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Cinnamon is a spice widely used as a flavouring agent in foodstuffs. Despite its commercial availability and low cost, C. burmannii aqueous extracts obtained by decoction originate high viscous solutions (1545 cP) when compared with C. verum (51 cP), preventing its broad use by food industry. Following the hypothesis that cinnamon polysaccharides are responsible for this viscosity, in this work, the hot water-soluble polysaccharides from C. burmannii were structurally characterized, using C. verum for comparison. The results showed that C. burmannii had a higher content of branched arabinoxylans in relation to C. verum. The hot water-soluble polysaccharides from C. verum comprised also glucans, arabinogalactans, and pectic polysaccharides. The partial mild acid-hydrolysis performed to C. burmannii allowed to reach a viscosity value near to the C. verum solutions, keeping the characteristic aroma profile of cinnamon by the predominance of cinnamaldehyde and other varietal compounds, namely mono and sesquiterpenoids. Therefore, C. burmannii can be used as flavouring and thickening agent, whereas low viscosity products can be obtained by a partial acid-hydrolysis, contributing to its wide application in food industry.

The profile of major families of extractives soluble in acetone and dichloromethane during the production of acid sulfite dissolving pulp from Eucalyptus globulus wood was assessed. Nearly 85% of total extractives were removed from wood during pulping and nearly 11% in the course of E-O-P pulp bleaching and secondary pulp screening. Unlike extractives of polyphenolic origin that were almost completely removed after the alkaline extraction stage (E), fatty acids were the main retained component in fully bleached pulp followed by sterols and fatty alcohols. Throughout the bleaching steps, the profiles of extractives were not necessarily decreasing and depended on their reactions with bleaching reagents and the presence of auxiliary chemicals (e.g. antifoams). In this context, the content of fatty acids and fatty alcohols was mostly vulnerable. It has been suggested that Fock reactivity of dissolving pulps is unaffected by extractives at concentrations up to 0.3%.

In this study, modification of LignoBoost™ softwood kraft lignin with epichlorhydrin in water-organic solvents media was realized. Lignin-based epoxy resins were obtained by two ways: acetone extraction of glycidylated lignin or glycidylation of the acetone soluble lignin fraction. The effect of glycidylation regimes on the yields of acetone soluble fractions, their functional composition and physical-chemical characteristics was investigated using wet chemistry methods, FTIR spectroscopy, size exclusion chromatography (SEC) and differential scanning calorimetry (DSC). The positive effect of the biphasic phase transfer catalytic system – KOH/quaternary ammonium salt – on glycidylation of both phenolic and aliphatic hydroxyl groups was testified, exemplified using a lignin-like model compound – 4-hydroxy-3-methoxylbenzyl alcohol (vanillyl alcohol). The partial substitution (up to 10%) of commercial epoxy resin on the basis of bisphenol A (Araldite® LY1564) by lignin-based epoxy resin significantly increased the viscosity of resin. Therefore, the possible practical application of lignin-containing epoxies as adhesive, mastic or crack filler instead of binder for fiber reinforced composites was considered. A tendency towards increasing Young’s modulus of cured lignin-containing epoxies, compared with the case of the reference composition, was observed. The lignin chemically incorporated into the matrix of cured commercial epoxy resin acts as a charcoal formation promoter in high temperature treatment.

A new method for the quantification of acetaldehyde in a water matrix, namely commercial ciders, was developed using solid phase micro-extraction (SPME) followed by detection with a coated acoustic wave sensor. The sensitive coating was a polyoxometalate salt specially synthesised for this application, a compound tailored to be insoluble in water. Although the sample gaseous flow reaching the sensor needed to be dried, as the sensor itself responds to water, there was no sensitivity deterioration after contacting with water vapour, as frequency recover under dried nitrogen carrier was complete. Calibration lasted at least for two months. Comparing this sensor with the analogue previously coated with the soluble decamolybdodivanado phosphoric acid, the main advantage comes from the superior stability, and the possibility of keeping it in a wet environment without deterioration. The flow injection analysis (FIA) methodology here reported for the first time for acetaldehyde analysis in cider, allowed to obtain results not statistically different from the ones obtained with Gas Chromatography-Flame Ionization Detection (GC-FID) (α = 0.05). Besides, the new methodology does not use expensive instrumentation and the analysis time is similar. Detection limit of this new method was 2.0 mg L−1, and quantification limit was 6.7 mg L−1, not much higher than the values of 1.4 mg L−1 and 4.6 mg L−1, respectively, of the GC-FID.

Reactive washing consists of treating cork stoppers with hydrogen peroxide under strong alkaline conditions at elevated temperature. This causes changes in the surface of the stoppers, affecting their wettability. This study aimed to relate the reactive washing with changes in the surface properties of cork stoppers and their affinity for hydroalcoholic solutions with different concentrations of ethanol. The surface composition was evaluated by Fourier Transform Infrared-Attenuated Total Reflectance spectroscopy, confocal Raman spectroscopy and the free surface energy by contact angle measurements with liquid probes using Owens-Wendt-Rabel-Kaelble method. The surface morphology and topology was assessed by scanning electron microscopy and 3D optical profilometry, respectively. Different wettability of the top and lateral of the cork stoppers is due to the difference in the exposure of phellogen cell wall layers. After reactive washing, the partial degradation of suberin and the increased exposure of hydrophilic biopolymers lead to an increase in the polar component of the free surface energy, thus promoting wettability with aqueous solutions. The changes in the surface observed imply an enhancement in the wettability of cork stoppers towards hydroalcoholic solutions mimicking alcoholic beverages, as revealed by modeling studies employing a wetting envelope.

