水溶性聚酯的流变行为

由对苯二甲酸(PTA)、乙二醇(EG)、间苯二甲酸乙二酯-5-磺酸钠(SIPE)共缩聚合成水溶性聚酯(WSP)。采用Rosand RH7型毛细管流变仪对自制WSP的流变行为进行研究。结果显示,随着温度升高,WSP剪切黏度下降,非牛顿指数增大;相同温度和相同剪切速率下WSP的剪切黏度比PET大;WSP的剪切黏度随剪切速率的变化较PET更敏感,随着剪切速率的增大WSP的黏流活化能显著降低。同时分析了第3单体SIPE和温度对WSP流变行为的影响。     

仿真丝共聚酯的合成及性能研究

在常规聚酯(PET)合成过程中加入间苯二甲酸(IPA)、聚乙二醇(PEG)进行共聚改性,制备仿真丝共聚酯(SPET)。探讨了改性剂的加入对共聚酯的熔点(Tm)、特性黏度(ηsp)的影响,用差示扫描量热仪(DSC)、热重分析仪(TGA)分析了SPET及PET的热力学性能和热稳定性。结果表明:与PET相比,SPET的玻璃化温度(Tg)下降,结晶温度(Tc)升高,熔点降低;SPET在350℃以下有良好的热稳定性,但在350℃以上SPET的热失重比PET明显。研究所制备的SPET可以用来制备仿真丝长丝。     

皮芯负氧离子涤纶长丝的研制

 将负氧离子粉体添加到聚酯载体中制备功能母粒,与常规聚酯（PET）复合纺丝制成皮芯负氧离子长丝。通过差示扫描量热仪（DSC）、流变仪、熔融指数仪对负氧离子功能母粒的结晶温度、熔融温度、流变性、表观粘度等可纺性能进行了表征,对负氧离子纤维的纺丝工艺进行了研究,并对复合功能纤维的负氧离子释放浓度、回潮率、比电阻进行了测试。结果表明：负氧离子母粒的结晶温度降低,熔融温度变化不大;在相同剪切速率下,负氧离子母粒的剪切黏度比PET大;当温度达到280℃时,负氧离子母粒和PET2种熔体才能进行复合纺丝;负氧离子母粒的熔融温度及纺丝温度要比PET高;功能纤维释放负氧离子浓度达到郊外田野的水平,回潮率比PET提高了1倍,并具有一定的抗静电性能。     

干燥工艺对回收聚酯瓶片性能的影响

研究干燥工艺对回收聚酯瓶片含水率、热学性能、特性黏度、结晶度等结构和性能的影响,并测试了回收聚酯瓶片的流变性能。结果表明:随着干燥温度的提高和干燥时间的增加,回收聚酯瓶片的含水率呈下降趋势,在T=160℃和t=6h条件下其含水率可控制在0.08%内。回收聚酯瓶片的干燥程度越高,其玻璃化温度、结晶温度、结晶热、熔融热以及特性黏度和结晶度均得到提高,对其熔点影响较小。回收聚酯瓶片熔体剪切应力、表观剪切黏度、非牛顿指数均随着剪切速率的增大而减小。相同剪切速率下,剪切应力随温度增加而减小,表观黏度与非牛顿指数随温度增加呈增大趋势。     

增强马氏珠母贝肌肉水溶性蛋白质热稳定胶体筛选研究

以珍珠产业副产物马氏珠母贝肉为研究对象,在前期研究结果基础上,筛选有效提高马氏珠母贝肌肉水溶性蛋白（WSP）热稳定性亲水胶体,并分析不同热处理条件下最佳亲水胶体对马氏珠母贝肌肉水溶性蛋白（WSP 和F-D WSP）热稳定性的影响,研究结果显示：同一热处理温度条件下,卡拉胶、果胶及瓜尔胶体对WSP的热稳定性的影响存在明显差异（P<0.05）。在热处理温度范围内（60～100 ℃）,卡拉胶对于稳定WSP的效果最好。卡拉胶对WSP 和F-D WSP的热稳定性影响作用存在明显差异性（P<0.05）,在热处理温度范围内（60～100 ℃）,随着热处理温度的不断提高,卡拉胶对WSP稳定性作用逐渐增强,而对F-D WSP的稳定性作用则呈先增强后减弱的趋势。     

