尼龙66织物微波法接枝丙烯酰胺的阻燃改性

采用微波接枝法,将丙烯酰胺(AM)接枝到尼龙66织物的表面。研究引发剂浓度、单体浓度、反应时间和反应温度对接枝率的影响,得到的优化反应条件为:引发剂浓度3%、单体浓度20%、反应温度80℃、反应时间90 min。采用衰减全反射-红外光谱和扫描电镜分析表征,接枝单体成功接枝到尼龙66织物表面;热重分析(TG)表征接枝后织物的热稳定性明显提高;极限氧指数(LOI)及垂直燃烧表征接枝后织物的耐燃烧性能明显改善。     

电子束辐照接枝HEMA涤纶织物的亲水性能

以甲基丙烯酸羟乙酯(HEMA)为接枝单体,采用1.5 Me V的电子加速器对经HEMA处理的涤纶织物进行共辐照接枝整理,以提高织物的亲水性能。采用傅里叶红外光谱(FTIR)和接触角测试仪对接枝样品进行表征,研究了单体质量分数、交联剂质量分数、辐照剂量、浸渍时间对接枝率的影响。红外光谱分析证明,HEMA接枝到涤纶织物上,接枝率随单体质量分数以及浸渍时间的增加而增大;随着交联剂质量分数以及辐照剂量的增大而先增后减,在交联剂5%、辐照剂量180 k Gy时达到最大;接枝改性后,涤纶织物亲水性能得到明显提高,接触角几乎为0°,且亲水性能随接枝率的增大而增大。经过20次水洗后,涤纶织物仍具有良好的亲水性。     

ATRP法在真丝表面接枝HEMA的研究

以2-溴异丁酰溴修饰过的真丝织物为大分子引发剂,CuBr/PMDETA为催化体系,在水介质体系中采用原子转移自由基聚合(ATRP)法,将甲基丙烯酸羟乙酯(HEMA)接枝在真丝织物表面.研究了单体及催化剂浓度、pH值、反应时间对实验影响,通过ATR-FTIR、X-射线衍射和SEM等表征了接枝真丝织物的结构,并测试了其各项物理性能.结果表明,通过ATRP法成功将HEMA接枝到真丝表面,接枝反应主要发生在丝素的无定形区,接枝聚合物在真丝表面分布均匀,且接枝后织物抗皱性有较大提高.     

基于原子转移自由基聚合的棉织物抗皱整理

以甲基丙烯酸羟乙酯(HEMA)为功能单体,采用原子转移自由基聚合反应(ATRP)对棉织物进行抗皱整理。研究了引发剂质量、反应温度和反应时间对棉织物前处理效果的影响;分析了接枝工艺中功能单体和催化剂浓度,反应时间和反应温度对接枝效果的影响。优化的棉织物前处理工艺为:棉织物、4-二甲氨基吡啶、三乙胺和2-溴异丁酰溴的质量比为1∶0.5∶1.5∶2,整个反应体系在较低温度下(8℃左右)反应1 h,然后在30℃反应24 h。优化的接枝反应工艺为:单体HEMA浓度0.25 mol/L,催化剂Cu Br浓度2.0 mmol/L,反应温度85℃,反应时间90 min。整理后棉织物的抗皱性能得到明显提高。     

亚麻织物紫外光接枝丙烯酸的改性

以丙烯酸(AA)为接枝单体,采用紫外光(UV)接枝的方法对亚麻织物表面进行接枝改性,采用红外光谱(FT-IR)和扫描电镜(SEM)对接枝聚合物进行表征,研究了单体质量分数、光引发剂用量、UV能量、UV波长、丙烯酸钠等因素对接枝率的影响,并探讨了接枝机制。FT-IR谱图在1 715 cm-1处增加了-C=O的特征吸收峰,表明光接枝丙烯酸反应的发生。SEM照片显示出光接枝亚麻织物表面出现覆盖物和纤维间的黏连。接枝率随单体质量分数的增加而升高,达到60%时,接枝率增幅不大。当光引发剂的用量为2%,UV能量为0.76 J/cm2时,接枝率较高。UV波长对接枝率的影响与光引发剂的UV吸收性有关。丙烯酸单体中存在丙烯酸钠会提高接枝率。     