In this study, aiming to reduce the environmental impact of plastics, new composite materials containing recycled fibers from used paper coffee cups and oil extracted from spent coffee grounds (SCG) were produced. Accordingly, the cellulose fibers were chemically modified using lactic acid to be used as poly(lactic acid) filler reinforcement. The obtained results revealed that its addition improved the mechanical properties of the ensuing composites. The addition of 30% wt/wt of unmodified and modified fibers increased the Young modulus by 53% and 72%, respectively. In addition, enhanced biodegradability was obtained due to higher water absorption (up to 4% wt/wt). In parallel, coffee oil was used as a plasticizer and the affinity between the plasticizer and polymer matrix was confirmed by the lack of phase separation, by the improved flexibility of derived materials (the addition of 40% wt/wt of plasticizer increased the elongation at break by 86%) and by the better processability of the ensuing materials (the addition of 30% wt/wt of plasticizer increased the MFI by 205%). Overall, the results suggest that the use of modified cellulose fibers and the addition of SCG oil-based plasticizer can be promising routes to produce eco-friendly plastics. This study was also performed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project N° 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). published

Two functionalized xylans, namely a carboxymethyl xylan (CMX) and a 2-dodecenyl succinic anhydride-modified xylan (X-2-DSA) were, i) synthesized from beechwood xylan (BX) and characterized for their structural properties, thermal behaviour and molar mass and, ii) used in the production of paper/xylan laminates for food packaging. Films prepared from the functionalized xylans by solvent casting were applied onto paper employing the calendering moulding under pre-selected conditions in order to produce the laminates. The obtained laminates, as well as the starting base paper and the xylan-derived films, were characterized for their mechanical and barrier properties. The novel type of laminates demonstrated a synergistic effect with respect to its individual constituents, as the Young's modulus, tensile, tear and burst strengths of laminates were significantly improved in comparison to those of the starting paper or the xylan films. The xylan-coated paper laminates showed good moisture barrier properties, reducing up to 30-fold the water vapor permeability of the paper. At the same time, despite of fairly good oxygen barrier properties of the bio-based films from functionalized xylan, their application in paper laminates did not permit maintaining the same order of magnitude of oxygen transfer rates, which were, however, comparable to those reported for packaging papers coated by polyethylene films.

Two industrial bleached Eucalyptus globulus kraft pulps (pulps A and B), cooked from the same wood stock with slightly different alkali charges and temperatures, showed different refinability in the laboratory beating of pulp using a PFI mill. The easy to refine pulp (A) and the difficult to refine pulp (B) did not reveal significant differences in their biometric data and general chemical composition, but pulp A showed ca. 5%–10% higher mechanical strength and twice as high refinability compared to pulp B. These differences were ascribed to slightly higher intrinsic viscosity and higher xylan content of pulp A compared to pulp B (1010 vs. 860 cm3 g−1 and 20.1 vs. 17.8%, respectively). The xylan structure and its location in fiber cells were also different, which affected the pulp’s refinability. The presence of high proportion of xylan in the bulk of fibers, rather than in their outer layers, seems to favor the pulp beating. An interpretation was also proposed, according to which the aggregation of cellulose fibrils during cooking, i.e. a partial coalescence of fibril crystallites, may also have a negative effect on pulp refinability.

High concentrations of 5-hydroxymethylfurfural (HMF) in honey provide an indication of overheating under inappropriate storage conditions or aging. Conventional methods for determining HMF are cumbersome and require expensive equipment or hazardous reagents. Hence the aim of this study was to propose a new analytical tool for HMF determination in honey, using a low cost acoustic wave sensor. Volatile organic compounds (VOCs) of honey samples were extracted, using the solid phase microextraction (SPME) technique, and HMF was quantified, using a piezoelectric quartz crystal with gold electrodes coated with a layer of decamolybdodivanado phosphoric acid, sensitive to HMF. The reliability of the proposed method was confirmed after comparing the results of HMF quantification with those obtained by the conventional spectrophotometric White method, and no statistical differences were found (α=0.05).

Sugarcane bagasse and straw are generated in large volumes as by-products of agro-industrial production. They are an emerging valuable resource for the generation of hemicellulose-based materials and products, since they contain significant quantities of xylans (often twice as much as in hardwoods). Heteroxylans (yields of ca 20% based on xylose content in sugarcane bagasse and straw) were successfully isolated and purified using mild delignification followed by dimethyl sulfoxide (DMSO) extraction. Delignification with peracetic acid (PAA) was more efficient than traditional sodium chlorite (NaClO

The identification of paper composition, pH, early signs of paper degradation, and emitting volatile organic compounds (VOCs) are mandatory for effective preventive conservation of paper/books. Sampling restrictions in the analysis of cultural heritage materials limit the choice of appropriate analytical methods. Solvent-free analytical techniques with nondestructive sampling are needed. Addressing this challenge, an electronic nose based on six-coated piezoelectric quartz crystals was assembled and used to analyze VOCs emitted from books. Careful selection of sensor coatings and cluster analysis allowed us to achieve a clear distinction between cotton/linen rag and wood pulp paper, and among the letter group, the discrimination between papers manufactured from alkaline and acidic stocks. This six-element sensor array was therefore able to replace destructive tests as the ones ordinarily used for paper pH measurements. The same electronic nose was able to separate aged pale-yellow paper, a visible initial sign of paper degradation, from well-preserved still white papers, even when made from the same raw material. One of the used sensors detected furfural, often seen as a marker of cellulose degradation, at lower levels than the detection limit found in the literature with gas chromatography-mass spectrometry, a much more complex bulky and expensive instrument.

This work studies the microwave-assisted extraction conditions for recovery of polysaccharides from spent coffee grounds, including their effect on arabinogalactans and galactomannans polymerization and branching structural features. Temperature (140, 170, and 200 °C) has the most significant impact on total extracted mass (ηtotal soluble solids) and sugars yield (ηsugars), arabinogalactans (ηAG) and galactomannans (ηGM), and polysaccharide mass ratio (ηAG/ηGM). Time (2, 5, and 10 min) and alkali (diluted 0.1 M NaOH) treatments have less influence. Alkali treatment and shorter time (2 min) provided a protective effect against polysaccharides degradation. At 170 °C, the yield of arabinogalactans was found to be significantly higher than that of galactomannans (ηAG/ηGM >1). Increasing temperature to 200 °C leads to decrease the polymerization of polysaccharides, promoting the formation of debranched polysaccharides and oligosaccharides. This study shows that the optimum conditions for polysaccharides extraction cannot be selected only by mass yield but need to be defined according to the desired structural features for the specific applications.

In this work, polysaccharides extracted with hot water from apple pomace were isolated by C18 cartridge solid-phase extraction at pH 7 (Fr7). Dialysis (12–14 kDa) of this fraction allowed to obtain 17% (w/w) of polymeric material composed by 65% of polysaccharides, mainly arabinose (58 mol%), galacturonic acid (16 mol%) and glucose (10 mol%). Folin-Ciocalteu assay showed 62 g of phloridzin equiv/kg of polyphenols. Moreover, adjusting to pH 3, it was possible to retain an additional fraction (Fr3) representing a further 4% of the polymeric material. Fr3 contained 53% of polysaccharides composed mainly by galacturonic acid (66 mol%) and polyphenols accounted for 37 g of phloridzin equiv/kg. Precipitation with ethanol and subsequent methylation and NMR spectroscopic analysis of Fr7 dialysate allowed the identification of covalently-linked pectic-polyphenol-xyloglucan and arabinan-polyphenol complexes. These structures are possibly formed as a result of polyphenol oxidation reactions during the industrial processing of apples, conferring hydrophobic characteristics to apple pomace polysaccharides.

