果糖/天冬酰胺模拟体系中丙烯酰胺产生机理的研究

系统研究了果糖/天冬酰胺模拟体系中丙烯酰胺形成规律。在单因素实验的基础上,选取加热温度、加热时间、天冬酰胺添加量、果糖加入量4个因素,进行响应面优化分析。结果表明:果糖的添加量、加热温度和天冬酰胺的添加量对丙烯酰胺的产生影响显著。丙烯酰胺最大产生量的条件为:加热温度200℃,加热时间6.0 min,果糖添加量1.2 mmol,天冬酰胺添加量1.2 mmol。丙烯酰胺的生成量为1640.0 nmol。     

葡萄糖/天冬酰胺模拟体系中丙烯酰胺的产生及其机理研究

油炸食品中丙烯酰胺的发现引起了科学家们的广泛重视。美拉德反应是形成丙烯酰胺的重要途径。为了进一步证实其形成机理,进行了葡萄糖和天冬酰胺模拟体系的研究。采用高效液相色谱-紫外检测器分析模拟体系中的丙烯酰胺,结果表明:不同的加热温度和加热时间对丙烯酰胺的产生量影响显著,且随着反应温度的升高和反应时间的延长,整个反应体系的颜色逐渐加深,丙烯酰胺的产生量也逐渐增多。     

姜粉及其有效成分对丙烯酰胺生成的影响及动力学研究

食品中的丙烯酰胺主要是由天冬酰胺和α-羟基羰基化合物(如葡萄糖等)在高温条件(120℃)下发生的美拉德反应产生的。研究发现,加热温度、加热时间、葡萄糖/天冬酰胺比例和水分含量对丙烯酰胺的形成均呈先升高后降低的趋势,且在试验范围内丙烯酰胺含量都有一个最大值。在研究姜粉、姜辣素和6-姜酚对高温低湿条件下葡萄糖/天冬酰胺模型中丙烯酰胺形成的影响时,发现3种物质可以有效地减少模型中丙烯酰胺的形成。并且,姜粉、姜辣素和6-姜酚的浓度变化和丙烯酰胺抑制率趋势均呈非线性变化,当三者的添加量水平分别为200、0.2、0.02 mg/g时,抑制率达到最大值依次为53.2%、62.8%和23.5%。最后,通过使用丙烯酰胺动力学模型确定了姜粉、姜辣素和6-姜酚对丙烯酰胺的形成具有抑制作用,而对丙烯酰胺的消除没有影响。     

Asn/Glc模拟体系中丙烯酰胺形成规律的研究

美拉德反应目前被认为是形成丙烯酰胺的重要途径。本文对葡萄糖和天冬酰胺模拟体系中丙烯酰胺的形成规律进行研究。结果表明,反应温度和时间对丙烯酰胺的产生量具有很大的影响,即随着温度和时间的增加,丙烯酰胺的产生量也相应增加;研究还发现,丙烯酰胺与天冬酰胺、吸光度之间呈线性关系,与葡萄糖、果糖也呈一定的相关性。     

丙烯酰胺天冬酰胺/葡萄糖低湿模式反应体系条件优化

试验主要研究了天冬酰胺/葡萄糖低湿模拟体系中丙烯酰胺生成及提取条件,对影响体系丙烯酰胺生成的反应条件和丙烯酰胺提取条件进行了优化。结果表明,天冬酰胺/葡萄糖低湿模拟反应体系中丙烯酰胺最佳反应条件为:40μL葡萄糖(0.25 mol/L)和40μL天冬酰胺(0.25 mol/L)加入40μL蒸馏水在160℃反应20 min,反应结束后向体系中加入1 mL蒸馏水超声重复提取2次,每次5 min,提取温度30℃。在上述条件下体系中生成和提取的丙烯酰胺量达到最大。     

绿原酸影响氨基酸消减丙烯酰胺的研究

绿原酸是马铃薯中的主要酚酸。试验将丙烯酰胺分别与7种氨基酸进行高温加工处理,研究添加绿原酸对体系中丙烯酰胺消减的影响。结果表明,绿原酸促进丙烯酰胺的消减。加入绿原酸在160℃反应30 min后,丙烯酰胺消减率显著提高,为9.58%(天冬酰胺)～33.46%(半胱氨酸)。采用甘氨酸/丙烯酰胺体系,进一步研究绿原酸添加量、加热温度和时间对丙烯酰胺消减的影响,发现丙烯酰胺消减率随绿原酸添加量、加热温度的增加和时间的延长而提高。绿原酸与丙烯酰胺物质的量比25∶1,180℃反应60 min后,丙烯酰胺消减率达到66.9%。     

葡萄糖/天冬酰氨模拟体系丙烯酰胺形成

采用葡萄糖与天冬酰氨的模拟体系来研究反应条件对丙烯酰胺的产生的影响.以色度、198 nm下紫外吸光度和丙烯酰胺含量为指标,考察反应温度、时间、初始pH值和摩尔配比对丙烯酰胺形成的影响.结果表明反应温度是影响丙烯酰胺形成关键因素,葡萄糖比天冬酰胺对模拟体系的丙烯酰胺形成影响要大,初始pH值在8时,丙烯酰胺形成最大.     

一种用于筛选丙烯酰胺抑制剂的模型的建立

本文建立了模拟丙烯酰胺形成的化学模型和食品模型,分别研究了150℃和170℃条件下2～10min范围内不同加热时间对上述模型中丙烯酰胺产生量及产物颜色的影响。确定的化学模型条件为：0．050g天冬酰胺、0．060g葡萄糖及3mL去离子水,于不锈钢密封管中170℃油浴加热5min;食品模型条件为：约2mm厚薯片,在蒸馏水或抑制剂溶液中浸泡3min后,于170℃油炸5min。     

葡萄糖-天门冬酰胺体系中丙烯酰胺的生成规律研究

对葡萄糖-天门冬酰胺(Glu-Asn)模拟体系中丙烯酰胺的生成规律进行了研究。探讨了氨基酸种类、反应底物摩尔比例、加热时间、加热温度和pH等单因素对丙烯酰胺生成量的影响。选取加热时间、加热温度和pH进行正交试验优化得到丙烯酰胺的最大生成量条件:0.1mol/L的等摩尔比Glu-Asn体系溶液于180℃(油浴)、pH 8.0(PBS)的条件下加热30min,丙烯酰胺的生成量为(164.80±13.26)nmol,在此基础上进行进一步的抑制作用研究。     

赖氨酸/葡萄糖美拉德反应产物对丙烯酰胺生成的抑制作用

建立天冬酰胺/葡萄糖模式反应体系,运用高效液相色谱法、自由基清除法等手段研究赖氨酸/葡萄糖美拉德反应产物对该模式体系中丙烯酰胺生成量及体系抗氧化性的影响。结果显示:高、低分子量的赖氨酸/葡萄糖美拉德反应产物(H-LGP和L-LGP)均能显著降低模式反应体系中的丙烯酰胺生成量,其中H-LGP和L-LGP的添加量为10 mg/mL时,对丙烯酰胺生成的抑制率最大,分别为32.0%和31.4%。H-LGP和L-LGP(均为10mg/mL)的添加还可显著提高反应体系清除自由基DPPH和ABTS的能力。结论:赖氨酸/葡萄糖美拉德反应产物(LGP)能够显著抑制天冬酰胺/葡萄糖模式反应体系中丙烯酰胺的生成,且高浓度的LGP能够显著提高反应体系的抗氧化性。     

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