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[Display omitted] • Multi-bed operation with cycles enhances the efficiency of hydrothermal treatment. • Start-up & bed shifting highly affects final concentration and process steadiness. • Carrot discards produced high purity hemicelluloses and pectins up to 80.4 kDa. • Ultrafiltration/diafiltration remove up to 100% of low molecular weight components. • Molecular weight increased up to 16.7 times and polydispersity reduced 13.5 times. Purified solid fractions of hemicellulose and pectin biopolymers with different molecular weight were produced on a pilot-scale from discarded carrots. The pulp was subjected to hydrothermal extraction on a pilot plant operating in cycles of three flow-through reactors in series at 140 and 180 °C. Two operational modes of start-up (with and without water pre-filling) were tested, showing that it influences the final hydrolysate concentration and the stability of the system. Free sugars, arabinogalactan hemicellulose and homogalacturonan pectin were produced at maximum recoveries of 379.5 g/kg dry pulp, 81.0 g/kg dry pulp and 5.35 g/kg dry pulp, respectively, with the extraction of arabinogalactan reaching a yield of 96.1 % (w/w). The extracted biopolymers were separated and purified through ultrafiltration and diafiltration cycles using a multi-membrane system (30, 10, 1 kDa). Ultrafiltration and especially diafiltration allowed going from extracts with molecular weight, polydispersity and purity values of 14.77 kDa, 19.2 and 22.2 % w/w (140 °C extract) and 8.08 kDa, 18.2 and 14.9 % w/w (180 °C extract), to fractions with values of 80.36 kDa, 67.77 kDa, 9.85 kDa, 5.23 kDa and 3.86 kDa (molecular weight), 1.3 – 3.8 (polydispersity), and 64.5 – 100 % w/w (purity). The five fractions were freeze-dried and spray-dried. The pilot-scale system allowed the production of purified biopolymer fractions of high purity, different average molecular weight, and in sufficient quantity for their subsequent transformation into products such as biodegradable films. [ABSTRACT FROM AUTHOR]

Highlights: [•] Steam explosion and steam pre-treatments were carried out before kraft pulping. [•] The rate of extraction of hemicelluloses was similar with both pre-treatments. [•] Steam explosion enhanced delignification more efficiently. [•] Pre-treatments reduced paper mechanical properties owing to the fiber morphology. [•] Paper optical properties were boosted when pre-treatments were carried out. [Copyright &y& Elsevier]

Highlights: [•] The chemical composition of alternative lignocellulosic biomass was evaluated. [•] Results showed that some materials could be used together as biorefinery feedstocks. [•] Autohydrolysis, soda and organosolv processes were applied to these feedstocks. [•] Appropriate treatments were found for the proper exploitation of these materials. [ABSTRACT FROM AUTHOR]

Various chemometric techniques were used to establish the relationship between the autohydrolysis conditions prior to pulping and the chemical compositions of the soluble organic materials removed from Scots pine (Pinus sylvestris) wood chips. The aqueous chip pre-treatments (autohydrolysis) were administered at 130 °C and 150 °C for 30, 60, 90, and 120 min, and the hydrolysates obtained were characterized in terms of total carbohydrates (various mono-, oligo-, and polysaccharides together with uronic acid side groups), volatile acids (acetic and formic acids), lignin, and furans (furfural and 5-(hydroxymethyl)furfural). Based on the analytical data gathered, a relatively accurate model for pine chip autohydrolysis was developed. [ABSTRACT FROM AUTHOR]