Grape pectic polysaccharides-malvidin-3-O- β - d -glucoside binding was studied, aiming to unveil the impact of structural diversity of polysaccharides on anthocyanins-polysaccharides interactions. Polysaccharides were extracted with solutions of imidazole (ISP) and carbonate at 4 °C (CSP-4 °C) and room temperature (CSP-RT) and also recovered from the dialysis supernatant of the remaining cellulosic residue after the aqueous NAOH extraction of hemicellulosic polysaccharides (Sn-CR). Polysaccharides richer in homogalacturonan domains, like those present in the CSP-4 °C fraction had approximately 50–fold higher binding affinity to malvidin-3-O- β- d -glucoside, than polysaccharides with side chains (as ISP and CSP-RT extractable polysaccharides). CSP-4 °C polysaccharides showed a positive effect on malvidin-3-O- β- d -glucoside colour fading. Hydration equilibrium constant of malvidin-3-O- β- d -glucoside in the presence of CSP-4 °C polysaccharides was higher, showing the preferential stabilization of the flavylium cation. The results showed that anthocyanins colour stabilization can be promoted by pectic polysaccharide structures such as those extracted by cold carbonate.

Cellulose/silica hybrid material produced by a sol-gel method from cellulosic fibres and silica precursors (tetraethoxysilane and 3-aminopropyltriethoxysilane) was functionalized with alpha-[SiW9O37Ru3III(H2O)(x)Cl3-x]((10-x)-) (Ru-POM), and thoroughly characterised by C-13 and Si-29 solid state NMR, FTIR spectroscopy, UV-vis reflectance spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy (SEM), and chemical analysis. The supported Ru-POM exhibited catalytic activity for the gas phase heterogeneous aerobic oxidation of formaldehyde (ca. 830 ppm in polluted air) at room temperature, in a packed-bed reactor operating at a linear velocity ca. 0.33 m/s and ca. 0.5 s residence time. Maximum formaldehyde uptake was 1.10 g/min per kg of hybrid material doped with Ru-POM (ca. 1.4% w/w). More than 400 turnovers were achieved without significant loss of catalytic activity and the only detected oxidation products of formaldehyde were carbon dioxide and water. A plausible mechanism for the catalytic oxidation of formaldehyde by supported Ru-POM has been proposed and includes formaldehyde oxidation in oxygenated ruthenium complex. (C) 2015 Elsevier B.V. All rights reserved.

Biofuels are suitable alternatives to conventional and fossil fuels that pose serious environmental adverse effects to society. Bioethanol is the most promising biofuel and can be generated from lignocellulosic biomasses. Forest residues are outside the human food chain and inexpensive raw materials, but they need a previous pretreatment, in order to improve the cellulose accessibility for further bioconversion. The study of bioethanol production from rockrose pretreated by steam explosion (SE) was carried out employing separate enzymatic hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF) approaches. Saccharification of untreated rockrose attained only 0.9% of sugars yield. However, the steam explosion pretreatment promoted the disruption of interfibrillar surfaces of fibers with partial degradation of lignin thus enhancing the accessibility of polysaccharides toward enzymatic hydrolysis. Alkaline extraction after steam explosion pretreatment of rockrose residue (R-SE-OH) led to the partial removal of lignin, hemicelluloses, and other degradation products from fibre surface allowing an increase of 75% in the glucose yield. Bioethanol production in SSF mode was faster and slightly more efficient process than SHE providing the best results: ethanol concentration of 16.1 g L-1, fermentation efficiency of 69.8% and a yield of 22.1 g ethanol/100 g R-SE-OH. (C) 2015 Elsevier B.V. All rights reserved.

A series of six industrial bleached hardwood kraft pulps produced from Eucalyptus globulus (BEKPs) under variable process conditions were dry-defiberized on a pilot scale hammermill at 3500 rpm and the nonwoven air-laid fabrics evaluated for their specific volume, absorption capacity/absorption rate and fiber network strength. The effect of non-defiberized fiber aggregates (knots) on the former properties was evaluated. Processual variations in pulping and bleaching conditions revealed variability within 15% in the absorption capacity of fluff pulps and within 25% in the network strength of the air-laid formulations. These variations were attributed to changes in the chemical composition of BEKPs and fiber morphology. The importance of pulp bleaching sequence on the quality of BEKPs for fluff applications was highlighted. BEKPs, having a high residual xylan content with a greater amount of uronic/hexenuronic moieties and coarser/deformed fibers, revealed the best performance in fluff applications. The coarseness was considered a critical morphological parameter of the fibers, strongly affecting the porosity of air-laid formulations, which determined the absorption capacity and the network strength. The absorption capacity of fluffed BEKP was comparable of commercial bleached softwood kraft pulp (BSKP), although the latter showed almost triple the network strength of air-laid formulations produced with BEKP. BSKP proved to be much more vulnerable to dry defiberization conditions than BEKP and suffered a pronounced cut of fibers, producing larger amounts of fines (dust) and stronger undesirable peeling and straightening of fibers. BEKPs can be considered a promising raw material for fluff applications, whose basic properties can be adjusted according to the needs by varying conditions in the pulping and bleaching process steps.

