• 02 MAY 2019

    Beating of hemp bast fibres: an examination of a hydro-mechanical treatment on chemical, structural, and nanomechanical property evolutions

    In this study, a gradually increased hydro-mechanical treatments duration were applied to native hemp bast fibres with a traditional pulp and paper beating device (laboratory Valley beater). There is often a trade-off between the treatment applied to the fibres and the effect on their integrity. The multimodal analysis provided an understanding of the beating impact on the fibres at multiple scales and the experimental design made it possible to distinguish the effects of hydro- and hydro-mechanical treatment. Porosity analyses showed that beating treatment doubled the macroporosity and possibly reduced nanoporosity between the cellulose microfibrils. The beating irregularly extracted the amorphous components known to be preferentially located in the middle lamellae and the primary cell walls rather than in the secondary walls, the overall increasing the crystallinity of cellulose from 49.3 to 59.1%, but a non-significant change in the indentation moduli of the cell wall was observed. In addition, beating treatments with two distinct mechanical severities showed a disorganization of the cellulose conformation, which significant dropped the indention moduli by 11.2 GPa and 8.4 GPa for 10 and 20 min of Valley beater hydro-mechanical treatment, respectively, compared to hydro-treated hemp fibres (16.6 GPa). Pearson’s correlation coefficients between physicochemical features and the final indentation moduli were calculated. Strong positive correlations were highlighted between the cellulose crystallinity and rhamnose, galactose and mannose as non-cellulosic polysaccharide components of the cell wall.
  • 19 APR 2019

    Improvement of protein content and decrease of anti-nutritional factors in olive cake by solid-state fermentation: A way to valorize this industrial by-product in animal feed

    The present work investigates the bioconversion of the olive cake (OC) generated by olive oil industries in Morocco through solid-state fermn. using selected filamentous fungi to increase its nutritional values for subsequent valorization as ruminants feed. The fungi -namely Beauveria bassiana, Fusarium flocciferum, Rhizodiscina cf. lignyota, and Aspergillus niger were cultured on OC for 15 days. Chem. compn. as well as enzymes activities were detd. Results showed (i) an increase in protein content of up to 94% for treated OC and (ii) significant (P < 0.05) decreases of phenolic compds., up to 43%, 70% and 42% for total phenolic content, total flavonoids content, and total condensed tannins, resp. Moreover, the RP-HPLC anal. of fermented OC confirmed the degrdn. of individual phenolic compds. by the strains. These findings demonstrate that F. flocciferum and Rhizodiscina cf. lignyota are efficient enzymes producers leading to a nutritive enhancement of this byproduct.
  • 18 APR 2019

    Proline-Mediated Knoevenagel–Doebner Condensation in Ethanol: A Sustainable Access to p-Hydroxycinnamic Acids

    Naturally occurring p-hydroxycinnamic acids were obtained in good yields (50–85%) using a pyridine/piperidine-free Knoevenagel–Doebner condensation of the corresponding p-hydroxybenzaldehydes with malonic acid in ethanol. This method uses fully renewable and cheap nontoxic reagents and solvents. By combination of a design of experiments (DoE) and a one variable at a time optimization (OVAT), the different reaction parameters were optimized in order to favor p-hydroxycinnamic acids production over that of the two other reaction byproducts, the corresponding diacid and vinylphenol
  • 04 MAR 2019

    Preparation of Renewable Epoxy-Amine Resins With Tunable Thermo-Mechanical Properties, Wettability and Degradation Abilities From Lignocellulose- and Plant Oils-Derived Components

    100% renewable triphenol - GTF - (glycerol trihydroferulate) and novel bisphenols - GDFx - (glycerol dihydroferulate) were prepared from lignocellulose-derived ferulic acid and vegetal oil components (fatty acids and glycerol) using highly selective lipase-catalyzed transesterifications. Estrogenic activity tests revealed no endocrine disruption for GDFx bisphenols. Triethyl-benzyl-ammonium chloride (TEBAC) mediated glycidylation of all epoxies afforded innocuous bio-based epoxy precursors GDFxEPO and GTF-EPO. GDFxEPO were then cured with conventional and renewable diamines, and some of them in presence of GTF-EPO. Thermo-mechanical analyses (TGA, DSC and DMA) and degradation studies in acidic aqueous solutions of the resulting epoxy-amine resins showed excellent thermal stabilities (Td5% = 282–310 °C), glass-transition temperatures (Tg) ranging from 3 to 62 °C, tunable tan α, and tunable degradability, respectively. It has been shown that the thermo-mechanical properties, wettability and degradability of these epoxy-amine resins can be finely tailored by judiciously selecting the diamine nature, the GTF-EPO content, and the fatty acid chain length.
  • 12 FEV 2019

    Eco-friendly extraction of Sinapine from residues of mustard production

    In this study, our efforts were focused on the optimization of phenolic compounds - mainly sinapine - extraction from residues of industrial mustard production. A preliminary work was conducted to discuss the way data from Folin-Ciocalteu analytical method are reported and exploited in the literature, and to determine whether methanol can be replaced by ethanol as extracting solvent. As this first question had found a positive answer, an optimization of the extraction process on crude and pretreated industrial residue was achieved using a Response Surface Methodology (RSM). Optimal conditions obtained through this Design of Experiments (DoE) allowed the extraction of more than 10 mg/g of defatted and dried matter (aka DDM) of phenolics from defatted and dried matter, and 13 mg/g DDM of phenolics from non-pretreated matter (results expressed as equivalent of DDM).
  • 12 FEV 2019

    Recovery of 3-hydroxypropionic acid from organic phases after reactive extraction with amines in an alcohol-type solvent

    Reactive extraction is a well-known method for the recovery of organic acids from dilute streams. The extraction through complex formation with amines is followed by its back-extraction. Their affinity for amine extractants makes their back-extraction a limiting step. The case of 3-hydroxypropionic acid is addressed here. Three methods were compared: salts additions, diluent swing and temperature swing. Mineral bases led to complete 3-HP recovery but as a salt. Diluent swing was tested using n-hexane as the anti–solvent. Results showed that increasing the n-hexane content led to a great increase of 3-HP recovery. However, high recovery yields are associated with high dilutions. The temperature was varied from 4 to 140 °C and it led to a high decrease of the acid-amine complex formation. Our thermochemical study showed an apparent heat of reaction of -25.3 kJ/mol and, at 140 °C, 78% of 3-HP can be recovered in a single step.
  • 10 DEC 2018

    Isolation and Synthesis of One of the Most Central Cofactors in Metabolism: Coenzyme A

    The isolation and synthesis of coenzyme A (CoA) has been an important field since this cofactor was discovered in 1947. CoA plays a central role in human metabolism and is vital in several metabolic pathways, including fatty acid transport and degradation as well as the biosynthesis of a wide variety of compounds, including fatty acids. The high cost of commercially available CoA ($2600/g with >85% purity) has motivated several research groups tofind alternatives for its production. The variety of strategies that have been investigated for CoA production can be divided in three categories: isolation from microorganisms, total chemical synthesis, and chemoenzymatic synthesis. These approaches provide access to CoA with different efficiencies. For example, direct isolation yields of∼25 mg/kg from dried yeast have been obtained. A variety of microorganisms such as Pseudomonas alkalytica, Sarcina lutea, and Brevibacterium ammoniagenes accumulate CoA in their cultures at levels ranging from 0.03 to 115 mg/mL. Total chemical synthesis yields have ranged between 25 and 54%, and chemo-enzymatic approaches have provided overall yields of ca. 73%. This review covers all published works on producing CoAin order to compare their efficiencies, scalabilities, and convenience.
  • 10 DEC 2018

    Enzymatic reduction of levoglucosenone by an alkene reductase (OYE 2.6): a sustainable metal- and dihydrogen-free access to the bio-based solvent Cyrene

