1-MCP对低温贮藏苹果灰霉病抗性的诱导作用

以红富士苹果为试材,研究1-甲基环丙烯（1-methylcyclopropene,1-MCP）对低温贮藏（0±1）℃苹果灰霉病的控制效果及其诱导抗病机理。结果表明：采后1 μL/L 1-MCP处理较对照可显著降低损伤接种苹果灰霉病的发病率,抑制病斑的扩展（P＜0.05）。同时1-MCP处理能够诱导果实中苯丙氨酸解氨酶、多酚氧化酶、过氧化物酶、β-1,3-葡聚糖酶、几丁质酶活性的提高,促进总酚、类黄酮和木质素的积累,降低膜脂过氧化程度,减少丙二醛的产生,从而提高果实的抗病性。研究结果可为1-MCP防治苹果采后病害提供理论依据。     

1-甲基环丙烯对岳冠苹果采后生理及抗氧化酶活性的影响

以优新品种"岳冠"苹果为试材,用不同浓度的1-甲基环丙烯(1-methylecyclopropene,1-MCP)处理采后果实,并用0.04 mm保鲜袋包装,低温(0±1)℃环境下贮藏,探究1-MCP处理对‘岳冠’苹果采后生理变化和抗氧化酶活性的影响。结果表明:与对照相比,1-MCP处理有效降低了呼吸强度和乙烯释放率,其中1.0、1.5和2.0μL/L 1-MCP处理的果实呼吸高峰和乙烯峰均延迟了15 d出现,1-MCP还增加了脯氨酸的积累,贮藏120 d时,处理组分别是对照的1.10、1.53、1.39倍和1.36倍,同时,1-MCP抑制了细胞膜相对电导率的升高,在贮藏后期,维持了果实较高的抗氧化酶(过氧化氢酶、过氧化物酶、超氧化物歧化酶)的活性,后3个处理活性高峰比对照分别晚15、15、30 d出现,从而延缓了果实衰老,综合各指标分析得出,用1.0μL/L的1-MCP处理岳冠苹果,其贮藏效果最好。     

1-MCP对‘粉红女士’苹果果实采后生理及其品质的影响

为探讨1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理对‘粉红女士’苹果采后生理特性及其品质的影响。用1.0 μL/L的1-MCP处理‘粉红女士’苹果24 h,以不处理为对照,20℃条件下贮藏,定期测定贮藏期间的主要品质及相关生理指标。结果表明:1-MCP处理可保持苹果贮藏过程中的硬度、可滴定酸含量,延缓果皮油腻化的发生,显著抑制果实的呼吸强度和乙烯释放速率,推迟果实过氧化氢酶、过氧化物酶两种酶活性峰值的出现,并在一定程度上提高了超氧化物歧化酶和过氧化氢酶的活性,有效抑制丙二醛含量的积累。因此,1-MCP处理可较好地调控‘粉红女士’苹果的相关生理代谢,改善果实的贮藏品质,从而有效延缓果实采后的成熟衰老进程。     

1-甲基环丙烯处理对台湾青枣果实采后病害的抑制

为研究1-甲基环丙烯(1-MCP)处理对果实病害与抗病性诱导的影响,采用1.8μL/L 1-MCP处理“中青”台湾青枣果实12 h后在(15±1)℃下贮藏。定期观察果实腐烂和病害情况,测定总酚、木质素含量及抗病相关酶[β-1,3-葡聚糖酶(GLU)、几丁质酶(CHI)、苯丙氨酸解氨酶(PAL)]活性的变化。结果表明:1-MCP处理在贮藏前期诱导了台湾青枣果实病程相关蛋白(GLU和CHI)活性上升,两者协同作用直接抵抗病原体;同时,1-MCP处理还诱导了台湾青枣果实PAL活性上升,增加了细胞内木质素和总酚含量的积累,有利于形成间接抵抗病原体的结构性障碍;1-MCP处理的果实腐烂指数和病害指数显著低于对照,台湾青枣果实采后1-MCP处理减轻了果实贮藏期间病害的发生,减少采后腐烂损失。这些结果说明1-MCP抑制台湾青枣果实采后病害与其诱导抗病相关酶活性的升高有关。     

1-MCP对寒富苹果常温贮藏效果的影响

为探讨不同浓度1-甲基环丙烯(1-MCP)对寒富苹果在常温下贮藏效果的影响,以沈阳寒富苹果为试材,分别用0、0.3、0.6、0.9μL/L 1-MCP处理后置于室温(20±2)℃下进行MAP贮藏,通过测定苹果在贮藏期间生理生化指标的变化,来研究不同1-MCP处理对其贮藏效果的影响.结果表明,1-MCP能维持果实较好的贮藏品质,并能调节一些与采后后熟衰老相关的酶活性.与对照相比,1-MCP处理可有效抑制寒富苹果常温贮藏期间呼吸强度和乙烯释放量的增加,减缓果实硬度、总酚和可滴定酸含量的下降,抑制丙二醛的积累,并能降低多酚氧化酶(PPO)的活性,提高过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)的活性.综合考虑0.6μL/L处理效果比0.3μL/L和0.9μL/L的好.     