Sulphated polysaccharides (SP) were extracted from Fucus vesiculosus seaweed by using two different hydrothermal processes: microwave-assisted extraction (MAE) and autohydrolysis (AH). The extraction yields, chemical composition, and antioxidant activity of the polysaccharides extracted were determined and compared. Although both processes afforded SP with similar yields (18.2 mass % and 16.5 mass %, for MAE and AH, respectively) and l-fucose as the main monosaccharide, the heterogeneous structure of the polysaccharide recovered was significantly affected by the AH process. The SP obtained by MAE contained 53.8 mole % of fucose, 35.3 mole % of xylose, and 10.8 mole % of galactose; while the SP obtained by AH was composed of 76.8 mole % of fucose and 23.2 mole % of galactose. Both samples presented comparable values of antioxidant activity by the di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (2,2-diphenyl-1-picrylhydrazyl, DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), and lipid oxidation inhibition methods, but the polysaccharide obtained by AH exhibited a higher antioxidant potential by the differential pulse voltammetry technique. This study demonstrates that the chemical composition and antioxidant activity of SP obtained from F. vesiculosus vary according to the process used for their extraction. However, the SP obtained by MAE or AH both have the potential for use as natural antioxidants in industrial applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Information on oligosaccharides production from oil palm biomass is very scarce. [•] Oligosaccharides production from OPEFB fibre via autohydrolysis is demonstrated. [•] Substantial yield of XOS is achieved using non-isothermal conditions. [•] High purity of refined XOS with wide ranges of DP were obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] Autohydrolysis severity affects the chemical composition of pretreated wheat straw. [•] The enzymatic hydrolysis efficiency was strongly related to pretreatment severity. [•] Mechanical refining improved enzymatic hydrolysis efficiency of wheat straw. [•] The levels of sugar recovery are comparable to other pretreatment methods. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different combinative pretreatments were used to isolate lignin from OPF. [•] Combined autohydrolysis pretreatment gave smaller lignin fragment with higher phenolic-OH content. [•] Repolymerization of lignin during dilute sulphuric acid treatment affects its structure and antioxidant activity. [•] 2-Naphthol has been confirmed to reduce lignin condensation reaction. [•] Higher phenolic-OH content and lower M w of lignin may affect its antioxidant properties. [ABSTRACT FROM AUTHOR]

Abstract: Polymeric phenolic fraction (PPF) was isolated by ethyl acetate extraction from hydrolyzed liquids from steam-treated alperujo and characterized. PPF is composed mainly of phenolic compounds with small amounts of carbohydrates, protein and ash. Phenols such as hydroxytyrosol (HT) and tyrosol were bound to PPF during the ethyl acetate extraction. Acid hydrolysis (3N HCl for 10min at 100°C) was used to liberate HT from the PPF. The properties of both sorption and desorption of the PPF were studied to enhance the purification of HT, up to 100%. The antioxidant activities of the PPF were evaluated in vitro using ferric reducing power and DPPH radical scavenging, showing activity but lower than HT and TROLOX. The inhibition of primary oxidation of PPF was similar to both HT and vitamin E. These antioxidant activities of the PPF were not a result of the presence of HT or similar phenols. [Copyright &y& Elsevier]

Furans (furfural and hydroxymethylfurfural) are the results of dehydration of monosaccharides, which can be obtained by acid hydrolysis of wood or other lignocellulosic materials. In this work, Pinus pinaster wood was subjected to aqueous autohydrolysis processing to obtain dissolved hemicellulose-derived polymeric or oligomeric saccharides made up of mannosyl, glucosyl, galactosyl, xylosyl, and arabinosyl structural units. The aqueous liquors were then heated in the presence of sulfuric acid and methyl isobutyl ketone to obtain furans. The effects of selected operational variables, such as the ratio of organic to aqueous phase, temperature, and reaction time, were assessed by empirical modeling in terms of the conversion into furans and levulinic acid. The maximum furfural conversion (71.4%) was predicted to occur operating at 165°C and a ratio of organic to aqueous phase of 2 for 68.5 min. In additional experiments, dimethyl sulfoxide and/or 1-butanol were added to the aqueous phase and the change in furan conversion rates was observed. [ABSTRACT FROM AUTHOR]

Olive tree pruning lignin was studied to be considered as a raw material candidate for biorefinery. Different extraction treatments (organosolv treatment: 60% wt ethanol, 180°C, 90 min; alkali treatment: 90 to 100°C, 7.5% wt NaOH, 90 min; and autohydrolysis process: 180°C, 30 min) were applied to extract lignin. The isolated lignins were deeply characterized to study the effect of the applied extraction conditions on lignin properties. Isolated lignins compositions were measured by determining acid insoluble lignin, acid soluble lignin, sugar content, and ash content. Functional groups (carboxyl groups, carbonyl groups, and OH-phenolic groups) were analyzed to evaluate the reactivity of the different lignins. Nitrobenze oxidation, structure analyses (attenuated-total reflection infrared spectroscopy and heteronuclear single quantum coherence) and high performance size exclusion chromatography analyses were carried out to meet olive tree pruning lignin structure. Organosolv treatment yielded the purest lignin while autohydolyisis process yielded medium purity lignin with low molecular weight. Finally, lignin obtained from alkali treatment was very impure and had high inorganic content and sugar contamination. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1187-1194, 2013 [ABSTRACT FROM AUTHOR]

Highlights: [•] Hemicellulose in the raw precursor was substantially reduced by autohydrolysis. [•] Autohydrolysis changed the decomposition mechanism of the AC precursors below 400°C. [•] Autohydrolysis of hardwood increased the surface area of activated carbons produced. [•] Mesopore rich activated carbons were made with pore volumes between 1.3 and 1.5cc/g. [•] Activated carbons with 90% total pore volume in pores ≤6nm were produced. [ABSTRACT FROM AUTHOR]