    Levoglucosenone (LGO) has been successfully converted into the green polar aprotic solvent 2H-LGO (aka Cyrene®) through an enzymatic process involving alkene reductases: wild-type Old Yellow Enzyme 2.6 (OYE 2.6 wt.) from Pichia stipitis and its mutant (OYE 2.6 Tyr78Trp) present the best conversion rates. This enzymatic process has been optimized in order to avoid the formation of the side-product (1R,2S)-2-hydroxy-6,8-dioxabicyclo[3.2.1]octan-4-one (OH-LGO) and reach total conversion (99%). Cyrene® was then successfully isolated by continuous extraction in quantitative yield (99%).
  • 10 DEC 2018

    Ferulic acid derivatives used as biobased powders for a convenient plasticization of polylactic acid in continuous hot-melt process

    Plasticizers are additives used to soften polymers, but most of them are oily or waxy and are difficult to process in a continuous hot-melt process. The plasticizing effect of four functionalized ferulic acid derivatives designed with controlled solubility parameters was investigated upon the study of both the thermal stability and the mechanical properties of polylactic acid (PLA) blends. The synthesized powders were incorporated into PLA through a continuous hot-melt process (extrusion) allowing the derivatives to turn from crystalline to an amorphous state. Such phase transition permitted the derivatives to act as plasticizers, reaching a reduction of the Young's modulus of PLA by 40% for one of the derivatives blended at 20 wt%. Another derivative decreased the glass transition of the PLA from 56.6 °C to 26.3 °C at the same content. These works demonstrate the interest of using phase transition additives to ease the mixing of efficient plasticizers by hot-melt processing.
  • 10 DEC 2018

    Higher Levels of Exhaled Dimethylcyclopropane in Patients with Small Intestinal Bowel Overgrowth, Periodontitis when Associated with a Medical History of Cancer

    Periodontitis (PO) is associated with an increased risk of cancer. Breath test is routinely used for detection of Small Intestinal Bowel Overgrowth (SIBO). Specific Volatile Organic Compounds (VOC) may firstly enable early non-invasive detection of cancers and secondly be markers of specific bacteria
  • 10 DEC 2018

    High yielding diastereoselective syn‐dihydroxylation of protected HBO: an access to D‐(+)‐ribono‐1,4‐lactone and 5‐O‐protected analogues

    A diastereoselective chemo‐enzymatic synthetic pathway to D‐(+)‐ribono‐1,4‐lactone, a versatile chiral sugar derivative widely used for the synthesis of various natural products, has been designed from cellulose‐based levoglucosenone (LGO). This route involves a sustainable Baeyer‐Villiger oxidation of LGO to produce enantiopure (S)‐γ‐hydroxymethyl‐α,β‐butenolide (HBO) that is further functionalized with various protecting groups to provide 5‐O‐protected D‐(+)‐ribono‐1,4‐lactones. The resulting 5‐O‐protected lactones then undergo a diastereoselective and high yielding syn‐dihydroxylation of the α,β‐unsaturated lactone moiety followed by a deprotection step to give D‐(+)‐ribono‐1,4‐lactone. Through this 4‐step synthetic route from LGO, D‐(+)‐ribono‐1,4‐lactone is obtained with d.r. varying from 82:18 to 97:3 and in overall yields between 32 and 41% depending on the protecting group used. Moreover, valuable synthetic intermediates 5‐O‐tert‐butyldimethylsilyl‐, 5‐O‐tert‐butyldiphenylsilyl‐ as well as 5‐O‐benzyl‐ribono‐1,4‐lactones are obtained in 3 steps from LGO in 58, 61 and 40%, respectively.
  • 29 NOV 2018

    Chemo-enzymatic synthesis and free radical polymerization of renewable acrylate monomers from cellulose-based lactones

    A chemo-enzymatic pathway involving a Candida antarctica type B lipase was developed to produce (S)-γ-hydroxymethyl-α,β-butenolide methacrylate (HBO-m) and (S)-γ-hydroxymethyl-α,β-butyrolactone methacrylate (2H-HBO-m) from (S)-γ-hydroxymethyl-α,β-butyrolactone (HBO), a biobased molecule obtained from cellulose-derived levoglucosenone. The acrylated monomer was then co-polymerized through a free radical process with methacrylamide and methylene-γ-valerolactone, a green intermediate. Finally, methylene-tetrahydropyranyl (S)- γ-hydroxymethyl-α,β-butyrolactone (M-THP-2H-HBO), synthetized via α-methylenation of 2H-HBO, was copolymerized with methyl methacrylate to access copolyacrylates exhibiting high glass transition temperatures.
  • 29 NOV 2018

    Chemo-Enzymatic Synthesis of Renewable Sterically-Hindered Phenolic Antioxidants with Tunable Polarity from Lignocellulose and Vegetal Oil Components

    Despite their great antioxidant activities, the use of natural phenols as antioxidant additives for polyolefins is limited owing to their weak thermal stability and hydrophilic character. Herein, we report a sustainable chemo-enzymatic synthesis of renewable lipophilic antioxidants specifically designed to overcome these restrictions using naturally occurring ferulic acid (found in lignocellulose) and vegetal oils (i.e., lauric, palmitic, stearic acids, and glycerol) as starting materials. A predictive Hansen and Hildebrand parameters-based approach was used to tailor the polarity of newly designed structures. A specific affinity of Candida antarctica lipase B (CAL-B) towards glycerol was demonstrated and exploited to efficiently synthesized the target compounds in yields ranging from 81 to 87%. Antiradical activity as well as radical scavenging behavior (H atom-donation, kinetics) of these new fully biobased additives were found superior to that of well-established, commercially available fossil-based antioxidants such as Irganox 1010® and Irganox 1076®. Finally, their greater thermal stabilities (302 < Td5% < 311 °C), established using thermal gravimetric analysis, combined with their high solubilities and antioxidant activities, make these novel sustainable phenolics a very attractive alternative to current fossil-based antioxidant additives in polyolefins.
  • 29 NOV 2018

    Towards an In Situ Product Recovery of bio‐based 3‐hydroxypropionic acid: influence of bioconversion broth components on membrane‐assisted reactive extraction

    Bioconversion broths are complex media with microorganisms that convert substrates into products in the presence of salts and nitrogen sources and that may release biomolecules. This paper deals with the impact of bioconversion broth components on the membrane‐based reactive extraction of 3‐hydroxypropionic acid (3‐HP), by tri‐n‐octylamine (TOA) in n‐decanol in preparation for an in‐situ product recovery. We focus here on the influence of 3‐HP concentration (0.5 – 10 g/L), initial pH of the solution (3 – 5), presence of proteins and salts on the extraction yields and kinetics.
  • 08 OCT 2018

    Microwave-Assisted Knoevenagel-Doebner Reaction: An Efficient Method for Naturally Occurring Phenolic Acids Synthesis

    The common chemical method to synthesize Phenolic Acids (PAs) involves a relatively considerable energy intake. In order to solve this issue, microwave-assisted Knoevenagel-Doebner condensations were developed. Nevertheless, these synthetic procedures prove difficult to reproduce. Herein, we developed and optimized—by using a combination of a Design of Experiment and a standard optimization approach—a reliable procedure that converts naturally occurring p-hydroxybenzaldehydes into the corresponding PAs with conversions of 86–99% and in 85–97% yields.
  • 08 OCT 2018

    Development of potential yield loss indicators to assess the effect of seaweed farming on fish landings

