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The massive research interest in whey has strengthened its position among coagulated milk products. Previously conducted reviews demonstrate that whey-derived functional foods provide a cascade of beneficial applications that promote health and wellbeing, and in managing numerous chronic diseases. To improve the understanding about how whey protein processing brings about new products that help in tackling health challenges is what we have attempted in this review paper. Herein, we provide an insight perspective into whey proteins processing and its derivatives from constituents, bioactivities, functionalities to therapeutic applications, drawing from: (a) prime constituents of whey protein; (b) composition and production of sweet/acidic whey; (c) bioactive peptides aspects of whey and its health/wellbeing benefits; (d) whey processing techniques: improving whey proteins’ functionalities; (e) whey and its derivatives-based products: generating new functional foods and beverages and (f) whey-derived products in health and wellbeing: some therapeutic applications. info:eu-repo/semantics/publishedVersion

International audience

Acid milk gels with fat (3.5 or 10%) or without fat containing 0.2–1% of whey proteins (WP) or 0.2–1.5% of protein aggregates (fractal aggregates, microgels and mixed casein/WP aggregates with an 80/20 ratio) were investigated. The fat-containing systems were homogenized and the systems were preheated (90 °C, 11 min) and acidified to a pH of 4.6 by adding glucono-delta-lactone. The protein composition of the fat droplet interface was characterized by SDS-PAGE and the textural and rheological properties, microstructure, and whey separation of acid networks were determined. WP and fractal aggregates showed the best ability to improve the textural properties and microstructure of all acid milk gels and reduce whey separation. Increasing the concentrations in microgels and mixed aggregates did not lead to an increase in gel firmness or generate a strong impact on the protein network, but a high concentration in mixed aggregates could reduce whey separation. The fat droplet interface was made almost exclusively of caseins, even if the fractal aggregates could also be adsorbed when the interfacial surface was increased either through fat content or through an increase in homogenization pressure. Adding proteins changes the textural properties of the acid gels in all the systems, mainly due to their role in the continuous phase.

[ES] En el presente Trabajo Final de Máster se recoge el estudio y el diseño preliminar de una instalación de valorización energética de lactosuero obtenido como residuo de los procesos de fabricación de queso a partir de leche de vaca, con el objetivo de determinar si la instalación propuesta es susceptible a ser utilizada en una industria láctea de tamaño mediano y con un caudal de lactosuero producido de 1.500 l/día. La tecnología inicial considerada, consiste en realizar una digestión anaerobia del lactosuero obtenido del proceso de coagulación y desuerado al que se somete la leche de vaca para obtener queso. El objetivo de esta biodigestión empleada es la obtención de biogás gracias a la acción de las bacterias anaerobias que se encuentran dentro del reactor y que transforman la materia orgánica presente en el lactosuero, principalmente proteínas y lactosa, en biogás. Para poder utilizar este biogás obtenido, se realiza el diseño preliminar de una instalación que incluya todos los elementos necesarios para el proceso de obtención de energía. Estos elementos incluyen: tanque y bomba de alimentación, digestor anaerobio, torre de desulfuración, gasómetro para almacenar el biogás producido, antorcha de combustión y motor de cogeneración para obtener energía eléctrica. Tras el proceso de digestión anaerobia y de cogeneración, se obtiene energía eléctrica que puede ser utilizada para el propio suministro de la industria láctea de donde se ha obtenido el lactosuero utilizado como sustrato inicial, completando así el proceso de valoración del residuo., [CA] En el present Treball Final de Màster es recull l'estudi i el disseny preliminar d'una instal·lació de valorització energètica de lactosèrum obtingut com a residu dels processos de fabricació de formatge a partir de llet de vaca, amb l'objectiu de determinar si la instal·lació proposada és susceptible a ser utilitzada en una indústria làctia de grandària mitjana i amb un cabal de lactosèrum produït de 1.500 l/dia. La tecnologia inicial considerada, consisteix a realitzar una digestió anaeròbia del lactosèrum obtingut del procés de coagulació i escorreguda al qual se sotmet la llet de vaca per a obtenir formatge. L'objectiu d'aquesta biodigestió empleada és l'obtenció de biogàs gràcies a l'acció dels bacteris anaerobis que es troben dins del reactor i que transformen la matèria orgànica present en el lactosuero, principalment proteïnes i lactosa, en biogàs. Per a poder utilitzar aquest biogàs obtingut, es realitza el disseny preliminar d'una instal·lació que inclogui tots els elements necessaris per al procés d'obtenció d'energia. Aquests elements inclouen: tanc i bomba d'alimentació, digestor anaerobi, torre de desulfuració, gasòmetre per a emmagatzemar el biogàs produït, torxa de combustió i motor de cogeneració per a obtenir energia elèctrica. Després del procés de digestió anaeròbia i de cogeneració, s'obté energia elèctrica que pot ser utilitzada per al mateix subministrament de la indústria làctia d'on s'ha obtingut el lactosèrum utilitzat com a substrat inicial, completant així el procés de valoració del residu., [EN] This Master's Final Project includes the study and preliminary design of a plant for the energy recovery of whey obtained as a waste from the cheese-making processes from cow's milk, with the aim of determining whether the proposed installation is susceptible to be used in a mediumsized dairy industry with a whey flow rate of 1,500 l / day. The initial technology considered consists of carrying out an anaerobic digestion of the whey obtained from the coagulation and deworming process to which cow's milk is subjected to obtain cheese. The objective of this biodigestion used is to obtain biogas thanks to the action of the anaerobic bacteria found inside the reactor and that transform the organic matter present in the whey, mainly proteins and lactose, into biogas. To be able to use this biogas obtained, a preliminary design of a plant is carried out that includes all the necessary elements for the energy production process. These elements include: tank and feed pump, anaerobic digester, desulphurization tower, gasometer to store the biogas produced, combustion torch and cogeneration engine to obtain electrical energy. After the anaerobic digestion and cogeneration process, electrical energy is obtained that can be used to supply the dairy industry itself, from which the whey used as the initial substrate has been obtained, thus completing the residue evaluation process.

