微波辐射下纸张增干强剂P（AM-DMC）的制备

对微波辐射下丙烯酰胺（AM）和甲基丙烯酰氧乙基三甲基氯化铵（DMC）的水溶液聚合反应进行了研究,制备了P（AM-DMC）阳离子聚丙烯酰胺纸张增干强剂。探讨了引发剂用量、单体配比、微波功率、反应时间等对聚合物相对分子质量和纸张增干强作用的影响,确定了最佳合成工艺,并用红外光谱对产物的结构进行了表征。结果表明：当微波辐射功率为528W,引发剂用量为0.35g,单体配比AM：DMC为12：3.75,辐射时间为4min时聚合物对纸张的增干强性能最好。     

反相微乳液聚合制备新型阳离子聚丙烯酰胺絮凝剂

以丙烯酰胺（AM）和丙烯酰氧乙基三甲基氯化铵（DAC）为共聚单体,采用反相乳液微聚合法合成了稳定的聚丙烯酰胺微乳液。探讨了乳化剂、油水质量比、单体浓度、引发剂用量和阳离子度等因素对产物相对分子质量的影响,确定了最佳合成条件,并将其与国内外产品进行了絮凝效果对比。     

阳离子胶原蛋白絮凝剂的制备及表征

以皮革废弃物提取的明胶为原料,丙烯酰胺(AM)和丙烯酰氧乙基三甲基氯化铵(DAC)为单体(AM∶DAC摩尔比为4∶1),叔丁基过氧化氢和焦亚硫酸钠为引发剂,接枝共聚合成了阳离子胶原蛋白絮凝剂P(C-AM-DAC)。以絮凝剂对油田模拟废水的浊度去除率为指标,通过响应面法优化了P(C-AM-DAC)接枝共聚条件:m(明胶)∶m(单体)为1∶1.92、引发剂用量0.03mol/L、接枝温度44.2℃、接枝时间3.0h。在此条件下制备的新型絮凝剂表现出优异的絮凝效果,对油田模拟废水中污染物去除率可达91.3%。同时利用傅立叶变换红外光谱(FT-IR)和热重分析(TGA)对其进行表征。     

阳离子胶原蛋白絮凝剂的制备及表征(续)

以皮革废弃物提取的明胶为原料,丙烯酰胺(AM)和丙烯酰氧乙基三甲基氯化铵(DAC)为单体(AM∶DAC摩尔比为4∶1),叔丁基过氧化氢和焦亚硫酸钠为引发剂,接枝共聚合成了阳离子胶原蛋白絮凝剂P(C-AM-DAC)。以絮凝剂对油田模拟废水的浊度去除率为指标,通过响应面法优化了P(C-AM-DAC)接枝共聚条件:m(明胶)∶m(单体)为1∶1.92、引发剂用量0.03mol/L、接枝温度44.2℃、接枝时间3.0h。在此条件下制备的新型絮凝剂表现出优异的絮凝效果,对油田模拟废水中污染物去除率可达91.3%。同时利用傅立叶变换红外光谱(FT-IR)和热重分析(TGA)对其进行表征。     

阳离子胶原蛋白絮凝剂的制备及表征(续)

以皮革废弃物提取的明胶为原料,丙烯酰胺(AM)和丙烯酰氧乙基三甲基氯化铵(DAC)为单体(AM∶DAC摩尔比为4∶1),叔丁基过氧化氢和焦亚硫酸钠为引发剂,接枝共聚合成了阳离子胶原蛋白絮凝剂P(C-AM-DAC)。以絮凝剂对油田模拟废水的浊度去除率为指标,通过响应面法优化了P(C-AM-DAC)接枝共聚条件:m(明胶)∶m(单体)为1∶1.92、引发剂用量0.03mol/L、接枝温度44.2℃、接枝时间3.0h。在此条件下制备的新型絮凝剂表现出优异的絮凝效果,对油田模拟废水中污染物去除率可达91.3%。同时利用傅立叶变换红外光谱(FT-IR)和热重分析(TGA)对其进行表征。     

