Gil Garrote - Academia.edu (original) (raw)

Papers by Gil Garrote

Methods: Oat straw was subjected to lime pretreatment at liquid to solid ratio of 10 g/g. The fol... more Methods: Oat straw was subjected to lime pretreatment at liquid to solid ratio of 10 g/g. The following operational conditions of lime pretreatment were evaluated: temperature (in the range 90-134 oC), time (30-120 min) and Ca(OH)2/g (01-04 g/g). The pretreated oat straw was recovered by filtration, washed until pH=7 and analysed for chemical composition. The enzymatic susceptibility of lime pretreated solids was evaluated under favourable conditions of solid and enzymes loadings (25 g/g and 25 FPU of CellicTec2/g). Selected condition of lime pretreatment (134 oC, 30 min and 0.1 g of Ca(OH)2/g of oat straw) was used for the bioethanol production by simultaneous saccharification and fermentation (14 % of solids and 20 FPU/g) using an industrial Saccharomyces cerevisiae PE-2 strain and its metabolic engineered version (MEC1133) for xylose consumption.

Susana Peleteiro *; Lucia Penin; Aloia Romani; Gil Garrote and Juan Carlos Parajo Chemical Engine... more Susana Peleteiro *; Lucia Penin; Aloia Romani; Gil Garrote and Juan Carlos Parajo Chemical Engineering Department, Science Faculty, University of Vigo, Ourense, Spain and CITI (Centro de Investigacion, Transferencia e Innovacion) – University of Vigo, Tecnopole, San Cibrao das Vinas, Ourense, Spain Phone: +34988387075, Fax: +34988387001, e-mail: speleteiro@uvigo.es 2Biological Engineering Center (CEB), Campus Gualtar, University of Minho, Portugal.

Romani, Aloia1; Peleteiro Susana2; Garrote, Gil2*; Ballesteros, Ignacio3, Ballesteros, Mercedes3 ... more Romani, Aloia1; Peleteiro Susana2; Garrote, Gil2*; Ballesteros, Ignacio3, Ballesteros, Mercedes3 and Parajo, Juan Carlos2 1Biological Engineering Center (CEB), Campus Gualtar, University of Minho, Portugal. 2Chemical Engineering Department, Science Faculty, Campus Ourense, University of Vigo, Spain 3Renewable Energies Department, CIEMAT, Research Centre for Energy, Environment and Technology, Madrid, Spain Phone: +34988387075, Fax: +34988387001, e-mail: gil@uvigo.es

Currently, the high demand of energy has led to the seek of new renewable sources, cutting down w... more Currently, the high demand of energy has led to the seek of new renewable sources, cutting down with fossil fuels. An interesting and novel way may be the use of macoralgae as raw material to obtain third generation bioethanol. Sargassum muticum is an invasive seaweed highly spread in Asia, Europe and America, which has not been commercially used yet. It has an abundant quantity of polysaccharides which can be used in the production of biofuels. In order to employ them, it is necessary to pretreat the material, and the hydrothermal treatments (as autohydrolysis) have demonstrated to be highly effective, simple, environmentally friendly and economic. In this work, the study of the autohydrolysis of Sargassum muticum has been studied. Consequently, Simultaneous Saccharification and Fermentation took place, using different industrial strains of Saccharomyces cerevisiae and two type of experiments: i) using only the autohydrolyzed solid phase, ii) using the liquid and solid phase from the autohydrolysis procedure.

Bioresource Technology, 2021

• Hydrothermal treatment was proposed as first stage of hardwood biorefinery. • Hydrothermal trea... more • Hydrothermal treatment was proposed as first stage of hardwood biorefinery. • Hydrothermal treatment allows the biofuel production coupled with oligosaccharides. • Hydrothermal treatment at high severity conditions improves enzymatic hydrolysis. • Combined processes allow the integral valorization of hardwoods. • The search for strategies that contribute to biorefinery feasibility is necessary.

