Search

International audience; Polyhydroxybutyrate-co-valerate (PHBV) is a very promising bio-sourced and biodegradable bacterial polyester, the commercial development of which being limited by its high cost. On the other hand, olive oil extraction generates a large amount of lignocellulosic solid residue, called olive pomace (OP), whose disposal raises environmental concerns, including the inhibition of soil microbial populations and the reduction of seed germination. To address these issues, PHBV/OP based biocomposites were produced (at a filler content of 15 wt%) using three different fillers obtained by dry fractionation of OP, i.e. a stone-rich fraction (SF), a pulp-rich fraction (PF) and a crude pomace (F0). The objective of the present work was to investigate how the composition of OP-based fillers influenced the biodegradability of resulting biocomposites. The biodegradation of PHBV, OP-based fillers and OP/PHBV-based biocomposites was assessed by respirometric tests conducted in a standardized soil environment over 4 months. Results showed that the incorporation of OP-based fillers in PHBV favored the overall biodegradability of the materials. Indeed, 100% of biodegradation was achieved after 75, 79 and 87 days for PHBV-F0, PHBV-SF and PHBV-PF formulations respectively, while a biodegradation rate of only 91% was obtained after 123 days in the case of neat PHBV. These results were discussed in the light of several parameters such as the material structure, the affinity of the fillers for the matrix, the composition and the degree of crystallinity of the filler, together with the antibacterial activity of the OP samples assessed by a direct contact technique on solid medium.

International audience; Lignocellulosic by-products are frequently disposed by means of combustion. This study investigates an alternative route for corn cob and Kraft lignin resources in order to support circular economy. The respective plant-based fibres and filler were compounded for the first time together with a poly(lactic acid) (PLA) matrix. Consecutively, seven different biocomposites were processed by injection-moulding and further characterized. The biocomposite containing a mixture of Kraft lignin and corn cob (12 wt% in total) exhibited the highest flexural strength (84 MPa). A proper wetting of PLA onto the corn cob particles demonstrated a good compatibility at matrix/fibre interface. PLA molecular structure changed in presence of 20 wt% lignin filler, with effect on the glass transition temperature and on the composite mechanical strength. The fibres moderately influenced composites surface tension, while Kraft lignin contributed to a slight increase of surface hydrophobicity. Surface energy (σsTotal) of composites have been estimated at 27.6, 28.7 and 27.8 mN/m for PLA/KL-20, PLA/CC-10 and PLA/KL-15/CC-5 respectively. While the polar component (σsPolar) have been estimated at 17.8, 20.0 and 18.7 mN/m for PLA/KL-20, PLA/CC-10 and PLA/KL-15/CC-5 respectively. Unlike the PLA/corn cob composite, those containing Kraft lignin were entirely biodegraded within 2 months in industrial composting conditions study. The materials could be utilized for end-use products thanks to their good mechanical and thermal properties. By adding wood-lignin and corn by-products, materials cost and carbon footprint shall decrease in comparison to pure PLA, while being a biodegradable and sustainable replacement of polyolefins.

Les comportements humains et l’utilisation intensive du plastique associes a une faible performance des systemes de gestion ont engendre une accumulation massive de dechets plastiques dans le milieu marin ou ils representent 50 a 80 % de l’ensemble des dechets. Leur distribution, leurs comportements en mer, leur degradation et leurs impacts decoulent directement de leur composition et proprietes d’usage. Cette infographie fait un bilan des connaissances et decrit les principaux enjeux scientifiques, environnementaux et socio-economiques, ainsi que les possibles solutions necessaires a la gestion d’un probleme environnemental devenu global.

The polymer nanocomposites have become unabatedly popular due to their exceptional properties which results in a plethora of applications including the food packaging. However, safety aspect of these materials is still under debate, specifically in view of the unknown interactions of nanoparticles with various additives added during the packages processing. For the commonly used polyolefins, the partitioning of additives rather than their diffusivity dictates the extant and extent of these interactions. In this work, the partitioning of various additives between a clay-polymer nanocomposite (CPN) and several food simulants was measured based on a worst-case scenario in viewpoint of the selected polymer and additives. The added value of the CPN in comparison with the pure polymer (LLDPE) was analyzed with regards to their Hansen solubility parameters and log K-log P linearity. Ultimately, an estimation method based on the Flory-Huggins theory was proposed to predict the partition coefficients in CPN.

