A new way of valorizing biomaterials: the use of sunflower protein for 1 a-tocopherol microencapsulation

Biopolymer based microparticles were efficiently prepared from sunflower protein (SP) wall material and a-tocopherol (T) active core using a spray-drying technique. Protein enzymatic hydrolysis and/or N-acylation were carried out to make some structural modifications to the vegetable protein. Native and hydrolyzed SP were characterized by Asymmetrical Flow Field-Flow Fractionation (AsFlFFF). Results of AsFlFFF confirmed that size of proteinic macromolecules was influenced by degree of hydrolysis. The effect of protein modifications and the influence of wall/core ratio on both emulsions and microparticle properties were evaluated. Concerning emulsion properties, enzymatic hydrolysis involved a decrease in viscosity, whereas acylation did not significantly affect emulsion droplet size and viscosity. Microparticles obtained with hydrolyzed SP wall material showed lower retention efficiency (RE) than native SP microparticles (62-80% and 93% respectively). Conversely, acylation of both hydrolyzed SP and native SP allowed a higher RE to be reached (up to 100%). Increasing T concentration increased emulsion viscosity, emulsion droplet size, microparticle size, and enhanced RE. These results demonstrated the feasibility of high loaded (up to 79.2% T) microparticles

The ergogenic impact of the glucocorticoid prednisolone does not translate into increased running motivation in mice

International audienceGlucocorticoids, such as prednisolone, are considered sport doping agents owing to their ergogenic properties. These are accounted for by peripheral mechanisms associated with energetic and anti-inflammatory processes. However, because glucocorticoids target brain tissues, it is likely that these ergogenic impacts are associated with central effects. One of these might be reward motivation, which relies on glucocorticoid receptor-expressing mesocorticolimbic dopaminergic neurons. In keeping with this possibility, this study has explored in mice whether repeated prednisolone administration (5 or 15 μg/ml of drinking water for 10 days) affected intrinsic motivation for running, a strong reinforcer in rodents. Running motivation was assessed by means of a cued-reward motivated instrumental task wherein wheel-running was conditioned by prior nose poke responses under fixed (FR), and then progressive (PR), ratio reinforcement schedules. Sub-chronic ingestion of prednisolone decreased the running distance covered during each rewarded sequence under FR schedules. This finding did not extend to wheel-running performances in mice provided free (i.e. unconditioned) wheel-running opportunities. Running motivation, as estimated under a PR reinforcement schedule, was found to be decreased (lowest concentration) or to remain unaffected (highest concentration) by prednisolone concentration. Lastly, an inter-individual analysis of the respective effects of prednisolone on muscular endurance (as assessed in the wire grid-hanging test) and on running motivation indicated that the former was not predictive of the latter. This observation suggests that prednisolone ergogenic impacts might occur without any concomitant increase in intrinsic exercise motivation

Breadmaking stability of wheat flours: Relation between mixing properties and molecular weight distribution of polymeric glutenins

International audienceABSTRACT The use of multi‐angle laser light scattering (MALLS) in conjunction with asymmetrical flow field‐flow fractionation (A‐FFFF) was investigated for the determination of the molecular weight distribution (MWD) of wheat proteins. The wheat flour proteins were dissolved by sonication in 0.1 M sodium phosphate (pH 6.9) containing 2% SDS. The results presented make it evident that efficient separation and size characterization of monomeric ( M < 10 5 g/mol) and polymeric protein (10 5 ≤ M < 10 8 g/mol) wheat proteins can be achieved with A‐FFFF/MALLS/UV in a single run. Therefore, this method appears to be able to detect significant modifications of MWD of wheat protein, whatever the factor inducing these alterations (i.e., genetic or environmental) and whatever the nature of these alterations (i.e., monomeric‐to‐polymeric ratio or MWD of polymeric protein). In the present study, we have indeed demonstrated that the MWD of wheat proteins can be altered from one cultivar to another in three main ways: by changing the relative amounts of monomeric and polymeric proteins, by changing the MWD of polymeric protein, and then by changing both the monomeric‐to‐polymeric ratio and the MWD of polymeric protein

Impact of Cultivar and Environment on Size Characteristics of Wheat Proteins Using Asymmetrical Flow Field‐Flow Fractionation and Multi‐Angle Laser Light Scattering