    In recent years, several indicators have been proposed to assess the effect of human activities on ecosystems provisioning capacity. Some of these methods focus on the Net Primary Production (NPP) available for ecosystem functioning through the comparison between the Human Appropriated Net Primary Production (HANPP) and the ecosystem's initial NPP at a given reference year. While some approaches have been proposed for marine ecosystems, most of the HANPP studies focus on terrestrial systems. This study highlights the relation between the HANPP methods and the production of natural resources in marine ecosystems. The linkage between current overfishing and future fish provisioning (ecosystem service) is well known. However, less studied before, is the relation between seaweed aquaculture and fish provisioning through the marine food web. Seaweed growth requires nutrients and light that will consequently be no longer available for natural phytoplankton production. As seaweed is periodically harvested, a fraction of the ecosystem's NPP (HANPP) is no longer available for ecosystem production. The HANPP of aquaculture reduces the ecosystem carrying capacity and thus affects commercial fish stocks. Therefore, an integrative approach is proposed in this study to assess the potential effect of seaweed farming on fish landings in the Greater North Sea. Three indicators are proposed to assess the Lost Potential Yield (LPY) in fish landings: LPYB, LPYV and LPYE, accounting respectively for reduction in biomass, monetary value and eco-exergy. For these three aspects, the LPY results remains smaller than the seaweed production, meaning that the overall natural resources balance for seaweed farming is positive.
  • 08 OCT 2018

    Detoxification of highly acidic hemicellulosic hydrolysate from wheat straw by diananofiltration with a focus on phenolic compounds

    Nanofiltration was studied for detoxification of lignocellulose hydrolysates obtained in harsh conditions. A hemicellulosic hydrolysate obtained from sulfuric acid steam explosion of wheat straw and presenting very low pH (= 1) and high osmotic pressure (28 bar) was studied and 8 inhibitory compounds were followed, among which 4 phenolic compounds. Several polymeric nanofiltration membranes were compared for separation performances and permeabilities; DK membrane (GE Osmonics) proved suitable with high rejection of sugars (> 99%) and lower rejections of inhibitors. Acetic acid and furfural were quasi-fully transmitted whereas the rejection of compounds ranked as follow: HMF (5-hydroxymethyl-furfural) < coumaric acid < levulinic acid < vanillin < ferulic acid < syringaldehyde with values of 40%, 50%, 60%, 80%, 90% and 98%, respectively, at a permeate flux of 14 L h−1 m−2. Diafiltration was carried out at a transmembrane pressure of 26 bar until 3 DV (Diafiltration Volume) to complete detoxification, and continuous and sequential-dilution modes were compared. Thanks to the permeability of the membrane to the monovalent form of sulfuric acid HSO4-, effective transmembrane pressure was increased and pH reached 2. At 3 DV, both modes showed removal performances between 92% (acetic acid and furfural) and 25% (syringaldehyde). Irreversible fouling was observed, leading to 30% permeability loss after diafiltration
  • 30 JULY 2018

    Importance of mediators for lignin degradation by fungal laccase

    Three of the major ligninolytic enzymes – lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase (LA) – as well as the secretome of a white-rot fungi – Grammothele fuligo– are tested on three industrial lignins (organosolv, alkali and Kraft), to investigate and study the differences in biodegradation reactions and mechanism of these three lignins. Strategies involving additives in laccase mediated systems were also considered to produce small phenolic compounds. Three new or underreported additives including 2,4,6-tri-tert-butylphenol (TTBP), 4-tert-butyl-2,6-di-methylphenol (TBDMP), and 3-hydroxyanthranilic acid (HAA), are compared to three classic laccase mediators violuric acid (VA), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 1-hydroxybenzotriazole (1-HBT). Decrease of molecular weight by up to 73 % could be obtained on organosolv lignin with LA-VA systems, and 49 %, 43 % and 39 % when LA was used with ABTS, TBDMP and 1-HBT, respectively. In-depth analysis of the degradation products by quantitative 2D HMQC NMR indicated that the oxidation is mediator-dependant and provides new insights on the enzymatic mechanism.
  • 18 JUNE 2018

    Gas‐Solution Phase Transient Absorption Study of the Plant Sunscreen Derivative Methyl Sinapate

    he plant sunscreen derivative methyl sinapate is studied in the gas and solution phase as an important step in understanding the structure‐ dynamics‐function relationship of plant sunscreens such as sinapoyl malate. Results from gas phase experiments suggest a three step deactivation process after photoexcitation. Photoexcitation to the S₁ state results in internal vibrational energy redistribution within 3 ps. Intersystem crossing then occurs in 30 ps between S₁ and T₁ and the latter state then persists outside our probe window (>> 1 ns). In solution with the weakly perturbing solvent cyclohexane, a dramatic change in the photophysical properties is observed. A trans‐cis isomerisation is observed to occur in 3 ps via a 1¹ππ*/S₀ conical intersection. The population which does not complete the isomerisation, relaxes via vibrational energy transfer to the solvent in 9 ps. A long lived photoproduct is then observed to persist and is identied as the cis‐isomer.
  • 18 JUNE 2018

    Synthetic Rhamnolipid Bolaforms trigger an innate immune response in Arabidopsis thaliana

    Stimulation of plant innate immunity by natural and synthetic elicitors is a promising alternative to conventional pesticides for a more sustainable agriculture. Sugar-based bolaamphiphiles are known for their biocompatibility, biodegradability and low toxicity. In this work, we show that Synthetic Rhamnolipid Bolaforms (SRBs) that have been synthesized by green chemistry trigger Arabidopsis innate immunity. Using structure-function analysis, we demonstrate that SRBs, depending on the acyl chain length, differentially activate early and late immunity-related plant defense responses and provide local increase in resistance to plant pathogenic bacteria. Our biophysical data suggest that SRBs can interact with plant biomimetic plasma membrane and open the possibility of a lipid driven process for plant-triggered immunity by SRBs..
  • 24 APR 2018

    Organic solvent- and catalyst-free Baeyer–Villiger oxidation of levoglucosenone and dihydrolevoglucosenone (Cyrene®): a sustainable route to (S)-γ-hydroxymethyl-α,β-butenolide and (S)-γ-hydroxymethyl-γ-butyrolactone

    A straightforward and sustainable route to (S)-γ-hydroxymethyl-α,β-butenolide (HBO) and (S)-γ-hydroxymethyl-α,β-butyrolactone (2H-HBO), two valuable chemical platforms for the synthesis of fine chemicals such as drugs, pheromones, flavors and fragrances, has been optimized using renewable cellulose-based levoglucosenone (LGO) and Cyrene® as starting materials and aqueous H2O2 as both a solvent and an oxidizing agent. Combined with short-path distillation, this procedure provides enantiopure HBO and 2H-HBO in yield as high as 72% at the kilo scale.
  • 7 MARS 2018

    Enzymatic synthesis of resveratrol α-glycosides from β-cyclodextrin-resveratrol complex in water

    Although resveratrol (3,5,4'-trihydroxy-stilbene) is one of the most studied natural product because of its biological properties such as antioxidant or anticancer, its low water solubility and stability (influenced by pH, light and increased temperature), as well as its propensity to oligomerize, limit its bioavailability and applications in nutraceutic, cosmetics or pharmaceutical industries. Besides, resveratrol production at the multigram scale through vine cell culture is limited by the tedious extraction of pure resveratrol from the bioconversion medium due to its complexation by cyclodextrins, the latter being used as elicitors in the bioproduction process. In this work, we have been able to overcome all these drawbacks by performing a single organic solvent-free enzymatic α-glycosylation directly from the β-cyclodextrin-resveratrol complex in water using β-cyclodextrin as glycoside-donor. The combined effects of five parameters (CGTase amount, cyclodextrin amount, cyclodextrin/resveratrol ratio, pH and temperature) were studied by design of experiments (DoE) to maximize the glycosylation yield. The optimal setting point of parameters was obtained by response surface methodology (RSM). After optimization, an efficient α-glycosylation was performed being obtained 35% of molar yield. The major glycosides - two mono-glycosides: 3-O-α-D-glucosyl-resveratrol and 4'-O-α-D-glucosyl-resveratrol and two di-glycosides: 3-O-α-D-maltosyl-resveratrol and 4'-O-α-D-maltosyl-resveratrol - were characterized using a hyphenated liquid chromatography-solid phase extraction-nuclear magnetic resonance system, then separated and purified using Centrifugal Partition chromatography (CPC). Their antiradical properties, as well as that of their crude mixture, were evaluated through DPPH analysis. Results confirmed that the position 4'-OH is the best position for the glycosylation to maintain the highest antiradical properties. 
  • 7 MARS 2018