Applied Energy, 2017

h i g h l i g h t s Autohydrolysis of Paulownia biomass was studied as first step of a biorefiner... more h i g h l i g h t s Autohydrolysis of Paulownia biomass was studied as first step of a biorefinery. At S 0 = 4.19, 78.9% of xylan was recovered as xylose and xylooligosaccharides. At S 0 = 4.19, 47% higher ethanol concentration was achieved by SHF than SSF. At S 0 = 4.72, 52.7 g/L of ethanol (80% of conversion) was obtained by SSF. An energy production of 648,074 MJ/ haÁyear could be produced from this process. g r a p h i c a l a b s t r a c t Cellulose 39.73 g/100 g RM Hemicellulose 17.98 g/100 g RM • 14.69 g Xylan/100 g RM • 3.29 g Acetyl groups/100 g RM Lignin 21.84 g /100 g RM

Carbohydrate polymers, Aug 1, 2016

Eucalyptus globulus wood samples were treated with hot, compressed water to separate hemicellulos... more Eucalyptus globulus wood samples were treated with hot, compressed water to separate hemicelluloses (as soluble saccharides) from a solid phase mainly made up of cellulose and lignin. The liquid phase was dehydrated, and the resulting solids (containing pentoses as well as poly- and oligo- saccharides made up of pentoses) were dissolved and reacted in media containing an Acidic Ionic Liquid (1-butyl-3-methylimidazolium hydrogen sulfate) and a co-solvent (dioxane). The effects of the reaction time on the product distribution were studied at temperatures in the range 120-170°C for reaction times up to 8h, and operational conditions leading to 59.1% conversion of the potential substrates (including pentoses and pentose structural units in oligo- and poly- saccharides) into furfural were identified.

Bioresource technology, 2016

The aim of this work was the evaluation of lime pretreatment combined or not with previous step o... more The aim of this work was the evaluation of lime pretreatment combined or not with previous step of autohydrolysis for oat straw valorization. Under selected conditions of lime pretreatment, 96% of glucan and 77% of xylan were recovered and 42% of delignification was achieved. Xylose fermentation to ethanol by metabolic engineered Saccharomyces cerevisiae (MEC1133) strain improved the ethanol production by 22% achieving 41g/L. Alternatively, first step of autohydrolysis (S0=4.22) allowed a high oligosaccharides recovery (68%) and subsequent lime pretreatment attained a 57% of delignification and 99% of glucan to glucose conversion. Oat straw processed by autohydrolysis and lime pretreatment reached the maximal ethanol concentration (50g/L). Both strategies led to oat straw valorization into bioethanol, oligosaccharides and lignin indicating that these pretreatments are adequate as a first stage within an oat straw biorefinery.

Industrial & Engineering Chemistry Research, 2015

The acidic 1-butyl-3-methylimidazolium hydrogen sulfate ([bmim][HSO 4 ]) ionic liquid was explore... more The acidic 1-butyl-3-methylimidazolium hydrogen sulfate ([bmim][HSO 4 ]) ionic liquid was explored as both a reaction medium and a catalyst in the furfural production from xylose. Preliminary experiments were carried out at 100−140°C for 15−480 min in systems containing just xylose dissolved in [bmim][HSO 4 ] in the absence of externally added catalysts. More than 95% xylose conversion was achieved when operating at 120 or 140°C for 300 and 90 min, respectively; but just 36.7% of the initial xylose was converted to furfural. Operation in biphasic reaction systems (in the presence of toluene, methyl-isobutyl ketone or dioxane as extraction solvents) at 140°C under selected conditions resulted in improved furfural production (73.8%, 80.3%, and 82.2% xylose conversion to furfural for the cited extraction solvents, respectively).