In this study, the impact of nanofillers on the performance of starch/chitosan composites produced by extrusion was investigated. Blends from three different proportions of starch/chitosan were produced and, for each blend, three different filler concentrations were tested. The natural -Na+ montmorillonite (Mt) and bamboo fibers were used as fillers. The composites were obtained using a twin-screw extruder from homo and nanostructured masterbatch pellets. The films were characterized concerning surface, mechanical, barrier, and thermal properties, as well as morphology and molecular changes. The results showed that the incorporation of Mt or bamboo fibers exhibited high water vapor barrier: films produced from only starch structured with 0.5 g Mt/100 g presented water vapor transmission of (4.9 ± 1.3) g/h m2, whereas films produced from starch/chitosan blend at proportion 75/25 structured with 1.0 g Mt/100 g presented (8.9 ± 0.5) g/h m2. Therefore, these materials showed competitiveness for their application to food packaging.

Polymer nanocomposites and specifically clay-based nanocomposites are emerging in the food packaging area and are promised to have a growing market. While the advantages of the nanoparticles on the gas barrier properties of the nanocomposites are already well-investigated and confirmed, the effect of these nanoparticles on the migration of other non-nano and potentially toxic components of the polymer packaging has still remained unclear. The present study addressed the effect of nanoclay on the migration of various additives from nanoclay/LLDPE nanocomposite packaging by determining the apparent diffusivity of these additives from the samples in contact with four different types of food simulants that distinctively exhibit hydrophilic and lipophilic characters. The results indicated that apart from the tortuosity effect that influence in a low extent the diffusivity of model migrants, the presence of nanoclays modifies the transport properties of materials as a result of their impact on other factors such as crystallinity and swelling capacity. PLS analysis on the influential geometrical and physical properties additionally revealed that the affinity between the food simulant and the polymer has the dominant effect on determining the order of apparent diffusivity as well as the effectiveness of barrier properties of nanoclays to reduce the diffusivity of additives through food packaging. Such statements suggest a benefit provided by nanoparticles incorporation in terms of the human exposure to plastic additives.

Certains materiaux ont la possibilite de subir une decomposition naturelle rapide en etant « consommes » par des bacteries, des champignons, des algues, des insectes, etc. C'est donc une alternative au mode de valorisation par recyclage (et donc de recuperation d'energie). Cet article se propose tout d’abord d’expliciter les etapes de la biodegradation en detaillant les principales reactions, les facteurs impliques ainsi que les methodes de mesure utilisees ; sont ensuite presentes les differents materiaux biodegradables issus de polymeres naturels ou artificiels, et les principales applications industrielles des polymeres biodegradables.

BACKGROUND New herbicidal formulations were designed by combining wheat gluten (WG), two montmorillonites (MMTs) (unmodified and organically modified) and a model pesticide (ethofumesate), and their performances were assessed through an integrative study conducted in soil using an experimental methodology with data modelling. RESULTS All the WG formulations tested were effective in decreasing the apparent diffusivity of ethofumesate in soil in comparison with the non-formulated active substance. The slow-release effect was significantly more pronounced in the presence of the organically modified MMT, confirming the importance of sorption mechanisms to reduce ethofumesate diffusion. The bioassays undertaken on watercress to evaluate herbicidal antigerminating performances showed that all the WG formulations (with or without MMT) were more effective than both the commercial formulation and the non-formulated ethofumesate, whatever the concentration tested. To explain such results, it was proposed that WG formulations would enable ethofumesate to be more available and thus more effective in inhibiting seed germination, as they would be less prone to be leached by water transport due to watering and also less subject to photodegradation. CONCLUSION The use of pesticide formulations based on wheat gluten and nanoclays appeared to be a promising strategy both to reduce the mobility of pesticides in soil and to protect UV-photosensitive pesticides from photodegradation.

