Emulsions stabilised by whey protein microgel particles: Towards food-grade Pickering emulsions

We have investigated a new class of food-grade particles, whey protein microgels, as stabilisers of triglyceride-water emulsions. The sub-micron particles stabilized oil-in-water emulsions at all pH with and without salt. All emulsions creamed but exhibited exceptional resistance to coalescence. Clear correlations exist between the properties of the microgels in aqueous dispersion and the resulting emulsion characteristics. For conditions in which the particles were uncharged, fluid emulsions with relatively large drops were stabilised, whereas emulsions stabilized by charged particles contained smaller flocculated drops. A combination of optical microscopy of the drops and spectrophotometry of the resolved aqueous phase allowed us to estimate the interfacial adsorption densities of the particles using the phenomenon of limited coalescence. We deduce two classes of particle arrangement. Complete adsorption of the particles was obtained when they were neutral or when their charges were screened by salt resulting in at least one particle monolayer at the interface. By contrast, only around 50% of the particles adsorbed when they were charged with emulsion drops being covered by less than half a monolayer. These findings were supported by direct visualization of drop interfaces using cryo-scanning electron microscopy. Uncharged particles were highly aggregated and formed a continuous 2-D network at the interface. Otherwise particles organized as individual aggregates separated by particle-free regions. In this case, we suggest that some particles spread at the interface leading to the formation of a continuous protein membrane. Charged particles displayed the ability to bridge opposing interfaces of neighbouring drops to form dense particle disks protecting drops against coalescence; this is the main reason for the flocculation and stability of emulsions containing sparsely covered drops. © 2014 the Partner Organisations

Pour la singularité des connaissances issues de la recherche en entrepreneuriat et PME

Pour la singularité des connaissances issues de la recherche en entrepreneuriat et PMEMoteur du tissu économique local et international, l’entrepreneuriat en Afrique est à la croisée des dimensions économique, sociale, culturelle, religieuse, … A travers le contenu de ce numéro, la Revue Africaine de Management souhaite traduire et diffuser la complexité humaine de cette réalité. Partager la réalité entrepreneuriale africaine et donner la parole aux chercheurs qui la vivent, tel est l’objectif de ce numéro

Datation des calcites et des grès de Fontainebleau : une remise à plat de l'âge des silicifications des terrains tertiaires du Bassin.de Paris

National audienceLa mise en lumière du rôle des périodes froides dans les mécanismes de précipitation de la silice permet de proposer un modèle de silicification unique, homogène et cohérent pour toutes les silicifications du Bassin de Paris : grès, calcaires silicifiés et meumières. Ce modèle doit être envisagé bien au-delà du Bassin de Paris, nombre de silicifications des formations tertiaires d’Europe, d’Amérique du nord et de régions altitudinales plus méridionales ( ?) méritent d’être revisitées avec un œil neuf

L’accompagnement entrepreneurial : Proposition d’une lecture critique

L’accompagnement entrepreneurial est un enjeu important pour le développement économique de nos sociétés. A la lumière de cet enjeu, l’article propose un regard critique en matière d’accompagnement entrepreneurial à travers les paradigmes utilisés. Les auteurs, en mobilisant une grille de lecture de l’accompagnement utilisé en psychosociologie, montrent que l’accompagnement entrepreneurial a été envisagé essentiellement dans une logique rationnelle et normative autour de la posture du réparateur. De ce constat, les auteurs proposent d’envisager l’accompagnement entrepreneurial sous un regard paradigmatique différent : celui du facilitateur. A partir d’une recherche-intervention, ils montrent l’apport de ce type de démarche pour l’accompagnement entrepreneurial

Are High-Tech Companies More Competitive Than Others? An Empirical Study of Innovative and Exporting French SMEs

The main objective of this research work is to question the relationship between the technological intensity of SMEs (defined by the share of R&D expenditure in turnover, according to the OECD) and their growth potential (defined by their innovation and export capabilities). Through a multiple case study conducted with a panel of nine French SMEs, and through an analysis combining a qualitative approach (illustrative cases study) and a quantitative one (multidimensional statistical methods), several hypotheses were tested. Finally, this study points out that technological intensity, as defined by the OECD, is not directly correlated with the growth potential of SMEs. On the other hand, a company’s technological intensity would have an impact on the way it manages its innovation and internationalization process, and thus the way it manages its internal practices

Concept on self-assembly and structure of globular protein fluids

Globular proteins are ubiquitous in our daily life. Not only they are naturally present in the biological matter, they also offer many possibilities to adjust the nutritional and flow properties of fluids or to design drug vehicles [1]. Globular protein systems interact through short range attractive forces; and the interaction between them may lead the system to form aggregates through self-assembling process. Since such biological monomers are complex systems, their aggregation process is most of the time out of control. The current main conceptual framework to describe that process is based on the idea that the monomers may self-assemble through a diffusion and reaction mechanism known as DLA for diffusion limited aggregation, and RLA for reaction limited aggregation respectively [2]. Beta-lactoglobulin (blg) solution gives, after heat-induced denaturation, a suspension of polydisperse aggregates as predicted by the random aggregation concept. Therefore, the transition from native blg to denatured blg aggregate suspension leads to complex correlation with the flow behavior [3]. Although the dependency of the aggregation process to physicochemical factors like, ionic strength, pH, temperature and concentration has been intensively investigated, it still remains much to do to control the aggregate polydispersity via self-assembling process. The composition of the raw product, thermal processing, pH and entropy instability during the aggregation process, are some of the factors influencing the polydispersity of the aggregates. We use different techniques such as SAXS/USAXS, LS, SEM, CSLM and image analysis methods to characterize thoroughly the structure of globular protein aggregates formed after heat-induced denaturation at different experimental conditions [4]. Whether these aggregates are in solution or entrapped by gelation, we do think that investigating their structure will provide us with relevant information to solve the issue related to their formation. Please click Additional Files below to see the full abstract