    Recovering ferulic acid from wheat bran enzymatic hydrolysate by a novel and non-thermal process associating weak anion-exchange and electrodialysis

    Agricultural by-products such as wheat bran and straw are rich in arabinoxylans. Composed of a main chain of β-(1,4) linked xylose ramified by arabinose and ferulic acid, these polymers are sources of valuable molecules, in particular ferulic acid and monomeric (xylose, arabinose and glucose) and oligomeric carbohydrates. Enzymatic hydrolysis using hemicellulasic cocktails obtained from Thermobacillus xylanilyticus provide an eco-friendly alternative to acid or alkaline deconstruction. In this article, downstream purification of the enzymatic hydrolysate of wheat bran with a weak anion-exchange resin (Amberlyst A21- Dow) in free-base form was studied and optimized to reach concentrated ferulate fractions in environment-friendly conditions. A demineralization step by homopolar electrodialysis prior to anion-exchange allowed most of the competing inorganic anions to be removed from the hydrolysate. The capacity of fixation of ferulic acid on the active sites of the resin was increased, as well as purity and concentration of the basic eluate, consequently. Ferulic acid could therefore be crystallized by adjusting the pH of the eluate. 83% was crystallized and purity (NMR) reached 90-95%. At last, 52% of ferulic acid released from wheat bran by the hemicellulasic cocktail was purified and recovered as a solid. Moreover, more than 50 BV (Bed Volume) of the hydrolysate could be recovered during the resin saturation step as rather pure carbohydrates under monomeric (xylose, arabinose and glucose) and oligomeric (xylobiose, xylotriose and xylotetraose) form.
  • 8 JANV 2018

    Investigating isomer specific photoprotection in a model plant sunscreen

    Sinapate esters are used throughout the plant kingdom, for example in photoprotection from ultraviolet radiation. Sinapate esters are naturally produced in their E-isomeric form; however, upon exposure to ultraviolet radiation, photoisomerization drives Z-isomer formation. To elucidate the photoprotection capacity of E vs. Z forms of sinapate esters, we explore the photochemistry of the model system, Z-ethyl sinapate. Following a novel Z-ethyl sinapate synthesis, we demonstrate that photoprotection is isomer independent. This suggests that, regarding photoprotection, there were no evolutionary pressures for biosynthesis of either isomer.
  • 26 DEC 2017

    Biocatalytic synthesis and polymerization via ROMP of new biobased phenolic monomers: a greener process toward sustainable antioxidant polymers

    Antioxidant norbornene-based monomers bearing biobased sterically hindered phenols (SHP) - NDF (norbornene dihydroferulate) and NDS (norbornene dihydrosinapate) - have been successfully prepared through biocatalysis from naturally occurring ferulic and sinapic acids, respectively, in presence of Candida antarctica Lipase B (Cal-B). The ring opening metathesis polymerization (ROMP) of these monomers was investigated according to ruthenium catalyst type (GI) vs. (HGII) and monomer to catalyst molar ratio ([M]/[C]). The co-polymerization of antioxidant functionalized monomer (NDF or NDS) and non-active norbornene (N) has also been performed in order to adjust the number of SHP groups present per weight unit and tune the antioxidant activity of the copolymers. The polydispersity of the resulting copolymers was readily improved by a simple acetone wash to provide antioxidant polymers with well-defined structures. After hydrogenation with p-toluenesulfonylhydrazine (p-TSH), the radical scavenging ability of the resulting saturated polymers was evaluated using α,α-diphenyl-β-picrylhydrazyl (DPPH) analysis. Results demonstrated that polymers bearing sinapic acid SHP exhibited higher antiradical activity than the polymer bearing ferulic acid SHP. In addition it was also shown that only a small SHP content was needed in the copolymers to exhibit a potent antioxidant activity.
  • 16 OCT 2017

    A microstructural and chemical approach to highlight how a simple methyl group affects the mechanical properties of a natural fibers composite

    Two ferulic acid derivatives (BDF and BDF-Me) were prepared using chemo-enzymatic synthesis and used as additives for the pretreatment of hemp fibers. Incorporation of these fibers into a polycaprolactone matrix by hot-melt extrusion process aimed to improve the dispersion of the fibers and the mechanical properties of the resulting materials. Young's modulus and tensile strength of the composites were investigated at the micrometer scale by chemical imaging. The very simple methylation of the phenolic functions led to significant mechanical properties differences due to the dispersion of the fibers caused by a plasticizing effect of the ferulic acid derivative. This significant plasticizing effect of BDF-Me is observed at a content as low as 0.8 w% and opens the way for synthesizing a new family of biobased plasticizers involving transition from crystal state to amorphous phase.
  • 25 SEPT 2017

    Isocyanate-free synthesis and characterization of renewable poly(hydroxy)urethanes from syringaresinol

    In a context of replacement of petro-sourced and toxic bisphenol-A (BPA), syringaresinol, a naturally occurring bisphenol deriving from sinapic acid, has been proposed as a greener and safer alternative. This work focuses on its applications for Non-Isocyanate PolyUrethanes (NIPUs) synthesis. A five-membered cyclic carbonate SYR-CC has been prepared by carbon dioxide addition to bis-epoxy monomer SYR-EPO derived from syringaresinol. Upon polyaddition of SYR-CC with different biosourced and petrosourced diamines, the resulting polyhydroxyurethanes were fully characterized by structural analyses (FT-IR, 1H NMR, HPLC-SEC), and thermal analyses (TGA, DSC). These thermoplastics displayed high molar mass ((Mn) ̅ = 5.4 kg.mol-1), excellent thermal stabilities (Td5% = 267-281 °C) and glass transition temperatures (Tg) ranging from 63 to 98 °C. Complementary, the coupling of SYR-CC with a triamine gave a thermoset material with interesting Tg (62 °C) and high thermal stability (Td5% = 225 °C).
  • 25 SEPT 2017

    Mechanistic modeling and equilibrium prediction of the reactive extraction of organic acids with amines: a comparative study of two complexation-solvation models using 3-hydroxypropionic acid

    A comprehensive study of equilibrium states involved in the reactive extraction of 3-hydroxypropionic acid (3-HP) by tri-n-octylamine (TOA) in n-decanol is described. Complexation phenomena between 3-HP and TOA were revealed by infrared spectroscopy (FT-IR). This study demonstrated that the main extraction mechanism is the formation of an ion pair involving the dissociated form of 3-HP. Chemical models were then formulated, taking the formation of the ion pair between 3-HP and TOA and the influence of the amount of solvent in the organic phase into account. Two models are proposed: (1) a stoichiometric model where the solvent is seen as a reagent that is involved in the complexation as a synergistic extractant, but with competition for solvation via H-bond interactions with TOA; (2) a model where the solvent is seen as a phase modifier that improves the physicochemical properties of the extractant and that changes the complexation equilibrium. Both models describe the extraction yields in the investigated ranges, with Model (2) being particularly predictive since it provides a mean absolute prediction error of less than 2% in yield units. According to this latter model, the complexation equilibrium coefficient increases with the increase of the n-decanol proportion in the organic phase. Model (2) shows that solvation effects are better described as non-stoichiometric interactions. Therefore, the two mechanistic models accurately represent extraction yields over a wide range of initial conditions and are potentially transposable to other reactive extraction systems. Such knowledge is essential for further implementation of downstream processes.
  • 14 JUIL 2017

    Wheat and Sugar Beet Coproducts for the Bioproduction of 3-Hydroxypropionic Acid by Lactobacillus reuteri DSM17938