Porphyra dioica is a commercial seaweed consumed all over the world, mostly in the shape of nori sheets used for “sushi” preparation. It is a well-known part of the Asian diet with health benefits, which have been associated, among others, to the high levels of n-3 and n-6 fatty acids in this red alga. However, other highly valued lipids of Porphyra are polar lipids that remain largely undescribed and can have both nutritional value and bioactivity, thus could contribute to the valorization of this seaweed. In this context, the present work aims to identify the lipidome of two life cycle stages of the Atlantic species Porphyra dioica: the early life stage conchocelis produced in an indoor-nursery, and young blades produced outdoors using an integrated multitrophic aquaculture (IMTA) framework. Both the blades (gametophyte) and conchocelis (sporophyte) are commercialized in the food and cosmetics sectors. Liquid chromatography coupled to Q–Exactive high resolution-mass spectrometry (MS) platform was used to gain insight into the lipidome of these species. Our results allowed the identification of 110 and 100 lipid molecular species in the lipidome of the blade and conchocelis, respectively. These lipid molecular species were distributed as follows (blade/conchocelis): 14/15 glycolipids (GLs), 93/79 phospholipids (PLs), and 3/6 betaine lipids. Both life stages displayed a similar profile of GLs and comprised 20:4(n-6) and 20:5(n-3) fatty acids that contribute to n-3 and n-6 fatty acid pool recorded and rank among the molecular species with higher potential bioactivity. PLs’ profile was different between the two life stages surveyed, mainly due to the number and relative abundance of molecular species. This finding suggests that differences between both life stages were more likely related with shifts in the lipids of extraplastidial membranes rather than in plastidial membranes. PLs contained n-6 and n-3 precursors and in both life stages of Porphyra dioica the n-6/n-3 ratio recorded was less than 2, highlighting the potential benefits of using these life stages in human diet to prevent chronic diseases. Atherogenic and thrombogenic indexes of blades (0.85 and 0.49, respectively) and conchocelis (0.34 and 0.30, respectively) are much lower than those reported for other Rhodophyta, which highlights their potential application as food or as functional ingredients. Overall, MS-based platforms represent a powerful tool to characterize lipid metabolism and target lipids along different life stages of algal species displaying complex life cycles (such as Porphyra dioica), contributing to their biotechnological application.

Bioethanol production potential from cardoon ( Cynara cardunculus ) and rockrose ( Cistus ladanifer ), pretreated by diluted acid hydrolysis (DAH), was studied and compared by both, separate enzymatic hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes. DAH pretreatment allowed an increase of 5 fold to cardoon and 16 fold to rockrose in cellulose accessibility towards enzymatic hydrolysis. Both plants showed better overall fermentation efficiency and ethanol yield in SSF than in SHF also with shorter processing periods, 24 h against 72 + 24 h, respectively. Results obtained for rockrose are about half the concentration and volumetric productivity of ethanol and 60% of the overall fermentation efficiency of those obtained for cardoon. The recalcitrance of rockrose to enzymatic hydrolysis was explained by higher abundance of lignin and extractives than in cardoon. Comparing the steam explosion (SE) and DAH pretreatments, the former was more advantageous for the recalcitrant rockrose in terms of enzymatic saccharification yield., This research was funded by INALENTEJO 2007.2013/QREN (BioEcos Project – Valorização Integrada de Biomassa (ALENT-09-0140-FEDER-000705 (QREN)). The author’s thanks, FCT (Fundação para a Ciência e Tecnologia) under projects CICECO-Aveiro Institute of Materials (Ref.FCTUID/CTM/50011/2013) and ICAAM-Instituto de Ciências Agrárias e Ambientais Mediterrânicas (Ref.FCTUID/AGR/00115/2013). Agrarian School from Instituto Politécnico de Beja and Associação de Defesa do Património de Mértola, are greatly acknowledged for kindly supplying cardoon and rockrose, respectively.

BACKGROUND Brightness stability of bleached chemical pulps is often associated with the final bleaching stages that should provide the removal of chromogenic species responsible for brightness reversion without compromising the papermaking potential. Aiming at promoting higher brightness stability, a partially bleached Eucalyptus globulus pulp (DED) of c. 88% ISO brightness was involved in a study of a final enzymatic stage (X) alternative to conventional chlorine dioxide (D) and hydrogen peroxide (P) bleaching stages (DEDX vs. DEDD and DEDX vs. DEDP). X stage was also applied before and after the final P or D stages (DEDDX/DEDXD and DEDPX/DEDXP) to produce high brightness pulps (c. 91%). RESULTS X stage with xylanase Pulpzyme HC allowed an increase of c. 1.5% in pulp brightness while decreasing the brightness reversion and a concomitant pulp yield loss of only 0.5%. Significant chemical savings were obtained in the final D (70%) or P (45%) stages to achieve targeted final brightness of c. 91%. DEDXD or DEDXP sequences had advantage over DEDDX and DEDPX, respectively, in terms of brightness stability of fully bleached pulps. CONCLUSIONS Xylanase interferes with structures responsible for the brightness reversion. X stage allows production of pulp with extra brightness in sequences with a final P stage. © 2014 Society of Chemical Industry

In this work bleached E. globulus kraft pulp was doped with polyhexamethylene biguanide (PHMB) from an aqueous solution or from a suspension of silica capsules (PHMB@silica) by impregnation under atmospheric or ultra-high pressure (UHP) conditions (500MPa). The antimicrobial properties of pulps were evaluated towards gram-negative E. coli and gram-positive L. innocua bacteria. PHMB loads below 500mg per kg of pulp revealed negligible bacteriostatic properties, whereas PHMB loads of ca 3000-4000mg per kg demonstrated bactericidal properties of pulp without significant deterioration of its mechanical strength. The UHP impregnation allowed significant improvement of PHMB uptake. Thus, under equal conditions, PHMB uptake was ca 25% greater under UHP than under atmospheric pressure impregnation, whereas the leachable amounts of PHMB in both pulps were comparable. The sorption of PHMB@silica on pulp in suspension under UHP conditions was ca 17% greater than under atmospheric pressure with almost 70% increase of leachable PHMB.

The oxidation of α-(1 → 5)-L-arabinotriose (Ara3), an oligosaccharide structurally related to side chains of coffee arabinogalactans, was studied in reaction with hydroxyl radicals generated under conditions of Fenton reaction (Fe(2+)/H2O2). The acidic and neutral oxidation products were separated by ligand exchange/size-exclusion chromatography, subsequently identified by electrospray ionisation mass spectrometry (ESI-MS) and structurally characterised by tandem MS (ESI-MS/MS). In acidic fraction were identified several oxidation products containing an acidic residue at the corresponding reducing end of Ara3, namely arabinonic acid, and erythronic, glyceric and glycolic acids formed by oxidative scission of the furanose ring. In neutral fractions were identified derivatives containing keto, hydroxy and hydroperoxy moieties, as well as derivatives resulting from the ring scission at the reducing end of Ara3. In both acidic and neutral fractions, beyond the trisaccharide derivatives, the corresponding di- and monosaccharide derivatives were identified indicating the occurrence of oxidative depolymerisation. The structural characterisation of these oxidation products by ESI-MS/MS allowed the differentiation of isobaric and isomeric species of acidic and neutral character. The species identified in this study may help in detection of roasting products associated with the free radical-mediated oxidation of coffee arabinogalactans.