[ES] Una parte del beneficio económico de todas las empresas lecheras, y en especial, las queseras, depende de la capacidad de recirculación de la materia prima que se utiliza durante los procesos de elaboración. Uno de esos flujos es el lactosuero o suero lácteo, el cual es rico en proteínas de alto valor biológico y sirve como suplemento dietético para personas con desorden alimenticio ya que también contiene una alta concentración en minerales y vitaminas. Dadas las propiedades anteriormente mencionadas, existen una gran variedad de productos, más o menos innovadores, que a muchas empresas de la industria láctea les interesa elaborar para poder llegar a un 90 % en el aprovechamiento de la leche que compran o producen de sus ganados. No obstante, no todas las empresas tienen los recursos económicos, energéticos o incluso espaciales para que dicha recirculación les proporcionen beneficios económicos. Para solucionar dicho problema, en la elaboración de este Trabajo fin de Grado, se va a llevar a cabo el estudio de estas corrientes, la disgregación o agrupación de las mismas, con el fin de realizar el diseño de una instalación capaz de transformar el lactosuero (aproximadamente un caudal de1000 L/día) resultante de una empresa de producción de quesos, en distintos productos finales, según las cantidades añadidas. Para la correcta aplicación de la recirculación del lactosuero es esencial que todas las fases de su obtención se realicen con un óptimo rendimiento. Estas fases constan de prensado, filtración, canalización, enfriamiento, recalentamiento, filtración, moldeado y conservación en frío. La mínima pérdida de lactosuero, sobretodo en las fases de prensado, filtrado y canalización es muy importante para que dicho proceso sea lo más rentable posible. Se va a llevar un seguimiento exhaustivo de la correcta preparación y elaboración de los distintos productos finales deseados, así como las temperaturas, caudales, tiempos y otros parámetros que afecten directamente a una producción idónea. Para finalizar, se realizará un presupuesto de la instalación diseñada, para el tratamiento de 1000 L de lactosuero al día., [CA] Una part del benefici econòmic de totes les empreses que treballen amb la llet, i especialment, les del formatge, depenen de la capacitat de recirculació de la matèria primera que utilitzen durant els processos d’elaboració. Un d’aquests fluxos es el lactosèrum o sèrum lacti, el qual és ric en proteïnes d’alt valor biològic i serveix com a suplement dietètic per a persones amb desordre alimentari ja que també conté una alta concentració en minerals i vitamines. Donades les propietats comentades anteriorment, existeixen una gran varietat de productes, més o menys innovadors, que a moltes empreses de la indústria làctia els interessa elaborar per a poder arribar a un 90 % a l’aprofitament de la llet que compren o produeixen a les seues ramaderies. Malauradament, no totes les empreses tenen els recursos econòmics, energètics o inclús espacials perquè dita recirculació els proporcione beneficis econòmics. Per a solucionar aquest problema, es va a dur a terme el disseny d’una instal·lació capaç de recircular alts percentatges de lactosèrum, segons les quantitats afegides, per a transformar-ho en diferents productes. Per a la correcta aplicació de la recirculació del lactosèrum es essencial que totes les fases de la seua obtenció es realitzen amb un òptim rendiment. Aquestes fases consten de premsat, filtració, canalització, refredament, rescalfament, filtració, modelat i conservació en fred. La mínima pèrdua de lactosèrum, sobre tot a les fases de premsat, filtrat i canalització es molt important perquè aquest procés siga el més rentable possible. Es va a dur un seguiment exhaustiu de la correcta preparació i elaboració dels diferents productes finals desitjats, així com les temperatures, caudals, temps i altres paràmetres que afecten directament a d’idònia producció. Per tant, es dissenyarà una instal·lació per tractar 1000 litres de sèrum al dia., [EN] A part of the economic benefit of every milk company, and in special mention, the cheese ones, depends on the capacity of recirculation of the raw material that it’s used during the process of elaboration. One of these flows it’s whey or dairy serum, which it’s rich in protein of high biological value and it worth as a dietary supplement for people with eating disorder since it also contains a high concentration in minerals and vitamins. Given the previously mentioned properties, there is a wide variety of products, more or less innovators, that for most of the companies of the dairy industry would be interested to elaborate, to be able to reach 90 % on the exploitation of the milk that they purchase or produced in their livestock. However, not every company has the economics, energetic, or even the space for such recirculation provide them economic benefits. To solve these problems, the design of an installation is going to be carried out, which is going to be able to recirculate high percentages of whey, depending on the amounts added, to transform it into different products. For the correct application of the recirculation of the whey it’s essential that each of the phases for its obtaining are made with an optimum yield. These phases are pressing, filtration, canalization, cooling, overheating, moulded and cold preservation. The minimum loss of whey, especially in the phases of pressing, filtration and canalization it’s very important to make the process as profitable as possible. It will be followed up exhaustively of the correct way to prepare and elaborate of the different desired end products, as well as temperatures, flow rates, timing and other parameters that could affect directly for the suitable production. Therefore, an installation will be designed to treat 1000 liters of whey per day.