    An experimental design based on Response Surface Methodology (RSM) was used for the formulation of a growth medium based on sugar beet and wheat processing coproducts adapted to the cultivation of Lactobacillus reuteri (L. reuteri) DSM17938. The strain was cultivated on 30 different media varying by the proportions of sugar beet and wheat processing coproducts, and the concentration of yeast extract, tween 80 and vitamin B12. The media were used in a two-step process consisting of L. reuteri cultivation followed by the bioconversion of glycerol into 3-hydroxypropionic acid by resting cells. The efficiency of the formulations was evaluated according to the maximal optical density at the end of the growth phase (ΔOD620nm) and the ability of the resting cells to convert glycerol into 3-hydroxypropionic acid, a platform molecule of interest for the plastic industry. De Man, Rogosa, and Sharpe medium (MRS), commonly used for the cultivation of lactic bacteria, was used as the control medium. The optimized formulation allowed increasing the 3-HP production.
  • 14 JUIL 2017

    Elucidating nuclear motions in a plant sunscreen during photoisomerization, through solvent viscosity effects

    We explore the effects of solvent viscosity on trans-cis photoisomerization of sinapoyl malate, which is utilized as a sunscreen molecule in plants. Our results demonstrate that viscosity has a signifcant effect on the timescale for isomerization, providing insight into the nuclear motions involved. The ramifications of these finding are discussed with reference to sinapoyl malate’s in vivo photoprotection properties.
  • 14 JUIL 2017

    Lignocellulosic fibers: a critical review of the extrusion process for enhancement of the properties of natural fibers composites

    Natural fiber composites have various applications, since they can bring interesting mechanical and sustainability properties. Extrusion with a single- or twin-screw is the main industrial process to incorporate lignocellulosic fibers into polymers. In this review, the origin and preparation of lignocellulosic fibers are first presented, before discussing the composite processing, with a particular emphasis on the impact of process conditions on the composites final properties that is highly related to the final application. A broad panel of composites reinforced with lignocellulosic fibers is reviewed along with their polymeric matrix, lignocellulosic fiber type and pretreatments, and extrusion process conditions. Finally, the most critical extrusion process parameters (screw profile, speed and temperature) are also examined in order to determine some guidelines to optimize lignocellulosic fiber composites preparation.
  • 06 JUIN 2017

    A novel and integrative process: From enzymatic fractionation of wheat bran with a hemicellulasic cocktail to the recovery of ferulic acid by weak anion exchange resin

    An integrated and eco-friendly process including enzymatic hydrolysis with a hemicellulasic cocktail and a chromatographic purification step was developed to obtain ferulic acid from wheat bran. Thermobacillus xylanilyticus, a thermophilic and hemicellulolytic bacterium, was able to produce enzymatic cocktails containing xylanase, xylosidase, arabinosidase and esterase activities. The cocktails produced were used to deconstruct destarched wheat bran, allowing the release of 6%, 20% and 37% (w/w) of monomeric arabinose, xylose and ferulic acid, respectively. A weak anionic resin under free-base form was proved successful to separate the carbohydrate fraction from the ferulate one after acidification. Ferulate was recovered at high concentration (15 g/L) during regeneration of the resin. This non-optimized purification step allowed recovering 67% of ferulic acid fixed on the resin. Global recovery of ferulic acid contained in wheat bran after both enzymatic fractionation and purification stages reached 21.8%.
  • 06 JUIN 2017

    Conversion of Glycerol to 3-Hydroxypropanoic Acid by Genetically Engineered Bacillus subtilis

    3-Hydroxypropanoic acid (3-HP) is an important biomass-derivable platform chemical that can be converted into a number of industrially relevant compounds. There have been several attempts to produce 3-HP from renewable sources in cell factories, focusing mainly on Escherichia coli, Klebsiella pneumoniae, and Saccharomyces cerevisiae. Despite the significant progress made in this field, commercially exploitable large-scale production of 3-HP in microbial strains has still not been achieved. In this study, we investigated the potential of Bacillus subtilis as a microbial platform for bioconversion of glycerol into 3-HP. Our recombinant B. subtilis strains overexpress the two-step heterologous pathway containing glycerol dehydratase and aldehyde dehydrogenase from K. pneumoniae. Genetic engineering, driven by in silico optimization, and optimization of cultivation conditions resulted in a 3-HP titer of 10 g/L, in a standard batch cultivation. Our findings provide the first report of successful introduction of the biosynthetic pathway for conversion of glycerol into 3-HP in B. subtilis. With this relatively high titer in batch, and the robustness of B. subtilis in high density fermentation conditions, we expect that our production strains may constitute a solid basis for commercial production of 3-HP.
  • 22 MARS 2017

    From Bench Scale to kilolab Production of Renewable Ferulic Acid-based Bisphenols: Optimisation and Evaluation of Different Purification Approaches Towards a Technical Feasibility and Process Environmental Sustainability

    In earlier authors work, a new class of non-toxic and renewable bisphenols able to substitute bisphenol A and exhibiting potent antioxidant and antiradical activities has been prepared from ferulic acid through a chemoenzymatic pathways at bench scale. Scaling-up a process is not always trivial and straightforward. Technical feasibility of synthesis and overall process yield must be assessed. All decisions should be justified regarding technical constraints and environmental sustainability. This work is focused on the kilolab production of bis-O-dihydroferuloyl 1,4-butanediol (BDF), one of these very promising renewable bisphenols. Recrystallization and organic diananofiltration in a single stage (SSD) and two stages (TSD) were compared taking into account the previous considerations. As result, the synthesis and purification of BDF by recrystallization were successfully scaled-up at kilolab scale, being obtained a significant improvement in the overall yield (from 63% at labscale to 84% at kilolab scale) for a purity grade of 95%. To assess the organic diananofiltration as an alternative purification method, a set of 6 commercial organic solvent resistant membranes were evaluated. Starting from a solution (1 g/L) containing 80%(w/w) of BDF and 20% (w/w) of an excess reagent (ethyl dihydroferulate, EtDFe), GMT-oNF1 membrane showed to be able to discriminate them. A two-stage membrane diafiltration (TSD) in cascade was proposed, being observed a drastic increase in the product yield (from 77% in a single stage to 95%) without compromising its final purity (95%). Since solvent recycling has a significant impact on the process sustainability, a nanofiltration step for solvent recovery was assessed, . 90% of the solvent was recovered with a level of impurities lower than 1%. Recrystallization and all filtration-based processes were compared in terms of green metrics such as mass and solvent intensity and energy consumption. Results showed that only the integration of solvent recycling in filtration-based processes and the use of a concentrated starting solution (150 g/L instead of 1 g/L) may lead to similar magnitude values observed for recrystallization. Thus, even being a less energetic intensive process (4-fold), the TSD is still a solvent intensive process (3-fold), which is inevitably reflected in a higher environmental footprint (evaluated by LCA).
  • 22 MARS 2017

    Towards an extractive bioconversion of 3-hydroxypropionic acid: Study of inhibition phenomena

    3-hydroxypropionic acid (3-HP) microbial synthesis through glycerol bioconversion by Lactobacillus reuteri is at the moment characterized by too low performances to consider production at industrial scale. To avoid its toxic accumulation in the medium and to recover this molecule of interest, 3-HP in situ reactive extraction from bioconversion broth was investigated using a hollow fiber membrane contactor (HFMC) in order to intensify its production. The so-called integrated system was compared with the conventional bioconversion system. The impact of the extractive bioconversion on the overall production performance and on cell physiological state was studied. Results underlined drastic inhibitory effects on the producing bacteria, especially under extractive bioconversion conditions despite the use of a HFMC supposed to avoid direct contact between organic phase and bacteria. Indeed, the extractant phase components (trioctylamine in n-decanol) were found to be toxic for the cells (due to solubility and by direct contact). These phenomena were increased by the presence of 3-hydroxypropionaldehyde (3-HPA) and 3-HP produced during glycerol bioconversion. These cumulative effects induced a complete loss of the cell membrane integrity and esterase activity after 1.5 h of extractive bioconversion. When the bioconversion was conducted alone, the bacterial inhibition was lower, as around 50% of L. reuteri cells remained active with unaltered membrane after 3 h. Hypotheses concerning the mechanisms of action of the observed inhibitions were proposed and discussed. This work highlighted the importance of performing such an integrative approach to address specific questions prior to the optimization of the whole process.
  • 16 FEV 2017

