用于纺制细旦长丝的熔体过滤器的改进

对普通纺丝设备进行改造以达到纺制细旦长丝的目的是一条投资少、见效快的途径。介绍了有关熔体过滤方面的改造方案,包括纺丝组件、熔体过滤器和二氧化钛过滤器的改进。     

聚酯熔体过滤器的改造

针对聚酯生产装置增容后，熔体过滤器滤芯以及熔体直纺长，短丝组件使用周期期短等问题，对熔体过滤器进行了改造，延了滤芯和长，短丝组件的使用周期，使生产成本大大降低，取得了显著的经济效益，并说明改造后存在的一些缺点和不足。     

聚合物熔体的连续过滤装置

聚合物加工中,连续过滤方法越来越显得重要,因为这种方法在切换过滤器时无需中断熔流。现有的过滤装置可分为两种:单位过滤面积熔体流量低的,单位过滤面积流量高的。第一种可采用双过滤腔系统,已有多家公司生产,其费用昂贵,但使用寿命较长。第二种的过滤器受     

聚合物熔体过滤器

近来在熔体纺丝工业中广泛应用了聚合物熔体过滤器。在熔体直接纺丝中过滤器安装在聚合釜之后,通常被称为终端过滤器,而在切片纺丝中安装在螺杆挤压机之后,通称为预过滤器。使用了聚合物熔体过滤器能     

卷烟厂节能自清洁型空气过滤系统的研制

为解决卷烟车间空气中粉尘浓度大及空调系统中过滤器存在的阻力高、维护量大等问题,基于粉尘粒径的分布特性,设计了一种节能自清洁空气过滤系统。该系统主要由过滤器、清洗装置、PLC控制柜3大部分构成。采用不锈钢纤维毡作为滤料,将过滤器单元采用模块化结构设计,安装在矩形立槽式支架上,以增加空气过滤面积;在线自动清洗机构采用空调机房的自来水,经喷嘴形成扇型的高压水流,对过滤器单元表面和内部粉尘进行清理。测试结果表明:该系统容尘量大,过滤效率高于70%,过滤初阻力在32~166 Pa之间;实现了系统在线自动清洗功能,降低了运行能耗及维护费用,有效提高了空气过滤效率。     

新一代应用于聚合物熔体过滤器的清洁技术

介绍了Longworth公司用于聚合物熔体过滤器的新一代DEECOM清洁技术以及检验方法。新技术可以降低运行成本和公用工程消耗,减少对环境的影响;在聚酯熔体过滤器的清洁中可以达到热解工艺和TEG化学清洁工艺的水平,并可用于聚酰胺、聚乙烯和聚乙烯醇等熔体过滤器的清洁。     

论熔体预过滤器

熔体预过滤器对提高纺丝质量、延长纺丝组件的使用周期和降低成本起着较重要的作用,我国目前正在积极研制和开发.本文对熔体预过滤器的工作原理、技术参数、设备结构,进行了较为详细的分析和探讨,着重论述了熔体滞留时间、过滤精度、过滤阻力、过滤介质等特性参数之间的相互关系,以及这些参数对熔体预过滤器设计的影响.我厂生产的熔体预过滤器是一种新型化纤设备,已于1991年4月在广东新会合成纤维厂FDY机上投入使用,至今工作运行基本正常,能够满足生产需要.     

盘式过滤器在锦纶66高强力丝生产线上的应用

介绍了一种新型熔体过滤器，这种熔体过滤器以包覆有不锈钢纤维烧结毡的圆盘状金属板作为主要过滤材料，具有过滤面积大，纳污能力强，使用周期长；耐高压，能过滤高粘度熔体；熔体停留时间短，聚合物热降解少等优点。详细介绍了这种熔体过滤器的内部结构和工作原理及在锦纶66原丝生产线上的应用。     

聚合物熔体连续过滤装置

最近,德国Gneuβ塑料工程公司研制出一种新型聚合物溶体连续过滤装置,其工作原理如图所示。该装置由熔体过滤器、滤液分析器和杂质分离器三部分组成,与传统的过滤装置相比,它具有高效、连续、投资费用低、占地面积小的优点,实际应用结果表明,这是一种理想的熔体连续过滤装置,其技术数据如表所示。     

熔体过滤器在纺粘法非织造布生产线中的应用

不同类型的熔体过滤器有不同的结构和功能。文章介绍了国内纺粘法非织造布生产线中主要应用的三类熔体过滤器和过滤器中使用的不同过滤材料的特性指标 ,指出过滤器类型和过滤材料的选择与纺粘法非织造布的生产关系紧密     

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.