Acetyl Content Research Articles

Effect of Soxhlet Method Extraction on Characterization of Pectin of Pumpkin Peels

With the present study was focused on the potential of pumpkin peel as a source of pectin, it was aim to determine a pratical follow-up to the extraction of pectin from pumpkin peels Extraction (Cucurbita spp.) using soxhlet with two different acids. Moreover to investigate the influence of time on pectin yield and to characterize the output, determinations were performed of methoxyl content, acetyl content, equivalent weight and degree of esterification in a laboratory, on a small scale. The result showed higher average yield of pectin obtained by using soxhlet acid extraction (7.72% for nitric acid and 6.80% for citric acid), while the lower yield were obtained with acid extraction without using soxhlet (6.24% for nitric acid and 5.36% for citric acid). Equivalent weight and acetyl contain of extracted pectin with both nitric and citric acids were (1250 g/mol and 0.43) respectively, while methoxyl content was (6.20% and 7.23 %), the degree of esterification was (66.53% and 66.57%) for nitric and citric acid respectively. The results showed that pumpkin peels are a promising commercial source of pectin.

Production and Rheological Properties of Welan Gum Produced by Sphingomonas sp. ATCC 31555 with Different Nitrogen Sources

This study aimed to investigate the effect of nitrogen sources on the production and rheological properties of welan gum produced by Sphingomonas sp. ATCC 31555. Six different nitrogen sources were used for ATCC 31555 fermentation, and 2 of these were further analyzed due to their more positive influence on welan gum production and bacterial biomass. Bacterial biomass, welan gum yield, welan viscosity, molecular weight, monosaccharide composition, acyl content, and welan structure were analyzed. Welan gum production and the biomass concentration of ATCC 31555 were higher in media containing NaNO₃ and beef extract. Welan viscosity decreased at higher temperatures of 30-90°C, and it increased with a higher welan concentration. In the media containing NaNO₃ (3 g·L^-1), welan viscosity was higher at 30-70°C and a welan solution concentration of 6-10 g·L^-1. With a reduced NaNO₃ concentration, the molecular weight of welan gum and the molar ratio of mannose decreased, but the molar ratio of glucuronic acid increased. With different nitrogen sources, the acetyl content of welan gum differed but its structure was similar. NaNO₃ and beef extract facilitated welan production. A reduced NaNO₃ concentration promoted welan viscosity.

Process for producing acetic acid in hardwood kraft pulp mills

To determine the economic feasibility of producing acetic acid from commercial hardwood chips in kraft pulp mills, laboratory experiments were conducted to obtain sufficient data to perform a preliminary economic analysis for a proposed acetic acid recovery process. The acetyl groups in northeast hardwood were hydrolyzed from the xylan polymers in the wood to obtain sodium acetate. The extraction experiments were performed by using 4%–6% sodium hydroxide at low temperature (50°C–80°C). Sodium acetate from the extract was concentrated and then converted into acetic acid and sodium hydroxide by salt splitting using bipolar membrane electrodialysis (BPMED). Flow diagrams were prepared and cost estimates made for the capital and operating costs for the proposed acetic acid recovery process. The discounted cash flow rate of return on investment was estimated for pulp mills in the range of 1000–2000 tons/day. A preliminary economic analysis showed that the discounted cash flow rate of return on investment is primarily a function of (1) the plant size, (2) the selling price of acetic acid, and (3) the content of acetyl groups present in wood species. The income for the process and thus the rate of return on investment increases with increasing acetyl content in the wood and selling price of the acetic acid. When food grade acetic acid is produced, for example, the rate of return varies between 9% and 16% depending upon the size of the pulp mill, assuming the wood contains 3.5% acetyl groups on a dry basis and the selling price of acetic acid is US$900/ton.