Master; Une stratégie a été mise en place pour essayer de comprendre les interactions entre les protéines sériques de lait et les protéines de lupin et ainsi étudier les plus-values texturales engendrées par l’élaboration de matrice mixte lait-lupin. Deux isolats de protéines de lupin (LPI), un LPI industriel et un LPI préparé au laboratoire à partir d’une farine de lupin ont été utilisés. Par la suite, des suspensions à différentes concentrations en protéines et à différents ratios de LPI et WPI (0LPI, 30WPI, 50WPI, 70WPI et 100WPI) ont été préparées et traités thermiquement (80°C x 20 min) afin de former des agrégats. Tous les échantillons avant et après traitement thermique ont été étudiés par granulométrie laser et électrophorèse SDS PAGE, pour déterminer la taille des particules et le type d’agrégats formés. Ces agrégats sont essentiels pour former un gel avec une texture intéressante. Une fois obtenus, ces agrégats thermo-induits ont été incorporés dans une suspension de caséines afin de tester s’ils modifient ou non les propriétés des gels acides obtenus avec un acidifiant chimique mimant l’évolution de pH d’une fermentation lactique. La texture des gels acides a ensuite été mesurée par enfoncement d’une sonde. La rigidité et la dureté des gels ont été comparées afin de mettre en avant les plus-values texturales ou non de chaque LPI. Nous avons montré que la rigidité des gels est un phénomène qui dépend de la concentration en WPI et ce quel que soit le LPI et que la dureté est améliorée lors de l’utilisation du LPI industriel.

International audience

International audience; Heat treatments induce changes in the protein structure in infant milk formulas (IMFs). The present study aims to investigate whether these structural modifications affect protein digestion. Model IMFs (1.3% proteins), with a bovine or a human whey protein profile, were unheated or heated at 67.5°C or 80°C to reach 65% of denaturation, resulting in six protein structures. IMFs were submitted to in vitro static gastro-intestinal digestion simulating infant conditions. During digestion, laser light scattering was performed to analyze IMF destabilization and SDS-PAGE, OPA assay and cation exchange chromatography were used to monitor proteolysis. Results showed that, during gastric digestion, α-lactalbumin and β-lactoglobulin were resistant to hydrolysis in a similar manner for all protein structures within IMFs (p > 0.05), while the heat-induced denaturation of lactoferrin significantly increased its susceptibility to hydrolysis. Casein hydrolysis was enhanced when the native casein micelle structure was modified, i.e. partially disintegrated in the presence of lactoferrin or covered by heat-denatured whey proteins. The IMF destabilization at the end of the gastric digestion varied with protein structures, with larger particle size for IMF containing native casein micelles. During intestinal digestion, the kinetics of protein hydrolysis varied with the IMF protein structures, particularly for IMFs containing denatured lactoferrin, exhibiting higher proteolysis degree (67.5°C and 80°C vs. unheated) and essential amino acid bioaccessibility (67.5°C vs. unheated). Overall, the protein structures, generated by modulating the whey protein profile and the heating conditions , impacted the IMF destabilization during the gastric phase and the proteolysis during the entire simulated infant digestion.

Milk contains two types of proteins: Caseins and whey proteins. There are four caseins: α/β/γ/κ caseins that formed micelles in milk. Whey proteins are globular proteins between 12 and 200 kDa: α-lactalbumin; β-lactoglobulin; Serum albumin; Immunoglobulin and Lactoferrin. Industrials fractionate milk to produce whey protein and casein isolate to make ingredients for the formulation of dairy products. Whey protein isolate can be heated to functionalize or pasteurize them. The objective of these three studies are to characterize the isolates of whey proteins and the impact of heating treatment on whey protein fractions and formulations using different FFF techniques: Asymmetrical-FFF; 2D AsFlFFF-RPLC and Centrifugal-FFFWhey protein isolate heated at high temperature were studied by Centrifugal-FFF coupled with MALS and RI. Aggregates with the lowest density and size elute in the void peak and represent 51% of the mass fraction. For the bigger one, there are two populations: one smaller than 1 micrometer and one higher, up to 4.5 micrometers. For size determination, the biggest population fractionated has been collected and analyzed by DLS in batch. Infant milk formulation without fat was investigated by Asymmetrical Flow FFF coupled with MALS; QELS and RI. The formulation contains bovine milk and isolate whey protein fractions. The technique separates the non-aggregated whey protein to the casein micelles. The addition of lactoferrin partially disintegrated the casein micelles. The formulations are heated at 67.5°C or 80°C. Native whey protein content decreases with the heat treatment, leading to their aggregation on with the casein micelles. The phenomena depend on the temperature and protein composition. At 80°C, shape ratio Rg/Rh of casein micelles increase with the temperature when the formulation is enriched in lactoferrin. The Rg and Rh decrease when the formulation is enriched in α-lactalbumin and lactoferrin. Transmission Electronic Microscopy are correlated with these results. At 80°C, whey protein aggregates are fixed outside the micelle for the first formulation and they are fixed inside the micelles for the second formulation.Whey protein isolate contains few quantities of caseins. The second objective of this study is to identify the presence of trace of caseins in whey protein isolate using 2D AsFlFFF-RP-HPLC. This technique allows to separate proteins by their size and by their polarity. A whey protein standard mix is studied: α-lactalbumin, β-lactoglobulin A and B, BSA, and 3 caseins. A 2D map is obtained with all separated proteins.

Hydrophobisation of whey proteins, followed by erythritol addition into the hydrophobised protein dispersion, enables formation of water-in-water (W/W) emulsions of the proteins and alginate. In this study, we investigated the interfacial and gel rheology of whey proteins as affected by hydrophobisation, heat denaturation and erythritol addition. Additionally, the gel rheology of the resultant W/W emulsion was assessed. Hydrophobisation shortened the linear viscoelastic region and decreased the surface storage modulus ( G s ' ), the flow stress and the flow strain of protein layer at the air-liquid interface. Erythritol addition into the hydrophobised protein caused a further reduction of G s ' . In accordance with interfacial rheology, protein hydrophobisation and erythritol addition decreased the dynamic moduli of acid-induced protein gels. Frequency sweep tests indicated that the gelled emulsion had higher dynamic moduli than all WPI gels. The higher firmness of the emulsion gel was ascribed, based on microstructural images, to micro-phase separation of alginate droplets.