Highlights: [•] Corn straw (CS) is rich in polysaccharides (71%) of which 41% hemicelluloses. [•] Autohydrolysis is highly selective towards hemicelluloses. [•] High XOS yields are obtained under mild conditions at 215°C and log R 0 =3.75. [•] Cellulose and lignin enriched solid fraction is adequate to further processing. [•] CS and autohydrolysis hold a high potential for biorefineries. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the influence of autohydrolysis on mechanical defibration of Eucalyptus wood chips. The autohydrolysis process changed notably the mechanical properties of Eucalyptus chips. The removal of mainly hemicelluloses undoubtedly decreased the overall pulp yield. Hemicellulose losses cannot be solely accounted for the changes in the wood and pulp properties, because the autohydrolysis also caused changes in lignin. When comparing the mechanical pulp fibers of the original wood chips with the fibers resulting from the autohydrolyzed wood material, it was clear that the rupture point shifted from the secondary wall to the middle lamella, confirmed by X-ray photoelectron spectroscopy measurements. This study revealed the mechanical behavior of autohydrolyzed wood chips and can provide useful information for integration of mechanical pulp mills into the biorefinery concept in the future. [ABSTRACT FROM AUTHOR]

Highlights: [•] P. pinaster wood was subjected to hydrothermal processing under different conditions. [•] The hydrolytic breakdown of polymers was studied by a first order kinetic modeling. [•] The resulting model allowed a close reproduction of the experimental data. [•] The model gives valuable information for process simulation and economic evaluation. [ABSTRACT FROM AUTHOR]

Autohydrolysis is a hot water pretreatment to extract soluble components from wood that can be used prior to converting the woody residuals into paper, wood products, fuel, or other goods. In this study, mixed softwood chips were autohydrolyzed in hot water at 150, 160, 170, and 180 °C for 1 and 2 h residence times. The objective was to understand the tradeoff between the extraction of fermentable sugar and the residual solid total energy of combustion quantitatively. This process strategy will be referred to as 'value prior to combustion'. High-performance liquid chromatography was used to determine chemical compositions (sugars and byproducts such as acetic acid, furfural, and hydroxymethylfurfural) of the extracted liquid and residuals; a bomb calorimeter was used to measure the heating value of original wood and solid residue. As the autohydrolysis temperature increased, material balances of the system indicated higher volatile byproducts loss. More hemicelluloses were solubilized by the hot water extraction process at higher temperatures and longer residence times, and a greater degree of sugar degradation was also observed. The maximum sugar yield was determined to occur at conditions of 170 °C for 2 h, during which 13 g of sugar was recovered from the extract out of 100 g of oven-dried wood. The heating value of the solid residues after extraction was greater than the original wood. The total energy content of the solid residual after extraction ranged from 85 to 98 % of the original energy content of the feed with higher temperatures reducing the total energy content. [ABSTRACT FROM AUTHOR]

Industrial Eucalyptus globulus wood chips were submitted to different autohydrolysis conditions followed by kraft cooking and soda-anthraquinone cooking. The autohydrolyzed wood chips were much easier to delignify than the control wood chips. Soda-anthraquinone cooking could be performed at a cooking temperature that was 20 ° C lower than that for the kraft cooking on control wood chips. Furthermore, the active alkali could be reduced. The resulting unbleached pulps reacted as well to oxygen delignification as the control pulps and could be further bleached to 90 % ISO brightness with a D(EP)D sequence. The autohydrolysis liquors were investigated for their suitability as a source for the synthesis of alkylpolyxylosides (APX). These surface-active agents are synthesized through the reaction between the saccharides of the autohydrolysates and a fatty alcohol, with the former being the hydrophilic and the latter being the hydrophobic part of the molecule. The impact of the substances detected in autohydrolysates on the APX synthesis was studied. It was demonstrated that lignin dissolved during autohydrolysis should at least partially be removed before the production of APX. [ABSTRACT FROM AUTHOR]