Optimization of Deacetylation Process for Regenerated Cellulose Hollow Fiber Membranes

Cellulose acetate (CA) hollow fibers were spun from a CA+ Polyvinylpyrrolidone (PVP)/N-methyl-2-pyrrolidone (NMP)/H2O dope solution and regenerated by deacetylation. The complete deacetylation time of 0.5 h was found at a high concentration (0.2 M) NaOH ethanol (96%) solution. The reaction rate of deacetylation with 0.5 M NaOH was faster in a 50% ethanol compared to a 96 vol.% ethanol. The hydrogen bond between CA and tertiary amide group of PVP was confirmed. The deacetylation parameters of NaOH concentration, reaction time, swelling time, and solution were investigated by orthogonal experimental design (OED) method. The degree of cross-linking, the residual acetyl content, and the PVP content in the deacetylated membranes were determined by FTIR analysis. The conjoint analysis in the Statistical Product and Service Solutions (SPSS) software was used to analyze the OED results, and the importance of the deacetylation parameters was sorted as Solution > Swelling time > Reaction time > Concentration. The optimal deacetylation condition of 96 vol.% ethanol solution, swelling time 24 h, the concentration of NaOH (0.075 M), and the reaction time (2 h) were identified. The regenerated cellulose hollow fibers under the optimal deacetylation condition can be further used as precursors for preparation of hollow fiber carbon membranes.

Light medium-density fibreboards (MDFs): does acetylation improve the physico-mechanical properties?

Light medium-density fibreboards (MDFs) with a target density of 580 kg m3 were produced from fibres, which were obtained by defibrillation of chips of commercially available acetylated solid wood (“Accoya®”). The fibres were produced by thermo-mechanical pulping under industry-oriented conditions in a laboratory refiner. Infrared spectra showed that after the refiner process and board production, the material exhibited the same acetyl content as the initially acetylated solid wood. The fibres were bonded with 4 and 8% (related to the dry fibre mass) polymeric methylene diphenyl isocyanate and the properties of the obtained MDFs were compared with comparable MDFs from untreated Scots pine fibres which were produced under the same conditions. The modulus of rupture tended to be slightly lower for the acetylated boards, while the modulus of elasticity and the internal bond strength (IB) were equal for the respective resin loads. Acetylation clearly reduced the thickness swelling and the water uptake during immersion in cold and boiled water compared to the unmodified boards. IB after the boil test increased with acetylation and with the resin content. The study indicates that acetylated MDFs can be produced with maintained mechanical properties but strongly enhanced moisture-related properties by defibrillation of acetylated solid wood chips in a refiner and subsequent conventional board production.

Comparison of hydrothermal, hydrotropic and organosolv pretreatment for improving the enzymatic digestibility of bamboo

Pretreatment is the crucial step to disrupt the recalcitrant structure of lignocellulosic biomass for improving the enzymatic hydrolysis efficiency. Typically, hydrothermal, organosolv and hydrotropic pretreatments are environmentally benign and effective methods. In this work, effects of hydrothermal, organosolv and hydrotropic pretreatments on improving enzymatic hydrolysis of bamboo were comprehensively compared. Hydrotropic pretreatment was more effective in removal lignin and xylose from bamboo fiber cell wall. However, the surface coverage by lignin and extractives were dramatically displaced during organosolv pretreatment as investigation by X-ray photoelectron spectroscopy. After pretreatments, the crystallinity of cellulose in pretreated substrates has a significant reduction, and pores were exposed on fiber surface. The residual content of acetyl and phenolic groups in hydrotropic pretreated substrates is lower than organosolv pretreated substrates. In order to deeply assess the delignification of pretreatments, the isolated lignins obtaining from pretreatments process were characterized by Fourier transform infrared spectroscopy also. It was revealed that hydrotropic lignin contained more phenolic hydroxyl group and syringyl units than organosolv lignin. Compared to hydrothermal and organosolv pretreatment, cellulase adsorption capacity of pretreated substrates was notably improved by hydrotropic pretreatment, which indicating the better enzyme accessibility of cellulose. Eventually, the maximum glucose yield was obtained from hydrotropic pretreated substrates.

Insight into the evolution of the proton concentration during autohydrolysis and dilute-acid hydrolysis of hemicellulose.