P（AM-DMDAAC-AA）两性聚电解质的合成及其对白水中Ca2+吸附性能的研究

以丙烯酰胺(AM)为分子骨架,丙烯酸(AA)和二甲基二烯丙基氯化铵(DMDAAC)分别为阴、阳离子单体,采用过硫酸钾(KPS)与偶氮二异丁脒盐酸盐(AIBA·2HCl)组成的复合引发体系,在水相中共聚合成了一种具有两性特征的水溶性高聚物P(AM-DMDAAC-AA).通过考察单体质量分数、引发剂用量、单体配比等因素对产物特性黏数和Ca2吸附性能的影响,确定了反应的最佳合成条件:单体摩尔比n(AM)∶n(DMDAAC)∶n(AA)=1∶0.3∶0.8,单体质量分数22.5％(单体总质量对反应体系总质量),引发剂用量0.2％(相对于单体总质量),其中KPS与AIBA·2HCl的质量比为3∶1,反应温度70 ～ 75℃,反应时间10h.合成的聚合物特性黏数为231.48 mL/g,Ca2吸附量最高能达到2.028 mmol/g.运用FT-IR和1H-NMR对聚合物结构进行了表征.     

AKD专用新型阳离子聚合物乳化剂的制备与应用

以阳离子聚合物为分散剂,丙烯酰胺（AM）、二烯丙基二甲基氯化铵（DMDAAC）为单体,过硫酸铵为引发剂,制备了一种AKD专用新型阳离子聚合物乳化剂,并用此乳化剂乳化AKD蜡,制得阳离子AKD乳液。考察了单体配比,反应温度,反应时间对聚合物乳化性能的影响。结果表明：阳离子分散剂用量20%,AM用量9%,DMDAAC用量1%,反应温度80℃,反应时间2 h,制得的聚合物对AKD具有较好的乳化性能。利用该乳化剂进行中试生产,产品粒径0.98μm,纸厂实际应用效果良好。     

AKD专用新型阳离子聚合物乳化剂的制备与应用

以阳离子聚合物为分散剂,丙烯酰胺（AM）、二烯丙基二甲基氯化铵（DMDAAC）为单体,过硫酸铵为引发剂,制备了一种AKD专用新型阳离子聚合物乳化剂,并用此乳化剂乳化AKD蜡,制得阳离子AKD乳液。考察了单体配比,反应温度,反应时间对聚合物乳化性能的影响,结果表明：阳离子分散剂用量20%,AM用量9%,DMDAAC用量1%,反应温度80℃,反应时间2h,制得的聚合物对AKD具有较好的乳化性能。利用该乳化剂进行中试生产,产品粒径0.98μm,纸厂实际应用效果良好。     

分散聚合法制阳离子聚丙烯酰胺及其对竹浆废水的絮凝性能

以丙烯酰胺(AM)和丙烯酰氧乙基三甲基氯化铵(DAC)为共聚单体,采用分散聚合法在无机盐水溶液中得到了性能稳定的聚合物乳液。产物的红外光谱及粒径分析表明,这种分散聚合法在制备阳离子聚丙烯酰胺乳液上是成功的。将所得阳离子聚丙烯酰胺乳液(CPAM)与聚硅氯化铝配合使用处理竹浆废水,结果表明自制阳离子聚丙烯酰胺具有良好的絮凝性能。     

过硫酸铵引发阳离子淀粉接枝共聚物合成与表征

采用水溶液聚合方法,以过硫酸铵(APS)为引发剂,将玉米淀粉(St)与丙烯酰氧乙基三甲基氯化铵(DAC)单体接枝聚合,制备阳离子淀粉高分子聚合物。讨论单体质量比、引发剂用量、反应温度和反应时间等因素对聚合物阳离子度的影响。结果表明：当加入淀粉质量1.0%的过硫酸铵,DAC与淀粉质量比2.5:1,50℃反应8h时,接枝共聚物的阳离子度最高可达53.68%。用红外光谱、扫描电镜、热失重分析对接枝共聚物结构进行表征,表征结果均证实阳离子淀粉高分子聚合物制备成功。     

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.