Highlights: [•] Bamboo culm was autohydrolyzed to generate xylo-oligosaccharides. [•] The maximum recovery of xylo-oligosaccharides of 47.49% was achieved at 180°C for 30min. [•] The yield and characteristic of xylo-oligosaccharides depend on the autohydrolysis condition. [•] Higher temperature and/or longer reaction time enhance the degradation rate of xylan. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize the changes in lignin structure during hydrothermal pretreatment of shrub Tamarix ramosissima. Lignins in residual wood meal were isolated with alkaline ethanol solution and recovered with acid precipitation. A comparison between the recovered lignin fractions with milled wood lignin has been made in terms of yield, purity, gel permeation chromatography, Fourier transform infrared spectroscopy, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), 1D C and 2D heteronuclear single quantum coherence nuclear magnetic resonance (HSQC NMR) spectroscopic techniques. Semiquantitative HSQC NMR showed that the relative amounts of β-O-4′ (around 76 % side chains) and resinol type substructures (16 %) of lignins were significantly modified during hydrothermal pretreatment. Py-GC/MS analyses brought direct evidences of these lignin samples with high S/G ratios ranging from 1.7 to 2.6. Moreover, the results indicated that an increase in the severity of the hydrothermal pretreatment enhanced the degradation of lignin unit side chains and the condensation of lignin and decreased the molecular weight of the recovered lignin fractions. This study demonstrated that the combination of autohydrolysis and alkaline ethanol process could potentially turn the recovered lignin fractions into value added products being in accordance with the 'biorefinery' concept. [ABSTRACT FROM AUTHOR]

BACKGROUND Ulex europæus ( UE) is a widespread invasive shrub species causing economic problems and environmental hazards. This work deals with the valorization of UE by hydrothermal processing (to obtain hemicelluloses-derived saccharides) followed by simultaneous saccharification and fermentation of the resulting solids for manufacturing second generation bioethanol. RESULTS Hydrothermal processing of UE resulted in the solubilization of up to 21.5 wt% of the oven-dry raw material, leading to the formation of hemicelluloses-derived saccharides as major reaction products. Treatments at various severities resulted in processed solids with enhanced susceptibility to enzymatic hydrolysis, allowing cellulose to glucose conversions up to 87%. Simultaneous saccharification and fermentation of solids pretreated under selected conditions, performed at various charges and solid loadings, resulted in bioethanol conversions up to 82% of the stoichiometric amount, with volumetric concentrations higher than 30 g ethanol L-1. CONCLUSION Hydrothermal processing of UE followed by simultaneous saccharification and fermentation of pretreated solids was suitable for the selective separation of hemicelluloses as soluble saccharides and for the manufacture of second generation bioethanol at high yield from the pretreated solids.© 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: Effect of autohydrolysis and aromatic scavengers on delignification patterns were evaluated using miscanthus (MxG), empty palm fruit bunch (EFB) and typha grass residue as feedstocks. Autohydrolysis was carried out without naphthol and in the presence of naphthol followed by delignification by ethanol organosolv process. Despite their close chemical composition, the three feedstocks demonstrated quite different patterns of delignification under the same condition of pretreatment. Nuclear magnetic resonance (NMR) spectroscopic characterization of ethanol organosolv lignins (EOLs) extracted from the three feedstocks revealed information concerning syringyl, guaiacyl and hydroxyphenyl content (S/G/H ratios) which underpinned the differences among the feedstock behavior. The (S + H)/G ratios for MxG, EFB and typha were determined as ̴1.27, ̴2.33 and 2.70 respectively. The major cause of difference in behavior of feedstock during the pretreatment process was attributed to the variation in lignin composition. A good relationship was observed between S/G ratio and the scavenging effect of 2-naphthol. The effect of four additional aromatic scavengers viz. p-cresol, o-cresol, hydroquinone and dihydroxyanthraquinone (DHAQ) tested in miscanthus demonstrated a significant enhancement on delignification; the effect of p-cresol and DHAQ was tantamount to that of naphthol. Cellulolytic enzyme lignin (CEL) extracted from typha grass was also subjected to 13C NMR characterization in order to obtain a more complete picture of typha lignin. Comparison of NMR spectra of CEL and EOL from TC was performed for determining the processing effect in lignin structure. [Copyright &y& Elsevier]

Abstract: The concept of a biorefinery that integrates processes and technologies for biomass conversion demands efficient utilization of all components. Hydrothermal processing is a potential clean technology to convert raw materials such as lignocellulosic materials and aquatic biomass into bioenergy and high added-value chemicals. In this technology, water at high temperatures and pressures is applied for hydrolysis, extraction and structural modification of materials. This review is focused on providing an updated overview on the fundamentals, modelling, separation and applications of the main components of lignocellulosic materials and conversion of aquatic biomass (macro- and micro- algae) into value-added products. [Copyright &y& Elsevier]

