中式灌肠生产中壳聚糖的抑菌效果研究

目的：研究壳聚糖在中式灌肠生产中的抑菌效果；方法：采用中性蛋白酶水解方法制备出不同黏均分子量的壳聚糖，添加到灌肠中，测定不同保存天数时的细菌总数和感观变化；结果：添加0．2％壳聚糖的灌肠在室温条件下的保质期提高2d以上，风味比其他添加量要好，且在同样添加量的条件下，黏均分子量低的壳聚糖比黏均分子量高的壳聚糖抑菌效果更好。     

甲壳素微波法脱乙酰制备壳聚糖的研究

本文采用微波技术由甲壳素脱乙酰制备壳聚糖，首次对在微波反应前采用乙醇浸泡对甲壳素进行预处理的条件进行了较为系统的研究，并通过单因素试验和正交试验分析了微波反应时间、碱液浓度、乙醇浸泡时间、乙醇浓度、微波功率对壳聚糖脱乙酰度和粘均分了量的影响，提出了制备高脱乙酰度、高粘均分予量壳聚糖的最优条件为（微波功率462W）：微波反应时间20min，NaOH浓度50％，乙醇浸泡时间2、5h，乙醇浓度80％。在该条件下制得的壳聚糖脱乙酰度为77.07％，粘均分子量为43．13万，得率为68．98％。     

不同黏均分子量壳聚糖制备及在染整中的应用

研究了壳聚糖在中性条件下用H2O2进行氧化降解的情况，讨论了反应温度和H2O2浓度对氧化降解反应的影响。结果表明，用H2O2使壳聚糖在中性条件下氧化降解是制备低分子量壳聚糖的一种简便易行的方法，以分子量为4.5万左右的壳聚糖预处理的棉织物，对活性染料染色增深效果最明显。     

超声波-微波协同H_2O_2降解壳聚糖的研究

采用正交实验方法优化超声波-微波联合H2O2氧化降解制备水溶性低分子量壳聚糖,并对水溶性低分子量壳聚糖进行红外光谱表征及热稳定性测定。正交实验结果显示,H2O2浓度8%,H2O2氧化10 min,超声-微波联合降解3 min,制备得到平均分子量为3.52 ku的低分子量壳聚糖。红外光谱分析表明壳聚糖在降解过程中分子骨架结构保持不变,引起了β(1→4)糖苷键部分断裂,降解过程伴随脱乙酰反应发生;差热分析表明降解后的低分子量水溶性壳聚糖的热稳定性低于原料壳聚糖。     

微波强化壳聚糖固相酸降解研究

本文研究了微波强化下的壳聚糖固相酸降解反应,分析了降解过程中微波辐射功率和盐酸用量等参数对降解产物分子量变化的影响,并利用红外光谱和核磁共振氢谱对降解产物的结构进行了表征.研究表明,微波辐射功率和盐酸用量的增加均有利于壳聚糖分子量的降低.采用微波辐射壳聚糖固相酸化物料15 min,即可获得重均分子量低于50000的低分...     

微波辐射下制备壳聚糖双胍盐酸盐抗菌剂的研究

采用微波辐射技术,以壳聚糖和双氰胺为反应原料,合成了一种壳聚糖双胍盐酸盐抗菌剂.利用红外光谱表征了产物的结构,利用单因素试验和正交试验考察了不同反应溶剂、微波辐射功率、微波辐射时间等因素对产率的影响.优化合成反应条件为:反应溶剂为0.15 mol/L盐酸,微波辐射功率为700 W,微波辐射时间为15 min.采用微波辐射合成壳聚糖双胍盐酸盐抗菌剂,在极短的时间内可以获得几乎和传统合成方法同样的产率,极大地节约时间和提高效率.     

微波辐射下水杨醛缩合壳聚糖的制备

对比研究了传统法与微波辐射条件下水杨醛缩合壳聚糖的制备，用红外光谱对其结构进行了表征。用正交法优化了溶剂、反应时间、酸度及物料比对缩合度的影响，结果表明，微波法在pH5.0反应3min，以95％的乙醇作溶剂，物料比5：1时，缩合度可达94．75％。与传统法比较，微波法具有反应时间短、产率高等特点。     

壳聚糖硬脂酸盐制备新方法及其结构性能研究

以固体壳聚糖醋酸盐为原料,水为反应介质,制备了壳聚糖硬脂酸盐。通过红外光谱、X-射线衍射、电子扫描显微镜等对壳聚糖硬脂酸盐的结构进行表征,并考察了其油脂吸附性能。实验结果表明:壳聚糖硬脂酸盐的制备适宜条件为:原料物质的量比1:1,反应温度70~75℃,反应时间30 min;产品微观结构表面粗糙、多空隙;在弱酸和中性条件下,壳聚糖硬脂酸盐的油脂吸附量比壳聚糖提高3~5倍,不受介质pH影响。新壳聚糖硬脂酸盐制备方法无需调节反应介质pH,无有机溶剂,反应快,产品易抽滤、洗涤,产率达85%以上,便于规模生产。     

微波条件下南美白对虾壳聚糖的制备及其动力学分析

本文研究了微波辐射对南美白对虾甲壳素制备壳聚糖的影响。试验结果表明：采用微波加热（300W）制备壳聚糖时碱液浓度应低于50％,加热时间应低于15min,这样可以制备出不同脱乙酰度的壳聚糖。所制得壳聚糖具有标准壳聚糖红外光谱特征峰。反应动力学分析表明,壳聚糖脱乙酰反应为一级反应,反应速率常数为0．0704。     

壳聚糖/活性白土糖用复合脱色剂的制备及其吸附特性研究

以活性白土和壳聚糖制备壳聚糖/活性白土复合脱色剂,糖汁脱色效果作为评价指标,分别考察制备过程中反应温度、反应时间、壳聚糖添加量、壳聚糖分子量等因素对其脱色效果的影响,获得最佳条件为:反应温度为60℃,反应时间为7 h,壳聚糖添加量为2.0 g,壳聚糖分子量为200万.该复合物的糖汁脱色率最高可达96.2％,明显优于活性...     

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.     

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.     

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.