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This study highlights the possibility of using brewers’ grains (BSGs) for the successive extraction of the main lignocellulosic biopolymers, namely, cellulose, hemicelluloses and lignin. An exhaustive chemical characterisation revealed a variability of composition in distinct batches of BSGs, depending on their origin and the brewing process used. In particular, the protein content can vary from 13wt% to 23wt%, which is accompanied by a change in the hemicelluloses content from 9% to 23% (in the samples of our study). By applying a two-step aqueous treatment, involving an acid (1.25% v/v aq. H2SO4) and a base (3% w/v aq. NaOH) at a temperature of 120°C and fixed reaction time of a few tens of minutes (15–90 minutes), more than 80% of hemicelluloses could be recovered. Cellulose could be isolated at more than 68%, while a high purity lignin could be recovered from a lignin-rich fraction (70wt%). Our work also suggests that the variability of the chemical composition of these BSGs is a hindrance to achieving process standardisation and large-scale exploitation. The pooling of various materials is therefore not a recommended option, and the preliminary chemical analysis of the composition is therefore a prerequisite for an efficient extraction process.

Lignin is the primary contributor to the high cost of biofuel-production from lignocellulosic biomass. In order to study lignin removal and the release of aromatic monomers, we applied hydrocracking and ionic liquid pretreatments on Arabidopsis thaliana biomass from both wild type (WT) and a mutant (CAD cxd) defective in two cinnamyl alcohol dehydrogenase genes involved in the lignin biosynthetic pathway. For Arabidopsis WT, our results highlight that pretreatments reduce average molecular weight of lignin by about 65% and decrease the content of β-O-4 linkages between lignin monomers. For Arabidopsis CAD mutant, an opposite effect is evidenced. Fewer differences were observed on depolymerization and molecular structure of lignin, which indicates that (8-O-4), (8-5), and (8-8) linkages observed in CAD mutant make lignin more resilient to pretreatment than wild-type lignin. Finally, our study shows the potential of hydrocracking pretreatment technology for extracting valuable aldehyde monomers such as vanillin and syringaldehyde from biomass.

Bio-composites elaboration is limited by poor interfaces between cellulose and polymer matrices and the cellulose degradation. Achieving cellulose grafting with ferulic acid should enhance those resulting bio-composites mechanical properties. Therefore, a cellulose suspension was modified with ferulic acid using laccase under reaction conditions set at 60 °C, acetate buffer pH 5 for 24 h. Grafted cellulose fibrils were extruded in polypropylene-grafted maleic acid (PPgMA) for mechanical properties studies. Even if ferulic acid interacted with cellulose without any enzyme presence, the acid resilience was only detected for cellulose fibres modified with ferulic acid proving the surface grafting. Cellulose fibrillary lengths were unaffected by the enzymatic treatment suggesting a tiny coating. The resulting bio-composites had a Young modulus reduction of 12%. The elongation at maximal stress had 23% improvement, corresponding to a material mechanical resistance. This result was also confirmed by bio-composite elaboration with natural fibres under the same conditions. Ferulic acid and cellulose blends have improved the hardness properties of the resulting bio-composites with PP-PPgMA.

Two organosolv methods involving Formic acid/Acetic (FA) acid and Sulphuric acid/Ethanol (SE) solvent mixtures were investigated for lignin extraction from banana rachis biomass residues. Different heating methods were also applied during each extraction process, respectively direct conduction heating and microwave heating. The chemical composition and structural features of the extracted lignin fractions were further analyzed by ATR-FTIR, TGA, elemental analysis and 13C NMR methods. SE extraction method showed a higher extraction yield (58.7%) and allowed also to obtain a lignin fraction with higher purity (76.5% Vs 71.0% for FA lignin). In addition, SE extraction method allowed a higher pulp yield which meant a better selectivity for lignin extraction thanks to the microwave heating method. SE lignin also showed a higher thermal stability due to its higher purity and higher density. The higher molecular weight found for FA lignin residues (7622.7g/mol Vs 5957.7g/mol for SEL) was suspected to be due to co-extracted carbohydrate residues bounded to extracted lignin macromolecules. These results allowed us to establish the SE extraction method (Sulphuric acid/Ethanol/water solvent with microwave heating) as effective for lignin extraction from banana rachis straw.