Abstract: The potential of hot water extraction of birch wood to produce highly purified dissolving pulp in a subsequent soda-anthraquinone pulping process was evaluated. After intermediate extraction intensities, pulps with low xylan content (3–5%) and high cellulose yield were successfully produced. Increasing extraction intensity further decreased the xylan content in pulp. However, below a xylan content of 3%, the cellulose yield dramatically decreased. This is believed to be due to cleavage of glycosidic bonds in cellulose during severe hot water extractions, followed by peeling reactions during alkaline pulping. Addition of sodium borohydride as well as increased anthraquinone concentration in the pulping liquor increased the cellulose yield, but had no clear effects on pulp purity and viscosity. The low intrinsic viscosity of pulps produced after severe extraction intensities and soda-anthraquinone pulping corresponded to the viscosity at the leveling-off degree of polymerization, suggesting that nearly all amorphous cellulose had been degraded. [Copyright &y& Elsevier]

Abstract: Samples of Eucalyptus globulus were subjected to isothermal autohydrolysis (temperature: 220–250°C and isothermal residence time 0–60min). The effect of the R 0 factor on the sugar yield and composition of both liquid and solid phases obtained after the treatments has been studied. The furfural concentration and composition has been determined. A central composite experimental design, in conjunction with the neural fuzzy model, was used to the furfural content maximization under isothermal autohydrolysis. A varied range, involving two independent variables at three different levels, was established for each process variable (viz. temperature and autohydrolysis time). The obtained models reproduced the experimental results of the dependent variables with errors below 6%. Under optimum experimental conditions, the yield of furfural (4.4g/100g dry raw material) could be obtained at 60min and 220°C). [Copyright &y& Elsevier]

Novel personal care products are necessary to cope with the growing market demand for sustainable green products. In this context, this work deals with the formulation and fundamental physicochemical and rheological characterization of different natural personal care products using bioactive fractions from Chondrus crispus red macroalgae extracted under optimized green conditions. Body milks, body oils and shampoos were supplemented with soluble extracts with antioxidant features recovered after hydrothermal (200 °C) and microwave (170 °C)- and ultrasound (80 °C)-assisted extraction of the red macroalgae used as raw material. Formulated products were also compared with those prepared using (±)-α-tocopherol and butylhydroxytoluene standards. Body scrubs were formulated with the remaining solids (<2.25%) after microwave hydrodiffusion and gravidity treatment of the macroalgae. Results indicated that selected extracts provided personal care products with similar or even better physicochemical, color and viscous features than those supplemented with (±)-α-tocopherol or butylhydroxytoluene commercial antioxidants. Rheological profiles indicated that it is possible to develop personal care products with adequate viscous behavior (102−105 mPa s, at 1 s−1), comparable with their synthetic counterparts. To conclude, the addition of antioxidant extracts led to lower apparent viscosity values suggesting an advantage from the skin applicability point of view, jointly with the absence of both the hysteresis phenomenon and water syneresis of the proposed formulations.

Miscanthus × giganteus samples were characterized for composition and treated with hot compressed water (hydrothermal or autohydrolysis treatments) at temperatures in the range of 190-240 °C. The liquid phases from treatments were analyzed to assess the breakdown of susceptible polysaccharides into a scope of soluble intermediates and reaction products. The experimental concentration profiles determined for the target compounds (monosaccharides, higher saccharides, acetic acid and sugar-decomposition products) were interpreted using a pseudohomogeneous kinetic mechanism involving 27 reactions, which were governed by kinetic coefficients showing an Arrhenius-type temperature dependence. The corresponding activation energies were calculated and compared with data from the literature. The kinetic equations allowed a quantitative assessment of the experimental results, providing key information for process simulation and evaluation.

The production of xylooligosaccharides (XOS) from Jiuzao was studied using a two-stage process based on autohydrolysis pretreatment followed by enzymatic hydrolysis. Jiuzao was autohydrolyzed under conditions where temperature, time, particle size, and solid-liquid ratio were varied experimentally. Optimal XOS production was obtained from Jiuzao with a >20 mesh particle size treated at 181.5 °C for 20 min with a 1:13.6 solid-liquid ratio. Subsequently, optimal enzymatic hydrolysis conditions for xylanase XynAR were identified as 60 °C, pH 5, and xylanase XynAR loading of 15 U/mL. Using these conditions, a yield of 34.2% XOS was obtained from Jiuzao within 2 h. The process developed in the present study could enable effective and ecofriendly industrial production of XOS from Jiuzao.

