蒸煮法提取玉米芯中木聚糖的条件研究

基于玉米芯中木聚糖与纤维素和木质素之间通过化学键紧密结合,为了从玉米芯中提取木聚糖,采用预处理与蒸煮相结合的方法。3种预处理液(H_2SO_4、NaOH和蒸馏水)中,NaOH预处理效果最好。碱液预处理可以使玉米芯充分溶胀,并去除部分杂质。预处理结束后,对玉米芯进行进一步的蒸煮提取,对蒸煮条件进行正交试验,确定木聚糖提取的最佳条件为蒸煮时间为40 min、蒸煮温度为120℃和料液比为1∶10(g/m L)。在此条件下,木聚糖提取率、平均聚合度和色度分别是26.7%、2.8和0.85。     

玉米芯蒸煮法提取木聚糖的优化工艺研究

介绍用蒸煮法从玉米芯中提取木聚糖的优化研究。结果表明，玉米芯用0．1％H2SO4在60℃条件下浸泡12h，滤去浸泡液，然后加水至固液比为1：15，于82．5℃下蒸煮120min，溶出的总糖量为20．10％，且提取液的还原糖与总糖之比小于25．6％，木聚糖的提取率可达31．21％。     

响应面法优化稻壳中木聚糖的提取工艺

为提高稻壳中木聚糖的提取率,稻壳经3％的硫酸预处理后再用碱法进行木聚糖的提取,采用响应面法优化工艺条件,先对提取温度、NaOH浓度、固液比、提取时间4个因素进行单因素试验.根据单因素试验结果设计中心组合试验,以木聚糖提取率为考察指标,采用响应面分析法确定最优工艺参数.结果表明:提取温度69.8℃、NaOH浓度10.7％、固液比1∶13(m∶V)、提取时间5.1h.该条件下,木聚糖提取率可达76.57％.     

从玉米芯中提取木聚糖工艺条件的优化

通过单因素及正交试验对从玉米芯中提取木聚糖的工艺条件进行了优化，最佳工艺如下：NaOH溶液的浓度为15％，固液比1：20，90℃抽提90min；离心，将上清液pH值调到5．0，静置过夜，离心得到木聚糖A，再将离心液用3倍95％的工业酒精沉淀60min得木聚糖B，在上述条件下木聚糖提取率为28．5％。     

碱液提取小麦麸皮木聚糖的研究

通过碱液浸提法及酸法干蒸与碱液浸提相结合两种方法，对已去除淀粉和蛋白质的小麦麸皮进行处理，提取木聚糖。并最终选取NaOH溶液浓度2％、料液比1：10、提取温度80℃、提取时间2h、60目麸皮为NaOH溶液浸提法提取木聚糖的试验条件。选取H2SO。溶液浓度0．1％、酸解时间8h、酸解温度60℃；蒸煮时间30min．蒸煮温度125℃；NaOH溶液浓度3％、碱液浸提时间2h、碱液浸提温度60℃为酸法干蒸与碱液浸提法相结合提取木聚糖的试验条件。     

微波辅助提取玉米芯中木聚糖条件优化

应用微波辅助法提取玉米芯木聚糖,通过正交试验设计,得出微波辅助法提取玉米芯木聚糖的最佳条件为:粒度80目的玉米芯,以体积分数为2.0%的硫酸溶液为提取溶剂,微波功率为539 W,微波时间为5 min,固液比为1∶10(g/mL)。在此条件下,通过试验得出,玉米芯木聚糖提取率达30.21%。与高温蒸煮提取方法相比,微波辅助法时间缩短了92%。     

超声波辅助酶法提取甜玉米穗轴黄酮及抑菌性检测

以甜玉米穗轴为原料,利用超声波辅助纤维素酶法提取其中的黄酮类物质,考察纤维素酶作用的酶解时间、酶解温度、pH值以及酶用量对甜玉米穗轴中黄酮类物质提取效果的影响。结果表明：超声波辅助纤维素酶法提取黄酮类物质最佳工艺条件为：超声处理20 min后,酶解温度55 ℃、pH 4.8、纤维素酶用量0.008 g/2.0 g甜玉米穗轴、酶解时间1.5 h,此条件下甜玉米穗轴中黄酮类物质提取率0.318%。甜玉米穗轴中黄酮类物质对白葡萄球菌、大肠杆菌和枯草芽孢杆菌有明显的抑制作用,最低抑菌质量浓度分别为0.5、0.25、2 mg/mL。     

麦秸秆的木聚糖提取及乙醇发酵研究

采用稀碱对麦秸秆木聚糖进行提取,提取后的残渣酶解发酵生产乙醇,以达到麦秸秆纤维素和半纤维素的分级利用.在0.95％NaOH、1∶10的料液比、129℃下保温2.45 h,木聚糖提取率可达44.62％(按麦秸秆半纤维素计);木聚糖提取后残渣经酶解后用酿酒活性千酵母进行发酵,乙醇浓度可达23.18 g/L,乙醇产率达0.329 g/g.     

用于低聚木糖生产的玉米芯木聚糖的蒸煮法提取

通过对几种不同的木聚糖提取方法的比较，确立了酸预处理后加水蒸煮的方法提取低聚木糖生产用木聚糖的工艺路线。首先将玉米芯用质量浓度为１ｇ／Ｌ的Ｈ２ＳＯ４在６０℃下浸泡１２ｈ，滤去浸泡液，然后加水至固液比为１∶１０，在１５０℃蒸煮３０ｍｉｎ．采用此工艺木聚糖的提取得率可达到１７％（按玉米芯计），提取液的还原糖与总糖质量之比小于３３％．该法得到的提取液（和渣一起）用自制的木聚糖酶水解，可获得ｍ（木糖）∶ｍ（木二糖）∶ｍ（木三糖）＝１∶５∶２．７的高纯度低聚木糖产品，产品总糖的得率达到２６．４％（按玉米芯计）。     

玉米芯水不溶性木聚糖的碱法提取及酶解分析

为研究碱法提取玉米芯中水不溶性木聚糖的优化条件及产物组成,用单因素试验评价预处理温度、NaOH浓度、料液比、提取温度与时间对提取率的影响之后,通过正交试验L16(45)确定最佳提取条件是:40℃预煮,15%NaOH溶液,固液比1∶15,100℃提取4 h,过滤,调节滤液pH值至7.0,静置过夜后离心得沉淀,洗涤沉淀,烘干后即得水不溶性木聚糖。在上述条件下玉米芯水不溶性木聚糖提取率为20.86%。对碱法提取的玉米芯水不溶性木聚糖进行木聚糖酶水解及产物分析,结果几种木聚糖酶均能使水不溶性木聚糖产生木二糖、木三糖及木四糖含量较高的低聚糖。     

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.     

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     

Chinese CTP Market

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%.     

Preparatory Work of Print China 2015 is Going Smoothly

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