评价纸质餐具降解性能的机理与方法

纸质餐具是一种顺应环境要求而产生的用于替代塑料发泡餐具的新型产品。纸质餐具在生态环境中的降解性能是衡量纸质餐具环境效益的一个重要指标。目前研究纸质餐具降解特性的方法有很多，例如光降解、热降解及生物降解法等。本文通过阐述这几种方法的作用机理及优缺点，为纸质餐具的降解性能评价提供了依据。     

新型纸质快餐具热降解性能研究

以热降解为主要手段，研究了在不同热降解度，不同热降解时间下新型纸质快餐具聚合度，白度的变化。实验结果表明，新型纸质快餐具有温度较纸时降解较慢，在100℃热降解16天后试样聚合度从初始的1000左右下降到600左右，约下降了40％，白度大约下降了30％，防水防油剂在降解初期会阻碍试样聚合度降低，但在降解后期却促进了试样聚合度的下降。而在较高温度下降解较快，在1600℃下热降解96h时试样聚合度从初始的1000左右下降到200左右，下降了80％以上，白度大约下降了80％，抗油剂会促进试样白度的降低，而抗水剂则阻碍了试样白度的降低。     

我国纸质餐具行业的现状与对策

为了走可持续发展之路，防止人类生活外境遭到白色的污染，积极开发纸质餐具是轻工行业责无旁贷的任务。为此，近年来我同纸质餐具正在下大力气积极开发这一新型餐具，以替代EPS发泡餐具。可喜的成果和市场纸餐具行业广大技术人员经过不懈的努力，已为纸质餐具的发展创造了有利条件，对纸质餐具的研究已取得了可喜的成果，纸浆模塑的一次成型技术已达到结构合理、使用方便。已有产品品种多样、外观悦目；质量＊能防火防加。纸质餐具市场前景广阔，凡胆使用E＊S发泡塑料制作的快餐具，一般都。J以也应该用纸制餐具来代替。纸制餐具的制作…     

光温条件对烤烟离体叶片叶绿素降解影响的研究

将烤烟离体叶片置于不同光强条件下，并配以不同的温度处理，在不同的时间内对叶片叶绿素含量进行测定。结果表明：１５００１ｘ光照处理与黑暗处理比较，烤烟叶绿素降解无明显差异，８５００１ｘ光照处理能够加快叶绿素的降解进程；不同温度对烤烟离体叶片叶绿素降解影响较大，３５～４０℃温度下比２０～３０℃温度下，７２ｈ内叶绿素降解速度快约１倍。     

苹果汁中维生素C热降解动力学研究

为了探索温度对苹果汁中维生素C降解的影响以及维生素C的降解动力学规律,采用可逆的一级反应模型,对加热温度30、40、50、60、70℃条件下苹果汁中还原型维生素C(AA)和氧化型维生素C(DHA)含量的变化及降解动力学进行了研究,结果表明:60℃的AA反应速率最大,DHA反应速率基本随着温度升高而增大;温度升高,可逆反应速率常数增大,其它降解途径速率常数变化不明显;AA无氧氧化速率与温度有一定关系,50℃的AA无氧氧化速率最大,70℃的AA无氧氧化速率最小;AA和DHA热降解反应活化能均低于一般化学反应活化能,说明苹果汁中维生素C热稳定性较差。维生素C的降解主要是有氧氧化反应,苹果汁中维生素C无氧降解速率比有氧降解速率慢;温度升高,苹果汁中维生素C有氧降解速度加快,无氧降解速度变化不明显。在苹果汁加工工艺中应尽量隔绝氧气,采用高温(70℃)短时热处理。对成品苹果汁应采用低温贮藏。     

生物降解淀粉餐具的工业化生产工艺条件及其性能研究

通过模压发泡工艺制备一次性淀粉餐具，研究了工业化生产过程中模压发泡工艺的参数及一次性淀粉餐具的性能。结果表明，模压发泡最佳工艺条件为上模温度190～200℃，下模温度为180～190℃，保压时间为25s。该工艺每件制备的一次性餐具其力学性能、卫生指标和生物降解性能达到国家标准要求。     

重庆市植物纤维餐具生产的卫生学调查及卫生监督的建议

我国不少企业和研究部门自80年代末以来开始投入力量,相继提出并研制开发各类可降解餐具和食品包装物.可降解餐具的原料目前有许多种,如植物纤维餐具、纸质餐具、淀粉填充型聚苯乙烯发泡餐具和光降解、生物降解或光-生物双降解聚丙烯餐具等.其中植物纤维餐具作为一种新型的餐具,具有表面光滑、耐水、耐高温、易自然降解等特点,已被国内多个城市立法确定为治理"白色污染"、替代发泡塑料的餐具种类之一.由于目前尚无植物纤维餐具国家卫生标准,给各地食品卫生监督部门加强该类产品的监督、监测带来了一定困难.为了了解我市植物纤维餐具的生产卫生状况,探讨植物纤维餐具可能存在的卫生问题,为制定植物纤维餐具国家卫生标准提供科学依据,我们于1999年10月对本市2家植物纤维餐具生产企业及生产的植物纤维餐具进行了卫生学调查,现将调查结果报告如下.     

利用一次性纸质餐具生产酒精

为了使纸质餐具中的大量纤维资源得到充分利用,采用纤维素酶对纸质餐具进行酶解,继而进一步用酵母茵进行发酵生产酒精.研究结果表明,利用纸质餐具进行纤维素酒精发酵是可行的,适宜的接种量为6%(v/v),适宜发酵时间为60h,可产生7%(v/v)的酒精含量,残余还原糖为26mg/mL.在相同的发酵条件下,经稀硫酸预处理纸质餐具发酵生产酒精含量高于未经稀硫酸处理纸质餐具,所以,稀硫酸预处理有利于纸质餐具纤维素酒精发酵.     

一次性降解餐具地方标准出台

3月1日，上海市技术监督局发布了一次性降解餐具强制性地方标准，从今年6月5日起，全市所有生产、经销一次性餐具的制造商、经销商必须严格执行该标准。近年来，上海每天因聚苯乙烯塑料为主的餐具所造成的“白色垃圾”达200多吨，这些垃圾的降解周期一般为200年左右，这将会污染大气和水资源，恶化人类的生存环境和生物的生长条件。要根除白色污染，必须依靠现代科技，生产对环境无污染，对人体无害的一次性餐具。上海市技监局此次出台的地方标准，对影响环境的降解指标作了明确规定，要求在一定的环境温度和土壤湿度下，埋入土中2周后开始…     

贮藏温度对蓝莓汁单个花色苷降解的影响

为了探讨贮藏温度对蓝莓汁花色苷降解的影响,本文研究了蓝莓汁在4、25、37℃贮藏120期间色泽的变化以及贮藏期间总花色苷和单个花色苷的变化规律,并在此基础上研究了花色苷的降解动力学。结果表明,在4℃下蓝莓汁颜色保存较好,25、37℃变化较大,而贮藏期间总花色苷和单个花色苷呈下降趋势。与零级动力学模型相比,总花色苷和单个花色苷在25、37℃下的降解更符合一级动力学模型,4℃总花色苷的降解与零级和一级动力学模型拟合系数小,单个花色苷中有4种符合一级动力学模型,且温度越高,花色苷的一级降解动力学常数越大,降解速度越快,半衰期越短。含有半乳糖苷的花色苷,其半衰期较阿拉伯糖苷的花色苷略长。总之,蓝莓汁色泽的改变与花色苷的降解密切相关,在较低温度下贮藏,可以明显减少花色苷的损失。     

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.