GCB Bioenergy, 2014

Sweet corn is a widely distributed crop that generates agricultural waste without significant com... more Sweet corn is a widely distributed crop that generates agricultural waste without significant commercial value. In this study, we show that sweet corn varieties produce large amounts of residual biomass (10 t ha À1) with high content of soluble sugars (25% of dry matter) in a short growing season (3 months). The potential ethanol production from structural and soluble sugars extracted from sweet corn stover reached up to 4400 l ha À1 in the most productive hybrids, 33% of which (1500 l ha À1) were obtained by direct fermentation of free sugars. We found wide genetic variation for biomass yield and soluble sugars content suggesting that those traits can be included as complementary traits in sweet corn breeding programs. Dual-purpose sweet corn hybrids can have an added value for the farmers contributing to energy generation without affecting food supply or the environment.

Trends in Food Science & Technology, 2004

Mild acid treatments of lignocellulosic materials result in hemicellulose conversion into sugar a... more Mild acid treatments of lignocellulosic materials result in hemicellulose conversion into sugar and sugar oligomers as well as in solubilization of phenolic compounds with potential food applications. The effect of the operational conditions (measured by the severity factor) on the yield of soluble phenolics and the utilization of these compounds (with antioxidant and antimicrobial activities) as food additives are reviewed. Additional information on other biological effects of phenolics that could be of interest for the formulation of functional foods is provided.

Trends in Food Science & Technology, 2004

The composition of xylan-containing raw materials (Eucalyptus globulus wood, corn cobs, rice husk... more The composition of xylan-containing raw materials (Eucalyptus globulus wood, corn cobs, rice husks and barley husks) has been determined, and substituted xylooligosaccharides (SXO) have been produced by reacting them with water (autohydrolysis reaction) under optimal conditions deduced from reported kinetic models. The composition of autohydrolysis liquors (defined by their contents of xylooligosaccharides, other sugar oligomers, monosaccharides, acetyl and uronic acid substituents of oligomers, free acetic acid, furfural, Folin-Denis phenols and other compounds) has been determined. The suitability of autohydrolysis reaction products for the manufacture of food ingredients is discussed.

Journal of Food Engineering, 2002

Corncob samples were treated with water (autohydrolysis reaction) under non-isothermal conditions... more Corncob samples were treated with water (autohydrolysis reaction) under non-isothermal conditions (reaction temperature up to 216°C) using a liquid to solid ratio of 8:1 kg/kg. The experimental variables considered were solid residue yield, solid residue composition (defined by the contents of cellulose, xylan, araban, acetyl groups and lignin in the solid residues) and composition of liquors (characterised by the concentrations of xylooligomers, xylose, glucose, arabinose, acetic acid and furfural). Most of the cellulose was retained in the solid phase, whereas partial delignification (up to 26% lignin removal) was achieved. Up to 94% of xylan was removed, producing xylooligomers (useful as food additives) and other reaction byproducts (including xylose and furfural). The decomposition of xylan into xylooligomers, with further generation of xylose, furfural and degradation products, was modelled by a series of parallel and consecutive reactions, which were assumed to be first order with coefficients showing an Arrhenius-type dependence on temperature.

Journal of Chemical Technology & Biotechnology, 1999

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Journal of Chemical Technology & Biotechnology, 2003

Non-isothermal processing of lignocellulosic materials in aqueous media (autohydrolysis reaction)... more Non-isothermal processing of lignocellulosic materials in aqueous media (autohydrolysis reaction) under mild conditions leads to solutions containing valuable chemicals (oligosaccharides, sugars and acetic acid) and other, undesired, compounds (belonging to the extractive and acid-soluble lignin fractions) which have to be removed in further purification treatments. Liquors obtained by non-isothermal autohydrolysis of Eucalyptus globulus wood and corncobs under a variety of operational conditions were extracted with ethyl acetate in order to remove non-saccharide components, and the suitability of the fraction dissolved in the organic phase was assayed for possible utilisation as an antioxidant. The yield and antioxidant activity of ethyl acetate extracts (measured by the a,a-diphenyl-b-picrylhydrazyl (DPPH) radical scavenging capacity) showed a strong dependence on the autohydrolysis conditions. The antioxidant activity of extracts obtained under selected operational conditions compared well with synthetic antioxidants.