BackgroundDuring pretreatment, hemicellulose is removed from biomass via proton-catalyzed hydrolysis to produce soluble poly- and mono-saccharides. Many kinetic models have been proposed but the dependence of rate on proton concentration is not well-defined; autohydrolysis and dilute-acid hydrolysis models apply very different treatments despite having similar chemistries. In this work, evolution of proton concentration is examined during both autohydrolysis and dilute-acid hydrolysis of hemicellulose from green bamboo. An approximate mathematical model, or “toy model”, to describe proton concentration based upon conservation of mass and charge during deacetylation and ash neutralization coupled with a number of competing equilibria, was derived. The model was qualitatively compared to experiments where pH was measured as a function of time, temperature, and initial acid level. Proton evolution was also examined at room temperature to decouple the effect of ash neutralization from deacetylation.ResultsThe toy model predicts the existence of a steady-state proton concentration dictated by equilibrium constants, initial acetyl groups, and initial added acid. At room temperature, it was found that pH remains essentially constant both at low initial pH and autohydrolysis conditions. Acid is likely in excess of the neutralization potential of the ash, in the former case, and the kinetics of neutralization become exceedingly small in the latter case due to the low proton concentration. Finally, when the hydrolysis reaction proceeded at elevated temperatures, one case of non-monotonic behavior in which the pH initially increased, and then decreased at longer times, was found. This is likely due to the difference in rates between neutralization and deacetylation.ConclusionsThe model and experimental work demonstrate that the evolution of proton concentration during hydrolysis follows complex behavior that depends upon the acetyl group and ash content of biomass, initial acid levels and temperature. In the limit of excess added acid, pH varies very weakly with time. Below this limit, complex schemes are found primarily related to the selectivity of deacetylation in comparison to neutralization. These findings indicate that a more rigorous approach to models of hemicellulose hydrolysis is needed. Improved models will lead to more efficient acid utilization and facilitate process scale-up.

Effects of localized environment on eucalyptus clone chemical composition

Eucalyptus wood is becoming the most important feedstock for bleached kraft pulp production, particularly in South America. However, pulp manufacturers have observed that some eucalyptus clones are resistant to wind action and others are not. Those lacking wind resistance are prone to breaking, which results in productivity losses. This study aims to investigate a correlation between the chemical composition of eucalyptus clones and their resistance to wind action. We found differences among the wind-resistant and non-wind-resistant clones, but that the fragility of trees studied for wind resistance does not correlate to the chemical composition of the wood. Four notable differences were observed. First, clones grown at lower altitudes differed from clones grown at higher altitudes in their acetyl, insoluble lignin, and extractives contents, and in their syringyl/guaiacyl (S/G) ratios. However, we found no relationship among these components and wind susceptibility. Second, soluble lignin content increased with the increase of wind resistance in the high altitude clones. Third, the low altitude clones showed slightly lower xylan content (12.4%) and higher lignin content (29.6%) than the others. Finally, the insoluble lignin content, total acetyl groups, extractives, ash contents, and S/G ratios of the clones were influenced by the region where they were grown.

Commercial cellulases from Trichoderma longibrachiatum enable a large-scale production of chito-oligosaccharides

Abstract Chito-oligosaccharides (COSs) are a substance class of high interest due to various beneficial bioactive properties. However, detailed mechanistic and application-related investigations are limited due to the poor availability of COSs with defined structural properties. Here, we present the large-scale production of COSs with defined degree of N-acetylation using a commercial cellulase preparation from Trichoderma longibrachiatum. The enzyme preparation was found to exclusively produce COSs lacking of acetyl groups while MS/MS analysis indicated a cellobiohydrolase to be the responsible for hydrolysis with the enzyme preparation. MS and NMR analysis proved the low content of acetyl groups in the COS mix and oligomers with a degree of polymerization (DP) of 2–6 were obtained. The low cost enzyme source was further exploited for large-scale production in a 20 g batch and resulted a COSs yield of 40%. An inexpensive enzyme source for the production of bioactive COSs was successfully implemented and thorough product analysis resulted in well-defined COSs. This strategy could improve the access to this substance class for a more detailed investigation of its various biological activities.

