e sobre o empedramento (caking) de produtos lactose-hidrolisados. Os resultados indicam a necessidade de redução das temperaturas do ar de entrada e saída (24 a 75ºC) e redução da vazão (45 a 66%) para minimizar a adesão e o empedramento, contudo soro hidrolisado em pó estável não foi obtido em nenhum dos spray dryers e em nenhuma das quatro condições de secagem aplicadas.

In this work, a simplified process from growth to spray drying of two probiotic strains, Lactobacilllus casei BL23 and Propionibacterium freudenreichii ITG P20, was proposed by utilizing concentrated sweet whey for growth and for achieving one-step drying of bacterial culture with higher dry matter of feed. Interestingly, after increasing the total solids of sweet whey from the original level of 5% to 20 - 30% (w/w), the two probiotic strains had higher final biomass production, instead of being inhibited by the high osmolality. The survival of the probiotics after spray drying was simultaneously improved, as well as during 6 months storage at 4 ºC. It was shown that this protective effect was due to enhanced multi-stress tolerance acquisition, overexpression of key stress proteins, and accumulation of intracellular storage molecules and compatible solutes upon growth in hyperosmotic medium.

The most frequently used technique for dehydration of dairy products is spray drying. This is an effective method to preserve biological products as it does not involve prolong exposure of materials to severe heat treatment. Due to the variety and complexity of the concentrates to be dried, a more rigorous understanding of spray-drying based on physico-chemical and thermodynamic properties is necessary. At the same time, the current state of the art did not allow easy determination of the parameters of spray-drying of dairy products prior to drying, except from performing several complex and expensive experiments with pilot-scale spray-dryer. Nevertheless, recent advances in the understanding of product behavior toward water transfer with the development of a desorption method makes it possible to give several answers to the following question: What is the best strategy to anticipate the behavior of concentrate toward drying and to improve the process, the economy and the quality of the dairy powders?The strategical approach can be developed on the knowledge of the thermodynamic parameters of the spray dryer coupled to physico-chemical characteristics of the concentrate. The software SD2P® (Spray Drying Parameters Simulation & Determination) developed by Schuck et al. (2009) is a way, among others, to predict the value of these parameters when they are not known. The combined results provide more precise determination of spray-drying parameters (including inlet/outlet air temperature, mass/powder flow rate, powder temperature, etc.), powder state during spray-drying (stickiness) and the cost of spray-drying with respect to weather conditions. Several cases will be presented to show the interest of this strategy in order to anticipate the spray-drying parameters and the powder behavior.

There are two essential stages in the elimination of water for the production of whey and permeate powders: concentration by vacuum evaporation followed by spray drying. These two operations alone represent 25% of the energy consumed by the French dairy industry, the major part of which is due to the drying stage. Indeed, 96.7% of the whey water is removed during the vacuum evaporation/concentration stage, whereas drying, which removes only 3.3% of the water, requires 31% of the total energy used over the entire process.One possible way to reduce energy consumption would be for the product to enter the drying tower at a higher level of dryness. We therefore propose replacing the drying tower with rotating evaporators, i.e. equipment adapted to highly viscous products able to pass from a liquid state to a granular state by a continuous process.The process begins as normal with the concentration of the whey/permeate from 6 to 60% dry matter in vacuum evaporators, followed by crystallisation of the concentrate in a tank. However, instead of passing through a drying tower, the concentrate then undergoes 60–80% superconcentration in a rotating fine layer evaporator. This highly viscous superconcentrate is then granulated in a second fine layer evaporator to recycle the powder created by the previous process. The granules thus obtained are then dried on a fluid bed to 96-97% dry matter.The patented PST process (Poudre Sans Tour/Towerless Powder – n° FR1457413) constitutes a true technological breakthrough in the manufacture of whey powders, with physical and rehydration properties comparable to those obtained with a drying tower. It has been validated on pilot equipment producing 50kg.h-1 powder and consuming significantly less energy. On the basis of theoretical calculations, the energy cost is 7.2 MJ/t of powder with the PST process compared to 11.9 MJ/t with the classical process, i.e. an energy saving of 40%. Setting up of the equipment does not require location investment such as the construction of a building to accommodate a tower, thus providing an additional saving of approximately 40% on the costs of installation.We are beginning a pre-industrial phase using the process in order to optimise and develop its application to other food powders (maltodextrin, sugars, etc.).

