芦苇乙醇法分离木素制浆研究(Ⅲ)

在前面[1]、[2]研究的基础上,仍采用L15(43)正交试验方法,研究了蒸煮时间由1.0h延长到2.0h后乙醇、催化剂和液固比等因素对木素、纤维素分离的影响.试验结果表明:延长蒸煮时间后,各试验因素仍在各因素中值处交汇,以后随着试验因素水平的增高,影响木素、α-纤维素分离的主要因素是乙醇;乙醇和液固比相互作用对木素分离具有显著的交互作用;在70%乙醇、3%催化剂和4:1液固比条件下,可以得到较好的木素、纤维素分离效果;与前文研究相比,结构没有发生变化,所得木素重均分子量和分散指数分别增加为3420.8和2.1 6.     

芦苇乙醇法分离木素制浆研究(Ⅱ)

以芦苇为原料,常压、蒸煮时间为1.5h,在乙醇(70%)、催化剂(7%)和液固比(6:1)条件下,得浆纯度较高,所得木素仍是由苯及其衍生物构成的大分子,所得木素的分子量远大于一般碱未素,分布范围板窄.     

高温蒸煮预处理甘蔗叶制备木聚糖

研究了高温蒸煮预处理甘蔗叶制备木聚糖的工艺过程,探究预浸方式、液固比、蒸煮时间、蒸煮温度4个因素对蒸煮结果的影响。研究表明:蒸煮液中总糖含量随蒸煮温度升高而增大;随蒸煮时间延长,先增大后减小;随液固比增大,先增高后降低。选用的最适工艺条件:用水将甘蔗叶在60℃下浸泡12 h,液固比是10∶1,浸泡液在126℃下密封蒸煮60 min。同时使用电子扫描显微镜分析蒸煮前后蒸煮渣的形态,表明高温蒸煮有利于木聚糖的溶出。     

芦苇乙醇法分离木素制浆研究(Ⅰ)

以芦苇为原料,在常压条件下利用乙醇的水溶液提取分离木素、纤维素,采用三因子二次正交旋转组合设计研究了乙醇、催化剂和液固比对木素、纤维素分离的影响,得到了相应单指标二次回归模型;并对分离出来的木素做了定性分析.研究结果表明:在乙醇50%、催化剂6%和液固比8:1条件下,得浆纯度较高,所得木素仍是由苯丙烷及其衍生物构成的大分子,其分子量远大于一般碱木素,分布范围较窄.     

芦苇乙醇法分离木素制浆研究(Ⅴ)

以芦苇为原料，在较温和条件下利用乙醇的水溶液提取分离木素，纤维素，研究了分离时间对粗浆及木素的影响，结果表明，蒸煮保温时间为2.0h时，木素，纤维素分离效果较好，粗浆中木素和α-纤维素含量分别为10.04%和68.23%，所得木素红外光谱，紫外光谱和凝胶色谱分析显示，随着蒸煮时间的增加，木素中紫丁香基单体增多，分子量有微小变化，简单展望了乙醇法分离木素制浆的前景。     

西瓜藤中黄酮类化合物提取工艺的优化

采用乙醇溶液提取西瓜藤中总黄酮,通过单因素试验和正交试验研究了固液比、提取时间、提取温度和乙醇浓度对总黄酮提取率的影响。结果表明,最优提取条件为：固液比1∶20、提取时间4h,提取温度80℃、乙醇浓度60%。     

利用有机溶剂从棉秆中提取纤维素的蒸煮工艺

机械粉碎至微米级的棉秆粉末经有机酸预处理后,采用乙醇和水的混合(体积比1∶1),在碱催化剂的作用下进行蒸煮,分离得到纤维素。研究了蒸煮过程中催化剂的硫化度、乙醇浓度、蒸煮时间及其温度对浆粕的卡伯值、得率、微观形貌的影响。研究结果表明:在蒸煮条件为温度150℃,硫化度23%,时间2 h,浴比1∶10,催化剂用量8%,助剂的量1%时,可以得到最佳的浆粕。     

龙须草自催化乙醇法制浆工艺及反应历程的研究

通过正交实验确定了龙须草自催化乙醇法制浆的工艺条件,并对其反应历程进行了研究。正交实验结果表明,最佳工艺条件为：蒸煮温度180℃,液比1：10,保温时间120min,乙醇浓度55％;反应历程研究结果表明：(1)木素的脱除分两个阶段：大量脱除阶段和残余脱除阶段;(2)木素和细浆卡伯值呈现很好的线性关系;(3)蒸煮至纤维分离点时,浆中仍有较多的木素,应继续保温;(4)成浆中保留了原料中的大部分灰分。     

正交试验优化酶法提取黄芪总黄酮工艺

以蒙古黄芪为试验材料,研究纤维素酶解辅助乙醇提取黄芪总黄酮的工艺条件。考察了酶添加量、酶解时间、液固比、乙醇浓度、提取时间、提取温度6个单因素对黄芪总黄酮提取率的影响,在单因素试验的基础上,选择四因素四水平进行正交试验优化工艺参数。结果表明:蒙古黄芪在纤维素酶添加量7.5μL/g,pH值4.0,温度55℃,酶解预处理1.5h后,液固比对黄芪总黄酮提取率影响显著,其次是提取时间和乙醇浓度,提取温度对黄芪总黄酮提取率的影响相对较小。在液固比30mL/g,乙醇浓度90%,提取温度75℃,提取时间2.5h的最优工艺条件下,黄芪总黄酮的提取率为0.57%。与传统醇提法(0.39%)相比,黄芪总黄酮提取率提高了46.15%。     

有机溶剂法制备丝瓜络浆粕的工艺探讨

经水蒸煮预处理后的丝瓜络在60%乙醇(体积分数)中进行蒸煮实验,研究了蒸煮中催化剂的比例、催化剂用量、蒸煮最高温度、蒸煮时间等参数对质量损失率和卡伯值的影响。结果表明,当催化剂Na2SO3/NaOH的质量比为5∶5,催化剂用量为8%,蒸煮最高温度为150℃,蒸煮时间为2.5 h时,电镜观测蒸煮后纤维表面附着物减少,红外光谱分析表明木素、半纤维素特征峰减小明显。     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the