季铵—磺酸型淀粉基高分子聚合物的合成及应用

研究了以淀粉为基材,以丙烯酰胺(AM)、丙烯酰氧乙基三甲基氯化铵(AAC)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为聚合单体,采用溶液聚合技术合成两性接枝共聚物的方法.考察了引发剂用量、反应温度、反应时间、溶解助剂用量、络合剂用量等因素对单体转化率、接枝率、产物特性粘数及溶解性的影响.最佳反应工艺条件为:引发剂质量浓度为0.1%,m(单体)∶m(淀粉)=7∶3,反应温度50℃,反应时间4h.所得产物的接枝率达217.92%、转化率达93.74%、特性粘数达543.31ml/g.该聚合物用于处理油田污水效果好于聚丙烯酰胺类絮凝剂.     

季铵—磺酸型淀粉基高分子聚合物的合成及应用

研究了以淀粉为基材,以丙烯酰胺(AM)、丙烯酰氧乙基三甲基氯化铵(AAC)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为聚合单体,采用溶液聚合技术合成两性接枝共聚物的方法。考察了引发剂用量、反应温度、反应时间、溶解助剂用量、络合剂用量等因素对单体转化率、接枝率、产物特性粘数及溶解性的影响。最佳反应工艺条件为:引发剂质量浓度为0.1%,m(单体)∶m(淀粉)=7∶3,反应温度50℃,反应时间4h。所得产物的接枝率达217.92%、转化率达93.74%、特性粘数达543.31ml/g。该聚合物用于处理油田污水效果好于聚丙烯酰胺类絮凝剂。     

蚕丝的丙烯酸六氟丁酯接枝改性及拒水性能

采用含氟单体丙烯酸六氟丁酯,在引发剂过硫酸钾作用下对蚕丝进行接枝改性,研究单体和引发剂用量、改性温度和时间以及改性pH值等对蚕丝接枝率的影响。采用扫描电镜(SEM)和X射线光电子能谱(XPS)对接枝改性的蚕丝进行表征,并测试整理后蚕丝织物的物理机械性能及拒水性。结果表明,丙烯酸六氟丁酯对蚕丝接枝的优化工艺参数为:单体质量分数150%(omf),引发剂质量分数1%(owm),pH值3,反应时间120 min、反应温度75℃。接枝改性对蚕丝织物的白度、黄度、断裂强力和透气性影响较小,而表面张力下降明显,拒水性明显提高。     

丙烯腈接枝改性羊毛纤维的影响因素研究

采用高锰酸钾-草酸氧化还原体系引发丙烯腈在羊毛纤维上进行接枝共聚。考察了氢氧化钠前处理、单体用量、接枝反应时间、引发剂浓度、温度等因素对接枝率、接枝效率及纤维强度的影响。傅里叶红外光谱(FTIR)和扫描电镜(SEM)形貌观察表明高锰酸钾-草酸氧化还原体系可以有效引发丙烯腈在羊毛纤维上的接枝共聚,接枝后聚丙烯腈均匀覆盖在毛纤维表面。接枝率随氢氧化钠处理时间的增加而增加,但羊毛纤维单纤强度减小;接枝率随丙烯腈单体用量增加而增加,但接枝效率却减小;接枝率随反应时间的延长而增加,直至达到平衡;升高反应温度会导致接枝率降低。接枝共聚后接枝羊毛的断裂强度和热稳定性提高。     

超疏水真丝织物的制备与性能

针对真丝织物难以护理的缺点,采用2-甲基-2-丙烯酸十八烷基酯(SMA)对真丝针织物进行表面接枝改性,以提高其疏水性能。研究了接枝改性工艺参数,如SMA单体质量分数、反应时间、反应温度对织物疏水性能的影响,并分析了疏水整理前后真丝织物的结构与性能。研究结果表明,SMA在真丝针织物表面的接枝改性处理可以赋予织物优异的疏水性能,接触角可达150°以上;真丝织物处理后透气性有所增强,透湿性基本保持不变;织物断裂强力基本保持不变,断裂伸长率有所下降。     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

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.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.