SYNTHESIS AND CHARACTERIZATION OF CHITIN co-(ACETATE/SUCCINATE) COPOLYMERS

*Corresponding Author Email: sksingh_gju@rediffmail.com ABSTRACT Chitin, composed of 2-acetamido-2-deoxy-β-D-glucose structural units interlinked through β-(1→4) bridges, is the second most plentiful natural polymer in the world. Crab and shrimp shells are the economic sources of chitin, despite the fact that it is synthesized by a large number of living organisms. The applicability of this biocompatible and biodegradable polymer is limited in the context of pharmaceutical and biomedical area owing to its insolubility in common solvents. In the present investigation, a series of chitin acetate/succinate copolymers with different content of acetyl and succinyl groups has been synthesized by reacting chitin with different ratios of acetic and succinic anhydride in the presence of perchloric acid as the catalyst of the reaction under heterogenous conditions. Pure chitin diacetate was also synthesized by using the same reaction and their structures were confirmed by FTIR and 1 H-NMR spectroscopy. The degree of substitution of the acetyl group and succinyl groups were in the range of 0.22-1.34 and 0.64-1.76, respectively as determined by 1 H-NMR spectroscopy. The expected solubility of these compounds in common solvents would open new domain of applications in the field of pharmaceutical and biomedical sciences.

Biosynthesis of xanthan gum by Xanthomonas campestris LRELP-1 using kitchen waste as the sole substrate

Herein, we report the production of xanthan gum by fermentation using kitchen waste as the sole substrate. The kitchen waste was firstly pretreated by a simple hydrolysis method, after which the obtained kitchen waste hydrolysate was diluted with an optimal ratio 1:2. In a 5-L fermentor, the maximum xanthan production, reducing sugar conversion and utilization rates reached 11.73g/L, 67.07% and 94.82%, respectively. The kinetics of batch fermentation was also investigated. FT-IR and XRD characterizations confirmed the fermentation product as xanthan gum. TGA analyses showed that the thermal stability of the xanthan gum obtained in this study was similar to commercial sample. The molecular weights of xanthan gum were measured to be 0.69–1.37×106g/mol. The maximum pyruvate and acetyl contents in xanthan gum were 6.11% and 2.49%, respectively. This study provides a cost-effective solution for the reusing of kitchen waste and a possible low-cost approach for xanthan production.

Pretreating biomass via demineralisation and torrefaction to improve the quality of crude pyrolysis oil

Pretreating biomass prior to pyrolysis was investigated. Three undesirable catalysts naturally present in biomass were identified: inorganics, acids, and water. A pretreatment sequence incorporating acid leaching and torrefaction was developed to reduce/remove these catalysts. Acid leaching targeted reducing the biomass's inorganic content. The acidic liquor produced during torrefaction was rich in acetic and formic acid; this solution was recycled as the acid leaching reagent. The optimal leaching conditions were at 30 °C with 1% acetic acid for 4 h, which decreased the inorganic content from 0.41 wt% to 0.16 wt% for leached biomass. Torrefaction targeted reducing the biomass's moisture and acetyl content and was optimal at 270 °C for 20 min. Bio-oil from pyrolysis of demineralisation and torrefied biomass was depleted in organic acids, pyrolytic lignin, and water but was rich in levoglucosan and aromatics. Decreasing the biomass's acetyl and inorganic content reduced organic acid formation. The water content in the bio-oil was lower because less water entered the system, and water plays an auto-catalytic role during pyrolysis, promoting the production of pyrolytic water. The high levoglucosan yield confirmed that secondary reactions were limited to a much higher degree when both pretreatments were implemented compared to demineralisation or torrefaction alone.