Les produits laitiers et ingrédients secs, d’une stratégie de report à un marché à forte valeur ajoutée:le point de vue de la Recherche. Assemblée générale de l'union laitière de la Meuse

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.

Digestion is a highly organized sequence of biochemical, enzymatic and mechanical processes needed to release nutrients, such as peptides or free amino acids from proteins structuring complex food matrices. During the gastric phase, they are gradually denatured through the acid released into the stomach and hydrolysed by pepsin. At the intestinal phase of digestion, proteases, such as trypsin, chymotrypsin, elastase and others, are secreted to further degrade the proteins and peptides until they are absorbed through the intestinal epithelium. Static or dynamic in vitro digestion models are widely used to study this step-by-step degradation of proteins to peptides and free amino acids, raising the question on the differences between digestion models. Generation and destruction of specific peptides during in vitro digestion of skim milk powder, following either the static international consensus COST Infogest digestion protocol or the dynamic digestion model DIDGI were compared, and verified in vivo in pigs. The hydrolysis of the five most abundant milk proteins during digestion – their peptides and free amino acids – were investigated by gel electrophoresis, mass spectrometry and HPLC after the gastric and the intestinal -phase. Moreover, time-resolved in vitro digestion experiment, generation and degradation of specific peptides and release of free amino acids were followed in the two in vitro digestion models and compared with the digestion in pigs. The protein specific hydrolysis for each digestion was visualized and compared by generation of abundance-dependent peptide patterns. Highly abundant peptides observed after complete digestion indicate digestion-resistant protein sequences and represent interesting sources of bioactive peptides or allergenic epitopes. Partial-least-square data analysis (PLS-DA) comparing static and dynamic in vitro digestion with the in vivo pig data showed a high correlation of gastric and intestinal samples at the peptide level. The same analysis at the level of free amino acids showed a good correlation at the gastric phase. However, at the intestinal level, the three models formed distinct groups which could be due to absorption mechanisms in the in vivo situation.

Particle formation during dairy powders production is ruled by protein mechanical properties. Drying Days Conference

Milk is extremely perishable, and yet it has to be preserved for later consumption. Membrane filtration, vacuum concentration lactose crystallization, homogenization and spray drying dehydration are valuable techniques to stabilize most dairy ingredients. Considering the ever increasing reach of international dairy trade, there is a need for the dairy industry to extend its ingredient process control capability through increased understanding of how these concentration and spray drying processes affect the quality of the resulting dairy powders. The 6th International Symposium of Dairy Dried Products (SDDP) in Dublin was hosted by the IDF National Committee of Ireland with the organizational support of Teagasc (Teagasc Food Research Centre Moorepark, Co. Cork, Ireland) under the supervision of Dr. Phil Kelly and Dr. Mark Fenelon. The aim of this event was to review and to discuss on the latest developments and innovations in dairy dried ingredients on the properties of spray-dried dairy products, on the modelling and simulation of water transfer processes and on spray drying equipment and energy consumption. The major items were 1. Overview of global markets for dried products including recent restructuring and investment trends 2. Concentrate and dry ingredients—new and emerging technologies 3. Concentration and drying fundamentals including modelling 4. Infant formula/nutritionals—processing and functionality 5. Powder functionality—physico-chemical effects and storage 6. Membrane—driven process innovation underpinning ingredient advances 7. Whey, permeate, lactose—powder processing and functionality

An innovative process scheme for the production of dairy permeate powders was tested at the pilot scale. It includes: (i) overconcentration of the permeate concentrate from 60 to 80% w/w dry matter (DM) content; (ii) granulation of the overconcentrate with powder up to 88% DM; and (iii) drying of the granules up to 97% DM. The quality of the resulting powder was comparable to a standard powder produced using conventional technologies. Furthermore, considering energy required for water removal, the new process led to significant savings: they were estimated in the range of 10.7 to 23.5% and up to 32% when taking into account the whole production process or the drying step alone, respectively.