<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ferreira, Rui</style></author><author><style face="normal" font="default" size="100%">Garcia, Helga</style></author><author><style face="normal" font="default" size="100%">Sousa, Andreia F.</style></author><author><style face="normal" font="default" size="100%">Petkovic, Marija</style></author><author><style face="normal" font="default" size="100%">Lamosa, Pedro</style></author><author><style face="normal" font="default" size="100%">Freire, Carmen S. R.</style></author><author><style face="normal" font="default" size="100%">Silvestre, Armando J. D.</style></author><author><style face="normal" font="default" size="100%">Rebelo, Luís Paulo N. Luis Paulo N.</style></author><author><style face="normal" font="default" size="100%">Pereira, Cristina Silva</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Suberin isolation from cork using ionic liquids: characterisation of ensuing products</style></title><secondary-title><style face="normal" font="default" size="100%">New Journal of Chemistry</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cholinium alkanoates</style></keyword><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">suberin</style></keyword><keyword><style  face="normal" font="default" size="100%">suberinic materials (voyant)</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2012</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2012///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://xlink.rsc.org/?DOI=c2nj40433hhttp://dx.doi.org/10.1039/C2NJ40433H</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">36</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Cholinium alkanoates, a class of benign ionic liquids, were demonstrated to efficiently extract suberin domains from cork. A detailed characterisation of the extracted material has yet to be attained. In the present study the significance of the alkylic chain length of the anion and the ionic liquid's basicity was investigated. The results obtained emphasise cholinium hexanoate's selection; it proved to be a straightforward process, also ensuring the recyclability and reusability of the ionic liquid. The extracted suberinic material has been thoroughly characterised for the first time by ATR-FTIR, NMR, GC-MS and thermal analyses. Data showed that it is mainly composed of oligomeric or polymeric aliphatic esterified structures, resulting from suberin partial cleavage. More than 40 wt% of the extracted suberinic material was found to be cross-linked. Even though, the composing monomeric units were similar to those usually identified in suberin samples obtained by the conventional extraction processes. These data pave the way for advanced studies of suberin monomers/oligomers as building-blocks for the development of novel biopolymers and biomaterials.</style></abstract><issue><style face="normal" font="default" size="100%">10</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;publisher: The Royal Society of Chemistry</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Bernardo-Gil, M. Gabriela</style></author><author><style face="normal" font="default" size="100%">Lopes, Isabel M. G.</style></author><author><style face="normal" font="default" size="100%">Casquilho, Miguel</style></author><author><style face="normal" font="default" size="100%">Ribeiro, M. Albertina</style></author><author><style face="normal" font="default" size="100%">Esquível, M. Mercedes</style></author><author><style face="normal" font="default" size="100%">Empis, José</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Supercritical carbon dioxide extraction of acorn oil</style></title><secondary-title><style face="normal" font="default" size="100%">The Journal of Supercritical Fluids</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">acorn</style></keyword><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus rotundifolia L.</style></keyword><keyword><style  face="normal" font="default" size="100%">Sovová model</style></keyword><keyword><style  face="normal" font="default" size="100%">Supercritical carbon dioxide</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2007///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://linkinghub.elsevier.com/retrieve/pii/S0896844606002191</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">40</style></volume><pages><style face="normal" font="default" size="100%">344 - 348</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Acorn fruit oil of Quercus rotundifolia L. (holm-oak) was extracted with compressed carbon dioxide in the temperature range of 35–60 ◦ C and in the pressure range of 12–21 MPa. The inﬂuences of particle size, CO2 density, solvent ﬂow rate, and extractor geometry were studied. Two different tubular extractors were used: extractor 1 of 0.2 L of capacity, internal diameter D = 45.7 mm, height/diameter ratio H/D = 1.5, and extractor 2 of 0.09 L of capacity, internal diameter D = 21.3 mm, and H /D = 12. It was found that the yield and the initial extraction rate depend on the carbon dioxide density and superﬁcial velocity, and on the ratio of bed height to D, at the same conditions of temperature, pressure, and particle size. In the beginning of extraction, CO2 density is the preponderant factor, but after some time of extraction, the fraction of oil directly exposed to the solvent, which is dependent on particle size, becomes the most important factor. The Sovova model was successfully applied to the description of the supercritical extraction curves of acorn oil</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Bernardo-Gil, M Gabriela</style></author><author><style face="normal" font="default" size="100%">Lopes, Isabel M G</style></author><author><style face="normal" font="default" size="100%">Casquilho, Miguel</style></author><author><style face="normal" font="default" size="100%">Ribeiro, M Albertina</style></author><author><style face="normal" font="default" size="100%">Esquível, M Mercedes</style></author><author><style face="normal" font="default" size="100%">Empis, José</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Supercritical carbon dioxide extraction of acorn oil</style></title><secondary-title><style face="normal" font="default" size="100%">The Journal of Supercritical Fluids</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">acorn</style></keyword><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus rotundifolia L.