Engineering of acidic O/W emulsions with pectin

Pectins with distinct molecular design were isolated by aqueous extraction at pH 2.0 or 6.0 and were examined in terms of their formation and stabilisation capacity of model n-alkane–in–water emulsions at acidic pH (pH 2.0). The properties and stability of the resulting emulsions were examined by means of droplet size distribution analysis, Lifshitz-Slyozov-Wagner modelling, bulk rheology, interfacial composition analysis, large-amplitude oscillatory surface dilatational rheology, electrokinetic analysis and fluorescence microscopy. Both pectin preparations were able to emulsify alkanes in water but exhibited distinct ageing characteristics. Emulsions prepared using pectin isolated at pH 6.0 were remarkably stable with respect to droplet growth after thirty days of ageing, while those prepared with pectin isolated at pH 2.0 destabilised rapidly. Examination of chemical composition of interfacial layers indicated multi-layered adsorption of pectins at the oil-water interface. The higher long-term stability of emulsions prepared with pectin isolated at high pH is attributed to mechanically stronger interfaces, the highly branched nature and the low hydrodynamic volume of the chains that result in effective steric stabilisation whereas acetyl and methyl contents do not contribute to the long-term stability. The present work shows that it is possible by tailoring the fine structure of pectin to engineer emulsions that operate in acidic environments.

Mutations of Arabidopsis TBL32 and TBL33 Affect Xylan Acetylation and Secondary Wall Deposition.

Xylan is a major acetylated polymer in plant lignocellulosic biomass and it can be mono- and di-acetylated at O-2 and O-3 as well as mono-acetylated at O-3 of xylosyl residues that is substituted with glucuronic acid (GlcA) at O-2. Based on the finding that ESK1, an Arabidopsis thaliana DUF231 protein, specifically mediates xylan 2-O- and 3-O-monoacetylation, we previously proposed that different acetyltransferase activities are required for regiospecific acetyl substitutions of xylan. Here, we demonstrate the functional roles of TBL32 and TBL33, two ESK1 close homologs, in acetyl substitutions of xylan. Simultaneous mutations of TBL32 and TBL33 resulted in a significant reduction in xylan acetyl content and endoxylanase digestion of the mutant xylan released GlcA-substituted xylooligomers without acetyl groups. Structural analysis of xylan revealed that the tbl32 tbl33 mutant had a nearly complete loss of 3-O-acetylated, 2-O-GlcA-substituted xylosyl residues. A reduction in 3-O-monoacetylated and 2,3-di-O-acetylated xylosyl residues was also observed. Simultaneous mutations of TBL32, TBL33 and ESK1 resulted in a severe reduction in xylan acetyl level down to 15% of that of the wild type, and concomitantly, severely collapsed vessels and stunted plant growth. In particular, the S2 layer of secondary walls in xylem vessels of tbl33 esk1 and tbl32 tbl33 esk1 exhibited an altered structure, indicating abnormal assembly of secondary wall polymers. These results demonstrate that TBL32 and TBL33 play an important role in xylan acetylation and normal deposition of secondary walls.

Roles of Arabidopsis TBL34 and TBL35 in xylan acetylation and plant growth

Xylan is one of the major polymers in lignocellulosic biomass and about 60% of its xylosyl residues are acetylated at O-2 and/or O-3. Because acetylation of cell wall polymers contributes to biomass recalcitrance for biofuel production, it is important to investigate the biochemical mechanism underlying xylan acetylation, the knowledge of which could be applied to custom-design biomass composition tailored for biofuel production. In this report, we investigated the functions of Arabidopsis TRICHOME BIREFRINGENCE-LIKE 34 (TBL34) and TBL35, two DUF231-containing proteins, in xylan acetylation. The TBL34 gene was found to be specifically expressed in xylem cells in stems and root-hypocotyls, and both TBL34 and TBL35 were shown to be localized in the Golgi, where xylan biosynthesis occurs. Chemical analysis revealed that simultaneous mutations of TBL34 and TBL35 caused a mild decrease in xylan acetyl content and a specific reduction in xylan 3-O-monoacetylation and 2,3-di-O-acetylation. Furthermore, simultaneous mutations of TBL34, TBL35 and ESKIMO1 (ESK1) resulted in severely collapsed xylem vessels with altered secondary wall structure, and an extremely retarded plant growth. These findings indicate that TBL34 and TBL35 are putative acetyltransferases required for xylan 3-O-monoacetylation and 2,3-di-O-acetylation and that xylan acetylation is essential for normal secondary wall deposition and plant growth.

