固体ClO_2保鲜剂的研制及应用

采用亚硫酸盐放出SO2气体还原氯酸盐产生ClO2气体的发生方法,研制出一种新型固体ClO2保鲜剂,同时考察了3种添加剂(硅藻土、Na2CO3、CaO)的用量对固体保鲜剂释放ClO2气体释放速度和时间的影响,并将该新型固体ClO2保鲜剂应用于甜瓜贮藏保鲜实验。结果表明:采用Na2S2O5作为SO2气体释放剂可以有效还原氯酸钠,获得最佳的ClO2释放效果;通过选择不同的硅藻土、Na2CO3、CaO用量可以调控固体保鲜剂的ClO2释放速度和时间;固体ClO2保鲜剂保鲜处理金皇后甜瓜3个月后商品瓜率可达85%左右,保鲜效果显著。     

缓释型固体二氧化氯保鲜剂的制备与应用

通过对吸附剂、钝化剂、吸水剂等助剂的选择和不同配方的筛选,制备出7 种反应型和5 种吸附型固体ClO2 杀菌剂。每种ClO2 杀菌剂均对甜瓜黑斑病菌表现出优异的杀菌和抑菌效果,并且稳定性好。改变助剂配比还可控制ClO2 气体释放速率,克服以往固体ClO2 杀菌剂释放周期短、释放量大、释放速率难以控制等缺点,这有利于加快固体ClO2 保鲜剂在水果保鲜贮藏行业中的应用。     

固体ClO_2及其在食品工业中的应用

介绍了新型杀菌防霉剂固体ClO2 的特性、研究进展和测定方法。对固体ClO2 的杀菌、消毒、漂白等机理作了分析。并介绍了固体ClO2 的制备方法及其在食品加工中的应用。     

锯末硫酸盐法制浆

过去,很多人在实验室或生产上研究过锯末制浆的问题。所用的方法有机械法,半化学冶碱法,半化学中性亚硫酸盐法,半化学硫酸盐法,高得率硫酸盐法,亚硫酸氢盐法和亚硫酸盐法,还有人研究用锯末制取人造丝浆。 在这些方法中,以硫酸盐法锯末浆的强度     

最近的亚硫酸盐法制浆

一、亚硫酸盐法制浆的进展 自从1930年以后,SP(亚硫酸盐法纸浆)比KP(硫酸盐法纸浆)处于劣势。其间SP法也不是裹足不前的,随着新的蒸煮法的发展,SP法的弱点逐渐在技术上得到解决,随着最近对纸浆研究的进展,SP法的特点逐渐被掌握,从而使这种方法得到重视,巩固     

微波辐射碱法稻草制浆及其对纸浆性能的影响

分别用微波辐射碱法和碱性亚硫酸盐法对稻草原料进行蒸煮.通过试验确定了微波辐射碱法制浆的优化工艺条件:用碱量13%(以Na2O计),其中氢氧化钠10%,亚硫酸钠3%,液比1:6,微波功率400W,辐射时间50min,最高温度100℃.微波辐射碱法纸浆与常规亚硫酸盐法纸浆的性能进行了对比,结果表明微波辐射碱法制浆对纤维损伤较小,成浆具有良好的可漂性,浆张抗张指数、耐破指数、撕裂指数比常规硫酸盐法均有所提高.     

第五讲 亚硫酸盐法制浆(二)

第三节 亚硫酸盐法制浆的分类 根据蒸煮液的主要离子浓度和pH值的不同,通常将亚硫酸盐法分成四类。 酸性亚硫酸盐法:药液中所含游离SO_2(或过剩的SO_2)较高,常用于钙盐基,但也可使用镁盐基,钠盐基或铵盐基,pH为1～2。 亚硫酸氢盐法:药液中以亚硫酸氢盐离子为主(通常超过50％),只含有少量或不含真游离SO_2,pH为2～6。此法需采用钠、镁或铵等溶解度较高的盐基。     

草类原料亚硫酸盐法和硫酸盐法制浆中几个问题的研究

硫酸盐法和亚硫酸盐法是目前化学制浆的主要方法,近年来我们对荻、芦苇,麦草、稻草等几种草类原料,主要围绕着亚硫酸盐法和硫酸盐法制浆方面的某些问题,进行了比较系统的研究。本文将这方面研究的主要结果,以及我们对草类原料制浆中一些问题的看法归纳整理,以供分析研究。内容包括:以荻为原料,研究了草类原料在硫酸盐法和三种亚硫酸盐法制浆中行为的差别,指出碱性亚硫酸盐法对于荻等草类原料是比较适宜的制浆方法;以芦苇为原料,阐明了碱性和中性亚硫酸钠法添加蒽醌,可以改进草类原料的亚硫酸盐法制浆效果;总结了荻和芦苇在不同方法蒸煮过程中,纸浆酸溶木素含量的变化规律,指出草类原料亚硫酸盐法制浆中,纸浆酸溶木素含量的测定应当引起重视;概括了几种草类原料纤维分离点的特点,从而为合理地制订蒸煮工艺条件提供了依据。     

芬兰Kemi浆厂开始采用Tampella回收法

Tampella回收法 Tampella回收法用途很广。它适用于中性亚硫酸盐半化学浆法,钠盐基亚硫酸盐法,多硫化物硫酸盐法的化学药品的回收,也可用于中性亚硫酸盐半化学浆法和亚硫酸盐法或硫酸盐法的交叉回收,或亚硫酸盐法和硫酸盐法的交叉回收。 达一方法所用的各个单元操作都是众所周知的,在其它过程中也是得到证明的,然而,在Tampella回收程中,这些单元操作是以     

碱性亚硫酸盐法制浆——一种高得率制浆方法

最近出现了一种被称为“碱性亚硫酸盐法”的新的制浆方法,它的得率此硫酸盐法高,纸浆强度也可以和硫酸盐法媲美,因而,引起人们的注意,认为这一发展使得快要被淘汰的亚硫酸盐法获得了新生。 本文介绍用碱性亚硫酸盐法制取抄造挂面纸板的高得率松木浆的研究情况。     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.