Journal of Agricultural and Food Chemistry, 2007

Eucalyptus globulus wood samples were reacted in aqueous media (hydrothermal treatments) at 160°C... more Eucalyptus globulus wood samples were reacted in aqueous media (hydrothermal treatments) at 160°C for 30-66 min. Liquors from the several experiments were analyzed by spectrophotometry, high-performance liquid chromatography, or gas chromatography-mass spectrometry for monosaccharides, oligosaccharides, oligosaccharide substituents (arabinose moieties, uronic acids, and acetyl groups), acetic acid, furfural, hydroxymethylfurfural, and dichloromethane-soluble compounds. Individual components of this latter fraction were identified and quantified. The molecular weight distribution of oligosaccharides was studied by high-performance size exclusion chromatography. The kinetics of xylan conversion into high-, medium-, and low-molecular-weight products was assessed in terms of the severity factor and by pseudohomogeneous kinetic models.

Industrial Crops and Products, 2014

Corn stover was used for manufacturing 2nd generation bioethanol following a biorefinery scheme b... more Corn stover was used for manufacturing 2nd generation bioethanol following a biorefinery scheme based on fractionation by autohydrolysis and further Simultaneous Saccharification and Fermentation (SSF) of pretreated solids. Autohydrolysis was performed under a wide range of severities to identify conditions leading simultaneously to a liquid phase containing hemicellulosic saccharides (accounting for up to 68% of initial xylan) and to a solid phase with high enzymatic susceptibility. SSF experiments were carried out under a variety of experimental conditions to assess the effects of the major operational variables. The glucan conversion into ethanol reached values up to 86%, with a bioethanol concentration of 37.8 g/L. Fed-batch operation in the SSF stage allowed the utilization of higher solid loadings, allowing an increase in the bioethanol concentration up to 51.6 g/L, or to reduce the amount of enzymes needed for reaching a given conversion.

Industrial & Engineering Chemistry Research, 2009

... arabinooligosaccharides (ArO, expressed as g equiv arabinan/100 g oven-dried raw material,. •... more ... arabinooligosaccharides (ArO, expressed as g equiv arabinan/100 g oven-dried raw material,. • acetyl groups bound to oligomers (AcO, expressed as g/100 g oven-dried raw material). ... ArO decompose into arabinose (Ar), which can be converted into furfural. ...

Industrial & Engineering Chemistry Research, 2010

Hydrothermal processing of Eucalyptus globulus wood was evaluated as a pretreatment for bioethano... more Hydrothermal processing of Eucalyptus globulus wood was evaluated as a pretreatment for bioethanol manufacture, to assess the effects caused by the severity of wood solubilization, composition of liquors, and spent solid and suceptibility of substrates toward enzymatic hydrolysis. A factorial design was employed to assess the hydrolysis kinetics of spent solids. The liquor to solid ratio (6-20 g/g) and the enzyme to substrate ratio (8-28 FPU/g) were considered as independent variables. Generalized empirical models suitable for predicting glucose concentrations were developed. Using selected substrates and hydrolysis conditions (LSR) 6 g/g, ESR) 28 FPU/g), media containing more than 82 g glucose/L were obtained (with cellulose-toglucose conversions of 75-80%), whereas cellulose-to-glucose conversions of 80-100% were obtained under a variety of experimental conditions.

Industrial & Engineering Chemistry Research, 2004

... Gil Garrote, Herminia Domínguez, and Juan Carlos Parajó*. Department of Chemical Engineering,... more ... Gil Garrote, Herminia Domínguez, and Juan Carlos Parajó*. Department of Chemical Engineering, University of Vigo (Campus Ourense), Polytechnical Building, As Lagoas, 32004 Ourense, Spain. Ind. Eng. ... of rice husks in aqueous media: a kinetic assessment. Collect. Czech. ...