Sterols are a group of molecules found in plants and animals, which have a number of valuable applications. The deodorization residue, referred to as “deodistillate”, was previously considered as a waste but its economical value nowadays increased due to the presence of high concentrations of sterols, tocopherols and other secondary metabolites attractive for the cosmetic, pharmaceutical or food industry. Sterols can be extracted from vegetable oil deodistillate through a variety of physical and chemical separation processes or their combination. Recently, the use of lipase enzymes has been demonstrated to separate sterols more selectively in higher yields and in milder conditions. This article reviews these lipase-assisted sterol extractions and their main advantages and drawbacks in economic and environmental terms.

Steam explosion (SE) is a versatile tool for the pretreatment of lignocellulosic plant 27 materials and the further separation of their main constitutive components, i.e. cellulose, 28 hemicellulose, lignin, etc. In this study, we propose to evaluate the effects of SE 29 treatment on the recovery of secondary metabolites. As a case study, the well-known 30 grape pomace phenolic compounds were considered. Our results demonstrate that the 31 efficiency of the steam explosion in term of yield (900 mg polyphenols per kg of dry 32 grape pomace) was relatively similar to conventional maceration methods in alcoholic 33 media (800 mg/kg). Advantages of SE compared to maceration were highlighted: the 34 process is organic solvent free, destabilize the biomass structure and release insoluble 35 bound phenolic compounds. In addition, it offers the possibility to modulate distinct 36 polyphenols profiles by modifying the process conditions.

Giant cell arteritis is not an uncommon disease, and its extension is furthermore finely assessed with new-generation PET/CT system. 18F-FDG PET/CT is increasingly used in case of large-vessel vasculitis for optimal diagnosis, activity monitoring (even when treated with interleukin 6 receptor inhibitor), and evaluation damage progression. We reported the case of a 61-year-old woman with common giant cell arteritis pattern on 18F-FDG PET/CT (aorta and large arteries) and uptakes in all aorta branches, mainly impressive and uncommon in the abdomen. After 2 years of therapeutic optimization including IV tocilizumab and monitoring with 18F-FDG PET/CT, a complete metabolical response was assessed.

Phloem sap is the diet of numerous sap-sucking insects, such as aphids or psyllids, which use it as a source of carbon and nitrogen. Cacopsylla pyri is a phloem sap-sucking insect specialised in pear trees that can cause great damage to most pear tree-growing regions. The main goal of our study is to determine the food requirements of C. pyri and to quantify the nutrients uptaken from the plant (sugars and amino acids), with a comparison between the composition of the phloem sap and the composition of the egested honeydew. We highlighted that phloem sap is composed of two sugars, sorbitol and sucrose and both are ingested by C. pyri. Seventeen free amino acids were also found in the phloem sap, including eight essential amino acids, serine, histidine, threonine, arginine alanine, valine, isoleucine, phenylalanine, leucine and lysine. Two essential amino acids were not found in the pear tree phloem sap (methionine and tryptophan), and two other amino acids (asparagine and glutamine) were egested in high amounts by both the adult females and the larvae. This probably indicates that these four amino acids are synthesised by the pear psylla endosymbiont(s). Finally, three amino acids (valine, glutamic acid and aspartic acid) were consumed only by the adults and not by the larvae and probably participate in actions only performed by adults, such as flying, jumping or reproduction.

Banana production in tropical countries generates significant quantity of waste. Biorefinery of food waste biomass into cellulose, hemicellulose, lignin or pectin macromolecules have grown interest in recent scientific literature. In this paper, hemicellulose from banana rachis (Musa cavendish) was extracted by steam explosion at three severity levels (2.97, 3.57 and 3.78) and was further fractionated by graded ethanol precipitation method (15%, 60% and 80%). The recovered hemicelluloses sub-fractions (H1, H2 and H3) were characterized for their chemical composition and structural features by HPSEC, TGA/DTG, FTIR, 1H and 2D NMR techniques. The hemicellulose extraction yield increased with the severity level and treatment duration. The average molecular weight of the extracted hemicellulose macromolecules decreased from H1-60% ethanol hemicellulose sub-fraction with 143 790 g/mol, followed by H3-60% ethanol hemicellulose sub-fraction with 110 841 g/mol and finally H2-60% ethanol hemicellulose sub-fraction with 61 404 g/mol. The H1-60% ethanol hemicellulose sub-fraction extracted during the steam explosion at the lowest severity level showed the largest molecular weight and exhibited rather a high arabinose/xylose ratio and uronic acid content. Structural analysis revealed that hemicellulose from the 60%-ethanol hemicellulose sub-fractions were mainly arabino-glucuronoxylan (AGX). However, chemical analysis also revealed significant contents of co-extracted residual lignin. Although the ethanol fractionation helped at lowering the lignin content in the 60%-ethanol hemicellulose sub-fractions (20.1% in H2-60%, 24.0% in H1-60% and 28.0 in H3-60%) relatively to 80%-ethanol hemicellulose sub-fractions, additional purification step was still required to improve the quality of the extracted hemicellulose sub-fractions (purity and coloration). Nevertheless these results proved that steam explosion was an effective technique for the extraction of high molecular mass AGX hemicellulose macromolecules from banana rachis residues.

