Functional properties of sodium and calcium caseinate antimicrobial active films containing carvacrol

Active edible films were prepared by adding carvacrol into sodium caseinate (SC) and calcium caseinate (CC) matrices plasticized with two different glycerol concentrations (25 and 35 wt%) prepared by solvent casting. Functional characterisation of these bio-films was carried out by determination of some of their physico-chemical properties, such as colour, transparency, oxygen barrier, wettability, dye permeation properties and antibacterial effectiveness against Gram negative and Gram positive bacteria. All films exhibited good performance in terms of optical properties in the CIELab space showing high transparency. Carvacrol was able to reduce CC oxygen permeability and slightly increased the surface hydrophobicity. Dye diffusion experiments were performed to evaluate permeation properties. The diffusion of dye through films revealed that SC was more permeable than CC. The agar diffusion method was used for the evaluation of the films antimicrobial effectiveness against Escherichia cell and Staphylococcus aureus. Both SC and CC edible films with carvacrol showed inhibitory effects on both bacteria. (C) 2013 Elsevier Ltd. All rights reserved.This research was supported by the Ministry of Science and Innovation of Spain through the projects MAT2011-28468-C02-01, MAT2011-28468-C02-02 and HP2008-0080. M.P. Arrieta thanks Fundacion MAPFRE for "Ignacio Hernando de Larramendi 2009-Medio Ambiente" fellowship (MAPFRE-IHL-01). Authors thank Ferrer Alimentacion S.A., for providing the caseinates powders.Arrieta, MP.; Peltzer, MA.; López Martínez, J.; Garrigós Selva, MDC.; Valente, AJM.; Jimenez Migallon, A. (2014). Functional properties of sodium and calcium caseinate antimicrobial active films containing carvacrol. Journal of Food Engineering. 121:94-101. https://doi.org/10.1016/j.jfoodeng.2013.08.015S9410112

Structure and mechanical properties of sodium and calcium caseinate edible active films with carvacrol

Edible active films based on sodium caseinate (SC) and calcium caseinate (CC) plasticized with glycerol (G) at three different concentrations and carvacrol (CRV) as active agent were prepared by solvent casting. Transparent films were obtained and their surfaces were analysed by optical microscopy and scanning electron microscopy (SEM). The influence of the addition of three different plasticizer concentrations was studied by determining tensile properties, while Fourier transformed infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to evaluate the structural and thermal behavior of such films. The addition of glycerol resulted in a reduction in the elastic modulus and tensile strength, while some increase in the elongation at break was observed. In general terms, SC films showed flexibility higher than the corresponding CC counterparts. In addition, the presence of carvacrol caused further improvements in ductile properties suggesting the presence of stronger interactions between the protein matrix and glycerol, as it was also observed in thermal degradation studies. FTIR spectra of all films showed the characteristic bands and peaks corresponding to proteins as well as to primary and secondary alcohols. In summary, the best results regarding mechanical and structural properties for caseinates-based films containing carvacrol were found for the formulations with high glycerol concentrations.Marina Patricia Arrieta thanks Fundacion MAPFRE for "Ignacio Hernando de Larramendi 2009- Medio Ambiente" fellowship (MAPFRE-IHL-01). The Spanish Ministry of Economy and Competitiveness is acknowledged by financial support (project Ref. MAT2011-28468-C02-01). Authors thank to Ferrer Alimentacion S.A., for providing caseinates and to Prof. Juan Lopez Martinez (Polytechnic University of Valencia, Spain) for his collaboration and useful discussions.Arrieta, MP.; Peltzer, MA.; Garrigós, MDC.; Jimenez, A. (2013). Structure and mechanical properties of sodium and calcium caseinate edible active films with carvacrol. Journal of Food Engineering. 114(4):486-494. https://doi.org/10.1016/j.jfoodeng.2012.09.002S486494114

Microstructure of protein-coated paper as affected by physico-chemical properties of coating solutions

International audienceWheat gluten (WG), calcium caseinate (CC) and corn gluten meal (CGM), were selected as protein raw material to prepare coating solutions. Different concentrations of protein (10-20%, w/w) and deposited solution layer (50-500 m) were used to obtain coated papers with thicknesses varying between 143(± 3) and 227(± 8) m. As expected, the thicknesses of coated paper increased with coating weight, but, for a given coating weight, different thicknesses were observed according to the raw material used and its concentration in the coating solution. A phenomenon involving a penetration of coating solution inside paper was suspected with WG-based solutions. The microstructure of coated papers was analyzed by SEM, OM and AFM and differences in structure and morphology were observed between the three raw materials. The percentages of coating agent impregnated inside paper were also calculated from the apparent density of coated paper and the density of self-supported films prepared in the same conditions but deposited on an inert and smooth Plexiglas ® support. These percentages of impregnation ranged from 4.8 to 63.3% and increased as following: CC < CGM < WG. Contact angle measurements were carried out in order to describe the behaviour of a coating solution drop just after its deposition on paper. Resulting absorption rates indicated significant differences as a function of the nature of coating agent and confirmed results obtained for the percentage of impregnation. To explain differences in the behaviour of coating solutions, it was finally concluded that not only their viscosity must be taken into account but also their affinity toward paper

Antimicrobial activity of carvacrol related to its chemical structure.