Methods: Oat straw was subjected to lime pretreatment at liquid to solid ratio of 10 g/g. The fol... more Methods: Oat straw was subjected to lime pretreatment at liquid to solid ratio of 10 g/g. The following operational conditions of lime pretreatment were evaluated: temperature (in the range 90-134 oC), time (30-120 min) and Ca(OH)2/g (01-04 g/g). The pretreated oat straw was recovered by filtration, washed until pH=7 and analysed for chemical composition. The enzymatic susceptibility of lime pretreated solids was evaluated under favourable conditions of solid and enzymes loadings (25 g/g and 25 FPU of CellicTec2/g). Selected condition of lime pretreatment (134 oC, 30 min and 0.1 g of Ca(OH)2/g of oat straw) was used for the bioethanol production by simultaneous saccharification and fermentation (14 % of solids and 20 FPU/g) using an industrial Saccharomyces cerevisiae PE-2 strain and its metabolic engineered version (MEC1133) for xylose consumption.

Susana Peleteiro *; Lucia Penin; Aloia Romani; Gil Garrote and Juan Carlos Parajo Chemical Engine... more Susana Peleteiro *; Lucia Penin; Aloia Romani; Gil Garrote and Juan Carlos Parajo Chemical Engineering Department, Science Faculty, University of Vigo, Ourense, Spain and CITI (Centro de Investigacion, Transferencia e Innovacion) – University of Vigo, Tecnopole, San Cibrao das Vinas, Ourense, Spain Phone: +34988387075, Fax: +34988387001, e-mail: speleteiro@uvigo.es 2Biological Engineering Center (CEB), Campus Gualtar, University of Minho, Portugal.

Romani, Aloia1; Peleteiro Susana2; Garrote, Gil2*; Ballesteros, Ignacio3, Ballesteros, Mercedes3 ... more Romani, Aloia1; Peleteiro Susana2; Garrote, Gil2*; Ballesteros, Ignacio3, Ballesteros, Mercedes3 and Parajo, Juan Carlos2 1Biological Engineering Center (CEB), Campus Gualtar, University of Minho, Portugal. 2Chemical Engineering Department, Science Faculty, Campus Ourense, University of Vigo, Spain 3Renewable Energies Department, CIEMAT, Research Centre for Energy, Environment and Technology, Madrid, Spain Phone: +34988387075, Fax: +34988387001, e-mail: gil@uvigo.es

Currently, the high demand of energy has led to the seek of new renewable sources, cutting down w... more Currently, the high demand of energy has led to the seek of new renewable sources, cutting down with fossil fuels. An interesting and novel way may be the use of macoralgae as raw material to obtain third generation bioethanol. Sargassum muticum is an invasive seaweed highly spread in Asia, Europe and America, which has not been commercially used yet. It has an abundant quantity of polysaccharides which can be used in the production of biofuels. In order to employ them, it is necessary to pretreat the material, and the hydrothermal treatments (as autohydrolysis) have demonstrated to be highly effective, simple, environmentally friendly and economic. In this work, the study of the autohydrolysis of Sargassum muticum has been studied. Consequently, Simultaneous Saccharification and Fermentation took place, using different industrial strains of Saccharomyces cerevisiae and two type of experiments: i) using only the autohydrolyzed solid phase, ii) using the liquid and solid phase from the autohydrolysis procedure.

Bioresource Technology, 2021

• Hydrothermal treatment was proposed as first stage of hardwood biorefinery. • Hydrothermal trea... more • Hydrothermal treatment was proposed as first stage of hardwood biorefinery. • Hydrothermal treatment allows the biofuel production coupled with oligosaccharides. • Hydrothermal treatment at high severity conditions improves enzymatic hydrolysis. • Combined processes allow the integral valorization of hardwoods. • The search for strategies that contribute to biorefinery feasibility is necessary.