For the first time, biocomposites from wheat by-products, i.e. wheat gluten and wheat straw fibers, were prepared using a thermomechanical process. Three types of wheat straw fibers displaying contrasted sizes (median diameter d(50) = 1.1 mm, 62 mu m and 8 mu m), morphologies and surface reactivities were prepared by successive grinding processes (cut milling (CM), impact milling (IM) and ball milling (BM), respectively). The main objectives of the present study were (i) to gain further scientific knowledge about the impact of fibers characteristics on the mechanical properties of these composite materials, and (ii) to evaluate in which extent the addition of wheat straw fibers could decrease the final cost of materials without altering their mechanical properties. Mechanical properties were assessed through tensile tests and discussed in relation to the structure of materials, especially to the interfacial adhesion between the fiber and the matrix. Globally, an increasing fiber content up to 11.1 vol% led to an increase in both the Young's modulus and the stress at break, and to a reduction in the strain at break. Experimental Young's moduli were well predicted by the Tsai-Pagano model for the three types of fibers. Data of specific mechanical energy consumed upon processing, contact angle measurements and observations of cryo-fractured surfaces allowed to demonstrate that the adhesion at the interface wheat straw fiber/wheat gluten was improved by (i) an increased hydrophobicity of wheat straw fibers, which was induced by successive grinding, and (ii) a higher specific surface of fibers which was favoured in the case of small fibers. The interfacial adhesion was improved in the order BM > IM > CM whereas the fiber aspect ratio decreased in the order CM > IM > BM. Thus, a competition between these parameters could occur, explaining why no significant difference in reinforcing effect was achieved between the three types of fibers. Finally, the reinforcing effect of wheat straw fibers was also ascribed to a deplasticizing effect, which was particularly pronounced for BM wheat straw fibers. (C) 2012 Elsevier B.V. All rights reserved.

An organically modified montmorillonite (C30B) was introduced within a wheat gluten (WG)-based formulation containing ethofumesate (as model pesticide) with the aim to enhance its slow release properties by modulating both biodegradation and release properties. For this purpose, biodegradation pattern in soil and release properties in model system have been investigated for ethofumesate alone, WG-ethofumesate and WG-C30B-ethofumesate formulations. Respirometric experiments undertaken with ethofumesate in soil have evidenced a non-biodegradable behavior whereas the incorporation of 0.26% of ethofumesate in WG-based formulation did not affect the final biodegradability of WG-based material in spite of a slight but significant delayed biodegradation pattern. This delaying effect, attributed to the ecotoxic effect of ethofumesate, was shown to disappear when introducing C30B in the formulation. The use of WG-based materials to formulate ethofumesate also resulted in a slow release effect (in water) that could be significantly enhanced by adding organoclays in the materials in spite of a very poor dispersion of the nanoclays within the matrix. Indeed, the presence of clay aggregates evidenced by TEM in the WG matrix would result in the entrapment of ethofumesate taking into account the huge affinity of this pesticide for this nanoclay. This hypothesis appeared fully consistent with the assumption that ethofumesate would be less available to reduce microorganisms respiration and also potentially less subjected to transport mechanisms. As a result, WG-based formulations appeared as a suitable ecofriendly strategy to design slow release delivery system for pesticides with the objective to reduce pesticide leaching in the environment.