ABSTRACT The use of multi‐angle laser light scattering (MALLS) in conjunction with asymmetrical flow field‐flow fractionation (A‐FFFF) was investigated for the determination of the molecular weight distribution (MWD) of wheat proteins. The wheat flour proteins were dissolved by sonication in 0.1 M sodium phosphate (pH 6.9) containing 2% SDS. The results presented make it evident that efficient separation and size characterization of monomeric ( M < 10 5 g/mol) and polymeric protein (10 5 ≤ M < 10 8 g/mol) wheat proteins can be achieved with A‐FFFF/MALLS/UV in a single run. Therefore, this method appears to be able to detect significant modifications of MWD of wheat protein, whatever the factor inducing these alterations (i.e., genetic or environmental) and whatever the nature of these alterations (i.e., monomeric‐to‐polymeric ratio or MWD of polymeric protein). In the present study, we have indeed demonstrated that the MWD of wheat proteins can be altered from one cultivar to another in three main ways: by changing the relative amounts of monomeric and polymeric proteins, by changing the MWD of polymeric protein, and then by changing both the monomeric‐to‐polymeric ratio and the MWD of polymeric protein

Evaluation of the size distribution of a multimodal dispersion of polymer nanoparticles by microscopy after different methods of deposition

International audienceParticle size distribution (PSD) is an important factor determining the efficiency of industrial manufacturing processes for nanomaterials, assuring the reproducibility and safety of the final product. Among the instruments that have been developed to determine size and PSD of nanoparticle dispersions, the easiest to handle are based on indirect measurements; therefore, it is recommended to use at least two approaches to evaluate the PSD. This work evaluates the possibility of using direct size measurement methods based on the analysis of images of multimodal dispersion of nanomaterials by electron microscopy. Samples for measurement of the PSD were prepared by different deposition methods from a multimodal dispersion of poly(isobutylcyanoacrylate) nanoparticles. Grids prepared by flotation showed particle agglomeration and segregation between large and small particles and was found unsuitable for obtaining relevant measurement of the PSD. In contrast, spin-coating produced a homogenous and random deposition of well isolated particles on the substrate used to prepare the samples for electron microscopy. This deposition method was suitable for evaluating the PSD of this highly heterogenous dispersion. Deposition strategies are therefore essential to provide a statistically representative sample for PSD measurement of nanomaterial-based products using a direct measurement method

Measurements of aerosol particles and gaseous pollutants in a canyon street in Rouen

International audienc

Structural characterization of heat-induced protein aggregates in model infant milk formulas

International audienceHeat treatments induce structural modifications of bovine milk proteins. In this study, we aimed to investigate how these structural modifications are affected by the whey protein profile of infant milk formulas (IMFs) and heat treatment parameters. Three model IMFs (1.3% of proteins; caseinwhey protein ratio 4060) differing by the whey protein profile (13.37 α-lactalbumin (α-LA)β-lactoglobulin (β-LG), 13.261.80 α-LAβ-LGlactoferrin (LF) or 10.130.40 α-LAβ-LGLF), were heated at 67.5 °C or 80 °C to reach an akin whey protein denaturation extent of 65%. Protein structures were analyzed by asymmetrical flow field-flow fractionation coupled with multiangle light scattering and differential refractometer, transmission electron microscopy and electrophoresis. The unheated IMFs were used as reference. The results showed that LF addition in IMFs induced partial casein micelle disintegration before heating. In the absence of added LF, the heat-denatured whey proteins either formed soluble whey protein aggregates or casein micelle-bound whey protein aggregates. The latter were favored at the expense of soluble aggregates in the heated IMFs with the LF content increase and the concomitant β-LG content decrease. Consequently, the casein micelle structure was strongly dependent on the β-LG and LF amounts in IMFs and on the heating temperature. In the IMFs containing β-LG and LF and at temperature greater than the β-LG denaturation temperature, the casein micelles exhibited filamentous appendages on its surface after heating. Below the denaturation temperature of β-LG and in IMFs containing trace β-LG amount, the heated casein micelles were perfectly spherical with a smooth surface. © 2020 Elsevier Lt

Extended photo-induced endosome-like structures in giant vesicles promoted by block-copolymer nanocarriers

International audienc