易染色聚酯熔体的流变性能

采用高压毛细管流变仪研究了易染色超仿棉聚酯熔体的流变行为,并将其与聚酯熔体的流变行为进行了对比。结果表明：易染色聚酯熔体属于典型的假塑性非牛顿流体,表现出明显的剪切变稀特性;随着温度的升高,易染色聚酯熔体的表观黏度下降,非牛顿指数逐渐增大,结构黏度指数减小;易染色聚酯熔体的黏流活化能随着剪切速率的增大而减小,即其表观黏度的温度敏感性随着剪切速率的增大而降低;与PET熔体相比,易染色聚酯熔体的表观黏度对温度和剪切速率的依赖性更高,且结构化程度更大。     

压力对不同特性黏度聚酯流变行为的影响

采用毛细管流变仪及其配套的反向压力腔组件控制毛细管出口压力,在平均压力为5~50 MPa下研究了3 种不同特性黏度的聚酯（PET）的流变行为。结果表明：PET的剪切黏度随着平均压力的增大都呈指数增加,符合Barus方程。压力系数随着特性黏度的增大而减小,当特性黏度由0.48增加至0.67 dl/g时,压力系数显著减小,且这种变化随着剪切速率的增大而衰减,当特性黏度≥0.67 dl/g时,压力系数随剪切速率的变化不大。压力系数随剪切速率的增大而减小,特性黏度为0.48 dl/g时变化显著,当特性黏度≥0.67 dl/g时,压力系数随剪切速率的变化不大。压力系数随着温度的升高而减小,且变化率随着温度的升高显著减小。不同特性黏度PET压力系数的变化表明,特性黏度较低时,自由体积较大,表现在玻璃化转变温度低,受压力的影响显著;当特性黏度为0.67和1.00 dl/g时,自由体积的减小不再明显,因此受压力的影响也不再明显。     

PET/WSPET聚酯共混物的结构与拉伸流变性能

以水溶性聚酯WSPET为改性剂,对普通聚酯PET进行改性,用毛细管流变仪测试PET、WSPET及其共混物在拉伸流场中的流变性能,用傅里叶红外变换光谱和X衍射仪对PET/WSPET共混纤维的结构进行分析。结果表明:PET/WSPET聚酯共混物熔体属于拉伸变稀型,熔体的表观拉伸黏度随拉伸应力的增加而降低,拉伸应力随拉伸应变速率的提高而增大,提高拉伸应变速率会导致熔体拉伸黏度下降;WSPET的加入不会明显改变PET的结构,但共混物的结晶性能会随WSPET加入量的增加而呈下降的趋势。     

钛系聚对苯二甲酸乙二醇酯的增黏行为及其性能

为了拓宽钛系聚对苯二甲酸乙二醇酯(PET)在聚酯工业丝领域的应用,通过超高效聚合物色谱-多角度激光光散射联用法研究其在不同温度下的增黏行为,建立增黏温度与钛系PET分子质量及其分布的关系,并利用紫外-可见分光光度计和差示扫描量热仪研究增黏PET的色相和热性能。结果表明:钛系PET分子质量随增黏温度的升高而升高,且色相受温度影响明显;增黏所需时间随温度升高而下降,270 ℃反应20 min的钛系PET重均分子量与220 ℃反应10 h时的相当,分子质量升高导致聚酯结晶性能和熔点下降;增黏温度超过熔点后,分子质量分布随温度升高而变窄,且分子质量可达到聚酯工业丝要求,高分子质量窄分布钛系聚酯的研究对其在工业丝领域的应用具有重要意义。     

新型改性聚酯的制备及其性能

为研究新型多功能黏土类材料（QE 粉）改性聚酯（PET）的可纺性及加工性能,采用共混法制备PET/QE共混物,并借助毛细管流变仪、热重分析仪、扫描电子显微镜对共混物的流变性能、热性能及其纤维形貌进行测试与表征。结果表明：QE 粉的添加使PET 发生降解,大幅减小了共混熔体的流动阻力和非牛顿性,添加质量分数为1%的QE 粉的共混物在剪切速率为900 s-1 时,剪切黏度和剪切应力较纯PET 分别下降了253% 和295%,非牛顿指数升高了19.4%;QE 粉对PET 的热降解性能基本无影响,其质量分数为2% 时,共混物的起始热分解温度下降3 ℃;采用皮芯纺丝法制备的改性纤维表面含大量QE粉颗粒,且纤维表面部分区域存有凹痕。     

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.     

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.     

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.     

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.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.