E-mail address: c-guillaume@univ-montp2.fr; International audience; The objective of the present work was to understand how the structural, surface, water vapour and gas barrier properties of wheat gluten (WG) coated paper could be influenced by the features of paper. For this purpose, a surface treated paper (TP) and an untreated paper (UTP) were compared. Penetration of WG-coating into the bulk of paper was more pronounced in UTP than TP. This led to the formation of a significant junction zone resulting in an interpenetrated structure for WG–UTP, suggesting a composite- like structure, while a bi-layer one was obtained for WG–TP. Differences in WG penetration were related to the hydrophilicity, roughness and porosity of the paper used. Even though the extent of penetration did not greatly affect the surface properties (water and oil resistance), the transfer properties (water vapour, O2 and CO2) of WG-coated papers were significantly improved when WG-coating highly penetrated: while the WG–TP behaved as a micro-perforated material, the WG–UTP behaved as WG-film

Wheat gluten/montmorillonite (WG/MMT) nanocomposite films were prepared by casting. Transmission electron microscopy observations showed that MMT nanoparticles were homogeneously distributed within the matrix but not completely exfoliated. Contact angles, water uptake and water vapour sorption measurements showed that the presence of MMT led to a significant reduction of the water sensitivity of WG-based materials. This effect was attributed to a different structuring of protein network in the presence of MMT. Significant changes in the permeability of films towards water vapour and aroma compounds were observed for MMT contents higher than 5 wt%, while O2 and CO2 permeabilities remained unchanged. Finally, a slight improvement in tensile properties was obtained for filler contents higher than 2.5 wt%.

International audience; The modification of sodium montmorillonite after a high pressure pasteurization treatment was followed by X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis. Regardless of the treatment intensity (300 and 800 MPa), the structure of montmorillonite was clearly modified. Such changes should be taken into consideration when binging montmorillonite polymer nanocomposites into contact with food.

In the current context, protein-based materials might be considered as an alternative to the petroleum-based plastics since fully biodegradable and characterized by remarkable functional properties that can be exploited in a wide range of non-food applications. To improve their performances that are often restricted by high water sensitivity and low mechanical properties, a relevant strategy consisted in the development of protein/clay nanocomposite. For this purpose, several examples of protein-based nano-biocomposites were presented with a special attention for the methods used for the incorporation of layered silicates (organically modified or not) into the matrices and the ultimate functional properties exhibited by the resulting materials. In terms of mechanical properties, the addition of nanoclays leads to a significant improvement of material performance with an increase of Young’s modulus and tensile strength ranging between 1.5 and 2 times. As regards as barrier properties, the improvement appeared quite moderate in spite of a rather good dispersion of layered silicates that would be expected to result in a tortuous pathway limiting diffusion of gases molecules. Thus, a two-fold reduction in water vapour permeability was obtained, and the same or no effect in the case of permeability toward O2 and CO2.

Biopolymers such as proteins offer unique functional properties that can be used in the field of edible or biodegradable active packagings. Among the barrier properties of biopolymer based packaging, the knowledge of the aroma compound transfer is required (i) to control losses and sorption of aroma compounds which are important contributors to the sensory product quality (ii) or to emit desirable flavour from active packaging in a controlled way. Permeability of 2-heptanone in protein coated papers was investigated. It was demonstrated that coating by gluten or casein decreased the permeability of 2-heptanone and that coated papers had promising aroma barrier compared to other packaging materials such as sulphuric or paraffin papers or LDPE. The ability of biopolymer films to control aroma release was also demonstrated. An aroma compound (carvacrol) was incorporated in a gluten protein matrix, which showed adequate ability to maintain aroma compounds during film processing. The release of the aroma compound into the headspace was followed under accelerated conditions of temperature and relative humidity (30°C and 60% RH). It was shown that the release rate was not dependent on carvacrol amount. The gluten film delayed aroma compound emission into the headspace for more than a month.