Applied Energy, 2017

h i g h l i g h t s Autohydrolysis of Paulownia biomass was studied as first step of a biorefiner... more h i g h l i g h t s Autohydrolysis of Paulownia biomass was studied as first step of a biorefinery. At S 0 = 4.19, 78.9% of xylan was recovered as xylose and xylooligosaccharides. At S 0 = 4.19, 47% higher ethanol concentration was achieved by SHF than SSF. At S 0 = 4.72, 52.7 g/L of ethanol (80% of conversion) was obtained by SSF. An energy production of 648,074 MJ/ haÁyear could be produced from this process. g r a p h i c a l a b s t r a c t Cellulose 39.73 g/100 g RM Hemicellulose 17.98 g/100 g RM • 14.69 g Xylan/100 g RM • 3.29 g Acetyl groups/100 g RM Lignin 21.84 g /100 g RM

Carbohydrate polymers, Aug 1, 2016

Eucalyptus globulus wood samples were treated with hot, compressed water to separate hemicellulos... more Eucalyptus globulus wood samples were treated with hot, compressed water to separate hemicelluloses (as soluble saccharides) from a solid phase mainly made up of cellulose and lignin. The liquid phase was dehydrated, and the resulting solids (containing pentoses as well as poly- and oligo- saccharides made up of pentoses) were dissolved and reacted in media containing an Acidic Ionic Liquid (1-butyl-3-methylimidazolium hydrogen sulfate) and a co-solvent (dioxane). The effects of the reaction time on the product distribution were studied at temperatures in the range 120-170°C for reaction times up to 8h, and operational conditions leading to 59.1% conversion of the potential substrates (including pentoses and pentose structural units in oligo- and poly- saccharides) into furfural were identified.

Bioresource technology, 2016

The aim of this work was the evaluation of lime pretreatment combined or not with previous step o... more The aim of this work was the evaluation of lime pretreatment combined or not with previous step of autohydrolysis for oat straw valorization. Under selected conditions of lime pretreatment, 96% of glucan and 77% of xylan were recovered and 42% of delignification was achieved. Xylose fermentation to ethanol by metabolic engineered Saccharomyces cerevisiae (MEC1133) strain improved the ethanol production by 22% achieving 41g/L. Alternatively, first step of autohydrolysis (S0=4.22) allowed a high oligosaccharides recovery (68%) and subsequent lime pretreatment attained a 57% of delignification and 99% of glucan to glucose conversion. Oat straw processed by autohydrolysis and lime pretreatment reached the maximal ethanol concentration (50g/L). Both strategies led to oat straw valorization into bioethanol, oligosaccharides and lignin indicating that these pretreatments are adequate as a first stage within an oat straw biorefinery.

Industrial & Engineering Chemistry Research, 2015

The acidic 1-butyl-3-methylimidazolium hydrogen sulfate ([bmim][HSO 4 ]) ionic liquid was explore... more The acidic 1-butyl-3-methylimidazolium hydrogen sulfate ([bmim][HSO 4 ]) ionic liquid was explored as both a reaction medium and a catalyst in the furfural production from xylose. Preliminary experiments were carried out at 100−140°C for 15−480 min in systems containing just xylose dissolved in [bmim][HSO 4 ] in the absence of externally added catalysts. More than 95% xylose conversion was achieved when operating at 120 or 140°C for 300 and 90 min, respectively; but just 36.7% of the initial xylose was converted to furfural. Operation in biphasic reaction systems (in the presence of toluene, methyl-isobutyl ketone or dioxane as extraction solvents) at 140°C under selected conditions resulted in improved furfural production (73.8%, 80.3%, and 82.2% xylose conversion to furfural for the cited extraction solvents, respectively).