Milk contains two types of proteins: Caseins and whey proteins. There are four caseins: α/β/γ/κ caseins that formed micelles in milk. Whey proteins are globular proteins between 12 and 200 kDa: α-lactalbumin; β-lactoglobulin; Serum albumin; Immunoglobulin and Lactoferrin. Industrials fractionate milk to produce whey protein and casein isolate to make ingredients for the formulation of dairy products. Whey protein isolate can be heated to functionalize or pasteurize them. The objective of these three studies are to characterize the isolates of whey proteins and the impact of heating treatment on whey protein fractions and formulations using different FFF techniques: Asymmetrical-FFF; 2D AsFlFFF-RPLC and Centrifugal-FFF Whey protein isolate heated at high temperature were studied by Centrifugal-FFF coupled with MALS and RI. Aggregates with the lowest density and size elute in the void peak and represent 51% of the mass fraction. For the bigger one, there are two populations: one smaller than 1 micrometer and one higher, up to 4.5 micrometers. For size determination, the biggest population fractionated has been collected and analyzed by DLS in batch. Infant milk formulation without fat was investigated by Asymmetrical Flow FFF coupled with MALS; QELS and RI. The formulation contains bovine milk and isolate whey protein fractions. The technique separates the non-aggregated whey protein to the casein micelles. The addition of lactoferrin partially disintegrated the casein micelles. The formulations are heated at 67.5°C or 80°C. Native whey protein content decreases with the heat treatment, leading to their aggregation on with the casein micelles. The phenomena depend on the temperature and protein composition. At 80°C, shape ratio Rg/Rh of casein micelles increase with the temperature when the formulation is enriched in lactoferrin. The Rg and Rh decrease when the formulation is enriched in α-lactalbumin and lactoferrin. Transmission Electronic Microscopy are correlated with these results. At 80°C, whey protein aggregates are fixed outside the micelle for the first formulation and they are fixed inside the micelles for the second formulation. Whey protein isolate contains few quantities of caseins. The second objective of this study is to identify the presence of trace of caseins in whey protein isolate using 2D AsFlFFF-RP-HPLC. This technique allows to separate proteins by their size and by their polarity. A whey protein standard mix is studied: α-lactalbumin, β-lactoglobulin A and B, BSA, and 3 caseins. A 2D map is obtained with all separated proteins.

Main goal of this research was to examine the emulsifying properties of acid and sweet wheys extracted from bovine and camel fresh milks after heating at 70 and 90 °C for 30 min at laboratory scale. Specifically, emulsifying properties (emulsification stability (ESI) and activity (EAI) indexes) and the physico-chemical characteristics (surface hydrophobicity, ζ-potential, interfacial tension and denaturation rate) of wheys were assessed. Maximum EAI and ESI were found for sweet wheys (EAI~ 2 m2/g; ESI~ 65%), with higher EAI values for the camel whey. This behavior was explained by the strongest electrostatic-repulsive forces between oil droplets under conditions away from the isoelectric-point of proteins in agreement with the ζ-potential measurements. Findings indicate that heating affected the physico-chemical properties of camel and bovine whey proteins in acidic conditions by increasing surface hydrophobicity and the ability to reduce the interfacial tension. These results confirmed the protein-protein aggregation of heated acid wheys as proved by electrophoreses.

Microfiltration, MF is largely used in dairy industry to separate casein micelles from whey proteins. The weak performances of polymeric membranes compared to ceramic membranes are a restriction for their implementation in industry. Adding a diafiltration step is promising to improve polymeric MF performances, however most of the works have focused on the hydraulic performances and few have investigated the repercussion of diafiltration on protein separation. This work aims at investigating the impact of both the nature of solvent and the diavolume ratio on the MF efficiency. Pilot-scale MF using polymeric membrane (Synder, 800 kDa) was carried out on thermized skimmed milk at 12 °C with a volume reduction ratio, VRR from 2.5 to 3.2 and a transmembrane pressure of 0.7 bar. Continuous diafiltration was performed using reverse osmosis water (ROW) or milk ultrafiltrate (PUF). Permeation flux and β-lactoglobulin transmission were evaluated. During PUF-diafiltration of VRR-2.8-retentate, permeation flux is stable and β- lactoglobulin transmission declines by 26 % after 4.8 diavolumes. During ROW-diafiltration, permeation flux increases linearly until 2.9 diavolumes, then reaching an upper value. Simultaneously β-lactoglobulin transmission follows a parabolic curve with a maximum increase of 68 % for VRR-3.2-retentate and 10 % for VRR-2.5-retentate. According to Darcy’s law, the reduction of permeate viscosity during ROW-diafiltration leads to the improvement of permeation flux. This behavor is accentuated by the fouling layer relaxation consequent to the diminution of the ionic strength. In case of high repulsive forces in the concentration layer (low ionic strength), the transmission of negatively charged whey proteins is however restricted. The decrease of protein concentration during diafiltration may also limit whey protein transmission for high diavolume ratios. Diafiltration using ROW is recommended to increase transmission of whey proteins. However, volume of solvent has to be adapted to the VRR reached prior diafiltration to enable an optimum transmission

International audience; Hydrophobised whey protein particles were prepared through successive acetylation and heat treatment practices, and the particle characteristics were modulated by CaCl 2 supplementation. Then, the usefulness of the hydrophobised protein particles for emulsification of a docosahexaenoic acid-rich oil was compared with that of heat-denatured whey protein. Addition of CaCl 2 into hydrophobised whey protein resulted in smaller protein particles and lower z-potential and interfacial tension values. It also decreased the creaming stability of the consequent emulsions. It was argued that besides Ca 2þ-protein charge interactions, Cl e anions bind to the hydrophobised particles, and the Pickering stabilisation of oil does not rely on interfacial tension reduction. Compared with heat-denatured whey protein, hydrophobised whey protein afforded a lower protection to oil against oxidation; the peroxide value of the oil emulsified using hydrophobised protein was higher during storage.