The acid-catalyzed reaction of 5-(hydroxymethyl)-2-furfural with ethanol is a promising route to produce biofuels or fuel additives within the carbohydrate platform; specifically, this reaction may give 5-ethoxymethylfurfural, 5-(ethoxymethyl)furfural diethylacetal, and/or ethyl levulinate (bioEs). It is shown that sulfonated, partially reduced graphene oxide (S-RGO) exhibits a more superior catalytic performance for the production of bioEs than several other acid catalysts, which include sulfonated carbons and the commercial acid resin Amberlyst-15, which has a much higher sulfonic acid content and stronger acidity. This was attributed to the cooperative effects of the sulfonic acid groups and other types of acid sites (e.g., carboxylic acids), and to the enhanced accessibility to the active sites as a result of the 2D structure. Moreover, the acidic functionalities bonded to the S-RGO surface were more stable under the catalytic reaction conditions than those of the other solids tested, which allowed its efficient reuse.

The relevance of microalgae biotechnology for producing high-value compounds with biomedical application, such as polysaccharides, has been increasing. Despite this, the knowledge about the composition and structure of microalgae polysaccharides is still scarce. In this work, water-soluble polysaccharides from Nannochloropsis oculata were extracted, fractionated, structurally analysed, and subsequently tested in terms of immunostimulatory activity. A combination of sugar and methylation analysis with interaction data of carbohydrate-binding proteins using carbohydrate microarrays disclosed the complex structural features of the different polysaccharides. These analyses showed that the water-soluble polysaccharides fractions from N. oculata were rich in (β1→3, β1→4)-glucans, (α1→3)-, (α1→4)-mannans, and anionic sulphated heterorhamnans. The immunostimulatory assay highlighted that these fractions could also stimulate murine B-lymphocytes. Thus, the N. oculata water-soluble polysaccharides show potential to be further explored for immune-mediated biomedical applications.

The oxidative modification of Biolignin (BL) has been investigated to make it more suitable as an adsorbent for transition/heavy metals. BL is a by-product of a wheat straw organosolv process for the production of pulp, ethanol, and pentoses (CIMV S.A. pilot plant, Levallois Perret, France). It was subjected to oxidation by a polyoxometalate (POM) H3[PMo12O40], aiming at the increment of oxygen-containing adsorption-active sites. The POM oxidation of BL was performed under moderate conditions (1 bar, 60–90°C, and 200°C) with the co-oxidants O2 or H2O2. The resulting lignin functionality and structure was evaluated by pyrolysis-gas chromatography/mass spectrometry, solid-state 13C nuclear magnetic resonance, Fourier transform infrared, and chemical analysis. The condensation degree of BL and its COOH and aliphatic OH group contents increased significantly, whereas the polymer structure was maintained. Under optimal conditions with POM/H2O2, the sorption capacity of lignins toward Cd(II) and Pb(II) was increased threefold and twofold, respectively.

The chemical composition and the structural features of macromolecular components from red grape skins (variety Touriga Nacional) have been evaluated. The results of chemical analyses revealed the following contents of the main constituents: cellulose (20.8%), hemicelluloses (12.5%), proteins (18.8%), tannins (13.8%), extractives soluble in dichloromethane (5.0%) and ash (7.8%). Cellulose of grape skins is typical cellulose I polymorph with a degree of crystallinity of 66.1% as assessed by X-ray scattering. The hemicelluloses were analyzed by neutral sugars analysis, methylation analysis and 1D/2D H-1 NMR. The water-soluble compounds (26.4%) are composed mainly of monomeric sugars (glucose and fructose) and a complex mixture of hemicelluloses, the most abundant being pectin and acetylated glucomannan. The major part of structural polysaccharides (cellulose, xylan, xyloglucan, etc.) is embedded in cuticular layer and is poorly accessible to the acid hydrolysis. The cuticular substances contributed to ca. 8.5% of grape skins and their chemical structure has been evaluated by methanolysis. The possibility of comprehensive utilization of grape skins has been discussed. (C) 2012 Elsevier B.V. All rights reserved.

Hardwood spent sulphite liquors (HSSLs) are by-products from the pulping industry rich in pentoses, which are not yet fully exploited for bioprocessing, namely for the production of bioethanol. The sustainable fermentation of pentoses into bioethanol is a challenge to overcome. Besides sugars, HSSLs contains inhibitors that decrease the possibility of bioprocessing of these by-products. Nevertheless, recent studies have brought new insights in using HSSLs for bioethanol production. This paper reviews the results of relevant studies carried out with HSSLs towards bioprocessing to bioethanol. The composition of SSLs was compared and related with the wood origin stressing specificity of microbial inhibitors from HSSL and their anti-microbial effect. The different fermentative processes, the microorganisms used, and the strategies to improve yield and productivity used so far were also reviewed. This review allowed concluding that research is still needed in several areas, including optimization of detoxification processes, fermentation strategies and selection of suitable microbial strains in order to achieve the integration of the different steps needed for HSSLs bioconversion into ethanol thus contributing for sustainability of pulping mills within biorefinary concept. (C) 2012 Elsevier Ltd. All rights reserved.

Industrially produced bleached recycled pulp (R) comprising essentially hardwood fibres was subjected to enzymatic treatment with endo-xylanase from Thermomyces lanuginosus with or without ultra-high hydrostatic pressure (UHP) pre-treatment at 300–600 MPa for 10 min. The kinetics and the extent of enzymatic hydrolysis after UHP pre-treatment under different conditions have been evaluated by released reducing sugars and the analysis of neutral sugars in pulps, respectively. The changes in surface chemical composition of pulps were assessed by UV-vis diffuse reflectance spectroscopy. UHP-pre-treated R under optimal conditions (400 MPa), with or without posterior enzymatic treatment, was used for the production of handsheets and evaluation of its mechanical properties. It was suggested that enzymatic modification improves significantly the papermaking properties of recycled pulp. These improvements were related with selective removal of xylan bound to impurities and to aggregated cellulose fibrils on the fibre surface, thus favouring the ensuing swelling and inter-fibre bonding in paper. UHP pre-treatment and posterior enzymatic treatment revealed a synergetic effect on the mechanical properties of recycled pulp. This fact was assigned to enhanced accessibility of fibres towards xylanase and by forced hydration and favourable rearrangement of cellulosic fibrils in fibres after UHP pre-treatment. The increase of basic strength properties after UHP-promoted xylanase treatment was up to 30 % being the most pronounced for the tensile strength and the burst resistance.