Because of their excellent tensile properties, low density, and natural abundance, cellulose-based plant fibers are a sustainable and biodegradable alternative for synthetic fibers in fiber-reinforced composite materials. However, the extraction of plant fibers can be costly and difficult to control because the fibers are enmeshed in a complex network of biopolymers (principally lignin, pectin, and hemicellulose), which serve both to strengthen the fibers and to bind them to their parent organism. It is necessary to extract or degrade these biopolymers to produce fine plant fibers without adversely altering the fibers themselves in the process. In particular, it is important that both the molecular weight and the degree of crystallinity of the cellulose in the fibers be kept as high as possible. This article reviews chemical treatments, which have been used to extract and refine fibers both from purpose-grown fiber crops, such as hemp and flax, and agricultural waste such as coconut husks and pineapple leaves. The treatments are discussed in terms of changes in the mechanical properties and surface chemistry of the fibers.

A new enzymatic methodology is herein proposed to measure free asparagine content in wheat grains and to predict their potential for Maillard reaction products. Our model estimates the acrylamide levels generated during the industrial heat treatment of whole-grain wheat based on free asparagine and glucose measurements. We selected fifteen wheat varieties currently grown in Belgium as benchmark for the present study. While conventional chromatographic methods require a long and tedious multi-step sample preparation, the proposed method takes advantage of being simple and quick. Statistical analysis of free asparagine content indicates that selected wheat varieties can be classified into seven content levels from 0.0149% to 0.0216% of the dry matter. Based on our analysis, the varieties KWS Ozon, Benchmark and Pionier appears to be the most suitable for thermal processing (i.e. cooking applications).

A combined dry and wet fractionation process is proposed to extract faba bean proteins with lower environmental impact. This fractionation process allowed to recover 87% of the total seeds proteins (92% of dehulled seeds proteins). This is achieved through the production of two protein concentrates (54 and 61% protein content w/w DM). After dry fractionation, wet extraction was performed on the protein-depleted fraction. The presented process consumed less energy and 5.5 times less water per kg extracted proteins, compared to traditional one-step wet extractions. Some anti-nutritional factors contents were also evaluated. Equivalent levels of phytic acid (about 11 mg/g), trypsin inhibitor activity (about 13 trypsin inhibition unit/g) and polyphenols (about 6 mg gallic acid equivalent/g) were observed in the 2 protein-rich fractions. These levels are mainly equivalent to those found after usual dry and wet one-step extractions. Significant differences of calcium, iron and zinc contents were observed between the 2 protein-rich fractions, causing a 30 to 50% difference between those fractions in terms of phytic acid/minerals ratio. Antinutritional factors content in the protein-rich fractions are equivalent to levels found in traditional legumes but still higher than existing recommendations.

High-purity cellulose nanofibers were isolated from wheat straw through an environmentally friendly, multistep treatment process that combined steam explosion, microwave-assisted hydrolysis, and microfluidization. The cellulose content of the processed nanofibers increased from 44.81% to 94.23%, whereas the hemicellulose and lignin contents significantly decreased. Scanning electron microscopy revealed the effects of the isolation treatments on fiber morphology and width. Atomic force microscopy was used to observe the changes in the components, surface roughness, and crystallinity of the fibers. Transmission electron microscopy showed long, loose nanofiber bundles that were 10–40 nm wide with an average individual diameter of 5.42 nm. Fourier transform infrared spectroscopy showed that noncellulosic components were effectively removed. X-ray diffraction analysis revealed the improved crystallinity of the processed fibers, as well as the partial crystalline transformation of cellulose I to cellulose II. T...