GCB Bioenergy, 2014

Sweet corn is a widely distributed crop that generates agricultural waste without significant com... more Sweet corn is a widely distributed crop that generates agricultural waste without significant commercial value. In this study, we show that sweet corn varieties produce large amounts of residual biomass (10 t ha À1) with high content of soluble sugars (25% of dry matter) in a short growing season (3 months). The potential ethanol production from structural and soluble sugars extracted from sweet corn stover reached up to 4400 l ha À1 in the most productive hybrids, 33% of which (1500 l ha À1) were obtained by direct fermentation of free sugars. We found wide genetic variation for biomass yield and soluble sugars content suggesting that those traits can be included as complementary traits in sweet corn breeding programs. Dual-purpose sweet corn hybrids can have an added value for the farmers contributing to energy generation without affecting food supply or the environment.

Trends in Food Science & Technology, 2004

Mild acid treatments of lignocellulosic materials result in hemicellulose conversion into sugar a... more Mild acid treatments of lignocellulosic materials result in hemicellulose conversion into sugar and sugar oligomers as well as in solubilization of phenolic compounds with potential food applications. The effect of the operational conditions (measured by the severity factor) on the yield of soluble phenolics and the utilization of these compounds (with antioxidant and antimicrobial activities) as food additives are reviewed. Additional information on other biological effects of phenolics that could be of interest for the formulation of functional foods is provided.

Trends in Food Science & Technology, 2004

The composition of xylan-containing raw materials (Eucalyptus globulus wood, corn cobs, rice husk... more The composition of xylan-containing raw materials (Eucalyptus globulus wood, corn cobs, rice husks and barley husks) has been determined, and substituted xylooligosaccharides (SXO) have been produced by reacting them with water (autohydrolysis reaction) under optimal conditions deduced from reported kinetic models. The composition of autohydrolysis liquors (defined by their contents of xylooligosaccharides, other sugar oligomers, monosaccharides, acetyl and uronic acid substituents of oligomers, free acetic acid, furfural, Folin-Denis phenols and other compounds) has been determined. The suitability of autohydrolysis reaction products for the manufacture of food ingredients is discussed.

Journal of Food Engineering, 2002

Corncob samples were treated with water (autohydrolysis reaction) under non-isothermal conditions... more Corncob samples were treated with water (autohydrolysis reaction) under non-isothermal conditions (reaction temperature up to 216°C) using a liquid to solid ratio of 8:1 kg/kg. The experimental variables considered were solid residue yield, solid residue composition (defined by the contents of cellulose, xylan, araban, acetyl groups and lignin in the solid residues) and composition of liquors (characterised by the concentrations of xylooligomers, xylose, glucose, arabinose, acetic acid and furfural). Most of the cellulose was retained in the solid phase, whereas partial delignification (up to 26% lignin removal) was achieved. Up to 94% of xylan was removed, producing xylooligomers (useful as food additives) and other reaction byproducts (including xylose and furfural). The decomposition of xylan into xylooligomers, with further generation of xylose, furfural and degradation products, was modelled by a series of parallel and consecutive reactions, which were assumed to be first order with coefficients showing an Arrhenius-type dependence on temperature.

Journal of Chemical Technology & Biotechnology, 1999

Skip to Main Content. ...

Journal of Chemical Technology & Biotechnology, 2003

Non-isothermal processing of lignocellulosic materials in aqueous media (autohydrolysis reaction)... more Non-isothermal processing of lignocellulosic materials in aqueous media (autohydrolysis reaction) under mild conditions leads to solutions containing valuable chemicals (oligosaccharides, sugars and acetic acid) and other, undesired, compounds (belonging to the extractive and acid-soluble lignin fractions) which have to be removed in further purification treatments. Liquors obtained by non-isothermal autohydrolysis of Eucalyptus globulus wood and corncobs under a variety of operational conditions were extracted with ethyl acetate in order to remove non-saccharide components, and the suitability of the fraction dissolved in the organic phase was assayed for possible utilisation as an antioxidant. The yield and antioxidant activity of ethyl acetate extracts (measured by the a,a-diphenyl-b-picrylhydrazyl (DPPH) radical scavenging capacity) showed a strong dependence on the autohydrolysis conditions. The antioxidant activity of extracts obtained under selected operational conditions compared well with synthetic antioxidants.