Three mixtures containing different molar proportions of (beta 1-4)-D-mannotriose and (alpha 1 -> 5)-L-arabinotriose, oligosaccharides structurally related to coffee polysaccharides (galactomannans and arabinogalactans), were roasted at 200 degrees C for different periods. Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MSn) analyses of labeled (180) and unlabeled samples allowed identification of not only nonhybrid oligosaccharides but also hybrid oligosaccharides composed of both hexose and pentose units. The identification of hybrid oligosaccharides allowed us to infer the occurrence of nonenzymatic transglycosylation reactions involving both oligosaccharides in the starting mixtures. Also, it was observed that using different proportions of the oligosaccharides in the starting mixtures and extents of thermal treatment led to a variation in the composition of the compounds formed. These results have led to the conclusion that, depending on the distribution of the polysaccharides in the bean cell walls and the roasting conditions, different nonhybrid and hybrid structures can be formed during coffee roasting.

High pressure laminates (HPLs) are attractive, resistant to environmental effects and good cost-benefit decorative surface composite materials whose properties can be tailored to meet specific market demands. In this study, the substantial improvement of dirt repellence of HPLs with simultaneous enhancement of its abrasion resistance was achieved for the first time by incorporating nonafluorohexyl polyhedral oligomeric silsesquioxane (FH-POSS) nanoparticles (up to 1% w/w) into a melamine formaldehyde (MF) resin matrix used to impregnate decorative and overlay papers required for HPLs production. FH-POSS particles were synthesized and thoroughly characterized by C-13 and Si-29 solid state nuclear magnetic resonance (NMR) spectroscopy, and by X-ray diffraction (XRD) analysis. Fluoroalkyl moieties in FH-POSS afforded increased hydrophobicity to HPLs thus providing improved surface clean ability, whereas abrasion resistance was improved due to the robust silica core of the POSS particles. Hydrophobicity of HPLs doped with FH-POSS increased with time, after resin curing, and this was attributed to migration of FH-POSS nanoparticles to the composite surface. (C) 2016 Elsevier B.V. All rights reserved.

A crucial problem for laminate producers is the dimensional instability of decorative papers during soaking in aqueous solutions, but the source of this dilemma is not completely understood yet. In this study, eight commercial decorative papers of similar fiber composition and sizing were analyzed for their structural, physical, and mechanical properties. These properties were examined for their correlations to the dimensional stability of papers when moistened, as assessed by the wet stretch dynamics. Structure-to-property relationships were evaluated by principal component analysis (PCA). Within the set of parameters examined, PCA revealed that fiber orientation and the content of fillers/pigments influenced the wet expansion of paper web and affected its margins and dimensions in longitudinal and transverse directions of the paper machine. These variables are discussed within the context of decorative paper engineering in order to produce high performance papers with regular wet expansion properties.

The removal of graffiti causes irreversible deterioration of fair-faced concrete. The protective products are often selected without counting the properties of concrete surface leading to its insufficient protection. Chemical and micro-structural effects of anti-graffiti products on the concrete surface were analyzed in relation to its protection efficiency against graffiti paints. Contact angles and wetting envelope graphs were examined, allowing the understanding and prediction of wetting behavior of concrete surfaces. The obtained results revealed the changes on the concrete surface produced by graffiti, graffiti protection and graffiti removal products, showing the advantage of permanent protection coating over sacrificial one., CICECO – Institute of Materials (Portugal) for the financing of this work within the scope of the FCT (Portugal) grant PEst-C/QUI/UI0062/2013

Many chemicals are used to prolong wood lifetime and protect wood against wood-destroying organisms and fire but there is not sufficient information about their possible corrosive effects on wood and its structural components from the perspective of long-term exposition in unsuitable condition. This study evaluated the combined effects of inorganic chemicals (borates, phosphates containing ammonia, sulphates with metal cations, chlorides) and wet-thermal accelerated ageing (T=80 °C, RH=65 %, for 30 days) on chemical composition of treated wood. Used analyses indicated that selected chemicals cause a decomposition of all wood constituents in varying degrees. Cellulose was degraded in the greatest extent due to acidic sulphates (Fe3+, Cu2+) and almost no deterioration of polysaccharides was caused with H3BO3. A negative effect on lignin had almost only Na2B4O7.10H2O and NaCl. At the same time the amount of extractives in hot water and acetone and ash content were compared at all samples. The wet-thermal ageing played an important role in wood degradation, but the effect of chemical treatment was certainly stronger.

In this work, the successful derivatization of a beechwood xylan (BX) by carboxymethylation and hydroxypropylation was achieved aimed to produce bio-based films. Carboxymethyl xylan (CMX) and hydroxypropyl xylan (HPX) with a substitution degree of 0.3 and 1.1, respectively, as determined by H-1 NMR, were synthesised. The xylan's characterization by thermogravimetric analysis showed that HPX is thermally more stable than CMX or BX. The ability of the xylan derivatives to form films and the effect of the glycerol addition on the films performance were evaluated. Tensile strength, Young's modulus and water vapour permeability of self-supporting CMX films were higher and the elongation at break lower than those of the corresponding HPX films. The water vapour barrier properties of CMX and HPX films were improved with 10% glycerol addition. Oxygen barrier property was exceptionably good for a CMX film plasticized with 25% of glycerol (oxygen permeability of 0.5 cm(3) mu m m(-2) d(-1) kPa(-1)) while higher oxygen permeability values were obtained for HPX films. Favourable characteristics were found that may enable the use of these films in, e.g., coatings for packaging. (C) 2016 Elsevier B.V. All rights reserved.

