二甲基乙酰胺溶剂热危险性研究

为研究二甲基乙酰胺（DMAc）的热稳定性和热安全性,利用微量量热仪（C80）对DMAc的热分解行为进行试验研究,得到了DMAc的分解过程的特性曲线及相关实验数据。根据得到的实验数据求解出DMAc的活化能、指前因子和反应焓等化学反应动力学和热力学参数。利用动力学参数算出DMAc自加速分解温度（SADT）,对其热危险性进行评估。结果表明：DMAc在空气气氛中发生自分解放热反应,反应热为32KJ/kg、活化能为178.1KJ/mol;根据Semenov模型推算得到自加速分解温度（SADT）为93.7℃。DMAc具有较大的热危险性,在使用存储过程中应防止温度超过其SADT而引发分解爆炸事故。     

知名抗性淀粉的热性质分析[Ⅱ]

采用热失重法(TG)和差示扫描量热分析技术(DSC)对罗盖特Nutriose?抗性淀粉进行热性质分析。TG曲线显示该抗性淀粉在296.73℃开始分解,314.77℃分解速度最快,332.81℃是分解的最终温度。DSC吸热曲线显示,样品第一次分析曲线在29.04℃出现吸热峰,在61.64℃出现冷结晶放热峰,在74.67℃左右开始出现吸热峰,相变高峰温度约在81.92℃(相变焓267.1J/g),另外在219.89℃出现小的吸热峰;分析系统经快速降温后,样品的第二次分析曲线在31.22℃开始出现吸热峰,相变高峰温度约在86.39℃(相变焓38.97J/g),在218.70℃仍然出现一个小的吸热峰,冷结晶吸热峰消失,表明样品经过热处理后,晶体结构发生变化。     

5 种淡水鱼肌肉热特性比较研究

为研究不同品种名优淡水鱼冷藏保鲜及热加工的特性,采用差示扫描量热法研究武昌鱼、草鱼、黄颡鱼、鲈鱼和鳜鱼5 种新鲜淡水鱼鱼肉的水分含量、冰点、变性温度、变性热焓和比热容并进行品种间的比较。结果发现：5 种淡水鱼冰点分布在－0.57～－0.1 ℃之间;50 ℃附近热吸收峰起始温度分布在37～41.57 ℃之间,终止温度分布在60.47～62.33 ℃之间;变性热焓在1.680 0～2.499 7 J/g之间;70 ℃附近热吸收峰的起始温度分布在66.33～71.13 ℃之间,终止温度分布在73.60～82.20 ℃之间,变性热焓在0.418 0～0.512 2 J/g之间;鱼肉的比热容在1.658 0～3.862 3 J/（g·K）之间。结果表明：在5 种新鲜淡水鱼中,武昌鱼水分含量和冰点相对较低;草鱼肌球蛋白和鳜鱼肌动蛋白变性温度和变性热焓相对较高,蛋白质稳定性更高;新鲜鱼肉的比热容高于冻结鱼肉,加工后鱼肉的比热容高于未加工鱼肉。     

抗性淀粉热性质分析[Ⅰ]

采用热失重法(TG)和差示扫描量热分析技术(DSC)对松谷Fibersol2抗性淀粉进行热性质分析。TG曲线显示该抗性淀粉在293.85℃开始分解,312.37℃分解速度最快,330.89℃是分解的最终温度。DSC吸热曲线显示,样品在24.36℃左右开始出现吸热峰,相变高峰温度约在98.54℃(相变焓179.1J/g),另外在204.23℃和225.48℃出现两个小的吸热峰,表明样品以支链晶体结构为主。     

发芽小米淀粉热分解机制及动力学研究

发芽是改善谷物品质的绿色加工方法。为了探究发芽对小米淀粉热力学性质的影响,采用差示量热扫描法、热重分析法对发芽小米淀粉的热分解机制及其动力学行为进行了研究。结果表明,小米发芽后淀粉糊化温度升高,糊化焓、回生度、回生速率均减小;未处理及发芽处理小米淀粉热分解均是一个连续的过程,热分解温度范围为295~360℃,分解速率最快的温度范围为298.49~305.01℃;发茅小米淀粉活化能、指前因子、焓值、熵值(绝对值)及吉布斯自由能均较未处理小米淀粉减小;未处理及发茅小米淀粉热分解最概然机制函数均为G(α)=lnα,最概然机制为单分子消除反应,为一级反应。     