    New insights in reactive extraction mechanisms of organic acids: An experimental approach for 3-hydroxypropionic acid extraction with tri-n-octylamine

    A detailed study of 3-hydroxypropionic acid (3-HP) reactive extraction with tri-n-octylamine (TOA) is proposed for the first time. It aims at uncovering some solvent-solutes interactions and providing global mechanisms to better understand and design the reactive liquid-liquid extraction of 3-HP in a biotechnological process. Eleven solvents of similar molecular sizes and several chemical types (alcohols, esters and alkanes) were investigated to understand their role on the extraction ability. Alcohols were found to be the best solvents thanks to their H-bond donor characteristic and water loading that allowed good solvation of the acid-amine complexes. Further investigations were then undertaken, for n-decanol and oleyl alcohol as solvents, varying acid (0.0028 – 0.56 mol/L corresponding to 0.25 – 50 g/L) and amine (0 – 2.3 mol/L corresponding to 0 – 100% v/v) concentrations. At 0.011 mol/L (1 g/L) of 3-HP, maximum extraction yields of 77% for n-decanol and 51% for oleyl alcohol were found for 0.46 mol/L TOA (20% v/v). The initial TOA purity proved to have a major impact on the extraction yield at low initial acid concentration ( < 0.1 mol/L = 10 g/L). Impurities from the TOA manufacturing process were identified as n-octylamine and di-n-octylamine and quantified in the aqueous phase after extraction. Their major effect on the extraction yield has been assessed (up to 86% decrease).
  • 16 FEV 2017

    Ultrafast Barrierless Photoisomerization and Strong UV Absorption of Photoproducts in Plant Sunscreens

    We study the photoprotectivemechanisms of sinapoyl malate and sinapic acid in aqueous solution by utilizing femtosecond transient absorption spectroscopy and time-dependent density functional theory.We find that excitedππ* states of the two molecules relax to the ground states via a barrierless trans-cis photoisomerizationin a few tens of picoseconds. The formation of cis-photoproducts largely reduces the efficacy of sinapic acid as a sunscreen. In contrast,the efficacy ofthe plant sunscreen sinapoyl malate is affected slightly due to the strong UVabsorption of its cis isomer.
  • 18 JAN 2017

    Syringaresinol: a renewable and safer alternative to Bisphenol A for epoxy-amine resins

    A renewable bis-epoxy, SYR-EPO, has been prepared from syringaresinol, a naturally occurring bisphenol deriving from sinapic acid, using a chemo-enzymatic synthetic pathway. Estrogenic activity test revealed no endocrine disruption for syringaresinol. Its glycidylation afforded bis-epoxy SYR-EPO with excellent yield and purity. This biobased safer epoxy precursor was then cured with conventional and renewable diamines for the preparation of epoxy-amine resins. The resulting thermosets were thermally and mechanically characterized (TGA, DSC and DMA). Thermal analyses of these new resins showed excellent thermal stabilities (Td5% = 279-309 °C) and Tg ranging from 73 to 126 °C, almost reaching the properties of those obtained with DiGlycidylEther of Bisphenol A (DGEBA), extensively used in polymer industry (Td5% = 319 °C and Tg = 150 °C for DGEBA-IPDA resins). Degradation studies in NaOH and HCl aqueous solutions also highlighted the robustness of the syringaresinol-based resins, similar to bisphenol A (BPA). All these results undoubtedly confirmed the potential of syringaresinol as a greener and safer substitute to BPA.
  • 31 DEC 2016

    Exploring the microstructure of natural fibre composites by confocal Raman imaging and image analysis

    We describe a combination of Confocal Raman Imaging (CRI) and quantitative image analysis to characterise biocomposite material microstructures. Both techniques offer lateral resolutions close to 1.3 μm and axial resolution of 13 μm, while simplifying sample preparation to hand-cutting without any surface preparation. Extruded and injected polycaprolactone/hemp fibre composites were used as demonstration biocomposites. A green macrobisphenol additive (bis-O-dihydroferuloyl-1,4-butanediol) was also used as a chemical probe to characterise the dispersion efficiency of additives, with a detection threshold of 2.3 wt% above which very local heterogeneity can be determined by this technique. CRI provided microstructure information for the entire binary structure formed by the fibre network. The fibre dispersion and orientation depend on their location in the matrix, and the specific surface of the fibres increases with the fibre content as aggregates start to develop. The technique also highlighted a possible core-skin effect in the injected composite
  • 31 DEC 2016

    Chemo-enzymatic synthesis and characterization of renewable thermoplastic and thermoset isocyanate-free poly(hydroxy)urethanes from ferulic acid derivatives

    This study presents the syntheses and characterization of renewable non-isocyanate polyurethanes from a new family of aromatic C5-cyclocarbonate precursors with different functionalities obtained from non-toxic ferulic acid derivatives by glycidylation and carbonation under high carbon dioxide pressure. Depending on the functionality, linear NIPU chains (thermoplastics) or cross-linked NIPU networks (thermosets) have been obtained. The thermoplastics NIPU molar masses were determined using SEC and 1H-NMR. The thermal and thermo-mechanical properties of the NIPUs were assessed by DSC, DMA (for thermosets), and TGA to determine the influence of the NIPU chemical structure on its properties. The range of Tg obtained (17 - 72 °C) was efficiently correlated with the degree of freedom and the molar mass of the NIPU repeat unit.
  • 31 DEC 2016

    Ferulic acid-based renewable esters and amides-containing epoxy thermosets from wheat bran and beetroot pulp: Chemo-enzymatic synthesis and thermo-mechanical properties characterization

    In this study, ferulic acid – a natural phenolic acid present in bagasse, wheat and rice brans, and beetroot pulp – was used as renewable starting material to prepare new biobased epoxy precursors. This biobased building block was first esterified then reduced to provide ethyl dihydroferulate which was then trans-esterified/amidified with biobased diols, triol and diamines. Immobilized Candida antarctica (aka CAL-B or Novozyme 435®) was used to perform the solvent-free-transesterification/amidation under mild conditions. The phenolic architectures synthesized were then glycidylated using a TEBAC-mediated procedure to afford four biobased epoxy precursors – with various linker structures between the ferulic units – which were then cured with conventionnal and biobased diamine curing agents. The thermal and thermomechanical properties of the thermosets prepared were assessed by TGA, DSC and DMA to highlight the influence of the linker configuration (aliphatic vs cycloaliphatic), that of the epoxy functionality (di vs tri), and that of the nature of the function used for coupling ferulic units (ester vs amide) on the thermosets properties. Analyses of these thermosets revealed glass transition temperatures ranging from 32 to 85 °C and high thermal stabilities around 300 °C. The mechanical behavior of the biobased thermosets proved equivalent to that of the DGEBA-IPDA reference sytem at low temperatures (up to 40–100 °C depending on the epoxy precursor and diamine).
  • 13 OCT 2016

    Optimization of the Laccase-Catalyzed Synthesis of (±)-Syringaresinol and Study of its Thermal and Antiradical Activities

    We report herein an optimized biocatalytic oxidative process for the synthesis of syringaresinol from sinapyl alcohol at a multigram scale (93% yield) in very high yield. Syringaresinol thereby obtained is of sufficient chemical purity and exhibits good thermal and antiradical activities to be used without further purification in many applications related to polymer synthesis as an alternative to bisphenol A. Different mechanistic pathways were discussed to better understand the impact of reaction conditions on the type of linkage formed during the oxidative process. Antiradical activity (DPPH analysis) and thermal properties of syringaresinol are also discussed.
  • 08 SEP 2016

    Ferulic acid-based bis/trisphenols as renewable antioxidants for polypropylene and poly(butylene succinate)