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.

Mucositis, a common and often debilitating side effect of cancer chemotherapy, is a clinically important gastrointestinal inflammatory disease. It consists in a painful inflammation and ulceration of the mucosa lining the digestive tract, which may compromise proper nutrition of the patient, as well as termination of the treatment. It thus increases mortality and morbidity and contributes to rising health care costs. Its treatment is mainly supportive and often fails to relieve symptoms. Several studies indicate a role of the microbiota and suggest a healing effect of probiotic ingestion. Probiotic bacteria may maintain homeostasis and reduce side effects of chemotherapy toxicity. A major limit to probiotic bacteria anti-inflammatory effect is their susceptibility to digestive stresses and several studies indicate the key protective role of food matrices in increasing probiotics’ effect via the protection of bacteria against digestive constraints. In this study, we investigated the role of fermented milk, using Lactobacillus casei or Propionibacterium freudenreichii as probiotic starter, and of its fortification via addition of whey proteins.Matériels et Méthodes/Materials and methodsWe evaluated the role of whey protein isolate (WPI), when added to skim milk fermented by L. casei BL23 or by P. freudenreichii 138, as a protective matrix against in vitro stress challenges. In addition, we investigated in vivo the therapeutic effect of these fermented beverages in a murine model of mucositis induced by 5-Fluorouracil (5-FU). The monitored outcomes included weight loss, ileum histopathological score, villus height, crypt depth and number of mucus-producing goblet cells.Résultats principaux/Main ResultsThis study demonstrated that milk supplementation with 30% (w/v) of WPI increases the survival rate of both strains when challenged with acid, bile salts, high temperature and cold storage stresses, compared to fermented skim milk without the addition of WPI. Moreover, treatment with the probiotic beverages prevented weight loss and intestinal damages in mice receiving 5-FU. All symptoms of mucositis were drastically reduced by the consumption of developed probiotic fermented milks.ConclusionThis study evidenced the protective effect of selected strains of both lactic and propionic acid bacteria, in the context of induced mucositis. It confirmed that selected strains might be used bot as starter and probiotic. It opens new avenues for the development of fermented functional foods for target populations.

Les protéines solubles du lait pour texturer les aliments. journée scientifique "science des aliments et valorisation des bio-produits"

International audience; Water-in-water (W/W) or aqueous two-phase system (ATPS) emulsions are finding increasing applications in diverse fields of technology, for instance as protocells [1], and reactors for the synthesis of hydrogel particles [2], and enzyme-laden microgels [3]. Successful ATPS emulsification depends on thermodynamic incompatibility between two (bio)polymers, causing segregative phase separation [4]. Herein, we demonstrate that hydrophobization of whey proteins, by grafting acetyl moieties and heat denaturation, makes the proteins immiscible with a co-charged polysaccharide solution (alginate). Addition of erythritol, which is a low-calorie and zero-glycemic sugar alcohol, to the hydrophobized protein solution, enhanced emulsification and increased the stability of the resulting emulsion. Subsequently, the acid-induced gel properties of the emulsion was studied by dynamic rheometry and confocal microscopy. Erythritol addition reduced the surface tension (at the air-water interface) of the hydrophobized protein solution, enhancing the incompatibility between protein and alginate. It also postponed the gelation time of the hydrophobized protein solution and resulted in formation of a softer gel. Confocal imaging of the emulsion gel confirmed micro-phase separation of alginate and the droplets aggregation in the protein-rich matrix.

Fouling of falling film evaporators during the concentration of wheys . STLOpendays

Background Reads assignment to taxonomic units is a key step in microbiome analysis pipelines. To date, accurate taxonomy annotation of 16S reads, particularly at species rank, is still challenging due to the short size of read sequences and differently curated classification databases. The close phylogenetic relationship between species encountered in dairy products, however, makes it crucial to annotate species accurately to achieve sufficient phylogenetic resolution for further downstream ecological studies or for food diagnostics. Curated databases dedicated to the environment of interest are expected to improve the accuracy and resolution of taxonomy annotation. Results We provide a manually curated database composed of 10’290 full-length 16S rRNA gene sequences from prokaryotes tailored for dairy products analysis (https://github.com/marcomeola/DAIRYdb). The performance of the DAIRYdb was compared with the universal databases Silva, LTP, RDP and Greengenes. The DAIRYdb significantly outperformed all other databases independently of the classification algorithm by enabling higher accurate taxonomy annotation down to the species rank. The DAIRYdb accurately annotates over 90% of the sequences of either single or paired hypervariable regions automatically. The manually curated DAIRYdb strongly improves taxonomic annotation accuracy for microbiome studies in dairy environments. The DAIRYdb is a practical solution that enables automatization of this key step, thus facilitating the routine application of NGS microbiome analyses for microbial ecology studies and diagnostics in dairy products. Electronic supplementary material The online version of this article (10.1186/s12864-019-5914-8) contains supplementary material, which is available to authorized users.