RATIONALE The structural characterization of unknown oligosaccharides remains a big challenge since a large number of isomeric structures are possible even for disaccharides. In this work, electrospray ionization collision-induced dissociation tandem mass spectrometry (ESI-CID-MS/MS) was used for the differentiation of isomeric pentose disaccharides, α-(1 → 5)-L-arabinobiose (Ara(2)) and β-(1 → 4)-D-xylobiose (Xyl(2)). METHODS ESI-MS/MS spectra of [M + Li](+) and [M + Na](+) ions of Ara(2) and Xyl(2), as well as these precursor ions of (18)O-labelled disaccharides, were acquired using two mass spectrometers equipped with different analyzers: LIT (linear ion trap) and Q-TOF (quadrupole time-of-flight). RESULTS Product ions observed in MS/MS spectra arise from the cleavage at the nonreducing side of the glycosidic bond (Y(1)(+)) and from cross-ring cleavages (0,1)A(2)(+), (0,2)A(2)(+), and (0,3)A(2)(+) at the reducing residue. Statistically significant differences were observed between the relative abundance of specific product ions, when comparing both disaccharides. These differences allowed discriminant models to be built and to propose a criterion using the relative abundances of selected ions capable of discriminating between the isomers for both adduct ions and spectrometers. CONCLUSIONS Isomeric pentose disaccharides can be distinguished based on the fragmentation of both [M + Li](+) and [M + Na](+) ions and using different mass spectrometers. However, LIT instrument has a better discriminant power.

The effect of urea on the cellulose degradation under conditions of alkaline pulping has been studied using purified cellulose powder. The increased cellulose yield in the presence of urea was assigned essentially to the carbamation reactions which were confirmed by elemental analysis, UV-resonance Raman and solid-state 13C nuclear magnetic resonance spectroscopy. The stabilizing effect of urea on the cellulose peeling reactions during heating up period of pulping process was suggested based on kinetic studies and additionally confirmed in model reactions using cellobiose. The reaction products formed in alkaline urea solutions were analysed by tandem electrospray ionization mass spectrometry and the occurrence of Maillard type reactions between reducing end groups of cellobiose and urea were evidenced. Both Maillard type reactions and carbamation of reducing end groups were proposed to be a part of cellulose protection mechanism against peeling under the conditions of alkaline pulping.

This study puts particular emphasis on the role of copper ions in the performance of hydrogen peroxide bleaching (P-stage). Owing to their variable levels across the bleaching line due to washing filtrates, bleaching reagents, and equipment corrosion, these ions can play a major role in hydrogen peroxide decomposition and be detrimental to polysaccharide integrity. In this study, a Cu-contaminated D0(EOP)D1 prebleached pulp was subjected to an acidic washing (A-stage) or chelation (Q-stage) before the alkaline P-stage. The objective was to understand the isolated and combined role of copper ions in peroxide bleaching performance. By applying an experimental design, it was possible to identify the main effects of the pretreatment variables on the extent of metals removal and performance of the P-stage. The acid treatment was unsuccessful in terms of complete copper removal, magnesium preservation, and control of hydrogen peroxide consumption in the following P-stage. Increasing reaction temperature and time of the acidic A-stage improved the brightness stability of the D0(EOP)D1AP bleached pulp. The optimum conditions for chelation pretreatment to maximize the brightness gains obtained in the subsequent P-stage with the lowest peroxide consumption were 0.4% diethylenetriaminepentaacetic acid (DTPA), 80ºC, and 4.5 pH.

The focus of this study is the chemistry of reductive bleaching of kraft pulps with sodium dithionite. A set of model compounds mimicking quinone structures, residual lignin structures with conjugated carbonyl/carboxyl groups and muconic acid, among others, was reduced with sodium dithionite and monitored by ultraviolet-visible (UV-vis) spectroscopy. Depending on the chromophore models, either reductive or sulfonation reactions are thought to be responsible for the degradation. No reductive degradation of hexeneuronic acid (HexA) residues was detected, but unsaturated structures of unknown origin were eliminated from the xylan. Additionally, the potential of the reductive stage with either sodium dithionite or sodium borohydride was tested using an industrial pine kraft pulp bleached by OOZEDD sequence. This pulp, with a 88.8% ISO brightness ceiling, exhibited a brightness increase to 90 ± 0.5% in the final reduction stage.

The reasons for the improved brightness stability of pulp bleached in the final stage with hydrogen peroxide than with chlorine dioxide have been studied. UV–vis Diffuse Reflectance and UV Resonance Raman micro-spectroscopy @ 325 nm were employed to evaluate the chromophores formation/degradation in fully bleached eucalypt kraft pulp while applying a final chlorine dioxide or a hydrogen peroxide bleaching stages. Spectroscopic data were coupled to wet chemistry and mass spectrometry analyses of degradation products arisen during hydrothermal ageing of bleached pulps. The complementary analyses have revealed the important role of partially oxidised carbohydrates and of the residual xylan–lignin complex in ageing reactions. The leaching of degradation products from pulp during the final bleaching stage, rather than specific oxidation patterns of pulp polysaccharides with the bleaching agent was suggested to be a crucial factor predetermining the extent of brightness reversion of pulp.

Ultrahigh hydrostatic pressure (UHP) was applied to enhance the enzymatic hydrolysis of xylan in cellulosic fibers. The pretreatment improved xylan accessibility in the fiber cell wall and a 5–10-fold increase in the initial hydrolysis rate of xylan by xylanase was observed when Eucalyptus globulus kraft bleached pulp was pretreated at hydrostatic pressures of 300–400 MPa for 15–45 min. The rate and the extent of hydrolysis can be controlled by varying the pressure and the exposure time of UHP treatment prior to enzymatic hydrolysis. Sequential UHP pretreatment and hydrolysis by xylanase disaggregated the hydrated cellulose fibrils and led to the gelation of cell wall regions accessible to enzymatic attack. UHP could therefore become a tool for the engineering of enzymatic reactions within cellulosic fibers to obtain products with tailored properties.

Modified eucalyptus kraft lignin doped with multiwall carbon nanotubes (MWCNTs) was used as a macromonomer in step-growth polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol) with the aim of producing a conductive copolymer for all-solid-state potentiometric chemical sensor applications. The crosslinked elastomeric polyurethane obtained was characterized by Fourier transform infrared attenuated total reflection spectroscopy, scanning electron microscopy, tunnelling electron microscopy and atomic force microscopy. Doping of lignin-based polyurethane with MWCNTs produced a significant enhancement of its electrical conductivity without deterioration of thermal and viscoelastic properties. The polymer composite displayed a low percolation threshold at an MWCNT concentration of 0.18% (w/w), which was explained by the oriented distribution of MWCNTs along lignin clusters. All lignin-based polyurethanes doped with MWCNTs at concentrations above the percolation threshold are suitable for sensor applications. Copyright © 2012 Society of Chemical Industry