Quantitative characterization of chitosan in the skin by Fourier-transform infrared spectroscopic imaging and ninhydrin assay: application in transdermal sciences.

The chitosan has been used as the primary excipient in transdermal particulate dosage form design. Its distribution pattern across the epidermis and dermis is not easily accessible through chemical assay and limited to radiolabelled molecules via quantitative autoradiography. This study explored Fourier-transform infrared spectroscopy imaging technique with built-in microscope as the means to examine chitosan molecular distribution over epidermis and dermis with the aid of histology operation. Fourier-transform infrared spectroscopy skin imaging was conducted using chitosan of varying molecular weights, deacetylation degrees, particle sizes and zeta potentials, obtained via microwave ligation of polymer chains at solution state. Both skin permeation and retention characteristics of chitosan increased with the use of smaller chitosan molecules with reduced acetyl content and size, and increased positive charge density. The ratio of epidermal to dermal chitosan content decreased with the use of these chitosan molecules as their accumulation in dermis (3.90% to 18.22%) was raised to a greater extent than epidermis (0.62% to 1.92%). A larger dermal chitosan accumulation nonetheless did not promote the transdermal polymer passage more than the epidermal chitosan. A small increase in epidermal chitosan content apparently could fluidize the stratum corneum and was more essential to dictate molecular permeation into dermis and systemic circulation. The histology technique aided Fourier-transform infrared spectroscopy imaging approach introduces a new dimension to the mechanistic aspect of chitosan in transdermal delivery.

Alginate-modifying enzymes: biological roles and biotechnological uses.

Alginate denotes a group of industrially important 1-4-linked biopolymers composed of the C-5-epimers β-D-mannuronic acid (M) and α-L-guluronic acid (G). The polysaccharide is manufactured from brown algae where it constitutes the main structural cell wall polymer. The physical properties of a given alginate molecule, e.g., gel-strength, water-binding capacity, viscosity and biocompatibility, are determined by polymer length, the relative amount and distribution of G residues and the acetyl content, all of which are controlled by alginate modifying enzymes. Alginate has also been isolated from some bacteria belonging to the genera Pseudomonas and Azotobacter, and bacterially synthesized alginate may be O-acetylated at O-2 and/or O-3. Initially, alginate is synthesized as polymannuronic acid, and some M residues are subsequently epimerized to G residues. In bacteria a mannuronan C-5-epimerase (AlgG) and an alginate acetylase (AlgX) are integral parts of the protein complex necessary for alginate polymerization and export. All alginate-producing bacteria use periplasmic alginate lyases to remove alginate molecules aberrantly released to the periplasm. Alginate lyases are also produced by organisms that utilize alginate as carbon source. Most alginate-producing organisms encode more than one mannuronan C-5 epimerase, each introducing its specific pattern of G residues. Acetylation protects against further epimerization and from most alginate lyases. An enzyme from Pseudomonas syringae with alginate deacetylase activity has been reported. Functional and structural studies reveal that alginate lyases and epimerases have related enzyme mechanisms and catalytic sites. Alginate lyases are now utilized as tools for alginate characterization. Secreted epimerases have been shown to function well in vitro, and have been engineered further in order to obtain enzymes that can provide alginates with new and desired properties for use in medical and pharmaceutical applications.

Expression of fungal acetyl xylan esterase in Arabidopsis thaliana improves saccharification of stem lignocellulose.