Tall fescue, a grass currently grown as forage, presents a good potential as a feedstock in the development of biorefining. In this study, combination of steam explosion and an acetic/formic acid “organosolv” pretreatments are applied on raw fescue to optimize lignin extraction yields and obtain specific products. In a first step, fescue is pretreated by steam explosion under severity factors from 1.4 to 4.2. These treatments allow hemicelluloses solubilization and open the lignocellulosic structure. Steam exploded solid residues are then treated with an acetic acid (50%)/formic acid (30%)/water (20%) mixture. Extracted lignins are precipitated and characterized by size exclusion chromatography (SEC), 31P NMR and HSQC NMR. Results show that acetic and formic acids extracted lignins present G, H and S units with ferulate and p-coumarate. Lignin typical linkages identified are of β-O-4 and spirodienone substructures. Combination of steam explosion and acetic and formic acid pretreatments increases extraction yields from 30% to 100%. Moreover, an increase of the steam explosion treatment intensity induces chemical modifications in lignin structure such β-O-4 and spirodienone substructure degradations, increase of free COOH and phenolic OH bonds, decrease of aliphatic OH ferulate and p-coumarate bonds and changes in G/H/S units proportions. Steam explosion intensity affects also lignin molecular weights.

It is commonly accepted that the current society needs to partially substitute fossil resources by renewable ones. Among many solutions, one approach consists in the development of biorefinery involving lignocellulosic biomass to produce bio-based materials and fuels. This study focuses on the comprehension of an organosolv treatment designed to break the complex lignocellulosic structure for high purity lignin extraction from tall fescue (Festuca arundinacea Schreb.). This grass benefits from an increasing interest in Western Europe and has been suggested as feedstock for biorefinery. However, its use as material for high purity lignin production has not been determined yet. Ethanol/water, 92/8% [v/v] with H2SO4 0.32 M was investigated at pilot scale under conventional heating (5 °C min−1 during 30 min and stabilized at 148 °C for 5 min). Precipitated lignin were analyzed as well as the composition of side-stream products (recovered cellulosic pulp and the aqueous hydrolysate). Lignin has been recovered at a purity level of 90% with a yield of 60%. The main contaminants were nitrogen containing compounds and degraded hemicelluloses. 2D-HSQC NMR (Two Dimension-Heteronuclear Single Quantum Correlation Nuclear Magnetic Resonance) revealed a co-extraction of ferulates and coumarates function as well as arabinoxylan. Cellulose was recovered at 53% purity with 60% yield. The conditions appear to be too harsh for tall fescue and led to significant amount of cellulose degradation. A process using a lower alcohol concentration will be developed to provide better yields of both cellulose and lignin.

In the context of green energy valorisation, this study reports the chemical analysis and improvement of biogas production via anaerobic digestion of treated and untreated agricultural waste lignocellulosic biomass from Williams Cavendish banana plants (WCLB). With a worldwide annual production of 26 million tons of dry matter (DM), large amounts of this waste are abandoned in plantations after fruit harvesting. Steam explosion (SE) and steam cracking (SC) pretreatments were investigated at severity factors of 3.16 and 4.29, respectively, to improve the biogas potential over 135 days under mesophilic conditions. The study revealed a carbon (C)/nitrogen (N) ratio of 27.3, indicating that WCLB has sufficient N content for successful fermentation. The proportions of liquid and solid fractions recovered after SC were 20 and 80%, respectively, whereas SE yielded 17 and 83% liquid and solids, respectively. The neutral sugar content of the studied fractions indicated that glucose and xylose constituted the highest hexose and pentose fractions, respectively, in WCLB. The highest and lowest total biogas potentials were obtained from LFSC (280 mL g−1 of DM) and untreated WCLB (240 mL g−1 of DM), respectively. The methane yield from untreated WCLB and combined solid and liquid fractions from SE and SC were 40, 42, and 51%, respectively, of the theoretical methane potential. The maximum biogas production rate (7.8 mL g−1 day−1) was obtained with SFSC. This study reveals that SC deconstructs WCLB efficiently and thereby greatly enhances methane production.

The application of sub-lethal stresses is known to be an efficient strategy to enhance survival of probiotic bacteria during drying processes. In this context, we previously showed that the application of heat stress upon the entry into stationary phase increased significantly the viability of Bifidobacterium bifidum. However, this heat shock has been considered only in small-scale bioreactor and no information is available for a possible scaling-up strategy. Five different operating scales (0.2, 2, 20, 200 and 2000 L) have thus been tested and the results showed that the viability of B. bifidum increases from 3.15 to 6.57 folds, depending on the scale considered. Our observations pointed out the fact that the heat stress procedure is scalable according to the main outcome, i.e., increases in cell viability, but other factors have to be taken into account. Among these factors, dissolved carbon dioxide seems to play a significant role, since it explains the differences observed between the test performed at laboratory scale and in industrial conditions.

