Coupling gas chromatography and electronic nose for dehydration and de-alcoholization of alcoholised beverages. Application to off-flavour detection in wine

International audienceAroma characterization of alcoholic beverages with sensor array electronic noses is a difficult challenge due to the masking effect of ethanol. Back-flush gas chromatography is proposed as a novel tool for the pretreatment of vapour samples before analysis in the electronic nose. The dehydration and desalcoholization step can be conducted in parallel with electronic nose detection, reducing significantly the analysis overall duration. As demonstration application, five molecules responsible for off-flavours in wines have been detected with a FOX 4000 system, after total dehydration and desalcoholization. Principal component analysis showed that discrimination between the control wine and off-flavour doped-wines became easy, even at concentrations corresponding to the human expert perception threshold. Back-flush gas chromatography is proposed as a novel tool for the pretreatment of vapour samples before analysis in the electronic nose. The dehydration and desalcoholization step can be conducted in parallel with electronic nose detection, reducing significantly the analysis overall duration. As demonstration application, five molecules responsible for off-flavours in wines have been detected with a FOX 4000 system, after total dehydration and desalcoholization. Principal component analysis showed that discrimination between the control wine and off-flavour doped-wines became easy, even at concentrations corresponding to the human expert perception threshold

Nanoparticles/aroma compound/protein complexes for antimicrobial coating applications

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Nanoparticles/aroma compound/protein complexes for antimicrobial coating applications

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Evolution de la teneur en androsténone du tissu adipeux dorsal chez le porc mâle entier de type Large White : variations selon les conditions d'élevage

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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

Production de viandes de Porcs mâles entiers ou castrés : efficacité alimentaire et composition corporelle chez les races hypermusclées

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