Cell wall hemicelluloses and pectins are O-acetylated at specific positions, but the significance of these substitutions is poorly understood. Using a transgenic approach, we investigated how reducing the extent of O-acetylation in xylan affects cell wall chemistry, plant performance and the recalcitrance of lignocellulose to saccharification. The Aspergillus niger acetyl xylan esterase AnAXE1 was expressed in Arabidopsis under the control of either the constitutively expressed 35S CAMV promoter or a woody-tissue-specific GT43B aspen promoter, and the protein was targeted to the apoplast by its native signal peptide, resulting in elevated acetyl esterase activity in soluble and wall-bound protein extracts and reduced xylan acetylation. No significant alterations in cell wall composition were observed in the transgenic lines, but their xylans were more easily digested by a β-1,4-endoxylanase, and more readily extracted by hot water, acids or alkali. Enzymatic saccharification of lignocellulose after hot water and alkali pretreatments produced up to 20% more reducing sugars in several lines. Fermentation by Trametes versicolor of tissue hydrolysates from the line with a 30% reduction in acetyl content yielded ~70% more ethanol compared with wild type. Plants expressing 35S:AnAXE1 and pGT43B:AnAXE1 developed normally and showed increased resistance to the biotrophic pathogen Hyaloperonospora arabidopsidis, probably due to constitutive activation of defence pathways. However, unintended changes in xyloglucan and pectin acetylation were only observed in 35S:AnAXE1-expressing plants. This study demonstrates that postsynthetic xylan deacetylation in woody tissues is a promising strategy for optimizing lignocellulosic biomass for biofuel production.

The use of demineralisation and torrefaction to improve the properties of biomass intended as a feedstock for fast pyrolysis

Pre-treatments of biomass were investigated to reduce its undesirable properties which may affect the quality of fast pyrolysis bio-oil. A pre-treatment sequence was developed in this study to incorporate both biomass demineralisation and torrefaction. Demineralisation was performed by dilute acid leaching, primarily to reduce the inorganic concentration in raw biomass, whereas torrefaction targeted a reduction of the carboxyl, moisture and oxygen content. The liquid produced during torrefaction was recycled back as the leaching reagent for demineralisation. This solution contained dilute organic acids; therefore, the viability of leaching with organic acids (acetic and formic acid) compared to commonly used mineral acids (sulphuric, nitric and hydrochloric acid) was validated. Synthetic leaching solutions reduced the inorganic content in raw biomass from 0.41wt% to 0.14wt% when leached with 1% formic acid and to 0.16wt% when leached with 1% acetic acid, which was comparable to leaching with the mineral acids. Recycled torrefaction liquid that contained other acidic compounds in small quantities reduced the inorganic content to 0.14wt%, suggesting it is effective to use the recycled torrefaction liquid as the leaching solution. From the experimental results, the optimal conditions for biomass torrefaction were 260°C for 20min to minimise the char formation during pyrolysis, based on the increase in the acid-insoluble fraction of the biomass. However, the torrefaction temperature may be increased to 280°C if further reductions in acetyl and oxygen content are required. Higher temperatures are associated with severe biomass loss and the initiation of hydrogen loss. It should be noted that even at 280°C, the oxygen reduction is minimal. If oxygen reduction is the principal target when pre-treating biomass, it is suggested that torrefaction alone is not a suitable method to obtain bio-oil with a low oxygen content due to the low pyrolysis yields obtainable. This study demonstrated that the combined use of demineralisation and torrefaction as biomass pre-treatments has the ability to decrease the inorganic, acetyl and moisture content of biomass, which reduces undesirable catalytic reactions during fast pyrolysis to improve the quality of bio-oil produced.

Effect of acetylation on the physico‐chemical properties of Indian Horse Chestnut (Aesculus indica L.) starch

The present work was carried out to study the effect of acetylation (0, 3, 6, and 9 g vinyl acetate/gram starch) on the physico‐chemical properties of starch, isolated from Indian horse chestnut (Aesculus indica). Work on starch acetylation and characterization from Indian horse chestnut has not been reported so far in the literature. Moisture, protein, fat, and ash content of native starch was found as 5.97%, 0.27%, 0.22%, and 0.01%, respectively. Acetyl content, swelling index, solubility index, and water absorption capacity of acetylated starch increased with increase in acetyl %, whereas, pasting temperature, syneresis, and amylose content reduced with acetylation. Granule morphology under the scanning electron microscopy revealed that granules were round, oval, irregular, or elliptical with smooth surfaces.