电子鼻对不同温度下生鲜羊奶贮藏时间的判定

利用电子鼻PEN3 系统判定常温和冷藏条件下羊奶的贮藏时间。通过电子鼻系统采集羊奶常温贮藏及冷藏期间挥发性成分的响应值,并利用主成分分析法(principal component analysis,PCA)及线性判别分析法(linear discrimination analysis,LDA)对其挥发性成分及贮藏时间进行分析。结果表明：PCA方法既可以区分常温贮藏及冷藏1～6d的生鲜羊奶,还可以对比常温和冷藏条件下贮藏1～6d的羊奶,并表现出了较好的区分性,但是不能分析出贮藏期间羊奶挥发性成分的变化趋势;LDA方法区分效果不及PCA,但明显体现出了羊奶贮藏期间挥发性成分的变化趋势。综合PCA及LDA方法的分析结果,说明电子鼻可以有效地判定常温和冷藏条件下生鲜羊奶的贮藏时间及贮藏期内挥发性成分的变化趋势。     

采用电子鼻检测羊奶中的牛奶掺入

通过电子鼻系统检测在羊奶中掺入不同比例的牛奶的混合物中挥发性物质的响应值,利用主成分分析法(PCA)及线性判别分析法(LDA)对羊奶牛奶混合物的挥发性成分进行分析。结果表明:电子鼻各感应器对于原料羊乳和牛乳及杀菌羊乳和牛乳的反应值均不同。对于生奶和杀菌奶,PCA和LDA分析均能够区分羊奶中混入不同比例的牛奶,具有较好的区分性。     

基于BP神经网络的电子鼻羊奶贮藏时间的预测

利用电子鼻PEN3系统判定室温和冷藏条件下羊奶的贮藏时间。通过电子鼻系统采集羊奶室温贮藏及冷藏期间挥发性成分的响应值,并采用PCA(主成分分析法)、LDA(线性判别分析法)和LM算法优化的BP神经网络(LM-BP)、遗传算法优化的神经网络(GANN)、4层BP神经网络进行模式识别。结果表明PCA和LDA均可区分室温贮藏及冷藏1～6d的生鲜羊奶,LDA方法还可以明显体现出羊奶贮藏期间挥发性成分的变化趋势,并且与羊奶酸度的变化有很好的一致性。采用LM-BP神经网络、GANN神经网络和4层神经网络均能较好地预测不同贮藏时间的羊奶,其中4层神经网络的预测正确率高于LM-BP神经网络和GANN神经网络。     

利用电子鼻区分羊奶中不同浓度抗生素

采用电子鼻方法,利用主成分分析(PCA)和线性判别分析(LDA)进行数据采集,对添加硫酸土霉素、盐酸链霉素、硫酸庆大霉素的羊奶进行快速检测与识别.结果表明,PCA只能区分盐酸链霉素样品,LDA的区分效果明显优于PCA.电子鼻能够有效的区分添加以上3种不同浓度抗生素的羊奶.     

基于fisher线性判别和BP神经网络的电子鼻羊奶贮藏时间预测

利用电子鼻PEN3系统快速检测室温和冷藏条件下羊奶的贮藏时间。通过电子鼻系统采集羊奶室温及冷藏期间挥发性成分的响应值,并用主成分分析法(PCA)、fisher线性判别分析法(FDA)和BP神经网络进行模式识别。测定结果表明FDA方法区分室温贮藏及冷藏1～5d羊奶的效果优于PCA,而且羊奶贮藏期间挥发性成分的变化趋势明显,这种气味的变化规律与酸度的变化规律相符。同时用FDA和BP神经网络预测羊奶贮藏时间,结果FDA预测常温及冷藏羊奶正确率分别为100%和98.9%,均高于BP神经网络。     

基于电子鼻判别富士苹果货架期的研究

利用电子鼻对不同货架期内的富士苹果挥发性成分进行检测。通过雷达图和负荷加载(Loadings)分析研究主要传感器响应值的变化,利用主成分分析(PCA)、线性判别分析(LDA)模式判别方法进行数据分析。结果表明,第7、8号传感器在苹果常温货架期判别中起主要作用,而第2、7号传感器在苹果贮后货架期的判别中起主要作用。PCA、LDA方法均可准确判别常温不同货架期的苹果;与PCA相比,LDA方法可以更准确对不同贮后货架寿命苹果进行判别,并呈现出良好的集中性和单向趋势。因此,电子鼻快速判别不同货架期的苹果具有可行性。     

电子鼻技术在区分酸羊奶发酵菌种中的应用

利用电子鼻技术快速区分酸羊奶的发酵菌种。通过电子鼻采集不同酸羊奶挥发成分的响应值,然后利用主成分分析（principal component analysis,PCA）、Fisher线性判别分析（fisher linear discriminant analysis,FLDA）以及BP神经网络（back propagation neural network,BP-NN）分析进行判别,建立基于电子鼻技术区分酸羊奶发酵菌种的方法。结果表明,FLDA及PCA都能够区分出不同菌种发酵的酸羊奶,FLDA区分效果优于PCA。利用FLDA和BP-NN分析预测酸羊奶发酵菌种类别的正确率分别为100.0%和98.4%。因此,利用电子鼻快速区分酸羊奶的发酵菌种是可行的。     

花生挥发性香味识别的研究

采用电子鼻技术和气质联用色谱对新鲜花生、烘烤花生的挥发性气味成分进行了研究,通过采集电子鼻不同传感器的数据,使用PCA和LDA方法分析图谱,建模形成了花生挥发性香味成分区域图谱。同时用气质联用色谱进行挥发性化合物的分析。结果表明:不同的新鲜品种的花生电子鼻图谱有显著差异,可以对各品种花生进行较好的识别,而LDA方法比PCA方法区分效果更好;烘烤花生的电子鼻图谱说明了花生烘烤后其香味成分比较统一,所以图谱的结果很集中。气质联用色谱可以清楚地分辨烘烤花生有别于新鲜花生的挥发性气味,由此为建立花生香味识别的判定方法奠定基础。     

电子鼻对不同年份赤霞珠葡萄酒香气的检测分析

以不同年份赤霞珠葡萄酒为研究对象,探索了电子鼻在葡萄酒香气中的应用可能性,并对电子鼻测定所获得的传感器响应值进行主成分分析(PCA)、分类判别分析(LDA)和雷达图分析。结果表明:不同年份的赤霞珠葡萄酒的电子鼻香气指纹图谱基本相同,以2,6,7和8号感应器响应值为主,只在响应值上有差异。PCA和LDA分析不同年份葡萄酒的累积贡献率分别高达95.21%和99%,说明可以有效区分各组样品。     

基于电子鼻分析的南美白对虾品质变化研究

利用电子鼻识别技术检测南美白对虾在不同贮藏温度下的挥发性成分变化,运用主成分分析(PCA)、线性判别分析(LDA)和Loading分析法,结合虾肉pH、TVBN含量变化,判定南美白对虾的新鲜程度与货架寿命。结果表明,贮藏过程中南美白对虾pH、TVBN呈不断升高的趋势;5℃和0℃组分别贮藏4 d和6 d后,肌肉TVBN含量超过国家限量标准。电子鼻传感器响应分析发现,PCA和LDA均能较好的判别不同贮藏时间的对虾样品,且LDA分析总体贡献率略高于PCA分析;Loading分析传感器负载参数值依次为:W5S>W1S>W2S>W3S,即在贮藏过程中对虾挥发性氮氧化合物、甲烷、乙醇及烷烃类物质发生了显著性变化,可依此类物质变化情况判定样品的鲜度及腐败进程。     

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