</style></keyword><keyword><style  face="normal" font="default" size="100%">Sovová model</style></keyword><keyword><style  face="normal" font="default" size="100%">Supercritical carbon dioxide</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year></dates><volume><style face="normal" font="default" size="100%">40</style></volume><pages><style face="normal" font="default" size="100%">344-348</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Acorn fruit oil of Quercus rotundifolia L. (holm-oak) was extracted with compressed carbon dioxide in the temperature range of 35–60 ◦ C and in the pressure range of 12–21 MPa. The inﬂuences of particle size, CO2 density, solvent ﬂow rate, and extractor geometry were studied. Two different tubular extractors were used: extractor 1 of 0.2 L of capacity, internal diameter D = 45.7 mm, height/diameter ratio H/D = 1.5, and extractor 2 of 0.09 L of capacity, internal diameter D = 21.3 mm, and H /D = 12. It was found that the yield and the initial extraction rate depend on the carbon dioxide density and superﬁcial velocity, and on the ratio of bed height to D, at the same conditions of temperature, pressure, and particle size. In the beginning of extraction, CO2 density is the preponderant factor, but after some time of extraction, the fraction of oil directly exposed to the solvent, which is dependent on particle size, becomes the most important factor. The Sovova model was successfully applied to the description of the supercritical extraction curves of acorn oil</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ferreira-Dias, Suzana</style></author><author><style face="normal" font="default" size="100%">Valente, Dina G</style></author><author><style face="normal" font="default" size="100%">Abreu, José M F</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comparison between ethanol and hexane for oil extraction from Quercus suber L. fruits</style></title><secondary-title><style face="normal" font="default" size="100%">Grasas y Aceites</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">acorns</style></keyword><keyword><style  face="normal" font="default" size="100%">Ethanol</style></keyword><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">Hexane</style></keyword><keyword><style  face="normal" font="default" size="100%">Oil</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2003</style></year></dates><volume><style face="normal" font="default" size="100%">54</style></volume><pages><style face="normal" font="default" size="100%">378-383</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The aim of this study was to (i) evaluate the feasibility of replacing n -hexane with ethanol for the extraction of oil from Quercus suber fruits and (ii) optimize, at lab scale, sample preparation and extraction time for both solvents used ( n -hexane vs . anhydrous ethanol). For both solvents, the effect of the conditioning process on extraction yield was evaluated. Therefore, a full factorial design was used as a function of four variables: dehulling (with vs . without husks), and thermal treatment of the crushed material (40ºC vs . 75ºC), at different times (5 min vs . 120 min) and pressures (10 kPa vs. 100 kPa). Higher oil yields were obtained with n -hexane when dehulled fruits were conditioned under atmospheric pressure. Better yields were obtained with n -hexane, when dehulled material was treated at 75ºC for 90 min. Ethanol was not adequate for oil extraction from Quercus fruits, since other materials rather than oil were also extracted.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ferreira-Dias, Suzana</style></author><author><style face="normal" font="default" size="100%">Valente, Dina G.</style></author><author><style face="normal" font="default" size="100%">Abreu, José M. F.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comparison between ethanol and hexane for oil extraction from Quercus suber L. fruits</style></title><secondary-title><style face="normal" font="default" size="100%">Grasas y Aceites</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">acorns</style></keyword><keyword><style  face="normal" font="default" size="100%">Ethanol</style></keyword><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">Hexane</style></keyword><keyword><style  face="normal" font="default" size="100%">Oil</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2003</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2003///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://grasasyaceites.revistas.csic.es/index.php/grasasyaceites/article/view/225/225</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">54</style></volume><pages><style face="normal" font="default" size="100%">378 - 383</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The aim of this study was to (i) evaluate the feasibility of replacing n -hexane with ethanol for the extraction of oil from Quercus suber fruits and (ii) optimize, at lab scale, sample preparation and extraction time for both solvents used ( n -hexane vs . anhydrous ethanol). For both solvents, the effect of the conditioning process on extraction yield was evaluated. Therefore, a full factorial design was used as a function of four variables: dehulling (with vs . without husks), and thermal treatment of the crushed material (40ºC vs . 