International audienceAims: To investigate the relation between the chemical structure and the antimicrobial activity of carvacrol, eugenol, menthol and two synthesized carvacrol derivative compounds: carvacrol methyl ether and carvacryl acetate against bacteria, Escherichia coli, Pseudomonas fluorescens, Staphylococcus aureus, Lactobacillus plantarum, Bacillus subtilis, a yeast Saccharomyces cerevisiae and one fungi Botrytis cinerea.Methods and Results: The antimicrobial activity was tested in liquid and vapour phases, by both broth liquid and microatmosphere methods, respectively. The same classification of the compound's antimicrobial efficiency was found with both methods. Eugenol and menthol exhibited a weaker antimicrobial activity than carvacrol, the most hydrophobic compound. Carvacryl acetate and carvacrol methyl ether were not efficient, indicating that the presence of a free hydroxyl group is essential for antimicrobial activity.Conclusions: The different extents of antimicrobial aroma compounds’ efficiency showed that hydrophobicity is an important factor and the presence of a free hydroxyl group and a delocalized system allows proton exchange.Significance and Impact of the Study: This study has identified the importance of the hydrophobicity and the chemical structure of phenolic aroma compounds for antimicrobial activity and may contribute to a most rational use of these compounds as antimicrobial agent

Adsorption of arabinogalactan-proteins from Acacia gums (senegal and seyal) and its molecular fractions onto latex particles

International audienceAdsorption of Acacia gums (GA) (A. senegal and A. seyal) and A. senegal molecular fractions, made ofarabinogalactan-proteins (AGPs) with different molecular weights, onto latex particles, with different sizes andsurface charges, was studied using molecular (fluorescence and nanoIR spectroscopies, microscopies includingAtomic Force Microscopy) and mesoscopic (Dynamic Light Scattering, zeta potential, Asymmetrical flow field-flow fractionation) methods. Adsorption of GA onto latex particles revealed a complex mechanism of adsorp-tion where the highest adsorption was observed when A. senegal and latex particles were negatively charged. Theinvert was observed for A. seyal where the maximum of adsorption was observed when gum and latex wereoppositely charged. The duality of positive and negative charges on GA macromolecules together with confor-mational changes certainly explain the complex mechanism of adsorption. A mechanism where either the proteinmoiety either the sugars blocks adsorb is to be preferred. This mechanism seems to produce differences ofbehaviour due to viscoelastic properties of adsorbed layers, and differences of hydration due to differences ofpolarity of AGPs. The consequence of electrostatics in the adsorption process is a water release from the adsorbedlayers and important gain in entropy. A fair agreement was found between protein content and adsorbed layerthickness of GA, with the formation of partial coverage, monolayer and multilayer films depending on GAconcentration. Structural changes induced by GA adsorption onto latex particles was probed using fluorescenceand nanoIR spectroscopies without giving clear evidence of conformational changes induced after GA adsorption.The results of this study highlighted that GA surface adsorption process depend not only on the protein moietyand electrostatic interactions but also on other parameters related to AGP hydration status. The protein structuralaccessibility, the molecular weight distribution, the AGPs intrinsic viscoelastic properties allowing structuralrearrangements on the surface and spreading in order to form a viscoelastic film onto latex particles should alsoplay a pivotal role in the adsorption process

Dispositif d'échantillonnage de composés volatils. n° 02291627.4-2204 demande de brevet européen

A sampler of volatile components combines dehydration and alcohol-removal processes so as to provide a sample in which these products are substantially absent. Upstream of an odour analyser, said volatile component sampler enables interference caused by water and ethanol to be avoided and enables improvements in the measurement sensitivity of the odour analyser. The sampler comprises a chromatography column having a system for reversing the direction of flow in the column once water and alcohol molecules have left the column. The other volatile components are regrouped and output so as to be introduced later on into an odour analyser. The basic system can be combined with pervaporation or solid-phase micro-extraction, so as to increase the concentration of the components of interest. Such hybrid systems can work on gas or liquid samples.L'invention porte sur un échantillonneur de composés volatils qui combine des procédés de deshydratation et de desalcoolisaton pour produire un échantillon dans lequel ces produits sont absents. En amont de l'analyseur d'odeur, ledit échantillonneur de composés volatils permet d'éviter l'interférence de l'eau et de l'éthanol et d'améliorer la sensibilité de l'analyseur d'odeur. L'échantillonneur comprend une colonne de chromatographie dotée d'un système d'inversion de flux une fois les molécules d'eau et d'éthanol sorties de la colonne. Les autres composés volatils sont regroupés en sortie de colonne et introduits ensuite dans un analyseur d'odeur. Le système de base peut être combiné à la pervaporation ou à la micro-extraction en phase solide, de manière à accroître la concentration en composés d'intérêt. De tels systèmes hybrides peuvent marcher aussi bien avec des échantillons gazeux que liquides

PASQUALINA : valse / P. CHALIER. GENETS D'AUVERGNE : valse / A. TOURNEL. NICOLO, NICOLINO : fox / G. WINKLER. DIS A TA MERE : fox / J. MARAIS ; Paul CHALIER et son ensemble musette

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Les substances alimentaires filmogènes

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