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- The organosolv fractionation of cork componentsPublication . Cordeiro, Nereid; Neto, Carlos Pascoal; Rocha, Joao; Belgacem, Mohamed N.; Gandini, AlessandroExtractive-free cork from Quercus suber L. was submitted to organosolv fractionation and the effects of different process variables, such as ethanol/water ratio, temperature, time and the presence of acidic or alkaline catalysts, were studied. The variation of the relative proportions of extracted components, as a function of the processing conditions, could thus be established. Whereas the addition of 0.1 M acetic acid only increased the yield of extracted materials from about 15 to 23%, the use of sodium hydroxide, at the same concentration, produced a jump to 76%. In the case of the alkaline organosolv fractiona tion, an increase in process temperature, time and catalyst concentration led to an increase in the extraction yield, although in some cases this increase did not follow a sustained trend, as in the case of reaction time. Increasing the ethanol/water ratio led to a higher selectivity in favour of suberin extraction. Residual cork from different organosolv processes was characterised by FTIR and 13C solid-state NMR. The latter technique provided some valuable information about both process selectivity and cork morphology, particularly with respect to the positioning of suberin macromolecules in the cell wall.
- Structural characterization of lignin from leaf sheaths of “dwarf cavendish” banana plantPublication . Oliveira, Lúcia; Evtuguin, Dmitry V.; Cordeiro, Nereida; Silvestre, Armando J. D.; Silva, Artur M. S.; Torres, Isabel C.Dioxane lignin (DL) isolated from leaf sheaths of banana plant (Musa acuminata Colla var. cavendish) and in situ lignin were submitted to a comprehensive structural characterization employing spectroscopic (UV, FTIR, solid state 13C CP-MAS NMR, liquid state 13C and 1H NMR) and chemical degradation techniques (permanganate and nitrobenzene oxidation). Results obtained showed that banana plant leaf sheath lignin is of HGS type with a molar proportion of p-hydroxyphenyl (H)/guaiacyl (G)/syringyl (S) units of 12:25:63. Most of the H units in DL are terminal phenolic coumarates linked to other lignin substructures by benzyl and Cgamma-ester bonds in contrast to ferulates that are mainly ether linked to bulk lignin. It is proposed that banana plant leaf sheath lignin is chemically bonded to suberin-like components of cell tissues by ester linkages via essentially hydroxycinnamic acid residues. beta-O-4 structures (0.31/C6), the most abundant in DL, comprise mainly S units, whereas a significant proportion of G units is bonded by beta-5, 5-5', and 4-O-5' linkages contributing to ca. 80% of condensed structures in DL.
- Cork suberin as an additive in offset lithographic printing inksPublication . Cordeiro, N.; Blayo, A.; Belgacem, N.M.; Gandini, A.; Pascoal Neto, C.; LeNest, J.-F.Suberin oligomers, isolated from cork (Quercus suber L.), were used as additives in ‘Waterless’ and vegetable-oil ink formulations, in the range of 2–10% w/w. The rheological behaviour of the suberin oligomers as well as of the inks, with and without suberin, were investigated as a function of temperature. It was shown that the addition of suberin induces a decrease of viscosity of both inks. The tack of pristine inks, suberin oligomers and their mixtures were determined at different temperatures: the variation of this parameter as a function of time provided information about the drying kinetics of these formulations. The tack of the ‘Waterless’ ink was found to increase with the introduction of suberin, whereas that of vegetable-oil based counterparts decreased. All the trends observed were interpreted in terms of the differences in composition between the two types of inks. Preliminary printing tests were carried out with the various suberin-containing inks.
- Pulp and paper from" Dwarf Cavendish" pseudo-stemsPublication . Cordeiro, N.; Belgacem, M. N.; Chaussy, D.; Moura, J. C. V. P.
- Lipophilic extracts from banana fruit residues: a source of valuable phytosterolsPublication . Oliveira, Lúcia; Freire, Carmen S. R.; Silvestre, Armando J. D.; Cordeiro, NereidaThe chemical composition of the lipophilic extracts of unripe pulp and peel of banana fruit 'Dwarf Cavendish' was studied by gas chromatography-mass spectrometry. Fatty acids, sterols, and steryl esters are the major families of lipophilic components present in banana tissues, followed by diacylglycerols, steryl glucosides, long chain fatty alcohols, and aromatic compounds. Fatty acids are more abundant in the banana pulp (29-90% of the total amount of lipophilic extract), with linoleic, linolenic, and oleic acids as the major compounds of this family. In banana peel, sterols represent about 49-71% of the lipophilic extract with two triterpenic ketones (31-norcyclolaudenone and cycloeucalenone) as the major components. The detection of high amounts of steryl esters (469-24405 mg/kg) and diacylglycerols (119-878 mg/kg), mainly present in the banana peel extract, explains the increase in the abundance of fatty acids and sterols after alkaline hydrolysis. Several steryl glucosides were also found in significative amounts (273-888 mg/kg), particularly in banana pulp (888 mg/kg). The high content of sterols (and their derivatives) in the 'Dwarf Cavendish' fruit can open new strategies for the valorization of the banana residues as a potential source of high-value phytochemicals with nutraceutical and functional food additive applications.