75ºC), at different times (5 min vs . 120 min) and pressures (10 kPa vs. 100 kPa). Higher oil yields were obtained with n -hexane when dehulled fruits were conditioned under atmospheric pressure. Better yields were obtained with n -hexane, when dehulled material was treated at 75ºC for 90 min. Ethanol was not adequate for oil extraction from Quercus fruits, since other materials rather than oil were also extracted.</style></abstract><issue><style face="normal" font="default" size="100%">4</style></issue></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Criquet, Stéven</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Measurement and characterization of cellulase activity in sclerophyllous forest litter.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of microbiological methods</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Buffers</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulase</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulase: analysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulase: isolation &amp; purification</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulose</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulose: metabolism</style></keyword><keyword><style  face="normal" font="default" size="100%">Endoglucanase</style></keyword><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrogen-Ion Concentration</style></keyword><keyword><style  face="normal" font="default" size="100%">Isoenzyme</style></keyword><keyword><style  face="normal" font="default" size="100%">Isoenzymes</style></keyword><keyword><style  face="normal" font="default" size="100%">Isoenzymes: analysis</style></keyword><keyword><style  face="normal" font="default" size="100%">litter</style></keyword><keyword><style  face="normal" font="default" size="100%">Plant Leaves</style></keyword><keyword><style  face="normal" font="default" size="100%">Plant Leaves: enzymology</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus: enzymology</style></keyword><keyword><style  face="normal" font="default" size="100%">Temperature</style></keyword><keyword><style  face="normal" font="default" size="100%">Trees</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2002///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/11997167</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">50</style></volume><pages><style face="normal" font="default" size="100%">165 - 173</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Cellulases are enzymatic proteins which hydrolyze cellulose polymers to smaller oligosaccharides, cellobiose and glucose. They consist in three major types of enzymes: endoglucanases (EC 3.2.1.4), cellobiohydrolases (EC 3.2.1.91) and beta-glucosidases (EC 3.2.1.21) which play an essential role in carbon turnover of forest ecosystem. The aim of this study was firstly to determine the parameters (i.e. buffer type, pH, temperature, quantity of litter, incubation time and reagent type) which affect the measurement of cellulase activity in a sclerophyllous forest litter, and secondly to compare two methods for measuring cellulase activity: a direct method and an extraction method. In the direct method, the litter was directly incubated with a buffered solution containing the enzyme substrate, whereas in the extraction method, the cellulases were firstly extracted before measuring their activity. The results were compared with other studies about soil cellulase activity, and it appeared that several parameters (buffer type, pH, temperature and sample quantity) which influence the measurement of cellulase activity differ according to whether a soil or a litter is considered. Concerning the procedure used for the measurement of cellulase activity, results showed that the activity values were higher when using an extraction procedure than when using a direct procedure. The extraction procedure, combined with a concentration stage of the extract, also allowed electrophoretic analysis (PAGE) of the cellulases extracted from the litter. The electrophoretic pattern revealed two cellulase isoenzymes which may be related to the occurrence of two pH-activity peaks of these enzymes when citrate buffer was used for the measurement of cellulase activity in the litter.</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;accession-num: 11997167</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Criquet, Stéven</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Measurement and characterization of cellulase activity in sclerophyllous forest litter.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of microbiological methods</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Buffers</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulase</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulase: analysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulase: isolation &amp; purification</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulose</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellulose: metabolism</style></keyword><keyword><style  face="normal" font="default" size="100%">Endoglucanase</style></keyword><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrogen-Ion Concentration</style></keyword><keyword><style  face="normal" font="default" size="100%">Isoenzyme</style></keyword><keyword><style  face="normal" font="default" size="100%">Isoenzymes</style></keyword><keyword><style  face="normal" font="default" size="100%">Isoenzymes: analysis</style></keyword><keyword><style  