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International audience; This study aims to investigate the ability of an imidazolium biobased Zwitterionic Ionic Liquids (ZILs) in enhancing the phytoavailability of copper from garden (G) and vineyard (V) soils using the model plant ryegrass. Uncontaminated and artificially contaminated CuSO4 soils, unamended and ZIL-amended soil modalities were designed. The copper/ZIL mo-lar ratio (1/4) introduced was rationally established based on molecular modeling and on the maximal copper concentration in artificially contaminated soil. Higher accumulation of copper in the shoots was detected for the uncontaminated and copper contaminated ZIL amended V soils (18.9 and 23.3 mg/kg, respectively) contrary to G soils together with a ZIL concentration of around 3% (W/W) detected by LC-MS analyses. These data evidenced a Cu-accumulation improvement of 38% and 66% compared to non-amended V soils (13.6 and 13.9 mg/kg respectively). ZIL would be mainly present under Cu(II)-ZIL4 complexes in the shoots. The impact on the chemical composition of shoot was also studied. The results show that depending on the soils modalitity, the presence of free copper and/or ZIL led to different chemical compositions in lignin and monomeric sugar contents. In the biorefinery context, performances of enzymatic hydrolysis of shoots were also related to the presence of both ZIL and copper under free or complex forms. Ecotoxicity assessment of the vineyard soil samples indicated that the quantity of copper and ZIL remaining in the soils had no sig-nificant toxicity. ZIL amendment in a copper-contaminated soil was demonstrated as being a promising way to promote the valorization of phytoremediation plants.

International audience; The pretreatment of Miscanthus x giganteus with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim] [OAc]), followed by enzymatic hydrolysis and oxidative depolymerization, resulted in the efficient production of monomeric sugars and selective production of phenolic intermediates. The liquid fractions containing monomeric sugars were obtained with high yields (>80%), while a solid fraction enriched with lignin (>50% w.w − 1) was isolated. The phenolic monomers released during [Emim][OAc]-pretreatment were identified and quantified by HPLC. A decrease in the content of vanillin, vanillic acid, and p-hydroxybenzaldehyde was observed during pretreatment, suggesting a selective solubilization of guaicyl and p-hydroxyphenyl units from the lignin polymer in [Emim][OAc]. The decrease in p-coumaric and ferulic acids content suggested a cleavage of lignincarbohydrate complexes during pretreatment. Both pretreatment and enzymatic hydrolysis affected the content of ferulic acid ether and ester bonds. The NMR structural study (2D HSQC) of the isolated lignin showed the preservation of β-O-4 ′ interunit bonds, while 31 P NMR analysis revealed a high content of aliphatic hydroxyl groups. The oxidative depolymerization of the isolated lignin, catalyzed by the laccase mediator system in the presence of 5% v.v − 1 recycled [Emim][OAc] in buffer, mainly led to the production of free p-hydroxybenzaldehyde as a promising platform molecule. The mass balance of glucan, xylan and lignin from Miscanthus was validated throughout this strategy.

The CoffeeCat process is an innovative and sustainable strategy for the selective extraction and co-valorisation of polymers from lignocellulosic biomass requiring only green solvents and reagents: water, coffee furanone, glutamic acid.

International audience; The effect of enzymatic modification of polysaccharides on the formed supramolecular structures was studied. Gum Arabic and chitosan were modified by covalent grafting of ferulic acid oxidation products so that they could establish new interactions such as π interactions. The stoichiometry of the interaction was studied by ITC measurements, as well as its strength and related thermodynamic parameters. These experiments were supported by Zeta potential and turbidity measurements and optical macroscopy observations. Grafting of phenolic compounds onto the polymers increased their ability to exhibit π-π stacking and π-cation interactions and led to the formation of various supramolecular structures. For native gum Arabic and chitosan assemblies, the stoichiometry value determined by ITC was consistent with optical microscopy, macroscopic observations and Zeta potential (around a molar ratio gum Arabic:chitosan of 3). The structures formed were coacervates. For the modified polymers, the optimal molar ratio determined by Zeta potential measurements (3.27) differed from the one determined by ITC (6.3). This meant the formation aggregates was not only due to electrostatic interactions but also to other type of interactions (new π-π stacking and π-cation interactions). It was concluded that by modifying the polymers, it was possible to control the supramolecular structures formed

The modification of gum Arabic with ferulic acid oxidation products was performed in aqueous medium, at 30 °C and pH 7.5, in the presence of Myceliophthora thermophila laccase as biocatalyst. First, this study aimed to investigate the structures of the oxidation products of ferulic acid that could possibly be covalently grafted onto gum Arabic. HPLC analyses revealed that this reaction produced several oxidation products, whose structures were investigated using LC-MS/MS analyses (liquid chromatography-mass spectrometry with mass fragmentation analyses) and NMR experiments. The chemical structure of one intermediate reaction product was fully elucidated as the 2-(4-hydroxy-3-methoxyphenyl)-4-[(4-hydroxy-3-methoxyphenyl) methylidene] cyclobutane-1, 3-dione, called by the authors cyclobutadiferulone. Secondly, this study aimed to locate the grafting of the oxidation products onto gum Arabic by performing several NMR experiments. This study did not determine how much and specifically which oxidation products were grafted but some of them were undeniably present onto modified gum Arabic, close to the glucuronic acid C5 carbon or close to the galactose C6 carbon.

Gum Arabic is a natural polysaccharide with valuable properties that enable its use in many industrial fields. Nevertheless, its application field may be enlarged to new properties. One way consists of the modification of the polysaccharide through an enzymatic process based on the oxidation of a phenolic compound. This work aims then to study the impact of the presence of ferulic acid oxidation products onto gum Arabic on its properties as its color, thermal properties, rheological and interfacial behaviors. For instance, modified gum Arabic powder underwent a change of color from white to orange and a glass transition was reported contrary to native gum. Though its rheological behavior did not change, its solubility decreased from 42.5 ± 2.6 to 10.6 ± 0.1% w/v. However, the amphiphilic behavior of functionalized gum Arabic seemed to be different from the one of native gum Arabic. For a given concentration, the surface tension of the modified polymer was lower (31.2 ± 0.8 mN m−1 for native gum Arabic against 52.5 ± 2.4 mN m−1 for the modified gum at 1% w/v). Finally, modified gum Arabic presented important antioxidant properties. The modification of gum Arabic with phenolic compounds appeared then as a promising way to produce a polysaccharide with new properties that could enlarge the field of its potential applications and could make it an interesting food ingredient.

The interactions between gum Arabic (GA) and chitosan (CN) in solution have been investigated upon pH (4.5, 5.0 and 5.5) and temperature (5, 25 and 45 °C). Isothermal titration calorimetry (ITC) has been used to determine the thermodynamic parameters involved in the complex coacervation process between these two polymers. Zeta potential, turbidity measurements and optical microscopy were used as complementary methods to have a better understanding of the phenomenon at the origin of the self-assembly. Unlike data already published by authors, concerning the GA-CN coacervation model, a raise in temperature seemed to favor electrostatic interactions. The enthalpy became more favorable upon temperature, a phenomenon probably related to the availability of CN charges. A raise in temperature would lead to a compaction of CN, decreasing its steric hindrance during self-assembly. According to all experiments conducted in this study, the GA/CN interaction optimal molar ratio would be 4:1. However, this optimal ratio changed upon pH-temperature combinations. The results presented in this study should lead to a better understanding of the interactions between charged polymers and in the end, help in their application in the food, pharmaceutical and cosmetic industries.