共查询到20条相似文献,搜索用时 62 毫秒
1.
稻米中普鲁兰酶的纯化与性质的研究 总被引:1,自引:0,他引:1
稻米的普鲁兰酶(PullulanaseE.C.3.2.1.41)用DEAE-纤维素吸附,SephadexG-100凝胶过滤,聚丙烯酰胺盘状凝胶电泳纯化,得到了聚丙烯酰胺凝胶电泳均一的纯酶。纯酶作用的最适温度为50℃,最适pH为5.5。以普鲁兰(Pullulan)为底物酶的米氏常数Km为0.0125%,以支链淀粉为底物,酶的米氏常数Km为2.5%,用SephadexG-100凝胶层析法测得酶的分子量为70000。 相似文献
2.
用两套处理Soda-AQ化学草浆黑液上流式厌氧污泥床(UASB)反应器作对比实验,研究处理这种废水的UASB反应器的污泥颗粒化过程,并达到了10kgCOD/m3·d的工作负荷及在此负荷下COD(cr)40%~50%、BOD556.5%~63.5%的去除率,去除1gCOD产气量达到511ml,其中CH4含量为66.8%。 相似文献
3.
4.
5.
6.
内硝基冠醚中间体的合成 总被引:1,自引:0,他引:1
研究了作为制备新型内硝基冠醚原料的中间体2-硝基-1,3-苯二酚(NB)及多甘醇双对甲苯磺酸酯(OEDT)的合成.通过改进NB的合成条件,使磺化、硝化、水解三步总收率由12.9%提高到37.5%;以吡啶为溶剂和HCl的束缚剂,控制反应物摩尔比为TsCl∶OEG=2.06∶1.00,在0℃~5℃反应2h后,加入适量水静置过夜,可明显提高OEDT的收率和纯度. 相似文献
7.
气相色谱—质谱法测定蜂王浆及其制品中10—羟基—α—癸烯酸 总被引:19,自引:2,他引:17
试样(鲜浆、冻干粉、口服液)经稀盐酸溶液调节pH为3.0以下,以乙醚萃取,气相色谱法(GC-MSD)测定,外标法定量。方法简便、快速、准确,回收率97.6% ̄98.9%,相对标准偏差2.08% ̄4.39%。 相似文献
8.
使用硫酸铵分级沉淀、SephadexG-25凝胶色谱脱盐、DEAE-SephadexA-25和CM-SephadexC-50离子交换色谱等分离纯化技术,从顶青霉(Penciliumcorylophilum)培养液中分离到3种木聚糖酶组分,分别称为PartA、PartB和PartC.PartB和PartC经SephacrylS-200凝胶过滤色谱和ConA-Sepharose4B亲和色谱进一步分离纯化,分别得到2个纯木聚糖酶组分.PartB经SDS-PAGE鉴定为单带,相对分子质量为24200;PartC经SDS-PAGE鉴定基本为单带,相对分子质量为48300 相似文献
9.
介绍了冷库温湿度电脑控制仪,该控制仪适用于各种类型冷库的温湿度控制。主要由MCS-51系列单片机、A/D转换板、输出控制电路、显示电路、报警电路、测温和测湿器件等组成。温湿度控制范围为:温度(-40±0.5)~(11±0.5)℃;相对湿度(0%~100%)±(2%~3%).几年来的试运行表明,利用该电脑控制仪控制冷库的温湿度,精度高,库内温湿度波动小,提高了冷冻产品的质量,而且能耗明显降低,平均节电8%~10%. 相似文献
10.
高效液相色谱快速测定食品及饲料中抗氧化剂BHT 总被引:2,自引:0,他引:2
用高效液相色谱法紫外检测食品和宠物饲料中抗氧化剂BHT含量,采用Nova-pakODS3.9×150mmi.d.(4μm)色谱柱,甲醇:水:36%乙酸(85:10:5)为流动相,紫外检测波长为280nm。宠物饲料的回收率为93.0-100.5%,食用油的回收率为93.5-117.0%,变异系数均小于8.3%。本方法快速、简便、灵敏,可用于食品的日常测定 相似文献
11.
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. 相似文献
12.
John Gilbert Catherine Simoneau David Cote Achim Boenke 《Food Additives & Contaminants》2000,17(10):889-893
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. 相似文献
13.
Sophie Guillot Laurence Peytavi Sylvie Bureau Renaud Boulanger Jean-Paul Lepoutre Jean Crouzet Sabine Schorr-Galindo 《Food chemistry》2006
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. 相似文献
14.
Jesus Simal-Gandara Miguel Sarria-Vidal Arjen Koorevaar Rinus Rijk 《Food Additives & Contaminants》2000,17(8):703-711
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. 相似文献
15.
16.
M. S. Garcí a-Falc n J. Simal-G ndara S. T. Carril-Gonz lez-Barros 《Food Additives & Contaminants》2000,17(12):957-964
A simple, rapid and inexpensive method has been developed for the determination of benzo[a 相似文献
17.
H. J. Van Den Top A. Boenke P. A. Burdaspal J. Bustos H. P. Van Egmond T. Legarda A. Mesego A. Mourino W. E. Paulsch C. Salgado 《Food Additives & Contaminants》2001,18(9):810-824
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. 相似文献
18.
《肉类研究》2014,(2)
<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 相似文献
19.
《印刷工业》2014,(11):95-95
According to Printing and Printing Equipment Industries Association of China(PEIAC)'s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%. 相似文献
20.
《印刷工业》2014,(8):103-103
正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press 相似文献