超声波结合1-MCP处理延缓苹果果实后熟与衰老

以未处理苹果(Malus domestica Borkh. cv. Fuji)果实为对照,探讨了超声波、1-甲基环丙烯(1-MCP)及其联合处理对苹果果实采后贮藏期间乙烯生成量、呼吸速率、硬度、可溶性固形物含量、过氧化物酶(POD)活性和超氧化物歧化酶(SOD)活性的影响。结果表明,与对照组相比,各处理组均能有效抑制苹果果实的乙烯生成量、呼吸速率和可溶性固形物含量,提高苹果果实的硬度、POD和SOD活性。其中,超声波和1-MCP联合处理对保持苹果贮藏品质的效果更显著,为超声波和1-MCP在果蔬采后贮藏保鲜的应用提供理论依据。     

酸性硫酸钙对红地球葡萄采后灰霉病的抑制

灰霉病是引起葡萄采后贮藏运输过程中的主要病害之一,为了探究酸性硫酸钙(ACS)对鲜食葡萄采后灰霉病的抑制及品质的影响。以红地球葡萄为试材,采用ACS(p H=5.45)喷洒处理20 s,在8±2℃条件下贮藏,分析ACS处理对果实灰霉病(Botrytis cinerea,B. cinerea)病斑面积、发病率和菌落直径的抑制效果;测定果实硬度、失重率、可溶性固形物、可滴定酸和电导率的变化,研究ACS处理对葡萄采后灰霉病抑制作用和品质参数的影响。结果表明,ACS处理能够显著抑制B. cinerea的生长,在贮藏期15 d时,病斑面积、发病率和菌落直径显著低于对照处理(p0.05),分别降低了67.02%、56.55%、98.16%,抑菌率达到96.06%。ACS处理能显著降低损伤接种灰霉病的病斑面积和发病率,在体外培养时对灰霉病发生也有显著的抑制作用。ACS处理能降低葡萄果实失重率,保持果实硬度,抑制果实可溶性固形物含量的下降,维持葡萄采后品质。ACS作为FDA和USDA认证的一种新型高效杀菌防腐剂,为鲜食葡萄采后保鲜技术的研究提供了新的方法。     

1- 甲基环丙烯及其结构类似物处理对寒富苹果贮藏品质的影响

研究1-甲基环丙烯(1-MCP)及其结构类似物1-戊基环丙烯(1-PentCP)和1-辛基环丙烯(1-OCP)在常温(20℃±1℃)条件下对寒富苹果果实生理及贮藏品质的影响。结果表明：与对照相比1-MCP及其结构类似物处理均不同程度抑制苹果贮藏期间的呼吸强度、乙烯释放量,保持苹果硬度,延缓酸度下降的速度,并且抑制果实软化相关酶纤维素酶和多聚半乳糖醛酸酶的活性。1-MCP及其结构类似物处理可延缓寒富苹果采后的成熟衰老保持较好的品质。1-MCP及其结构类似物处理间无明显的差异。     

1-MCP和乙烯利处理对采后‘金冠’苹果常温贮藏过程中生理变化及活性氧代谢的影响

以‘金冠’苹果为试材,研究1μL/L 1-甲基环丙烯(1-MCP)和0.2 mmol/L乙烯利处理对其采后常温贮藏过程中生理变化及活性氧相关代谢的影响。结果表明:与对照相比,1-MCP处理有效延缓果实软化、可滴定酸(TA)含量下降及可溶性固形物(TSS)含量上升,明显抑制叶绿素降解、呼吸强度及乙烯生成,提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的活性,减缓O-2·产生速率、H2O2及丙二醛(MDA)的积累;乙烯利处理主要在前期促进果实软化和TA含量下降,促进叶绿素降解及乙烯生成,使呼吸高峰提前,对上述活性氧相关代谢有相反效果,但对TSS无显著影响。结论:1-MCP处理保持了采后苹果果实的常温贮藏品质,而乙烯利处理则相反,苹果果实采后贮藏过程中活性氧的代谢与乙烯有关。     

1-MCP处理对杨桃果实采后生理和贮藏品质的影响

该文探讨1-甲基环丙烯(1-MCP)处理对"香蜜"甜杨桃果实采后生理和贮藏品质的影响。采后"香蜜"甜杨桃果实用0.6μL/L的1-MCP处理12 h后,在(15±1)℃、相对湿度90%下贮藏。贮藏期间测定果实呼吸强度、细胞膜相对渗透率、果皮叶绿素和类胡萝卜素含量、果实硬度、可溶性固形物和可滴定酸含量、果实好果率、失重率及感官品质等指标的变化。结果表明:与对照果实相比,1-MCP处理能有效降低杨桃果实的呼吸强度和呼吸峰值,抑制果实外观颜色转变,保持较高的果实硬度和可滴定酸含量,延缓果实细胞膜相对渗透率升高,减少果实失重和腐烂。经1-MCP处理的果实在(15±1)℃、相对湿度90%下贮藏20 d时的好果率为78%,而对照果实只有63%。因此认为,0.6μL/L 1-MCP处理可延缓采后‘香蜜’甜杨桃果实成熟衰老和保持果实贮藏品质。     

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.