乳酸/己内酯共聚物的差示扫描量热分析

以乳酸/己内酯共聚物(PLA-co-PCL)为例,对差示扫描量热法(DSC)测定聚合物的热性能参数进行探讨.详细讨论了消除热历史、升温速率、样品用量、样品形态等因素对DSC曲线的形状及特征峰位置的影响.结果表明:消除热历史对PLA-co-PCL的DSC曲线形状及特征峰位置影响很大,消除热历史后DSC曲线出现了结晶峰,并且熔融单峰变成双峰.随着升温速率的增大,玻璃化转变温度有所提高,结晶温度明显提高,升温速率为5K/min.样品用量为3～5mg,样品形态对DSC曲线形状及特征峰位置几乎无影响.     

山嵛酸酰胺与芥酸酰胺的氧化稳定性研究

目的研究山嵛酸酰胺与芥酸酰胺的氧化稳定性。方法应用油脂氧化稳定性仪研究山嵛酸酰胺与芥酸酰胺的氧化稳定时间,并比较光照的影响;通过红外光谱仪与差示扫描量热仪(differential scanning calorimetry,DSC)研究加速氧化前后红外光谱图与热分析图谱的差异性;应用DSC研究芥酸酰胺在升温-降温-升温过程中的热特性以及山嵛酸酰胺升温过程中的热特性,并研究光照对样品热特性的影响。结果光照明显影响稳定时间,对芥酸酰胺的影响则更为敏感;加速氧化后出现羰基峰,山嵛酸酰胺在3300 cm~(-1)处峰形基本没有变化,而芥酸酰胺由双峰变为单峰,山嵛酸酰胺在700 cm~(-1)左右峰的强度无明显变化,而芥酸酰胺峰形明显增强;光照使芥酸酰胺熔融温度与结晶温度发生改变,山嵛酸酰胺除了熔融峰之外还有2个脂肪酸峰,光照影响熔融峰峰形。另外在加速氧化后进行热特性测试时,山嵛酸酰胺与芥酸酰胺熔融峰峰形正常,但峰值温度略有变化。结论山嵛酸酰胺与芥酸酰胺的油脂氧化稳定性,可以应用油脂氧化稳定性仪、差示扫描量热仪及红外光谱仪进行评价。     

DSC在油脂加工过程及产品中的应用

在油脂加工业以及对油脂产品的深入研究过程中，选择合适的分析方法非常重要，这要求综合考虑该方法的灵敏性、精确性以及实用性。油脂在加热以及冷却过程中表现出大量的由加热而引起的相转变，差示扫描量热法(DSC)可用来测量样品相变过程中吸收或放出的热量或样品的热容，测量转变所发生的起始温度，最大反应时的温度和反应终了的温度。     

通过热重量的测定评价油脂的品质

一、绪言 热分析中常用的方法有示差热分析(DTA),示差扫描热量测定(DSC)及热重量测定(TG)。DTA、DSC是根据物质加热和冷却时产生的吸热、放热现象进行测定的一种方法,在油脂领域中已经用于油脂同货多晶的研究和固体脂的质量管理等。 TG是应用于物热加热过程中引起的热重量变化,因而得出重量变化和温度的关系或者在一定的温度下质量和时间的关     

高灵敏度DSC技术的突破性进展

差示扫描量热技术（DSC）的发展已有半个世纪的历史。在材料、药物、食品等领域已得到了广泛的应用。热流型DSC基于Boersma原理（1955年）：仪器的热阻与样品无关，因此热流可以定量测定。功率补偿型DSC基于Watson和O’Neill在1963年提出的原理，测量输入到样品和参比之间的功率差。     

基于热重法的植物油氧化动力学研究

采用热重(TG)及微商热重(DTG)法研究了6种市售植物油的氧化特性,探究了不同升温速率对TG及DTG曲线的影响,通过DTG曲线确定了不同植物油在不同升温速率下的起始氧化温度,并利用Ozawa-Flynn-Wall方程及Arrhenius方程对油脂的氧化进行了动力学参数的推导,同时分析了油脂热降解特性与其主要脂肪酸组成间的相关性。研究表明:随着升温速率的升高,氧化分解的温度随之升高,油脂的起始氧化温度、活化能等参数均可用于表征油脂的氧化稳定性,且植物油的热降解特性与其脂肪酸组成间有着不同程度的相关性;其中油脂的起始氧化温度与其饱和脂肪酸、单不饱和脂肪酸及代表脂肪酸含量成正比,与多不饱和脂肪酸含量成反比;油样的活化能及前指数因子同样也与饱和脂肪酸含量成正比且前者相关性显著,而速率常数κ与样品组分相关性与Ton-组分相关性趋势相反。热重分析法采样量少,操作简单快速,精密度高,可为油脂加工及储藏条件的控制、新型抗氧化剂研发等提供实验依据。     

DSC法测定硬化油的固体脂肪指数

热分析技术广泛用于研究物质的组成、结构和性能。在油脂工业中,应用热分析技术研究了三甘油脂的多晶形态;研究了晶形对油脂物理性质的影响;研究了可可脂的口熔问题以及人造奶油的粘度;还研究了奶油,起酥油,各种硬化油以及油脂中掺和物的物理性质和检测等问题。DSC方法(Differential ScanningCalorimetry)则是热分析技术中较为普遍的一种方法。     

大米抗性淀粉糊化特性的研究

采用差示扫描量热分析技术(DSC)对大米原淀粉及抗性淀粉样品的糊化温度和吸热焓进行了测试和研究.差示扫描量热分析结果表明,抗性淀粉的开始吸热温度和完成温度均高于原淀粉,且吸热焓增大,说明沸水浴处理使淀粉形成了致密的结晶结构.     

人造奶油的热熔性与组成结构的关系研究

本文对人造奶油申油脂成分的性质(熔点、碘价、反式酸含量和脂肪酸组成)进行了测定,并用差示扫描量热法(DSC)研究脂肪的熔化性质。研究结果表明,DSC曲线能确切地反映人造奶油的口熔性、热稳定性与流变性。通过改变油脂的组成结构可以改变油脂的熔化性质,因此在人造奶油生产中可以用DSC曲线进行质量控制。     

抗性淀粉糊化规律的研究

采用差示扫描量热分析技术(DSC)对原淀粉及各抗性淀粉样品的糊化温度及糊化热效应进行了测试和研究。DSC吸热曲线显示,经处理过的样品晶体完全不同于原淀粉晶体。抗性淀粉的吸热曲线除了在85℃左右出现一个小峰外,在125℃左右又开始出现吸热峰,相变高峰温度约在155℃。随着样品中抗性淀粉含量的升高,曲线中第二吸热峰的相变焓逐渐升高,相变高峰温度也遵循同样的规律。     

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