face="normal" font="default" size="100%">litter</style></keyword><keyword><style  face="normal" font="default" size="100%">Plant Leaves</style></keyword><keyword><style  face="normal" font="default" size="100%">Plant Leaves: enzymology</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus: enzymology</style></keyword><keyword><style  face="normal" font="default" size="100%">Temperature</style></keyword><keyword><style  face="normal" font="default" size="100%">Trees</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year></dates><volume><style face="normal" font="default" size="100%">50</style></volume><pages><style face="normal" font="default" size="100%">165-173</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Cellulases are enzymatic proteins which hydrolyze cellulose polymers to smaller oligosaccharides, cellobiose and glucose. They consist in three major types of enzymes: endoglucanases (EC 3.2.1.4), cellobiohydrolases (EC 3.2.1.91) and beta-glucosidases (EC 3.2.1.21) which play an essential role in carbon turnover of forest ecosystem. The aim of this study was firstly to determine the parameters (i.e. buffer type, pH, temperature, quantity of litter, incubation time and reagent type) which affect the measurement of cellulase activity in a sclerophyllous forest litter, and secondly to compare two methods for measuring cellulase activity: a direct method and an extraction method. In the direct method, the litter was directly incubated with a buffered solution containing the enzyme substrate, whereas in the extraction method, the cellulases were firstly extracted before measuring their activity. The results were compared with other studies about soil cellulase activity, and it appeared that several parameters (buffer type, pH, temperature and sample quantity) which influence the measurement of cellulase activity differ according to whether a soil or a litter is considered. Concerning the procedure used for the measurement of cellulase activity, results showed that the activity values were higher when using an extraction procedure than when using a direct procedure. The extraction procedure, combined with a concentration stage of the extract, also allowed electrophoretic analysis (PAGE) of the cellulases extracted from the litter. The electrophoretic pattern revealed two cellulase isoenzymes which may be related to the occurrence of two pH-activity peaks of these enzymes when citrate buffer was used for the measurement of cellulase activity in the litter.</style></abstract><accession-num><style face="normal" font="default" size="100%">11997167</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Criquet, S.</style></author><author><style face="normal" font="default" size="100%">Tagger, S.</style></author><author><style face="normal" font="default" size="100%">Vogt, G.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Laccase activity of forest litter</style></title><secondary-title><style face="normal" font="default" size="100%">Soil Biology and Biochemistry</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">laccase</style></keyword><keyword><style  face="normal" font="default" size="100%">litter</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1999///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.sciencedirect.com/science/article/pii/S0038071799000383</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">31</style></volume><pages><style face="normal" font="default" size="100%">1239 - 1244</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Laccases are blue-copper enzymatic proteins involved in the transformation of polyphenolic compounds, such as lignin, into forest litter. A method to measure their activity was developed using an evergreen oak litter as a model system. We considered factors that aect the extraction of these enzymes and the measurement of their activity. The factors studied included powdering of the leaves, adding polyvinylpolypyrrolidone or Tween 80, adsorption of enzymes on centrifugation pellets, concentration of the extracts, nature and molarity of the extraction solvent, amount of powdered leaves used for enzymatic extraction, extraction time, pH, and temperature during the measurement of the activity</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Criquet, S</style></author><author><style face="normal" font="default" size="100%">Tagger, S</style></author><author><style face="normal" font="default" size="100%">Vogt, G</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Laccase activity of forest litter</style></title><secondary-title><style face="normal" font="default" size="100%">Soil Biology and Biochemistry</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">laccase</style></keyword><keyword><style  face="normal" font="default" size="100%">litter</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year></dates><volume><style face="normal" font="default" size="100%">31</style></volume><pages><style face="normal" font="default" size="100%">1239-1244</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Laccases are blue-copper enzymatic proteins involved in the transformation of polyphenolic compounds, such as lignin, into forest litter. A method to measure their activity was developed using an evergreen oak litter as a model system. We considered factors that aect the extraction of these enzymes and the measurement of their activity. The factors studied included powdering of the leaves, adding polyvinylpolypyrrolidone or Tween 80, adsorption of enzymes on centrifugation pellets, concentration of the extracts, nature and molarity of the extraction solvent, amount of powdered leaves used for enzymatic extraction, extraction time, pH, and temperature during the measurement of the activity</style></abstract></record></records></xml>