用DSC方法研究挤压参数对脱胚玉米热性能影响

为研究不同挤压参数对脱胚玉米热性能的影响,以挤压温度(40、50、60、70、80℃)、螺杆转速(70、90、110、130、150 r/min)、水分含量(22%、26%、30%、34%、38%)以及酶添加量(5、10、15、20、25 U/g)为变量,运用单螺杆挤压机对脱胚玉米进行挤压,对不同挤压参数的脱胚玉米运用差示扫描量热法(differential scanning calorimetry,DSC)进行热性能分析。DSC测试结果为以挤压温度为变量的处理中,挤压温度为80℃时,脱胚玉米粉的焓变值为267.2 J/g,糊化度高于其他处理;以螺杆转速为变量的处理中,转速为70.0 r/min的脱胚玉米粉焓变值为253.1 J/g,糊化度最高;以水分为变量的处理中,水分含量为38.0%的脱胚玉米焓变值为234.4 J/g,糊化度最高;以酶添加量为变量的脱胚玉米中,添加量为15 U/g的脱胚玉米焓变值为284.8 J/g,糊化度高于其他酶添加量的脱胚玉米。说明不同挤压参数对脱胚玉米颗粒的破坏程度不同,能够不同程度地改变脱胚玉米的糊化度,改变脱胚玉米粉的热性能。     

红小豆和红花豆淀粉热性质及回生性质的比较

以红小豆和红花豆为研究对象,分析比较了两种淀粉的化学组成、颗粒形状、结晶性质、热性质及回生性质。SEM结果表明,大颗粒红小豆和红花豆淀粉大颗粒成肾状或卵形,小淀粉颗粒成球形;XRD试验结果表明,红小豆和红花豆淀粉结晶类型为A型,结晶衍射峰2θ角均在15.0°,17.0°,19.0°和22.8°左右;DSC扫描结果表明,红小豆和红花豆淀粉的熔点温度分别为62.12℃±0.29℃和62.17℃±0.22℃,峰值温度分别为68.87℃±0.22℃和68.76℃±0.31℃,糊化焓变值分别为11.73±0.62 J/g和14.63 J/g。回生试验结果表明,红小豆和红花豆淀粉凝胶在4℃贮藏期间,回生淀粉熔点和峰值随时间延长而下降,回生焓变随时间延长而增长,红小豆和红花豆淀粉凝胶在7 d时重结晶过程基本结束,且与直链淀粉含量相关。因此,在工业应用中可以通过测定淀粉热性质来预测其用途,也可通过控制淀粉基食品中直链淀粉比例加速或抑制淀粉基食品老化过程,进而提高淀粉基食品的食用价值。     

米制松糕淀粉回生动力学研究

以米制松糕为研究对象,采用热力学分析的方法研究松糕淀粉的回生动力学.结果表明:早期的重结晶(晶核)融化顶点温度TP为52.331℃,略高于后期的重结晶融化顶点温度,随着储藏时间的延长.融化支链淀粉重结晶所需的热焓△H由0.747J/g增加到1.352J/g.应用Avrami回生动力学模型,研究松糕中淀粉回生动力学,结果发现,松糕淀粉的Avrami参数n值小于1,表明淀粉重结晶的成核方式为一次成核.     

脆肉鲩低温相变区热特性的研究

采用差示扫描量热仪,研究脆肉鲩鱼肉在低温相变区的冰点、表观比热和热焓以及NaCl、NaCl 与蔗糖混合物添加量对脆肉鲩热特性的影响。结果表明,脆肉鲩鱼肉的冻结相变温区为－ 12.5～－ 11℃,熔融相变温区为－ 1.9～0.1℃,冰点为－ 0.2℃,冰点的表观比热和热焓值分别为130.56J/g·℃、305.57J/g。随着NaCl、NaCl和蔗糖混合物添加量的增加,脆肉鲩肌肉的相变温区向低温方向移动,冰点的表观比热和热焓值下降。鱼肉中NaCl添加量较低时,添加蔗糖可减缓相变温度的下降,当NaCl 添加量大于2% 时,添加蔗糖对鱼肉相变区温度的影响不大,NaCl 起主导作用。     

普通玉米杂交种间淀粉糊化过程中热力学性质的差异研究

采用湿法在试验室条件下提取了52种普通玉米杂交种淀粉。采用差示扫描量热仪(DSC)分析了这些玉米杂交种淀粉的糊化过程中的热力学性质。结果表明:52种普通玉米杂交种间淀粉糊化过程中的热力学性质存在明显区别:热焓值变化范围为8.95~15.54 J/g,起始糊化温度、峰值糊化温度、终止糊化温度及温度变幅的变化范围分别为64.72~70.28℃、70.37~75.03℃、77.16~84.16℃及9.49~17.43℃;52种普通玉米杂交种淀粉平均热焓值、起始糊化温度、峰值糊化温度、终止糊化温度及温度变幅分别为10.87 J/g、68.17℃、72.68℃、81.01℃和12.85℃;某些热力学性质参数间存在显著的相关性;依据热焓值大小,可以将52种普通玉米杂交种分为5个组别。     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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