核磁共振技术研究冷冻处理对魔芋粉丝中水分的影响

利用核磁共振技术测定魔芋粉丝在不同处理温度过程中质子的自旋-自旋弛豫时间(T2)以及质子信号密度(A)。魔芋粉丝体系中水分流动性不同,T2和A不同。结果表明,在魔芋粉丝冷冻处理过程中,其“束缚水”和“自由水”迁移行为不同。当处理温度为－12℃,处理时间为3h时,复水后的魔芋粉丝持水性质最佳。     

利用核磁共振及成像原理研究鸡蛋的煮熟过程

利用核磁共振技术研究在不同的煮熟时间下带壳鸡蛋的弛豫特性.采用IR、CPMG脉冲序列来测定不同煮熟时间下质子的自旋-晶格弛豫时间(T1)和自旋-自旋弛豫时间(T2).在蛋清和蛋黄不同的凝固和成形过程中,其表现出不同的弛豫时间.实验结果表明,蛋清先于蛋黄逐渐变性,弛豫时间T23对应的质子密度逐渐降低,最后达到稳定的状态,说明整个带壳鸡蛋的流动性下降.通过核磁共振成像能够直观地说明带壳鸡蛋在煮熟过程中内部结构的变化情况.     

利用核磁共振及成像原理研究鸡蛋的煮熟过程

利用核磁共振技术研究在不同的煮熟时间下带壳鸡蛋的弛豫特性。采用IR、CPMG脉冲序列来测定不同煮熟时间下质子的自旋-晶格弛豫时间（T1）和自旋-自旋弛豫时间（T2）。在蛋清和蛋黄不同的凝固和成形过程中,其表现出不同的弛豫时间。实验结果表明,蛋清先于蛋黄逐渐变性,弛豫时间T23对应的质子密度逐渐降低,最后达到稳定的状态,说明整个带壳鸡蛋的流动性下降。通过核磁共振成像能够直观地说明带壳鸡蛋在煮熟过程中内部结构的变化情况。      

核磁共振技术在脐橙保藏和质量评估中的应用

采用低场核磁共振技术研究脐橙储藏过程中水分的状态、变化以及水分的迁移.利用Carr-Purcell-Mei-boom-Gill(CPMG)序列采集样品的核磁共振受激回波信号,采用多重指数衰减模型对收集的信号数据进行分析并计算组织中不同水分自旋-自旋弛豫时间.探讨脐橙在储藏过程中品质变化与核磁共振弛豫参数变化的相关性.发现在脐橙的后成熟期、稳定期和腐烂期,对应的自旋-自旋弛豫时间变化呈现一个上升-稳定-急速下降的过程,且在脐橙腐烂前出现了一个自旋-自旋驰豫时间急剧下降的过程.该方法可以作为脐橙质量评估的有效手段,对于脐橙的质量评估和保藏方法的评估等具有指导意义.     

核磁共振研究膳食纤维面包制作过程的水分迁移行为

利用核磁共振测定三种不同配方面包在制作过程(和面、发酵、醒发和焙烤)中质子的自旋-自旋弛豫时间(T2),面团中流动性不同的水分,表现出不同的弛豫时间。实验表明,在面包制作过程中,其束缚相和自由相的迁移行为不同,此外140MPa处理的膳食纤维具有强持水性,添加至面包中可改善其储藏性。     

核磁共振研究蔗糖对面团中分子流动性的影响

利用脉冲梯度场核磁共振技术(PFG-NMR)研究蔗糖对面团自旋-自旋弛豫特性的影响。分子的自旋-自旋弛豫特性与分子的流动性呈正相关。采用CPMG脉冲序列检测面团中质子的自旋-自旋弛豫时间(T2)。在面团中流动性不同的水分,表现出不同的弛豫时间。实验结果表明,蔗糖的亲水性能够显著改变面团的自旋-自旋弛豫时间。通过磁共振图像可以发现蔗糖能够明显促进面团中质子的均匀分布,增强其流动性。当水分含量一定时,面团的自旋-自旋弛豫时间随蔗糖含量的增加而增加。     

南酸枣糕烘干过程中水分的迁移和分布

利用核磁共振及其成像技术,探究南酸枣糕在烘干过程中水分含量、迁移和分布情况。通过分析南酸枣糕烘干过程中核磁共振的自由衰减弛豫时间、自旋-自旋弛豫时间和核磁共振成像图发现:南酸枣糕的水分含量与体系的质子密度高度线性相关,其相关系数达到0.990 6。因此,可以通过建立水分含量与核磁共振质子密度的标准曲线实现南酸枣糕水分含量的核磁共振定量测定;在烘干过程中,随着时间的延长,南酸枣糕中的束缚水的流动性(T21)呈降低的趋势,自由水的流动性(T22)呈先增加后降低的趋势,核磁共振成像图逐渐变暗;从成像图也可直观地看出,南酸枣糕内部弛豫信号比外部强,证实南酸枣糕干燥是一个不均匀的干燥过程。     

琼胶大豆牛奶布丁货架期的研究

采用加速试验对琼胶大豆牛奶布丁进行货架期研究,定期进行感官、理化和微生物检测,结果表明,产品储藏期间未发生腐败现象,理化及微生物指标未有明显变化。对储藏在30、35和40℃的琼胶大豆牛奶布丁进行色差分析,试验组A、B、C即琼胶大豆牛奶布丁储藏在30、35和40℃条件下的亮度L*均随着时间的延长而减小。琼胶大豆牛奶布丁中存在着3种不同含量的水分,随着储藏时间的延长,弛豫时间T22、T23都呈现上升趋势,质子密度M22呈下降趋势,而M23呈上升趋势。     

谷物稳定化技术及稳定化对谷物品质的影响研究进展

含油量高及脂酶活力高的谷物,如燕麦、米糠、青稞、麦胚等,在加工过程中及加工后易酸败劣变,导致加工及储藏过程中的产品品质下降、风味恶化。因此,钝化谷物中的酶对提高谷物的储藏稳定性,延长其货架期是非常必要的。在分析国内外谷物稳定化技术的基础上,综述了不同技术的稳定化效果及稳定化过程对谷物本身品质的影响。     

低场核磁共振研究热烫对纤丝干酪水分状态的影响

利用低场强核磁共振技术研究热烫温度对纤丝干酪水分状态的影响。通过考察不同热烫温度纤丝干酪贮藏1～10d可榨乳清质量分数,探讨热烫温度对纤丝干酪持水力的影响。利用低场核磁共振仪测定不同热烫温度制作的纤丝干酪贮藏1～10d自旋-自旋弛豫时间T21、T22以及质子强度A1、A2,探讨热烫温度对纤丝干酪水分状态以及分布的影响。结果表明,低热烫温度,纤丝干酪持水力高,结合水、自由水自由度增幅大,同时在纤丝干酪贮藏过程中内部水分发生了迁移,由相对自由态向结合态转移,热烫温度越低水分迁移量越大。     

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