The extraction of sulfated polysaccharides (fucoidan) by autohydrolysis (AH) of brown seaweed Fucus vesiculosus was studied. Experimental assays were performed under different conditions of temperature (160 to 200°C) and reaction time (10 to 30 min) according to a 2 central composite design, and the conditions able to maximize the fucoidan yield were selected. The alga degradation and the total sugar yield in the liquor after AH were also determined to each experimental condition. The highest fucoidan yield (∼16.5% w/ w) was obtained when the AH process was performed at 180°C for 20 min. This product was characterized by high-performance liquid chromatography, infrared analysis spectroscopy, and thermal gravimetric analyses, which verified the presence of fucose and galactose as main components (70:30% mol ratio, in average) and an SO content higher than 20%. AH process under optimum reaction conditions was an effective method to recover fucoidan from F. vesiculosus. The use of this technology brings also important advantages from economical and environmental viewpoints since it does not require the use of chemical solvent and generates less waste when compared to conventional extraction procedures. [ABSTRACT FROM AUTHOR]

The effects of hydrothermal treatments of Eucalyptus globulus wood have been evaluated in terms of the solid yield and the composition of the treated wood. The contents of cellulose, xylan, and Klason lignin in treated solids were determined and interpreted by means of kinetic models. Particular attention was paid to the degree of polymerization (DP) lowering of cellulose caused by hydrothermal treatments, which was assessed by measurements of intrinsic viscosity. [ABSTRACT FROM AUTHOR]

Lignocellulosic material from Leucaena leucocephala was subjected to a two-stage fractionation process to obtain a valorized effluent containing hemicellulose derivatives and a solid phase for producing cellulose pulp by conventional soda-anthraquinone delignification. This solid phase allows the production of cellulose pulp, under less rigorous conditions from NaOH-AQ process (177 °C, 21%, 120 min) than without pretreatment delignification (185 °C, 25%, 150 min) and better or similar properties in the paper sheets obtained (yield 27.6 and 34.0%, brightness 39.3 and 31.6% ISO, tensile index 7.8 and 10.5 N m/g, burst index 0.43 and 0.29 MPa m 2 /kg with and without previous autohydrolysis) have be found. Also, the first autohydrolysis stage allows up to 46.6% of the initial hemicellulose in the raw material to be extracted as xylooligomers, xylose and furfural into the liquid phase. [ABSTRACT FROM AUTHOR]

Sargassum muticum is an invasive brown alga which could be regarded as a renewable resource susceptible to fractionation and integral valorization. S. muticum biomass was processed according to a scheme consisting of conventional alkaline extraction of alginate, ultrafiltration to concentrate antioxidant compounds lost in the waste streams and autohydrolysis of the solid residue remaining after alginate extraction. The effect of temperature during non isothermal autohydrolysis was optimized to maximize yields and antioxidant activity of the solubilized fraction. The overall solubilization yield reached 88% of the initial material and the solubilization yield from the alginate-exhausted solid up to 82%. The waste fraction concentrated by membrane technology and that solubilized during autohydrolysis showed radical scavenging and reducing activities comparable to commercial antioxidants. The solid insoluble by-product from the autohydrolysis stage could be potentially useful for agricultural purposes. [ABSTRACT FROM AUTHOR]

Abstract: The production of oligosaccharides (OS) by olive tree pruning autohydrolysis in the range 170–230°C was studied. The best results in terms of maximum yield of OS along with a low amount of byproducts were obtained at 180°C. After purification by preparative gel filtration chromatography a range of OS-fractions with average degree of polymerisation (DP) from 25 to 3 was selected for further characterisation. Gluco- and xylooligosaccharides were the predominant OS in these fractions. OS yields in the range 80–90% were obtained for fractions with average DP between 25 and 7, practically free of low molecular compounds. Both OS total yields and xylooligosaccharides proportion decreased for lower DP fractions while monosaccharides and other products concentrations increased. OS production and the recovery of other high value compounds can be envisaged as an interesting contribution to develop an olive-biomass biorefinery. [Copyright &y& Elsevier]

Abstract: Biomass pretreatment aims at separating and providing easier access to the main biomass components (cellulose, hemicellulose and lignin), eventually removing lignin, preserving the hemicellulose, reducing the cellulose crystallinity and increasing the porosity of the material. Pretreatment is an essential step towards the development and industrialization of efficient 2nd generation lignocellulosic ethanol processes. The present work reviewed the main options available in pretreatment. Autohydrolysis and steam explosion were then selected for further investigation. Experimental work was carried out on batch scale reactors, using Miscanthus as biomass feedstock: the effects on sugar solubilization and degradation products generation have been examined for each of these two pretreatment systems. A new process using only water and steam as reacting media was then developed, experimentally tested, and results compared to those achieved by the autohydrolysis and steam explosion processes. Products obtained with the new pretreatment contained a lower amount of usual fermentation inhibitor compounds compared to that typically obtained in steam explosion. This result was achieved under operating conditions that at the same time allowed a good xylan yield, preventing degradation of hemicelluloses. The new pretreatment process was also able to act as an equalization step, as the solid material from the pretreatment phase had a similar composition even under different operating conditions. As regards the effect of pretreatment on enzymatic hydrolysis, the new process achieved yields similar to steam explosion on glucans: however, this was obtained reducing the formation of degradation products from sugars, mainly from C5 sugars. These results made the proposed pretreatment system suitable for further development and industrialization on pilot and industrial scale. [Copyright &y& Elsevier]

