可降解阻隔涂层在纸基食品包装材料中的应用

本文综述了可降解阻隔涂层在纸基食品包装材料中的应用,系统地介绍了涂层的阻隔机理和涂料流变性,基底材料特性对涂层结构和材料阻隔性能的影响;并对纳米纤维素、聚乙烯醇（PVA）、聚羟基丁酸酯（PHB）、聚乳酸（PLA）、淀粉5种常见的可降解聚合物涂层材料的突出优势、不足之处和改性方法进行了对比和总结,对其应用价值进行了展望。     

纳米纤维素材料氧气与水蒸气阻隔性能的研究现状

纳米纤维素主要来源于植物纤维,具有比表面积高、强度高、密度低、透明性高、热膨胀低等特点,其特有的形态结构和表面性能使得纳米纤维素材料可以形成致密的网络结构进而提供优良的阻隔性能。本综述就纯纳米纤维素膜、纳米纤维素复合材料以及纳米纤维素涂布纸基材料重点讨论了纳米纤维素材料氧气与水蒸气阻隔性能的研究现状,以探讨纳米纤维素应用于包装材料的可能性。     

单糖或双糖聚合物改善纸基包装材料回抄性研究

本研究通过调控阻隔涂层的涂料和单糖（葡萄糖）或双糖（蔗糖）类辅助型物料种类和比例以达成协同效应,构建具有良好热封、防水、防油,且易于回抄的绿色纸基包装材料。结果表明,在阻隔涂料中引入单糖或双糖,可明显提高纸基材料的可回抄性能;在单糖或双糖质量分数达10%（相对于阻隔涂料）时,即可在不影响纸基包装材料性能的前提下,达到90%以上可回抄。     

壳聚糖/聚乙烯醇改善纸基材料的水蒸气和氧气阻隔性能研究

研究了壳聚糖和聚乙烯醇在改善纸基材料水蒸气(极性气体)和氧气(非极性气体)阻隔性能上的应用效果,探讨了壳聚糖/聚乙烯醇不同质量比和不同复合方式(共混和分层)对纸基材料水蒸气和氧气阻隔性能、机械性能和涂层稳定性的影响。结果表明,随着壳聚糖和聚乙烯醇质量比的降低,纸基材料的水蒸气阻隔性能逐渐增强,同时氧气阻隔性能逐渐降低;壳聚糖/聚乙烯醇分层涂布纸的水蒸气和氧气透过量均低于壳聚糖/聚乙烯醇共混涂布纸。当壳聚糖和聚乙烯醇的质量比为1∶1时,壳聚糖/聚乙烯醇分层涂布纸的水蒸气透过量和氧气透过量分别为9.36 g/(m~2·d)和31.93cm~3/(m~2·d);与纯壳聚糖涂布纸相比,水蒸气透过量降低了约92%,与壳聚糖/聚乙烯醇共混涂布纸相比,水蒸气透过量降低了约68%,氧气透过量降低了约67%。     

阻隔涂层在纸基包装材料中应用现状

综述了阻隔涂层在纸基包装材料中的应用现状。随着“以纸代塑”成为现今的一种趋势,为了给纸基材料提供防护性能,可以利用涂布工艺将阻隔涂层涂覆在纸张表面。这种涂层能够防止水分和油脂渗透到纸张中,得到防水防油性能更加良好的纸基涂层阻隔材料。分析比较了不同类型的阻隔材料性能的优劣,指出可持续发展的生物质基复合阻隔材料会是未来的发展方向,较高的可回收性和可降解性使其符合现代社会循环利用的要求。     

环保型PLA/CNF应用于纸张阻隔性涂布的研究

以聚乳酸（PLA）为基体、乙酰化改性纤维素纳米纤丝（m-CNF）为增强材料制得复合涂料,将其涂覆于A4纸表面制得PLA/m-CNF阻隔纸,探讨了复合涂料中m-CNF添加量对纸张阻隔性能、疏水性能、强度性能等的影响。结果表明,与原纸相比,当m-CNF添加量为3%时,PLA/m-CNF3%阻隔纸的抗张指数、耐破指数、疏水性能分别提高了30.6%、40.1%、24.8%,透气度降低了36.6%。原纸水蒸气透过量为1815 g/（m²·d）,PLA/CNF阻隔纸的氧气和水蒸气阻隔性能相较原纸显著提升;其中,PLA/CNF3%阻隔纸的水蒸气透过量为443 g/（m²·d）、氧气透过量为45 cm³/（m²·d·（0.1 MPa））;PLA/m-CNF3%阻隔纸的水蒸气透过量为385 g/（m²·d）、氧气透过量为35 cm³/（m²·d·（0.1 MPa））,与PLA/CNF3%阻隔纸相比,分别下降了13.1%和22.2%;表明PLA/m-CNF阻隔纸具有优异的保鲜效果。     

纸基材料水蒸气阻隔性能的研究现状及发展趋势

本课题从纸基材料（PBM）的多层级结构和物化改性方法的角度,系统阐述了PBM水蒸气阻隔性能的研究现状及发展趋势。首先,分析了水蒸气阻隔的特殊性及在PBM不同层级结构上的传输机制;其次,论述了PBM的3D网络内部结构修饰处理对水蒸气阻隔性能影响的研究进展;再次,基于PBM界面结构的改性研究,对比分析了各类阻隔性涂层对水蒸气阻隔性能的影响;最后重点总结了超疏水PBM的研究现状,分析了超疏水性能和水蒸气阻隔性能之间的协同对立关系,探讨了改善超疏水PBM水蒸气阻隔性能的必要性,并为超疏水PBM实现实际应用提出了研发思路和方向。     

纳米纤维素在纸和纸板生产中的应用

纳米纤维素（NFC）在造纸领域主要用于增强纸和纸板（通过湿部添加提高干强度）及提高涂层阻隔性能。造纸资源、能源效率和用NFC替代化石基薄膜的愿望是扩大NFC应用的主要驱动力。干态NFC对石油、脂肪和氧气具有优异的阻隔性能,但在相对湿度较高的条件下,其对氧气的阻隔性能会变差,文中探讨了减弱其湿度敏感性的方法,指出了NFC生产过程中容易出现的问题,介绍了其用途,以及为扩大NFC在纸和纸板生产中的应用而需要克服的主要障碍。     

纳米纤维素的制备及其在食品包装材料中应用的研究进展

纳米纤维素作为包装材料的填充成分,可以提高材料的力学性能和阻隔性能,并可改善复合材料的热学性能及降解性能.本文简要介绍了纤维素及纳米纤维素,重点阐述了纳米纤维素的制备方法(化学法、生物法和物理机械法等)及其在食品包装材料中的应用(保鲜及抗菌包装材料、活性包装材料和高阻隔包装材料等).最后,对纳米纤维素在食品包装材料领域...     

聚合物密封层在原子层沉积Al_2O_3涂层的纤维基包装材料上的附着力研究

<正>0引言随着环保问题日益得到重视,纤维基(纸基)包装材料将朝着使用更少材料、更薄涂层的方向发展。人们正在研究涂层技术以获得更好的阻隔性能。其中原子层沉积(ALD)技术显示出无限的潜力。原子层沉积Al_2O_3涂层具有更好的阻隔性能。本实验以纸基覆膜PET为基底材料,采用原子层沉积法在基底上沉积Al_2O_3涂层,然后将带有Al_2O_3涂层的基底黏附到一个纸板卷筒表面,通过挤压涂布过程制得密封层,对聚合物密封层(PET、LDPE、PLA等)和     

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.