    Green chemistry principles recommend the use of renewable feedstocks and biocatalysis to decrease environmental impact of chemicals manufacturing. In this scope, three ferulic acid based bisphenols and one triphenol were synthesized using enzymatic catalysis. Their antioxidant activity at polymer processing and service temperature was investigated in polypropylene (PP) and polybutylene succinate (PBS). The results were compared to the commercial antioxidant Irganox 1010®. The analysis of the Oxygen Induction Time (OIT) of the polymer degradation at high temperatures showed that Irganox 1010® was more efficient to protect PP than the ferulic acid based bis/trisphenols, while, in the case of PBS, the biobased antioxidants, and in particular tris-O-dihydroferuloyl glycerol, were more efficient. FT-IR analysis of neat and formulated PP stored for two years at room temperature showed no degradation using any antioxidant. Aging studies of PBS at room temperature in dry atmosphere showed that all antioxidants had an equal stabilizing effect on the molecular weight averages of the polymer. The analysis of the mechanism of the antioxidant activity of the ferulic acid derivatives showed the possibility of dimerization through biaryl coupling. In conclusion, ferulic acid based antioxidants can be efficient primary antioxidants for the thermo-oxidative stabilization of polymers.
  • 08 SEP 2016

    Chemo-enzymatic synthesis of chiral epoxides ethyl and methyl (S)-3-(oxiran-2-yl)propanoates from renewable levoglucosenone: An access to enantiopure (S)-Dairy Lactone

    Chiral epoxides—such as ethyl and methyl (S)-3-(oxiran-2-yl)propanoates —are valuable precursors in many chemical syntheses. Until recently, these compounds were synthesized from glutamic acid in four steps (deamination, reduction, tosylation and epoxide formation) in low to moderate overall yield (20%–50%). Moreover, this procedure requires some harmful reagents such as sodium nitrite ((eco)toxic) and borane (carcinogen). Herein, starting from levoglucosenone (LGO), a biobased chiral compound obtained through the flash pyrolysis of acidified cellulose, we propose a safer and more sustainable chemo-enzymatic synthetic pathway involving lipase-mediated Baeyer-Villiger oxidation, palladium-catalyzed hydrogenation, tosylation and treatment with sodium ethoxide/methoxide as key steps. This route afforded ethyl and methyl (S)-3-(oxiran-2-yl)propanoates in 57% overall yield, respectively. To demonstrate the potentiality of this new synthetic pathway from LGO, the synthesis of high value-added (S)-dairy lactone was undertaken from these epoxides and provided the target in 37% overall yield from LGO.
  • 28 JUIN 2016

    Structure Property Relationships of Biobased n-Alkyl Bisferulate Epoxy Resins

    In this work, a series of bio-based chemically recyclable epoxy resins were synthesized from n-alkyl bisferulate esters that do not activate human estrogen receptor alpha (ERα). Viscosities of corresponding glycidyl ether n-alkyl bisferulate resins, determined by steady shear rheology, range from 12-9.4 Pa.s. Activation energies of flow range from 83-96 kJ/mol and are similar to the diglycidyl ether bisphenol A (DGEBA). Thermomechanical properties of diglycidyl ether n-alkyl bisferulate resins cured with isophorone diamine were governed by the length of α,ω-diols that link glycidyl ether ferulate units. That is, the glassy phase modulus and alpha transition temperatures range from 3400-2400 MPa (at 25 °C) and 40-53°C (peak of E”), respectively. Furthermore, the onset of thermal degradation (Td5%) varied from 331-300°C. Chemical recycling of cured epoxy resins was performed by static immersion in 10 w/w sodium hydroxide aqueous solutions at 60 °C. Times required for complete conversion of cured resins to water-soluble degradation products was also α,ω-diol length dependent and varied from 5 to 65 h. Thus, diglycidyl ether of n-alkyl bisferulate resins provides a viable biobased alternative to BPA epoxy resins as well as the option of chemical degradability and recovery of fillers in composite applications.
  • 25 MAI 2016

    ADMET polymerization of biobased monomers deriving from syringaresinol

    Renewable α,ω-dienes have been prepared from syringaresinol, a naturally occurring bisphenol deriving from sinapyl alcohol, and further studied as monomers in ADMET polymerizations. Polymerization was optimized according to catalyst loading and reaction conditions (in mass vs. in solvent), and led to polymers with molecular weight up to 14.1 kDa. Thermal analyses of these new polymers showed excellent thermal stabilities (257–360 °C) and tunable Tg (18–70 °C) depending on the structure of the starting α,ω-diene monomer.
  • 19 AVR 2016

    Lipase-catalyzed Baeyer-Villiger Oxidation of cellulose-derived Levoglucosenone into (S)-gamma-hydroxymethyl-alpha,beta-butenolide: Optimization by Response Surface Methodology

    Cellulose-derived levoglucosenone (LGO) has been efficiently converted into pure (S)-gamma-hydroxymethyl-alpha,beta-butenolide (HBO), a chemical platform suited for the synthesis of drugs, flavors and antiviral agents. This process involves two-steps: a lipase-catalyzed Baeyer-Villager oxidation of LGO followed by an acid hydrolysis of the reaction mixture to provide pure HBO. Response surface methodology (RSM), based on central composite face-centered (CCF) design, was employed to evaluate the factors effecting the enzyme-catalyzed reaction: pka of solid buffer (7.2 - 9.6), LGO concentration (0.5 - 1 M) and enzyme loading (55 - 285 PLU.mmol-1).

    Enzyme loading and pka of solid buffer were found to be important factors to the reaction efficiency (as measured by the conversion of LGO) while only the later had significant effects on the enzyme recyclability (as measured by the enzyme residual activity). LGO concentration influences both responses by its interaction with the enzyme loading and pka of solid buffer.

    The optimal conditions which allow to convert at least 80% of LGO in 2 hours at 40 °C and reuse the enzyme for a subsequent cycle were found to be: solid buffer pka = 7.5, [LGO] = 0.50 M and 113 PLU.mmol-1 for the lipase. A good agreement between experimental and predicted values was obtained and the validity of the model confirmed (p-value 0.05).
  • 02 MAR 2016

    Chemo-enzymatic preparation and characterization of renewable oligomers with bisguaiacol moieties: promising sustainable antiradical/antioxidant additives

    The synthesis, structural characterization and properties of new
bio-based oligomers with bisguaiacol-type moieties esterified by diverse aliphatic linkers are described. These oligomers, produced by oxidative oligomerization of renewable dihydro ferulic acid-based bisphenols with commercially available Trametes versicolor laccase, are proposed as promising sustainable antiradical/antioxidant additives for polymers. This environmental friendly biocatalyzed process is performed under very mild conditions in open vessels, aqueous solution at room temperature.

    Modifications of the reaction conditions (use of an organic co-solvent up to 80% v/v and rise of the reaction temperature up to 60 °C) revealed that the polymerization degree of the oligomers may be controlled by adjusting the nature and the ratio of the co-solvent, the reaction time and the reaction temperature. Thermal analyses (TGA and DSC) demonstrated that these phenolic oligomers exhibit high
 thermal stability and that their Td5% and Tg can be easily tailored by playing with both the structure of the bisphenol and the degree of polymerization.

    Similarly, these phenolic oligomers exhibit tunable potent antiradical/antioxidant activity as shown by DPPH analyses. These aliphatic-aromatic oligomers with bisguaiacol-type moieties are thus promising easily accessible, eco-friendly antiradical/antioxidant
additives for the stabilization of polymers in packaging and other applications.
  • 27 JAN 2016

    Reactive extraction of bio-based 3-hydroxypropionic acid assisted by hollow-fiber membrane contactor using TOA and Aliquat 336 in n-decanol

    Reactive liquid–liquid extraction is a promising technique for the direct recovery of carboxylic acids from bioconversion media. This work focused on the optimization of 3-hydroxypropionic acid (3-HP) reactive extraction assisted by hollow-fiber membrane contactor (HFMC), using tri-n-octylamine (TOA) and Aliquat 336 as extractants in n-decanol, and on its practical application for the recovery of 3-HP obtained from glycerol bioconversion by Lactobacillus reuteri.