Lactoserum, a byproduct of cheese industry, is rich in nutrients, but it is discharged directly into the environment. It has many human applications that promise to be a complete nutraceutical for the future generations. It is of high nutritive value and its products can be used as functional ingredients in food and pharmaceutical applications and as nutrients in dietary and health foods. They contain full spectrum of amino acids including essential and branched-chain amino acids which are important in tissue growth and repair. The other biological activities of lactoserum are antibiotic, anti-cancer, anti-toxin, immune-enhancer, and prebiotic (growth enhancement of gut microflora such as bifidobacteria). Lactoserum can thus be used as nutraceutical in various products like infant formulas, food supplements, cheese spreads, sports bars, and beverages to meet a variety of health goals for people of all ages, including animal feed. Fil: Gupta, Charu. Amity University; India Fil: Pacheco, Consuelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina Fil: Dhan Prakash. Amity University; India

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

[ES] El objetivo de este trabajo fue aplicar un sistema de filtración basado en micropartículas de sílice funcionalizadas con ácido ferúlico y eugenol para reducir la carga microbiana del suero de leche. Se estudiaron dos tamaños de partícula de sílice que fueron funcionalizadas con los compuestos bioactivos, empleándose también partículas sin funcionalizar (controles). Las muestras de lactosuero fueron filtradas a través de las diferentes partículas (funcionalizadas y control) y se evaluó la influencia del tamaño de partícula y del tipo de compuesto activo sobre parámetros fisicoquímicos (pH, acidez, sólidos solubles, color y contenido en proteínas) y recuentos microbiológicos (microorganismos aerobios mesófilos, psicrófilos y mohos y levaduras) del lactosuero. Los resultados mostraron la capacidad de las micropartículas funcionalizadas para inhibir la microbiota típica del lactosuero. El ácido ferúlico inmovilizado mostró mayor eficacia antimicrobiana, especialmente empleando partículas de sílice de 200 µm, aunque afectó a algunos parámetros fisicoquímicos, como el color y el pH. Las partículas desnudas y funcionalizadas con eugenol afectaron el contenido de proteína. Sin embargo, la inmovilización de compuestos bioactivos sobre la superficie de micropartículas de sílice presenta un alto potencial como una tecnología alternativa no térmica, obteniendo una reducción microbiana que permite la conservación del lactosuero fresco., [EN] The objective of this work was to apply a filtration system based on silica microparticles functionalized with ferulic acid and eugenol to reduce the microbial load of whey. Two sizes of silica particles that were functionalized with the bioactive compounds were studied, also using non-functionalized particles (controls). The whey samples were filtered through the different particles (functionalized and control) and the influence of the particle size and the type of active compound on physicochemical parameters (pH, acidity, soluble solids, color and protein content) and microbiological counts (aerobic mesophilic microorganisms, psychrophiles and molds and yeasts) of the whey was evaluated. The results showed the ability of functionalized microparticles to inhibit the typical microbiota of the whey. Immobilized ferulic acid showed greater antimicrobial efficacy, especially using 200 µm silica particles, although it affected some physicochemical parameters, such as color and pH. The naked and functionalized particles with eugenol affected the protein content. However, the immobilization of bioactive compounds on the surface of silica microparticles has a high potential as an alternative non-thermal technology, obtaining a microbial reduction that allows the conservation of fresh whey., [CA] L'objectiu d'aquest treball va ser aplicar un sistema de filtració basat en micropartícules de sílice funcionalitzades amb àcid ferúlico i eugenol per a reduir la càrrega microbiana del sèrum de llet. Es van estudiar dues grandàries de partícula de sílice que van ser funcionalitzades amb els compostos bioactius, emprant-se també partícules sense funcionalitzar (controls). Les mostres de lactosèrum van ser filtrades a través de les diferents partícules (funcionalitzades i control) i es va avaluar la influència de la grandària de partícula i del tipus de compost actiu sobre paràmetres fisicoquímics (pH, acidesa, sòlids solubles, color i contingut en proteïnes) i recomptes microbiològics (microorganismes aerobis mesòfils, psicròfils i floridures i llevats) del lactosèrum. Els resultats van mostrar la capacitat de les micropartícules funcionalitzades per a inhibir la microbiota típica del lactosèrum. L'àcid ferúlico immobilitzat va mostrar major eficàcia antimicrobiana, especialment emprant partícules de sílice de 200 µm, encara que va afectar alguns paràmetres fisicoquímics, com el color i el pH. Les partícules nues i funcionalitzades amb eugenol van afectar el contingut de proteïna. No obstant això, la immobilització de compostos bioactius sobre la superfície de micropartícules de sílice presenta un alt potencial com una tecnologia alternativa no tèrmica, obtenint una reducció microbiana que permet la conservació del lactosèrum fresc.

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.

Dans l’industrie laitière et fromagère, les protéines du lactosérum ne sont pas ou que très peu valorisées dans les produits transformés. En effet il est assez aisé de se servir des protéines micellaires (caséines) pour faire des yaourts ou encore des corps gras, matière première du beurre. Il est vrai que le comportement des protéines sériques est difficilement compréhensible au premier coup d’oeil, elles sont de petites tailles et ne forment pas facilement de structures macroscopiques notables. Ceci explique qu’aucune valorisation à forte valeur ajoutée n’ai été trouvé de façon empirique. Cependant l’étude fondamentale des interactions entre ces protéines sériques est très prometteuse, nous savons qu’elles ont tendance à former des coacervats dont l’exploitation est indéniablement vouée à de nombreuses applications (encapsulation, protection de molécules d’intérêts, …). L’équipe ISFPL du STLO travaille depuis de nombreuses années sur l’étude de ces interactions. Ils les ont déjà étudiés par plusieurs méthodes physico-chimiques : titration calorimétrique isotherme (ITC), fluorescence, dialyse à l’équilibre, … La majorité de ces méthodes d’analyses sont appliquées sur un très grand nombre de molécules et résultent donc d’un comportement de milieu. Dans le cadre de mon stage, nous nous intéresserons uniquement à l’interaction entre deux protéines individuelles. Au sein du STLO, nous avons la chance de posséder un microscope à force atomique qui permet de réaliser des spectres de forces d’interactions entre deux molécules. L’objectif de mon stage est d’obtenir et d’interpréter des spectres de forces résultant des interactions entre protéines sériques., In dairy and cheese industry, whey proteins are not too much used. In fact, understand their chemical comportement isn’t as easy as micellar proteins (yoghurt base) or as fatty substance (butter base) because of their little size and their hard coagulation. However, the fundamental study of whey protein’s interactions can be really interresting. They make coacervates with lot of applications. The ISFPL team is working on this subject since many years, they already studied it by isotherm titration calorimetry, fluorescence, nuclar magnetic resonance 2D, ... Most of them measure moleculs in group and don’t give us informations about just two protein’s interaction. During my practice I will learn how to use an atomic force microscop, in order to establish force spectres. The results would help us to understand better whey protein’s interactions.