Despite their potential for chemical recycling, residues from forest harvesting and wood processing are mostly used for industrial applications with low added value (energy, paper pulp, and panels). Bark of both oak species, Quercus robur L. 1753, Quercus petraea (Matt.) Liebl. 1784 is a by-product from sawmill and pulp mill activities. Bark is mainly used as a fuel for the same wood plants. The aim of this study is to look at the feasibility of enhancing the value of this material through the extraction of bioactive molecules, such as polyphenols (i.e. catechin, gallic, and ellagic acids). First, the effect of industrial storage of logs and bark on their polyphenol content was explored. Then, referring to the selection of tan oaks in the past, the question of an optimum harvesting age is addressed in order to maximize the polyphenol content of the barks. In the end, molecular diversity of bark is examined through the identification of molecules of interest, using different chromatographic analyses. The results show an effect of the industrial context and an effect of the raw material age on the chemical properties of the bark. First investigations also highlight molecules of interest and the molecular diversity, which needs to be further explored.

Lignocellulosic biomass residues have attracted attention for the sustainable production of molecules for material and energetic use through biochemical conversion. Their recalcitrant structure prevents a broader use and asks for the development of sustainable techniques that can efficiently separate, recover and valorize the constituting components. In a cascading concept, residual streams of such processes can be further exploited in an attempt to valorize the largest possible fraction of the initial material. Three lignocellulosic substrates, namely dried sugar beet pulp, wheat bran and miscanthus straw, were upstream fractionated by steam explosion to extract the hemicellulose fraction. This study evaluated the valorization of the residual solid fraction through mixed acidogenic fermentation for the production of volatile fatty acids (VFA) as platform chemicals. Batch experiments have been conducted for the reference material (non-treated) and the solid fraction remaining after steam explosion, with and without the addition of an external mixed inoculum. Steam explosion residues contained less hemicellulose than the initial materials. The difference in the fermentation profile between steam explosion residues and non-treated substrates is dependent on the substrate. Maximum total VFA (tVFA) concentration was 18.8 gCOD/kgmixed_liquor, and maximum yield of chemical oxygen demand (COD) conversion into tVFA was 33 % for the case of non-treated inoculated beet pulp.

Steam explosion is a thermo-mechanicochemical pretreatment which allows the breakdown of lignocellulosic structural components by the action of heating, formation of organic acids during the process, and shearing forces resulting in the expansion of the moisture. Two distinct stages compose the steam-explosion process: vapocracking and explosive decompression which include modification of the material components: hydrolysis of hemicellulosic components (mono- and oligosaccharides released), modification of the chemical structure of lignin, and modification of the cellulose crystallinity index, etc. These effects allow the opening of lignocellulosic structures and influence the enzymatic hydrolysis yield of the material.

Chemical composition of banana rachis from three varieties (Grande naine, Pelipita, and CRBP969) was analyzed, and the genotype contribution to composition variability was investigated. Wet chemistry and instrumental analysis procedures (X-ray diffraction, 31P NMR spectroscopy, and thermogravimetry) were used. Some significant differences were found among the three genotypes: GN-AAA genotype was found to be significantly the highest in ash fraction (30.16 %) and the lowest in acid insoluble lignin (6.58 %) at 95 % confidence level. It showed also the highest content in potassium (43.5 % in ash). Implication of compositional differences on valorization efficiency by biochemical or thermochemical pathways was investigated. For this purpose, correlation coefficients between compositional characteristics and yields in volatile compounds from pyrolysis and glucose yields from enzymatic saccharification were analyzed. Ash content was revealed to be the main drawback parameter for volatile yields from pyrolysis (r = −0.93), while for glucose yields during saccharification were limited mainly by the content in guaiacyl units of the lignin fraction (r = −0.98). However, a strong and positive correlation was established between the volatiles yield and the acid insoluble lignin content (r = 0.98) Thus, according to these observations and based on their compositional significant differences, GN-AAA was the better candidate for bioconversion pathway while PPT-ABB and CRBP969-AAAB samples were shown to be better candidates for thermochemical conversion pathway. This work gives important preliminary information for considering banana rachis as an interesting feedstock candidate for biorefinery.