Cellulosic fibre/silica hybrid materials functionalized with Keggin-type polyoxometalates ([PV2Mo10O40]52, [PVMo11O40]42, ([PMo12O40]32 or [PW12O40]32) were prepared by a sol–gel method at room temperature. The novel materials are composed of ca. 56 wt% of polysaccharides, ca. 37 wt% of propylamine-modified silica, 2 wt% of polyoxometalate, and 5% of hydration water. The silica network of these hybrids exhibits relatively high degree of condensation being distributed mainly on the surface of the cellulosic fibres as a dense film. The functionalization of silica with polyoxometalates via electrostatic interactions with protonated propylamino groups of modified silica was unambiguously confirmed. Despite their high silica content cellulose/silica hybrids retained basic cellulosic pulp properties—supramolecular and fibrous structure, porosity, relatively low density, etc. The novel bio-based material functionalized with 2% of [PVMo11O40]42 shows particularly high activity towards the oxidation of volatile organic compounds (VOCs) present in urban air thus anticipating future environmental applications. published

The hydroxyl radicals are widely implicated in oxidation of carbohydrates during biological and industrial processes being responsible for their structural modifications and causing functional damage. The identification of intermediate oxidation products is hampered by a lack of reliable sensible methods for their detection. In this study, the oxidation of two models of galactomannans (Man 3 and GalMan 2 ) has been studied in reaction with hydroxyl radical generated by Fenton reaction. The oxidation patterns were assessed using preparative ligand-exchange/size-exclusion chromatography (LEX/SEC) coupled with tandem electrospray mass spectrometry (ESI-MS/MS). This allowed the identification of derived oligosaccharides (OS) containing hexuronic, hexonic, pentonic and erythronic acid residues and neutral OS bearing hydroperoxy, hydrated carbonyl moieties and residues from pyranosyl ring cleavage. The depolymerization products have been also detected upon oxidation of oligomers. This study allowed developing a simple, effective ‘fingerprinting’ protocol for detecting the damage done to mannans by oxidative radicals.

The chemical composition of oleo-gum-resin from Ferula gummosa collected in the northern part of Iran has been studied. The fraction of oleo-gum-resin soluble in ethanol (ca 67 wt.%) is composed by three major fractions: (i) monoterpenes and monoterpenoids (ca 15 wt.% fraction), (ii) sesquiterpenes and sesquiterpenoids (ca 30 wt.%) and (iii) triterpenes and triterpenoids (ca 55 wt.%). The major families of terpenes and terpenoids were identified employing gas chromatography coupled with mass spectrometry detector (GC–MS). Almost 25 wt.% of oleo-gum-resin was insoluble in ethanol and, according to wet chemistry analyses, assigned to arabinogalactane structurally associated with protein complex (AGP). This arabinogalactan possessed the molecular weight of ca 30 kDa, as revealed by size exclusion chromatography, and the main backbone was constituted by β-(1 → 3)/β-(1 → 3,6)-linked d -galactopyranosyl residues ramified predominantly by terminal α- l -arabinofuranosyl and β- d -glucuronopyranosyl residues, as assessed by 1D/2D 1 H NMR.

The structural features of four different kraft papers were related to their surface properties and to the response upon industrial impregnation with phenol-formaldehyde (PF) resin. The chemical composition and the structure of paper were suggested to be important factors determining the interaction with PF resin, which was assessed by contact angle measurements and surface energy analysis. The presence of fatty matter (extractives) and inorganic fillers together with structural anisotropy of paper confers the difference in affinity of the face and backside of papers toward PF resin. This affects the resin distribution in impregnated precured kraft papers as revealed by microfluorescence spectroscopic analysis of transversal cuts.

Among new potential solvents for lignocellulosic materials, ionic liquids (ILs) are attracting considerable attention. Hence, the knowledge of the thermophysical properties of such fluids is essential for the design of related industrial processes. Therefore, in this work, a set of thermophysical properties, namely, density, viscosity, and refractive index, as a function of temperature, and isobaric thermal expansivity and heat capacities at a constant temperature, were determined for eight ionic liquids with the 1-ethyl-3-methylimidazolium cation combined with the following anions: acetate, methylphosphonate, methanesulfonate, trifluoromethanesulfonate, dicyanamide, thiocyanate, tosylate, and dimethylphosphate. Imidazolium-based ILs were chosen since these are the most studied ionic fluids in biomass dissolution approaches, while a large array of anions was investigated because it was already demonstrated that it is the IL anion that mainly governs the dissolution.

The oxidation kinetics of lignosulfonates (LS) from acidic magnesium-based sulfite pulping of Eucalyptus globulus wood with oxygen under alkaline conditions was studied. The analysis of oxidation products in the reaction system O(2)/NaOH revealed a predominance of aromatic aldehydes (vanillin and syringic aldehyde) though small amounts of vanillic and syringic acids and acetophenone/phenylacetaldehyde derivatives have also been detected. The rate constant of syringic aldehyde formation was roughly twice of that for vanillin. The effective activation energies for the oxidation of LS to aromatic aldehydes (ca. 60-70 kJ/mol) were rather different to those found for the formation of aromatic acids (ca. 110 kJ/mol) indicating different mechanisms involved in the rate-determining reaction step. The addition of catalyst (copper salt, 20% w/w) promoted the LS oxidation with increments of aromatic aldehyde yields by 25-50%. The maximum yields of syringic aldehyde and vanillin upon LS oxidation were 16.1 and 4.5%, respectively (150 degrees C, 20 min, P(O2) = 10 bar, 0.9 M NaOH solution). The highly negative effect of concomitant sugars in sulfite liquor to the yield of aromatic aldehydes was highlighted.

Ultraviolet-resonance Raman (UV-RR) micro-spectroscopy is an appropriate and sensitive tool to assess the chromophore structures in bleached cellulosic pulps used for papermaking. The particular selectivity in detection and identification of chromophores in pulps is achieved by acquiring the UV-RR spectra in the solid state with laser excitation at 325 nm. This wavelength corresponds to absorption of poly-unsaturated chromophore structures in partially bleached/fully bleached pulps, and linearly correlated with the signal at ca 1600 cm−1 in the UV-RR spectra. The characteristic vibrations from particular pulp chromophore structures have been assigned from experiments with model compounds, thus allowing the establishment of a UV-RR database. Among the components of bleached pulp, the xylan–lignin complex was suggested to be an important source of chromophores. The monitoring of pulp bleaching by UV-RR allowed us to suggest that it is the formation of new polysaccharide-derived chromophores upon bleaching that hinders development of further brightness and is co-responsible for the brightness reversion of fully bleached pulps. Copyright © 2010 John Wiley & Sons, Ltd.