New sequencing technologies allowed the development of methods such as metabarcoding. They use 16S rRNA, the ubiquitous gene of the bacteria domain, as a biomarker to study bacterial communities from samples of complex environments. The bioinformatic pipelines used to handle this type of data are well known but the taxonomic assignment is still a critical point. Misannotations are caused by short size sequences and high identity between bacterial species. Indeed, current technologies only allow to sequence two hyper-variable regions among the nine which compose the 16S rRNA. The available generalist databases (Greengenes, SILVA) do not reach enough accuracy to assign to the species rank. It is needed to create a curated reference database dedicated to the studied environment. Here we introduce the DAIRYdb, a manually curated database composed of full length 16S rRNA sequences from samples of dairy products and close environments (cheese, milk, teat surface, starter, whey). The DAIRYdb was constructed using the 16S rRNA sequences deposited in EMBL and NCBI. After bioinformatic treatments, automatic and manual curative steps, DAIRYdb is finally composed of 10290 complete 16S sequences. It shows a higher assignment accuracy compared to other databases, at all taxonomic ranks and with any assignment tool tested. Depending on the variable region used, up to 90% of the tested sequences are reassigned to the species level with DAIRYdb. DAIRYdb significantly improves taxonomic assignment accuracy for dairy environmental microbiome studies. It is available on public a repository (https://forgemia.inra.fr/umrf/dairydb).

Dry heating (DH) at 100 °C of a whey protein isolate powder conditioned at pH 9.5 leads to the formation of stable, large and porous whey protein microparticles (WPM), resulting from crosslinking of proteins in the powder. The Maillard reaction (MR) is probably involved in the formation of these WPM. To confirm the role played by the MR and understand the protein changes occurring during particle formation, we analyzed the properties of the powders (such as their water activity (aw) and color) and characterized the WPM formed after 3 and 36 h of DH in powders with increasing amounts of added lactose. Adding lactose and prolonging the time of DH increased the extent of protein denaturation and the rate of formation of WPM and the yield of conversion of powder into WPM, but led to decreases in their water content. Addition of lactose also altered the kinetics of the MR, the increase in aw and the formation of WPM. The MR, as followed by powder browning, was complete within 3 h of DH irrespective of the amount of added lactose. In contrast, the increase in aw, thought to be due to progress of the MR, continued to increase from 3 to 36 h of DH. Formation of WPM went on increasing from 3 to 36 h of DH at low to medium levels of lactose, but was complete by 3 h of DH at high levels of lactose. In conclusion, the formation of WPM was not simply related to the MR and needs further investigation.

[EN] The presence of antimicrobial residues in milk and dairy products could cause negative technological effects and represents a risk for consumer health. During the cheese-making process, antibiotics could be retained in curd or eliminated in whey to a greater or lesser extent. Whey is a by-product used in the manufacture of foodstuffs for human consumption and animal feeding and therefore, the presence of antibiotic residues in this product should be controlled. Thus, it is crucial to develop an analytical strategy to screen antibiotics in whey. A new system for screening antibiotics in raw milk was recently developed, in which a microbial inhibitor tube test (Eclipse Farm) and a device (e-Reader) are coupled. The new system allows the incubation of the test and a continuous monitoring of the test colour change. The aim of this work was to study the performance of the new system for the detection of ß-lactam and tetracycline residues in goat¿s cheese whey. A preliminary study demonstrated the necessity to include a one-hour diffusion period at room temperature. The performance was validated in agreement with European Commission Decision 2002/657/EC. Specificity of microbial test was evaluated by analysing one hundred and thirty whey samples. Results showed a low percentage of false-positive results. The detection limits for amoxicillin, benzilpenicillin, cephalexin and oxytetracycline in goat¿s cheese whey were calculated and the detection capabilities (CCß) were below or at the MRL levels, with the exception of amoxicillin, which was slightly above them. In conclusion, Eclipse Farm coupled to e-Reader represents an appropriate method to screen ß-lactams and tetracycline residues in whey., [Otros] La présence de résidus d'antibiotiques dans le lait et les produits laitiers peut entraîner des problèmes technologiques et un risque pour la santé des consommateurs. Pendant le processus de fabrication du fromage, les antibiotiques peuvent rester attachés au caillé ou peuvent être éliminés dans le sérum. Le lactosérum est un sous-produit utilisé dans la fabrication de denrées alimentaires destinées à la consommation humaine et à l'alimentation animale et, par conséquent, la présence de résidus d'antibiotiques dans ce produit doit être bien contrôlée. Il est donc essentiel de mettre en place une stratégie analytique pour l'analyse des antibiotiques dans le lactosérum. Un nouveau test d'inhibition microbienne (Eclipse Farm) couplé avec un dispositif d'incubation et de lecture (e-Reader) a été récemment développé pour le dépistage d'antibiotiques dans le lait cru. Le nouveau système permet l'incubation et la surveillance continue du changement de la couleur du test. L'objectif de ce travail consistait à étudier la performance du nouveau système pour la détection des résidus de ß-lactames et de tétracyclines dans le lactosérum du fromage de chèvre. Une étude préliminaire a démontré la nécessité d'inclure une étape de diffusion d'une heure à température ambiante. Le système a été validé conformément aux procédures décrites dans la décision 2002/657/CE de la Commission Européenne. La spécificité du test a été évaluée en analysant 130 échantillons de lactosérum. Les résultats ont montré un faible pourcentage de résultats faussement positifs. Les limites de détection pour l'amoxicilline, la benzilpenicilline, la céphalexine et l'oxytétracycline dans le lactosérum du fromage de chèvre ont été calculées, ainsi que les capacités de détection (CCß), toutes en dessous ou au même niveau que les Limites de Résidus Maximum (LRM), sauf pour l'amoxicilline, avec une limite légèrement supérieure. En conclusion, Eclipse Farm couplé à e-Reader représente une méthode appropriée pour la détection des résidus des ß-lactames et tétracyclines dans le lactosérum de chèvre.