© 2017, Public Library of Science, All rights reserved. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Lignin in plant biomass represents a target for engineering strategies towards the development of a sustainable bioeconomy. In addition to the conventional lignin monomers, namely p-coumaryl, coniferyl and sinapyl alcohols, tricin has been shown to be part of the native lignin polymer in certain monocot species. Because tricin is considered to initiate the polymerization of lignin chains, elucidating its biosynthesis and mechanism of export to the cell wall constitute novel challenges for the engineering of bioenergy crops. Late steps of tricin biosynthesis require two methylation reactions involving the pathway intermediate selgin. It has recently been demonstrated in rice and maize that caffeate O-methyltransferase (COMT) involved in the synthesis syringyl (S) lignin units derived from sinapyl alcohol also participates in the synthesis of tricin in planta. In this work, we validate in sorghum (Sorghum bicolor L.) that the O-methyltransferase responsible for the production of S lignin units (SbCOMT / Bmr12) is also involved in the synthesis of lignin-linked tricin. In particular, we show that biomass from the sorghum bmr12 mutant contains lower level of tricin incorporated into lignin, and that SbCOMT can methylate the tricin precursors luteolin and selgin. Our genetic and biochemical data point toward a general mechanism whereby COMT is involved in the synthesis of both tricin and S lignin units.

The size of wheat starch granules was measured during isothermal and non-isothermal treatments and fitted using mathematical models in order to elucidate the time–temperatures dependence of the swelling phenomenon and to improve our understanding of the mechanism followed by granules during gelatinization. Upon the onset temperature of gelatinization, starch granules size increase rapidly and tend to reach equilibrium values that depend on the temperature and heating rate applied. The most accurate fitting of granule size observed overall isothermal treatments was obtained with the third-order kinetic and the Weibull empirical models. The activation energy of swelling calculated for isothermal treatment varied between 41 and 318 kJ mol −1 , depending on the mathematical model considered. Therefore, without a consensus on the mechanism and order of reaction followed during gelatinization, the meaningful of kinetic parameters calculated using mathematical models seems highly questionable. During non-isothermal treatments at lower heating rate, it seems like a limitation of the swelling capacity of granules was induced. This phenomenon was attributed to restructuration occurred inside of granules. So, forecasting the swelling behaviour of starch granules during non-isothermal treatment has to consider both the time–temperature and the heating rate applied.

In order to improve the hydrolysis of cellulose fiber and to obtain highly concentrated hydrolysate, two methods based on successive addition of enzyme and substrate were assessed. The first method, which required only substrate addition, allowed to increase by 50% the hydrolysate concentration and to decrease by 30% enzyme units needed. The second method highlighted the ability to reach very high concentrated hydrolysate (up to 170 g/l) by simultaneous addition of enzyme and substrate. In parallel, relationships between some limiting factors and the yields of hydrolysis were investigated. In conclusion, viscosity evolution of cellulose suspension during hydrolysis step was investigated with an aim to improve the management of enzyme and substrate addition.

The aim of this study is to compare the effect of different steam explosion treatments on the physicochemical properties and the hydrolysis rate of a pure bleached cellulose. The results showed that moderate steam explosion treatments (severity factor below 5.2) did not appear to improve the enzymatic hydrolysis rate of the cellulose fibers. However, characterization of the samples showed a modification of the physicochemical properties of the cellulose, resulting in an increase of the water retention values (WRV) coupled to an increase of the overall crystallinity. For higher treatment intensities, an important thermal degradation of the cellulose was highlighted. This thermal degradation caused an important modification of the cellulose composition which leads to a decrease of the hydrolysis rate.

A Box–Behnken experimental design and response surface methodology were employed to optimize the pretreatment parameters of a formic/acetic acid delignification treatment of Miscanthus × giganteus for enzymatic hydrolysis. The effects of three independent variables, namely cooking time (1, 2 and 3 h), formic acid/acetic acid/water ratio (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107 °C) on pulp yield, residual Klason lignin content, concentration of degradation products (furfural and hydroxymethylfurfural) in the black liquor, and enzymatic digestibility of the pulps were investigated. The major parameter influencing was the temperature for pulp yield, delignification degree, furfural production and enzymatic digestibility. According to the response surface analysis the optimum conditions predicted for a maximum enzymatic digestibility of the glucan (75.3%) would be obtained using a cooking time of 3 h, at 107 °C and with a formic acid/acetic acid/water ratio of 40/40/20%. Glucan digestibility was highly dependent on the delignification degree.

Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 °C and 80 °C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 °C. The effects of these fractionation processes on chemical structure, physico-chemical properties and antioxidant activity of extracted lignins were investigated. Lignins were characterized by their purity, carbohydrate composition, thermal stability, molecular weight and by Fourier transform infrared (FTIR), 1H and quantitative 13C nuclear magnetic resonance (NMR), adiabatic broadband {13C–1H} 2D heteronuclear (multiplicity edited) single quantum coherence (g-HSQCAD). The radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) was also investigated. Formic/acetic acid pretreatment performed in milder conditions (80 °C for 3 h) gave a delignification percentage of 44.7% and soaking in aqueous ammonia 36.3%. Formic/acetic acid pretreatment performed in harsh conditions (107 °C for 3 h) was more effective for extensive delignification (86.5%) and delivered the most pure lignin (80%). The three lignin fractions contained carbohydrate in different extent: 3% for the lignin obtained after the formic/acetic acid pretreatment performed at 107 °C (FAL-107), 5.8% for the formic/acetic acid performed at 80 °C (FAL-80) and 13.7% for the ammonia lignin (AL). The acid pretreatment in harsh conditions (FAL-107) resulted in cleavage of β–O-4′ bonds and aromatic C–C. Repolymerisation was thought to originate from formation of new aromatic C–O linkages. Under milder conditions (FAL-80) less β–O-4′ linkages were broken and repolymerisation took place to a lesser extent. Ammonia lignin was not degraded to a significant extent and resulted in the highest weight average 3140 g mol −1 . Despite the fact of FAL-107 repolymerisation, significant phenolic hydroxyls remained free, explaining the greater antioxidant activity.

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which allows breakdown of the structural lignocellulosic material was determined by a correlation between time and temperature of the process. Results of this study showed that thermal degradation of cellulose fibres was limited when the severity factor applied was below 4.0. For higher intensities, determination of the degradation products in the water-soluble extract showed an important increase of the 5-hydroxymethyl-furfural concentration with the temperature. When the severity factor reached 5.2., TGA analysis showed that the increase of degradation products was coupled to an increase of the char level meaning a strong degradation of the cellulose. dTGA behaviour also showed that thermal stability of the steam explosion samples decreased with the intensity of the treatment. To conclude, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established.

Homogenization has been used to release microfibrils from cellulose fibres to produce microfibrillated cellulose (MFC) Oven drying, atomization or freeze-drying were used to dry MFC Morphological differences were observed linked to the compaction of the system and the formation of microfibril agglomerates Thermal stability of the dried MFC, checked by TGA, decreased after homogenization and drying Char level at the end of the pyrolysis was higher than for cellulose fibres Derivative TGA (dTGA) showed a shoulder around 250 degrees C for the dried MFC Volatile degradation product detection by FTIR spectroscopy (FTIR) coupled to TGA and DSC showed that the shoulder corresponds to expected dehydration reactions of the cellulose Increasing the contacts between microfibril(s) (bundles) and agglomerates of the freeze-dried MFC by compression promoted dehydration reactions Homogenization and drying modified the thermal properties of the MFC No significant influence of freeze-drying kinetics on the thermal behaviour of the MFC was observed (C) 2009 Elsevier Ltd All rights reserved.

Honey polyphenols have been studied with the objective of relating honeys to their floral sources. Initially synthesized by plant, these polyphenols can be found in the plant's nectar, which are collected by bees, which convert the nectar into honey. Consequently, polyphenols constitute minor components of honey. The development of a solid-phase extraction method for honey polyphenols is presented in this study. The technique employs Amberlite XAD-2 adsorbent and was tested on monofloral honeys from six different plants: acacia, chestnut, eucalyptus, thyme, sunflower, and wild carrot. Analyses were performed using high-performance liquid chromatography coupled with UV detection and mass spectrometry. Several phenolic acids and flavonoids were identified: caffeic and p-coumaric acids, quercetin, kaempferol, naringenin, chrysin, and pinocembrin. Generally, the quantity of a given polyphenol in the honey was around 0.2 mg/100 g of honey, except for chestnut honey, which contained around 3.0 mg of p-coumaric acid/100 g of honey. Analyses highlighted significant formation of cis isomers for phenolic acids during the extraction despite protection from light.