Abstract: Rapid mass spectrometric investigation of oligosaccharides, obtained by autohydrolysis of fucoidans from brown algae Silvetia babingtonii and Fucus evanescens (Fucales, Phaeophyceae) has shown both similarities and differences in structural features/sulfation pattern of their fragments, obtained in the same conditions. Tandem MALDI-TOF MS of fucooligosaccharides with even DP (degree of polymerization) was close to that observed for fucoidan from F. evanescens. Slight differences in tandem mass spectra of fragments with odd DP indicated, probably, sulfation at C-3 (instead of C-2 in F. evanescens) of some (1→4)-linked α-l-Fucp residues and/or the presence of short blocks, built up of (1→3)-linked α-l-Fucp residues. [Copyright &y& Elsevier]

Carbohydrate-containing hydrolysates (1.1 to 14.9% of wood dry matter) obtained from auto hydro lysis (at 130 to 150°C for 30 to 120 minutes) of birch (Betula pendula) chips prior to pulping were purified with respect to non-carbohydrate materials, without carbohydrate losses, either by ethyl acetate extraction or XAD-4 resin treatment. In the former case, about 50% of lignin and practically all the furanoic compounds (2-furaldehyde and 5-(hydroxymethyl)furfural) could be removed, whereas in the latter case, the corresponding amounts were about 30% and 50 to 90%, respectively. A partial recovery of various unsaturated impurities is of importance, because they may act as inhibitors when biochemically converting carbohydrates in hydrolysates into value-added products. [ABSTRACT FROM AUTHOR]

Abstract: Eucalyptus globulus wood samples were subjected to non-isothermal autohydrolysis in order to solubilize hemicelluloses, leading to treated solids of increased cellulose content and enzyme digestibility. Autohydrolyzed solids obtained under a variety of operational conditions were assayed as substrates for bioethanol production by Simultaneous Saccharification and Fermentation (SSF). SSF was optimized using the Response Surface Methodology. The experimental plan included as independent variables the autohydrolysis severity (S o defined as the logarithm of the severity factor), the liquor to solid ratio and the enzyme to substrate ratio. The dependent variables considered were the maximum ethanol concentration achieved in individual experiments, the volumetric productivity, the maximum ethanol conversion, the yield of solids after SSF and the cellulose recovery in solids coming from SSF. Operating at high solids loading (S o =4.67, LSR=4g/g, ESR=16FPU/g), media containing up to 67.4g ethanol/L and corresponding to 91% of the stoichiometric amount calculated from the cellulose content of wood were obtained. Wood processing resulted in the generation of soluble products from hemicelluloses, in the generation of up to 291L ethanol/1000kg oven-dry wood from cellulose, and in a solid material mainly made up of lignin. [Copyright &y& Elsevier]

Abstract: Three different acids (acetic, oxalic and sulfuric acid) were tested for their catalytic activity during the pretreatment of Eucalyptus globulus wood comparatively to autohydrolysis in order to extract valuable products prior to kraft pulping and to reduce lignin precipitation in the pretreatment step. The utilization of oxalic and sulfuric acid reduces treatment temperatures at a given wood yield as compared to autohydrolysis and acetic acid addition and thus decreases the insoluble lignin content in the hydrolyzates. Due to the high temperatures of autohydrolysis xylose dehydration to furfural occurs at high wood yield losses, while during acid catalyzed hydrolysis degradation of cellulose to glucose is more pronounced. The main difference between the acid catalyzed and non-catalyzed reaction constitutes the ratio of monomeric xylose and xylooligosaccharides in solution. [Copyright &y& Elsevier]