Journal of Agricultural and Food Chemistry, 2007

Eucalyptus globulus wood samples were reacted in aqueous media (hydrothermal treatments) at 160°C... more Eucalyptus globulus wood samples were reacted in aqueous media (hydrothermal treatments) at 160°C for 30-66 min. Liquors from the several experiments were analyzed by spectrophotometry, high-performance liquid chromatography, or gas chromatography-mass spectrometry for monosaccharides, oligosaccharides, oligosaccharide substituents (arabinose moieties, uronic acids, and acetyl groups), acetic acid, furfural, hydroxymethylfurfural, and dichloromethane-soluble compounds. Individual components of this latter fraction were identified and quantified. The molecular weight distribution of oligosaccharides was studied by high-performance size exclusion chromatography. The kinetics of xylan conversion into high-, medium-, and low-molecular-weight products was assessed in terms of the severity factor and by pseudohomogeneous kinetic models.

Industrial Crops and Products, 2014

Corn stover was used for manufacturing 2nd generation bioethanol following a biorefinery scheme b... more Corn stover was used for manufacturing 2nd generation bioethanol following a biorefinery scheme based on fractionation by autohydrolysis and further Simultaneous Saccharification and Fermentation (SSF) of pretreated solids. Autohydrolysis was performed under a wide range of severities to identify conditions leading simultaneously to a liquid phase containing hemicellulosic saccharides (accounting for up to 68% of initial xylan) and to a solid phase with high enzymatic susceptibility. SSF experiments were carried out under a variety of experimental conditions to assess the effects of the major operational variables. The glucan conversion into ethanol reached values up to 86%, with a bioethanol concentration of 37.8 g/L. Fed-batch operation in the SSF stage allowed the utilization of higher solid loadings, allowing an increase in the bioethanol concentration up to 51.6 g/L, or to reduce the amount of enzymes needed for reaching a given conversion.

Industrial & Engineering Chemistry Research, 2009

... arabinooligosaccharides (ArO, expressed as g equiv arabinan/100 g oven-dried raw material,. •... more ... arabinooligosaccharides (ArO, expressed as g equiv arabinan/100 g oven-dried raw material,. • acetyl groups bound to oligomers (AcO, expressed as g/100 g oven-dried raw material). ... ArO decompose into arabinose (Ar), which can be converted into furfural. ...

Industrial & Engineering Chemistry Research, 2010

Hydrothermal processing of Eucalyptus globulus wood was evaluated as a pretreatment for bioethano... more Hydrothermal processing of Eucalyptus globulus wood was evaluated as a pretreatment for bioethanol manufacture, to assess the effects caused by the severity of wood solubilization, composition of liquors, and spent solid and suceptibility of substrates toward enzymatic hydrolysis. A factorial design was employed to assess the hydrolysis kinetics of spent solids. The liquor to solid ratio (6-20 g/g) and the enzyme to substrate ratio (8-28 FPU/g) were considered as independent variables. Generalized empirical models suitable for predicting glucose concentrations were developed. Using selected substrates and hydrolysis conditions (LSR) 6 g/g, ESR) 28 FPU/g), media containing more than 82 g glucose/L were obtained (with cellulose-toglucose conversions of 75-80%), whereas cellulose-to-glucose conversions of 80-100% were obtained under a variety of experimental conditions.

Industrial & Engineering Chemistry Research, 2004

... Gil Garrote, Herminia Domínguez, and Juan Carlos Parajó*. Department of Chemical Engineering,... more ... Gil Garrote, Herminia Domínguez, and Juan Carlos Parajó*. Department of Chemical Engineering, University of Vigo (Campus Ourense), Polytechnical Building, As Lagoas, 32004 Ourense, Spain. Ind. Eng. ... of rice husks in aqueous media: a kinetic assessment. Collect. Czech. ...