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.

Dry heating (DH) at 100 °C for 36 h of a whey protein isolate powder conditioned at pH 9.5 leads to the formation of stable, large and porous whey protein microparticles (PMs), resulting from the crosslinking of proteins inside the powder. These PMs could be used as high-viscosity food ingredients. Casein, present as a contaminant in whey protein powders, has been shown to become incorporated into the PMs. In this study, we investigated the effect of adding increasing amounts of sodium caseinate to whey protein powders on the formation of PMs during DH at 100 °C for 36 h. In addition, we studied PM formation during DH of a micellar casein-enriched milk protein powder (Casmic). The browning index of the dry-heated powders, and the size and water content of the microparticles were also characterized. We confirmed that sodium caseinate was incorporated into the PMs. The highest PM D[4,3] values (270 μm) were observed for powders with around 40% caseinate. Powders without added caseinate displayed D[4,3] values of 150 μm. The yield of conversion of proteins into PMs increased from 0.6 to 0.8 g/g with caseinate addition, whereas the amount of water entrapped in the PMs decreased from around 30 to 20 g/g. PMs were also formed by DH of the Casmic powder, but these particles were smaller, with sizes of around 80 μm. In conclusion, our study shows that the process of DH at pH 9.5 could be applied to all milk proteins to obtain PMs with functional properties that could be used in the food industry.

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)

National audience; Whey protein (WP) have been extensively studied in the past and are commonly used for their functional and nutritional properties in food products. Recently, a particular interest was drawn in designing whey protein aggregates by adjusting physicochemical (pH, salt and protein concentration) and processing conditions in order to obtain new functional properties, depending on aggregate structure and size obtained (compact sphere, fibril or strand like). Namely, WP aggregates obtained at pH 7 and 80°C present a fractal structure that could be interesting for increasing dairy products texture. In this view, the aim of this study was to assess the influence of pilot scale continuous process conditions (temperature rise kinetics, outlet heating temperature, Reynolds number value) on the structure, size and properties of experimentally elaborated WP aggregates. Aggregates were obtained from the heat treatment of a WP solution (5% w/w), with a pH adjusted at 7 and a salt concentration of 0,01 M. The heat treatment pilot included a feed tank, a preheating exchanger to increase the temperature up to 50°C or 55°C, a tubular heat exchanger to achieve the target outlet heating temperature (80°C or 85°C) and finally a water-bath for a static holding. Moreover, it was possible to vary in an independent way the temperature rise kinetics and the flow regime depending on the mass flow rate and the tubular heat exchanger inner diameter chosen (6 to 22,5 mm). WP aggregates were separated and analysed by Asymetrical Flow Field-Flow Fractionnation coupled with Multi-Angle Light Scattering and Differential Refractometer (AF4-MALS-DRi) and by Transmission Electron Microscopy (TEM). After 80°C heat treatment, three populations of aggregates were observed in the solution : non-aggregated proteins, and 2 types of WP aggregates with an average radius of gyration (Rg) of 10 nm for the first, and 60 nm to 100nm for the second one. It was shown that both temperature rise kinetics and flow regime affected mean size of this latter : namely decreasing Reynolds number from 10000 to 2000 induced an increase of the aggregates size. Moreover, increasing temperature led to the formation of a fourth population of larger aggregates (Rg ≥200nm). These results show that process parameters are efficient levers to modulate the size and structural properties of fractal aggregates in a semi-industrial scale and should be carefully assessed in order to monitor their functional properties.

Texture and flavour are crucial for low-fat yogurts acceptance and consumer pleasure. Taking into account the dynamic dimension of perception is essential to understand texture-flavour interactions occurring in complex foods and achieve desirable sensory characteristics for consumers. This work aims to study the impact of texture modifications on the perception of flavour in low-fat set-type yogurts enriched with tailored Whey Protein Aggregates (WPA). Two complementary sensory methods were performed: the reference method for static evaluation (Quantitative Descriptive Analysis (QDA)) and an original approach of dynamic evaluation (Temporal Dominance of Sensations (TDS)). Low-fat set style yogurts prepared by adding three concentrations (0.5%, 1.0%, 1.5%) of extra WPA or whey protein isolate (WPI) were flavoured with a model strawberry flavour. WPA were obtained from WPI through a controlled process. Two trained panels (n=15) evaluated texture and flavour properties of the yogurts using respectively QDA and TDS by sensory modality (texture and flavour) with a multi-intake approach. For the same protein concentration, yogurts enriched with WPI were perceived as firm and brittle whereas yogurts enriched with WPA were perceived as viscous and melting. These differences evidenced by the QDA panel were complemented by the TDS results which provided information about the sequence of attributes that were dominant during consumption. Texture differences impacted aroma perception not only by changing the intensity perceived, but also by modifying the sequence of sensory attributes perceived as dominant throughout consumption. Thanks to the complementarity between QDA and TDS it was evidenced that the use of WPA has an impact on both texture and aroma perception, which was confirmed by instrumental measurements. Combination of static and dynamic methods allows a complete characterization of yogurts which is very useful to improve the texture and/or flavour of yogurts during consumption in order to offer a better food experience for consumers.