The accessibility of fermentable substrates to enzymes is a limiting factor for the efficient bioconversion of agricultural wastes in the context of sustainable development. This paper presents the results of a biochemical analysis performed on six combined morphological parts of Williams Cavendish Lignocellulosic Biomass (WCLB) after steam cracking (SC) and steam explosion (SE) pretreatments. Solid (S) and liquid (L) fractions (Fs) obtained from SC pretreatment performed at 180°C (SLFSC180) and 210°C (SLFSC210) generated, after diluted acid hydrolysis, the highest proportions of neutral sugar (NS) contents, specifically 52.82 ± 3.51 and 49.78 ± 1.39 %w/w WCLB dry matter (DM), respectively. The highest proportions of glucose were found in SFSC210 (53.56 ± 1.33 %w/w DM) and SFSC180 (44.47 ± 0.00 %w/w DM), while the lowest was found in unpretreated WCLB (22.70 ± 0.71 %w/w DM). Total NS content assessed in each LF immediately after SC and SE pretreatments was less than 2 %w/w of the LF DM, thus revealing minor acid autohydrolysis consequently leading to minor NS production during the steam pretreatment. WCLB subjected to SC at 210°C (SC210) generated up to 2.7-fold bioaccessible glucan and xylan. SC and SE pretreatments showed potential for the deconstruction of WCLB (delignification, depolymerization, decrystallization and deacetylation), enhancing its enzymatic hydrolysis. The concentrations of enzymatic inhibitors, such as 2-furfuraldehyde and 5-(hydroxymethyl)furfural from LFSC210, were the highest (41 and 21 µg ml−1, respectively). This study shows that steam pretreatments in general and SC210 in particular are required for efficient bioconversion of WCLB. Yet, biotransformation through biochemical processes (e.g., anaerobic digestion) must be performed to assess the efficiency of these pretreatments.

High-Performance Anion-Exchange Chromatography Coupled with Pulsed Amperometric Detection (HPAEC-PAD) was used to quantify and to determine the nature of saccharides released after the digestion of two corn grains submitted to different drying and harvesting protocols. Five saccharides were quantified: glucose, maltose, isomaltose, maltotriose and glucosyl-maltotriose. After a subsequent hydrolysis with amyloglucosidase of the released sugar, the amount of total glucose recovered increased with the increase in drying temperature and the moisture content of grain at harvest. These results suggest that structural changes induced within corn starch granules during drying affect their hydrolysis by amylases. These changes may lead to different pathways of sugar absorption in the small intestine of monogastrics. Thus, corn grains with a similar composition may lead to different levels of metabolizable energy upon gastro-intestinal digestion.

The aim of this study is to compare the effect of different homogenization treatments on the physicochemical properties and the hydrolysis rate of a pure bleached cellulose. Results obtained show that homogenization treatments improve the enzymatic hydrolysis rate of the cellulose fibers by 25 to 100 %, depending of the homogenization treatment applied. Characterization of the samples showed also that homogenization had an impact on some physicochemical properties of the cellulose. For moderate treatment intensities (pressure below 500 b and degree of homogenization below 25), an increase of water retention values (WRV) that correlated to the increase of the hydrolysis rate was highlighted. Result also showed that the overall crystallinity of the cellulose properties appeared not to be impacted by the homogenization treatment. For higher treatment intensities, homogenized cellulose samples developed a stable tridimentional network that contributes to decrease cellulase mobility and slowdown the hydrolysis process.

Three pectic oligosaccharides (POS) obtained by enzymatic hydrolysis of sugar beet pectin by combining endopolygalacturonase and pectinmethylesterase, were characterized using high performance liquid chromatography, thermogravimetric analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray diffraction. According to chromatographic analyses, POS are composed of mixture of polymers with different molecular weights and different galacturonic acid contents. The thermal analysis showed no major variation in thermal behavior regarding POS composition but showed that POS were more sensitive to thermal degradation than the parent pectin as well as the deesterified pectin. No change in composition of the gaseous products was obtained through TGA-FTIR analysis. The X-ray pattern of POS clearly indicated a considerable decrease in crystallinity when compared to the native pectin. Thus, thermal characterization of POS may have practical repercussions if the formulation in which POS is incorporated is submitted to a high temperature treatment. © 2012 Elsevier B.V. All rights reserved

Lignin is a co-product from the biorefinery and paper industries. Its non-energetic valorisation remains a field of extensive research and development. In this perspective, this study was undertaken to evaluate the radical scavenging ability of selected herbaceous lignins. These lignins, extracted from either Miscanthus (Miscanthus × giganteus) or switchgrass (Panicum virgatum L.), were selected as benchmarks for this study based on their chemical structure and average molecular weight. These technical lignins, which are side-products in the bioethanol production process, displayed a moderate antioxidant activity as evaluated by the 1,1-diphenyl-2-picrylhydrazil free radical scavenging test system. A correlation between the radical scavenging properties and the molecular features is proposed and discussed. Infrared spectroscopy was employed as a straightforward qualitative prediction tool for assessing the radical scavenging capacity.