A Doehlert design was performed to study the effect of calcium and phosphate supplementation at 0 to 25 mmol/kg and 0 to 16 mmol/kg, respectively, on the rennet gelation of reconstituted skim milk subjected to pH-reversible CO(2) acidification. Supplemented reconstituted skim milk samples were acidified to pH 5.80 by the addition of CO(2) under pressure and depressurized under vacuum to restore the initial pH value. The second-order polynomial models satisfactorily predicted the effect of salt addition on the micellar molar Ca:P ratio and the average diameter of the casein micelles, whereas only trends were used in the analysis of the rennet-clotting behavior of salt-supplemented, CO(2)-treated milk. Whether added Ca was the most determinant factor on the micellar molar Ca:P ratio, added Pi (a mixture of Na(2)HPO(4) and NaH(2)PO(4)) was the most determinant factor on the other responses studied, and its effect was most pronounced when Ca was simultaneously added. By comparison with control samples, changes observed in this study were essentially due to salt supplementation and not to the CO(2) treatment. Therefore, this CO(2) treatment could be considered as an entirely reversible treatment rather than only pH-reversible, and predictions might be applied to untreated milk. In the case of Ca-supplemented milk, the micellar molar Ca:P ratio increased, the average micellar diameter decreased, and the rennet-clotting properties were improved, whereas opposite effects were observed upon Pi supplementation. Since modification of the micellar molar ratio is the result of change in the chemical composition of micellar calcium phosphate, the effect of calcium and phosphate supplementation on the rennet clotting of milk was found to be also dependent on the nature of the interaction between caseins and colloidal calcium phosphate.

The extrusion of biopolymers is a promising technology for the plastic industry since enables to lead to wide range of innovative and environmentally friendly products displaying many advantages for the food packaging sector such the ability to extend food shelf life (Azevedo et al., 2017; Rathod & Annapure, 2017; Rodríguez-Núñez et al., 2017). Starch (St) is one of the most commonly available and cost effective biopolymer with high biodegradability and renewability and the chitosan (Cs) is a natural polysaccharide stemming from the deacetylation of chitin which can be considered as the largest world widespread biomaterial after cellulose in terms of utilization and distribution. On the other hand, the montmorillonite (MT) and bamboo fibers (BNFs) are used as fillers for improving the films mechanical and barrier properties. In this study, nanostructured films of cassava starch/chitosan blends (100/0; 75/25 and 50/50 g/100 g) were prepared from homo pellets and masterbatch-base nanostructured pellets until adjust a final nanocomposite concentration of 0.5 and 1.0 g of nanofillers per 100 g of blend (Fig. 1). The films were obtained by extrusion using a co-rotating twin-screw extruder (Thermo Scientific™ EuroLab 16) equipped with a plate die and was connected to calendaring system (2 Roll Haul 567-5040, Germany) leading to films with 160 mm wide and 0.3 mm thickness. The films based on starch nanostructured with 0.5 g MT/100 g exhibited a water vapor transmission (WVT) of (21.9±1.2) g/m2d, value 52 % less in relation to control film. On other hand, these films show great competitiveness with some already marketed, such as Poly(butylene-succinate) (PBS) Bionolle™ (330 g/m2d) and Poly(butylene adipate-co-terephthalate) (PBAT) Ecoflex® (272 g/m2d) (Robertson, 2013). Subsequently, the films produced from the blends starch/chitosan 75/25 nanostructured with 0.5 g BNFs/100 g exhibited an increase of 24 % in the tensile strength (0.62±0.05) MPa in relation to control films due to strong hydrogen link interaction between the bamboo fibers and polymer matrix. Thus, the processing conditions selected for the extrusion and concentrations of the components allowed a good dispersion of fillers in the biopolymeric matrix leading to improve some physical properties due to the nanoclay exfoliated structure and the intercalated composite in the case of bamboo fibers addition.

Pour faire face à l'accumulation massive de déchets plastiques dans tous les compartiments de l'environnement, on assiste à l'émergence de nouveaux polymères dont le temps de résistance à la biodégradation serait équivalent au temps d'utilisation. Cependant concevoir un matériau rapidement biodégradable signifie aussi que l'on puisse évaluer cette propriété de façon rapide et standardisée. Or, il existe plusieurs manières de caractériser la biodégradation d'un polymère mais toutes ne permettent pas de démontrer cette propriété de façon fiable et sans équivoque. Le domaine des polymères biodégradables véhicule ainsi un nombre important de termes et de notions qu'il est nécessaire d'expliquer pour éviter les controverses. Cet article a donc pour objet de tenter d'éclaircir les différentes notions en lien avec la biodégradabilité des polymères et de proposer une synthèse critique des différentes méthodes d'évaluation de cette propriété.