热水预水解对松木及其水解液主要化学成分的影响

研究了热水预水解对松木原料中主要碳水化合物的影响,探讨了阿拉伯糖、半乳糖、葡萄糖、木糖和甘露糖的溶出规律及热水预水解对水解液中各聚糖浓度变化的影响;并研究了170℃水解温度对松木原料的化学组成如聚戊糖、苯-醇抽出物、综纤维素、木素、灰分含量的影响。结果表明,预水解过程中,各种聚糖的溶出速度从快到慢依次是:阿拉伯糖、半乳糖、甘露糖、木糖和葡萄糖,水解过程只有部分半纤维素被降解,大量半纤维素还将依赖后续蒸煮和漂白过程予以除去;在180℃的水解温度下,水解液中各聚糖的浓度随水解时间快速下降,糠醛和羟甲基糠醛的浓度则迅速增加,不利于水解液发酵制备乙醇;随着水解时间的延长,松木聚戊糖、灰分含量逐渐减少;苯-醇抽出物含量逐渐增加;综纤维素含量先快速下降,90 min后基本保持不变;木素含量先减少后又略有增加。     

聚木糖酶在溶解浆制备中的应用研究

本文通过对毛竹预水解浆与非预水解浆的对比研究发现：预水解处理后浆料的灰分含量、铁离子含量高，锰酸钾值高，白度较低，不利于后续蒸煮和漂白。非预水解浆性能优于预水解浆，但聚戊糖含量偏高。实验在此前提下探索非预水解浆生物处理降低聚戊糖的可行性及其浆料性质，结果表明：细菌性聚木糖酶和真菌性木聚糖酶能降低聚戊糖含量18．8％左右，二者差异不显著（P〉0．05），但EDTA和Tween80的加入可以进一步降低聚木糖酶处理后浆料中聚戊糖含量、铁离子含量和灰分含量，同时可以提高溶解浆白度。     

竹柳材性、纤维质量及制浆性能的研究

对竹柳的材性特点、纤维质量及制浆性能进行了研究.研究结果表明:竹柳的木材密度在0.384～0.443g/cm3范围;竹柳的灰分、冷热水抽出物和1%NaOH抽出物含量高于速生杨木但比杂交构树低,Klason木素和多戊糖含量与速生杨木相当,但是纤维素含量比速生杨木低3%.竹柳的纤维平均长度为0.84mm、平均宽度为21.44μm.采用硫酸盐法制浆,打浆后竹柳的裂断长为9.44km,撕裂指数4.11mN·m2/g.     

加拿大一枝黄花制浆研究(系列报道之一)生物特性与化学组成

对加拿大一枝黄花生物特性、化学组成及纤维形态进行了分析。结果表明，其主要化学组成：灰分2．92％，克拉森木素18．78％，综纤维素80．28％，戊聚糖19．34％。加拿大一枝黄花茎秆灰分比麦草低得多，与芦苇相当；热水、1％NaOH抽出物比麦草低；苯-醇抽出物与麦草相差不大；木素与麦草相当；综纤维素与杨树相当；戊聚糖含量较低。其纤维形态特征是：纤维长度0．98mm，长宽比86，纤维细胞壁厚3．03μm，壁腔16．86μm，其壁腔比0．56。研究结果表明，加拿大一枝黄花是一种可利用的较好的制浆造纸原料。     

芦苇原料、亚硫酸镁盐苇浆及碱法苇浆性能分析

研究了芦苇原料、亚硫酸镁盐苇浆及碱法苇浆的化学成分。结果表明:亚硫酸镁盐苇浆的灰分、硅含量远高于芦苇原料和碱法苇浆,而聚戊糖含量和Klason木素含量最低;碱法苇浆的1%NaOH抽出物最高,热水抽出物和苯醇抽出物最低。     

椴木化学热磨机械浆

技木是我国北方诸多树种之一，由于其木质较软，建筑业上很少使用。我们将根本列为化学热磨机械浆的研究课题，几个月来取得了可喜的进展。1原料特征1．l原木东北地区产的权木，直径。95mm左右，重度0，39g／cm’。刑律老皮，清除木材表面泥沙、杂物等，削木片长庆13～30mm作试验用。1．2木材化学成分冷水抽出物1．10％，热水抽出物1．40％，苯醇抽出物2．14％，减抽提物20．16％。纤维素含量52．05％，多戊糖含量2505％，木素含量19．08％，灰分0．46％。2试验方法经过削片后的无朽材报木木片，在实验室内测定水分，称取5009绝于木片进行洗…     