- Properties and processing of cork powder filled cellulose derivatives compositesPublication . Godinho, Maria Helena; Martins, Assis Farinha; Belgacem, Mohamed Naceur; Gil, Luís; Cordeiro, NereidaThis paper deals with the use of cork powder, a by‐product from cork industry, as a filler to reinforce hydroxypropyl cellulose (HPC) matrix. Several films were prepared using HPC, as a matrix, filled with different amounts of cork powder (average diameter < 50 μm) (0.0; 0.5; 1.0 and 10.0% w/w) and in the presence or not of 1,4‐diisocyanatobutane (BDI) (7.0% w/w). Before the elaboration of these films, the surface properties of cork powder as well as that of suberin (main component of cork) were determined by Inverse Gas Chromatography (IGC). The tensile properties of the solid films obtained were studied and, as expected, for the films with BDI but without cork powder, the Young's modulus and the tensile strength increased, while the elongation decreased. However with the filled films it seemed that the Young's modulus decreased and the elongation increased. The Scanning Electron Microscopy showed that the fractured plane of samples with cross‐linking agent and cork powder displayed some nucleation points (0.3 μm) which indicates a strongly bonded interface and which could be considered as a responsible for the high mechanical properties observed.
- Chemical composition and pulping of banana pseudo-stemsPublication . Cordeiro, Nereida; Belgacem, M.N.; Torres, I. C.; Moura, J.C.V.P.This paper deals with the determination of chemical composition and the study of the pulping potentialities of banana pseudo-stems growing in Madeira Island (Portugal). First, the raw material was both studied as a whole (type I) and as the outer bark part (type II), which is richer in cellulose fibres. Before starting the cooking of banana wastes, the main components of the two types of material were quantified, and showed that the polysaccharide content was high enough (about 60–70%) to justify the pulping investigations. Moreover, the lignin content was very low (approximately 12%). The only discouraging finding was the relative high amounts of ashes and extractives. The pulping of these residues was carried out using soda, kraft and soda-anthraquinone (AQ) cooking processes and the optimal pulping conditions were established. Thus, pulps with a yield of about 37–38% with a Kappa number (Kappa no.) about 30–32 were obtained when cooking in the presence of 0.25–0.35% of anthraquinone at 120 ◦C for a short cooking time, i.e. 30 min. The longer times and higher temperatures of cooking as well as the use of kraft pulping conditions did not give rise to better performances, comparing to those mentioned above. These severe conditions were detrimental to the hemicellulose preservation.
- Valorisation of different agricultural crops in papermaking applicationsPublication . Schott, Séverine; Chaussy, Didier; Mauret, Evelyne; Desloges, Isabelle; Anabela, Antunes; Cordeiro, Nereida; Belgacem, Mohamed Naceur
- Non-conventional reactive dye systems for attaching chromophores to wool, protein and polyamide substratesPublication . Moura, J. C. V. P.; Cordeiro, N.Reactive dyes, which form a covalent bond to the substrate onto which they are applied, have been used in textile applications for many years, and various reactive systems have been researched and commercialised. Reactive dyes also find use in biochemical and biotechnology areas, in particular as biolabels and tracers. This review examines reactive textile dye systems which have not achieved commercial acceptance, and also considers reactive systems that have been proposed solely for biochemical application to proteins.
- Steryl glucosides from banana plant Musa acuminata Colla var cavendishPublication . Oliveira, L.; Freire, C.S.R.; Silvestre, A.J.D.; Cordeiro, N.; Torres, I. C.; Evtuguin, D.The chemical composition of the dichloromethane extracts of several vegetal fractions of banana plant, Musa acuminata Colla var cavendish have been studied by GC–MS. Several bioactive steryl glucosides, namely campesteryl 3- -d-glucopyranoside, stigmasteryl 3- -d-glucopyranoside and sitosteryl 3- -d-glucopyranoside were identified as the major components of the ex tracts, accounting for 838.4–1824.3 mg/kg of the plant fractions dry weight. The high abundance of these compounds might be an important contribution to the valorization of banana plant agricultural residues.