Influence of Gelatin-Based Coatings Crosslinked with Phenolic Acids on PLA Film Barrier Properties

Single-use plastics are a major source of pollution and biodegradable polymers could be the best substitute, as they possess similar barrier and functional properties. Aiming at improving barrier properties and providing antioxidant bioactivity, PLA (PolyLactic Acid) films were coated with a crosslinked suspension of plasticized gelatin incorporating phenolic compounds. The coating process induced weak modifications of PLA properties due to plasticization by moisture and glycerol from the coating suspension. Indeed, a double glass transition was displayed. The water vapor barrier properties of the PLA-coated films were not significantly affected. Phenolic compounds induced a crosslinking of the gelatin network, slightly decreasing the moisture sensitivity and surface hydrophilicity. Therefore, the mechanical properties of PLA were maintained after coating and their barrier properties were highly improved, with up to a 600-fold reduction of the oxygen transfer rate. These results make possible new applications for oxidation-sensitive foods, and even for semi-moist foods

Photopolymerizable Synthons from Glycerol Derivatives

International audienc

Coupling tyrosol, quercetin or ferulic acid and electron beam irradiation to cross-link chitosan–gelatin films: A structure–function approach

International audienceMarine industry by-products, chitosan and fish gelatin, entrapping natural antioxidants (ferulic acid, quercetin and tyrosol) were used to prepare edible active films by casting. The films were composed of chitosan and fish gelatin (1:1 w:w) and incorporating antioxidants (∼50 mg/g). After solvent evaporation (drying), the films were irradiated at 60 kGy by electron beam. This treatment aims at investigating the coupled effect of irradiation with the presence of active compound on the structure and functional properties of the films. Electron Spin Resonance (ESR) unravelled free radical formation during irradiation in films containing ferulic acid or tyrosol which favoured cross-linking between biopolymers. Then, some films became stiffer, the tensile strength increased after the incorporation of antioxidants and/or after irradiation. As expected, as the tensile strength increased, the % of elongation of irradiated and antioxidant-containing films was reduced, except for the irradiated control films. The enhancement of water barrier properties, measured using a 0–30% RH gradient, was observed after ferulic acid and tyrosol additions but remained unchanged after irradiation treatment. A synergic effect of irradiation and active compounds addition was noteworthy on the oxygen barrier properties. Irradiation and antioxidants also induced a slight enhancement of the thermal stability. The surface tension and its dispersive component significantly increased after the incorporation of antioxidants. On the contrary, a significant increase of the polar component is observed for the film containing ferulic acid. Irradiation accentuated the wettability and the hydrophilicity of the film containing quercetin and tyrosol. These results clearly showed that interactions between the polymer chains and/or between the polymer chains and the antioxidants after irradiation were favoured by both antioxidant addition and electron beam treatment. This is confirmed on a molecular scale from the peak shifts observed in amide and carbonyl groups as observed from FTIR

Impact of electron beam irradiation on fish gelatin film properties

International audienceThe objective of this work was to display the effect of electron beam accelerator doses on properties of plasticized fish gelatin film. Electron spin resonance indicates free radical formation during irradiation, which might induce intermolecular cross-linking. Tensile strength for gelatin film significantly increases after irradiation (improved by 30% for 60 kGy). The vapour permeability is weakly affected by irradiation. Surface tension and its polar component increase significantly and are in accordance with the increase of wettability. So, irradiation may change the orientation of polar groups of gelatin at the film surface and crosslink the hydrophobic amino acids. No modification of the crystallinity of the film is observed. These findings suggest that if structure changes, it only occurs in the amorphous phase of the gelatin matrix. It is also observed that irradiation enhances the thermal stability of the gelatin film, by increasing the glass transition temperature and the degradation temperature

Effect of Plasticizer Type on Tensile Property and In Vitro Indomethacin Release of Thin Films Based on Low-Methoxyl Pectin

International audienceThis study developed the interests of low-methoxyl pectin (LMP) together with plasticizers for the preparation of elastic thin films. The effect of different plasticizer types (glycerol: Gly; sorbitol: Sor; propylene glycol: PG; and polyethylene glycol 300: PEG 300) and concentrations (20–40% w/w) on mechanical and thermal properties of LMP films as well as on in vitro release of indomethacin were evaluated. Without any plasticizer, a brittle LMP film with low tensile strength and % elongation at break was obtained. Addition of plasticizers from 20% to 40% caused reduction in the tensile strength and Young’s modulus values, whereas percent elongation was increased. Forty percent Gly-plasticized and PG-plasticized films were selected to deliver indomethacin in comparison with non-plasticized film. No significant difference in indomethacin release profiles was displayed between the films. The analysis of indomethacin release model indicated that more than one drug release mechanism from the film formulation was involved and possibly the combination of both diffusion and erosion. Even though indomethacin incorporated in non-plasticized film showed similar release profile, Gly or PG should be added to enhanced film flexibility and decrease film brittleness

Synthesis of polybutadiene-polycaprolactone multi-blokcs based on hydroxyl telechelic polybutadiene. Composition and kinetic study

International audienc

Efficient microwave-assisted synthesis of glycerol monodecanoate

International audienc

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

The ring-opening polymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) under solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as precatalyst is described. Linear and star-branched polyesters were synthesized by successive use of benzyl alcohol, ethylene glycol, glycerol and pentaerythritol as initiator alcohols, and the products were fully characterized by 1H and 13C{1H} NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). BMIM-2-CO2 acts as an N-heterocyclic carbene precursor, resulting from in situ decarboxylation, either by heating under vacuo (method A) or by addition of NaBPh4 (method B). Possible catalytic and deactivation mechanisms are proposed

One step grafting of monomethoxy poly(ethylenglycol) during synthesis of maghemite nanoparticles in aqueous medium

International audienc