引种四川桤木木材化学组分的分析与评价

首次报道了四川桤木５、８和１１２年生３种树龄木材的化学组分测定结果。与其它制浆阔叶木的比较表明,虽然四川桤木的木素含量略高,但木材密度适中,灰分含量中等,各种抽出物含量较低,纤维素含量较高,是优良的纸浆纤维用材。研究发现,木材密度、灰分和热水、苯醇同物含量在个体间差异很大,而其它组分在个体间较为均一。树龄与木材密度和灰分含量的关系不大,而对其它组分影响显著,年幼树木的木材抽出物和戊聚糖含量高,而木     

日本落叶松化学组成与纤维特性的研究

对不同树龄和不同部位日本落叶松的化学组成、糖类组成、纤维形态和纤维素结晶度进行了研究。结果表明，不同树龄日本落叶松的化学组成存在一定的差异：随着树龄的增大，总碳水化合物含量逐渐降低；冷水抽出物、热水抽出物和1％NaOH抽出物的含量增加；灰分含量逐渐降低；聚糖组成中葡萄糖和木糖降低，半乳糖增加；纤维素结晶度指数有所减小。从化学组成与纤维特性分析，12年生和15年生日本落叶松适合用作造纸原料，比20年以上树龄的树木更适合制浆造纸。与我国兴安落叶松相比，日本落叶松的水抽出物与1％NaOH抽出物含量较低，聚糖中葡萄糖含量较多和半乳糖含量较少，从化学组成来说，日本落叶松是一种优于兴安落叶松的造纸原料。     

福建引种区四川桤木的木材化学组分分析与评价

为开发利用四川桤木阔叶木浆,本文首次报道了５、８和１１年和３种种树龄木材的化学组分测定结果,与其它纸浆阔叶木的比表较表明,虽然四川桤木的木质素含量略高（２４．１４％－２５．３９％）,但木材密度适中（０．３４－０．３６g.cm^-3),灰分含量中等（０．４３％－０．４５％）,热水（０．８８％－２．００％）、１％ＮaOH(１６．７７％－１９．８６％）和苯醇抽出物含量（１．２％－１．８５％）较低,纤维含量较高（４７．９３％－５２．３６％）,是优良的纸浆纤维用材,可生产优势的ＢＫＰ、ＣＴＭＰ或ＢＣＴＭＰ等浆种。研究发现,木材密度,灰分和热水、苯醇抽出物含量在个体间差异很大,而其它组分在个体间较为均一,树龄与木材密度和灰分含量的关系不大。而对其他组分影响显著,年幼树木的木材抽出物和戊聚糖含量高,而木质素和纤维素含量低。相关分析说明生长速率对四川桤木人工林的木材密度和化学组分作用较小。     

烟秆的化学成分、纤维形态与生物结构

为促进烟秆在造纸法再造烟叶中的应用,采用制浆造纸原料分析方法和烟草化学分析方法,分析了四川产烟秆的化学成分、纤维形态和生物结构。结果表明:1烟秆的灰分、冷水抽出物、热水抽出物、1%NaOH抽出物、苯醇抽出物和果胶含量均远远低于烟梗和烟叶碎片,高于常规造纸纤维原料;烟秆的综纤维素、硝酸-乙醇纤维素、木素和聚戊糖含量均远远高于烟梗和烟叶碎片,与阔叶材和禾本科原料相当。2除总氮和蛋白质含量与烟梗和烟叶碎片相当外,烟秆的总糖、还原糖、总植物碱含量均较低。3烟秆的重均纤维长度为0.69 mm、宽度为17.74μm,长宽比为38.97,壁腔比为0.68,柔性系数为69.9,纤维细胞含量为71.5%。4烟秆木质部的细胞类型包括导管、木射线和木纤维,具有与阔叶材十分相似的生物结构。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.