    The results underlined the influence of the initial pH and 3-HP concentration of the aqueous medium and the impact of extractant phase composition on the extraction performances. The highest distribution coefficient of 3-HP (KD = 13.0) was observed at pH = 3 with 10% v/v TOA mixed with 10% v/v Aliquat 336 in n-decanol. This study showed that the acid concentration and the ratio of amines used between TOA and Aliquat 336 in n-decanol did not have a great impact on the KD during 3-HP reactive extraction, whereas it had an influence on the extraction kinetics. Moreover, 3-HP reactive extraction assisted by HFMC from real bioconversion broth with glycerol as the substrate was shown to be feasible, with the same order of magnitude of extraction kinetics but with a lower KD compared to reactive extraction using model broth.

    3-HP was predominantly extracted from the bioconversion broth, confirming the high selectivity of the extraction process studied and the high potential of this approach applied to the biotechnological production of 3-HP..
  • 26 NOV 2015

    Structure–Activity Relationships and Structural Design Optimization of a Series of p-Hydroxycinnamic Acids-Based Bis- and Trisphenols as Novel Sustainable Antiradical/Antioxidant Additives

    Chemo-enzymatic synthesis and screening of a library of renewable saturated and unsaturated bis- and trisphenols deriving from p-hydroxycinnamic acids (i.e., p-coumaric acid, ferulic acid, and sinapic acid) and biobased diols/triol (i.e., isosorbide, 1,4-... Analysis of bis- and trisphenols deriving from p-hydroxycinnamic acids showed them to be promising, ecofriendly, and sustainable antiradical/antioxidant additives.
  • 05 NOV 2015

    3-Hydroxypropionaldehyde (3-HPA) quantification by HPLC using a synthetic acrolein-free 3-hydroxypropionaldehyde system as analytical standard

    HPLC-based quantification of 3-HPA using a synthetic acrolein-free 3-HPA standard obtained from commercially available 1,2,4-butanetriol through a straightforward and easy synthetic process has advantages over previous colorimetric methods of easier and safer implementation, and greater specificity. This HPLC method is very simple to implement in a lab, does not need any extra handling of the sample to be analyzed, and is suitable even in the presence of other aldehydes and 3-HPA derivatives, provided that the latter do not have similar retention times.
  • 22 OCT 2015

    Diversity of Lactobacillus reuteri Strains in Converting Glycerol into 3-Hydroxypropionic Acid

    The present study aims at comparing the performances of three Lactobacillus reuteri strains (DSM 20016, DSM 17938, and ATCC 53608) in producing 3-hydroxypropionic acid (3-HP) from glycerol and at exploring inhibition phenomena during this bioconversion. Differences were highlighted between the three strains in terms of 3-HP production yield, kinetics of substrate consumption, and metabolite production. With a maximal productivity in non-optimal conditions (free pH) around 2 g.L(-1).h(-1) of 3-HP and 4 g.L(-1).h(-1) of 3-hydroxypropionaldehyde (3-HPA) depending on the strain, this study confirmed the potential of L. reuteri for the biotechnological production of 3-HP. Moreover, the molar ratios of 3-HP to 1,3-propanediol (1,3-PDO) obtained for the three strains (comprised between 1.25 and 1.65) showed systematically a higher 3-HP production. From these results, the DSM 17938 strain appeared to be the most promising strain. The impact of glycerol bioconversion on the bacteria's physiological state (a decrease of around 40 % in DSM 17938 cells showing an enzymatic activity after 3 h) and survival (total loss of cultivability after 2 or 3 h depending on the strains) was revealed and discussed. The effect of each metabolite on L. reuteri DSM 17938 was further investigated, displaying a drastic inhibition caused by 3-HPA, while 3-HP induced lower impact and only at acidic pH.
  • 22 OCT 2015

    Relationships between the use of Embden Meyerhof pathway (EMP) or Phosphoketolase pathway (PKP) and lactate production capabilities of diverse Lactobacillus reuteri strains

    The aims of this study is to compare the growth and glucose metabolism of three Lactobacillus reuteri strains (i.e. DSM 20016, DSM 17938, and ATCC 53608) which are lactic acid bacteria of interest used for diverse applications such as probiotics implying the production of biomass, or for the production of valuable chemicals (3-hydroxypropionaldehyde, 3-hydroxypropionic acid, 1,3-propanediol). However, the physiological diversity inside the species, even for basic metabolisms, like its capacity of acidification or glucose metabolism, has not been studied yet. In the present work, the growth and metabolism of three strains representative of the species diversity have been studied in batch mode. The strains were compared through characterization of growth kinetics and evaluation of acidification kinetics, substrate consumption and product formation. The results showed significant differences between the three strains which may be explained, at least in part, by variations in the distribution of carbon source between two glycolytic pathways during the bacterial growth: the phosphoketolase or heterolactic pathway (PKP) and the Embden-Meyerhof pathway (EMP). It was also shown that, in the context of obtaining a large amount of biomass, DSM 20016 and DSM 17938 strains were the most effective in terms of growth kinetics. The DSM 17938 strain, which shows the more significant metabolic shift from EMP to PKP when the pH decreases, is more effective for lactate production.
  • 22 OCT 2015

    Reactive extraction of 3-hydroxypropionic acid from model aqueous solutions and real bioconversion media. Comparison with its isomer 2-hydroxypropionic (lactic) acid

    Bioconversion is a promising route to produce bio-based building blocks such as 3-hydroxypropionic acid (3-HP). Reactive extraction can be used for 3-HP recovery, and ultimately integrated to the bioconversion process. To the best of our knowledge, there is no published experimental data about the reactive extraction of 3-HP. This work aimed to study the extraction of 3-HP using tri-n-octylamine and Aliquat 336 as extractants in n-decanol. Comparison was also made with its positional isomer, lactic acid. Finally, the extraction of 3-HP from model and real bioconversion broths was examined.
  • 29 NOV 2014

    Renewable polymers derived from ferulic acid and bio-based diols via ADMET

    Renewable α,ω-diene monomers have been prepared from ferulic acid, bio-sourced diols (isosorbide and butanediol) and bromo-alkenes using a chemo-enzymatic synthetic pathway then studied as monomers in ADMET polymerisation. All monomers and polymers have been thoroughly characterised using NMR, GPC, DSC and TGA. ADMET polymerisation was optimised with regard to catalyst loading (Hoveyda–Grubbs II), reaction medium (in mass vs. in solvent), and temperature, which led to polymers with molecular weight up to 25 kDa. Thermal analysis of these new poly(ester-alkenamer)s showed excellent thermal stabilities (283–370 °C) and tunable Tg depending on the nature of the bio-based diol and the chain length of the alkene in the α,ω-diene monomer.
  • 05 SEP 2014

    Chemo-enzymatic synthesis of key intermediates (S)-γ-hydroxymethyl-α,β-butenolide and (S)-γ-hydroxymethyl-γ-butyrolactone via lipase-mediated Baeyer–Villiger oxidation of levoglucosenone

    Levoglucosenone, a valuable chiral platform chemical that can be efficiently produced from catalytic fast pyrolysis of cellulose, has been efficiently converted into optically pure (S)-γ-hydroxymethyl-α,β-butenolide using a two-step sequence involving a lipase-mediated Baeyer–Villiger oxidation and an acid hydrolysis. In the same fashion, (S)-γ-hydroxymethyl-γ-butyrolactone was successfully obtained through a three-step sequence (Baeyer–Villiger, palladium-catalysed hydrogenation and acid hydrolysis). The use of solid buffers in the lipase-mediated Baeyer–Villiger oxidation has been proved beneficial in two ways: not only the reaction time and the enzymatic load were both reduced four-fold (from 8 to 2 hours and 464 to 113 U mmol−1) to reach conversions ≥83%, but solid buffers also prevented lipase from denaturation, thus preserving its enzymatic activity and allowing its use for further oxidation cycles.