Abstract: A combination of two environment-friend processes for hemicelluloses and lignin recovery from red grape stalks were investigated: an autohydrolysis pretreatment at 180°C for 30min followed by a non-catalysed ethanol organosolv step at 180°C for 90min. Hemicelluloses were precipitated by ethanol addition to autohydrolysis liquor, while lignin was tentatively precipitated by acidification of liquors from both the processes. Results suggest that stalks hemicelluloses can be easily hydrolysed requiring a milder treatment to reduce sugar degradation, while the organosolv process did not give a consistent delignification. Autohydrolysis allowed a recovery of 2% (on stalks d.m.) of total phenols in the liquor. Organosolv liquor had a higher concentration of phenols (corresponding to 0.72% of stalks d.m.) which almost completely precipitated with lignin. [Copyright &y& Elsevier]

Abstract: Chestnut is a valuable fruit with traditional food applications due to its nutritional value. The shell accounts for around 10% of the fruit weight and have no commercial applications, so they are destined for fuel. The development of alternative applications for the shells could contribute to valorization of the major constituents and to an integral utilization of renewable resources of low cost and residual origin according to a sustainable development philosophy. Husks come from two different peeling treatments, a dry dehusking process and a wet dehusking process. Husks from the dry process contained more lipophilic compounds as those hulls coming from the wet dehusking process. Treatments of chestnut husks were performed to release tannins and hemicelluloses components. High temperature extraction (HTE) was the selected technology, and aqueous and alkaline media were the solvents chosen. Treatments allowed the solubilisation of 37.7% of the chestnut husks, with maximum values of 55.5% of phenolic compounds solubilisation at treatment temperature of 180°C. The higher antioxidant activity had a maximum value of 1.87g Trolox/gram of extract at 160°C. The extract produced under the optimal processing alkaline conditions was processed by membrane technology and the phenolic concentration in the final product was about 15% higher than the initial phenolic concentration in the hydrolyzates. This product showed an antioxidant activity comparable to that of synthetic antioxidants. [Copyright &y& Elsevier]

Abstract: The enzymatic saccharification kinetics of untreated wheat straw, pretreated solids obtained by a sequence of autohydrolysis (solubilization of hemicellulose) and organosolv (solubilization of lignin) were studied together with two pure cellulose model substrates, filter paper and Avicel. Two kinetic models for glucose production were compared and its kinetic constants calculated. According to the obtained results, enzymatic saccharification of the autohydrolysis pretreated solids (APS) proved to be more effective than when the organosolv pretreated solids (OPS) were used. The maximum extent of the enzymatic conversion of cellulose to glucose was 90.88% and 64.04%, for APS and OPS respectively, at 96h. This result was probably due to an increase in accessible area for APS and a possible inhibition by phenolic acids deposited on the surface of OPS, acting as a barrier for enzymatic saccharification. Initial saccharification rate for APS and OPS was 0.47g/(Lh) and 0.34g/(Lh), respectively. Models based on first and second order cellulase deactivation kinetics satisfactory predicted the behavior of glucose production, however the second order model had a higher accuracy than the first order one. Visualization of structural modification induced by enzymatic saccharification at 12h for the pretreated solids was done using scanning electron microscopy. [Copyright &y& Elsevier]

To improve enzymatic hydrolysis, hydrothermal treatment was carried out on the shrub Tamarix ramosissima. Milled wood lignin (MWL) was isolated from T. ramosissima stems before and after hydrothermal treatment, and its chemical structure was characterized by carbohydrate analysis, elemental analysis, methoxy group determination, FT-IR spectroscopy, quantitative 13C NMR spectroscopy, 2D heteronuclear single quantum coherence spectroscopy, and gel permeation chromatography. The analyses confirmed that T. ramosissima MWL is very rich in syringyl units. It was found that the main reaction responsible for the lignin degradation is the homolytic cleavage of aryl-ether bonds resulting in a reduced amount of β-O-4′ interlinkages and, as a consequence, in elevated amounts of β-β′ and β-5′ linkages. The MWL isolated from the pretreated solid residue was more condensed and had a lower molecular weight than the MWL isolated from untreated material. [ABSTRACT FROM AUTHOR]

Abstract: Wood from the leguminous tree, Leucaena diversifolia, was subjected to hydrothermal treatment (autohydrolysis) at 160–180°C for 0–30min followed by ethanol–soda–anthraquinone delignification. The liquid phase contained 18.65g of sugars per liter, and the solid phase had a gross heating value of 19.083MJ/kg, but could also be used as a source of cellulose pulp for the production of paper with tear, burst, and tensile indexes of 2.4Nm2/kg, 2.6MPam2/kg and 40.7kNm/kg, respectively. L. diversifolia lends itself readily to valorization for energy production, and also to integral, fractional exploitation by autohydrolysis and ethanol–soda–anthraquinone delignification, which can additionally bring environmental benefits to cropping zones. [Copyright &y& Elsevier]