1-MCP对火龙果低温贮藏期品质的影响

以白肉火龙果新品种晶红龙为试验材料,研究3种不同浓度的1-MCP处理对低温贮藏期火龙果品质的影响。结果表明,1-MCP熏蒸处理的整体效果优于对照,在贮藏前期(0～24 d)对抑制火龙果果实呼吸作用具有一定的作用;对照在贮藏18 d后出现腐烂,1-MCP处理贮藏期可延长3 d~6 d;1-MCP处理延缓了可滴定酸和VC含量的下降,抑制还原糖含量增加,显著延缓火龙果贮藏期的品质劣变。综合来看,以0.5μL/L和1.0μL/L 1-MCP处理对维持冷藏期间果实的保鲜效果最好。     

低温及1-MCP处理对天水‘花牛’苹果贮藏品质与生理变化的影响分析

以甘肃天水‘花牛’苹果为原料,通过测定其果实硬度、VC含量、有机酸质量分数、可溶固形物质量分数及腐烂率等指标,研究低温贮藏及1-甲基环丙烯（1-methylcyclopropene,1-MCP）处理对‘花牛’苹果果实品质与生理变化的影响。结果表明：低温处理的保鲜作用优于1-MCP处理;低温及1-MCP处理均能显著减缓果实硬度及VC含量下降,降低腐烂率,能较好地维持外观色泽与口感,并在一定程度上稳定了有机酸质量分数变化,但对可溶固形物质量分数的影响极小。     

壳聚糖结合1- 甲基环丙烯处理对李果实货架期品质的影响

为改善贮藏后李果实品质和开发综合贮藏保鲜技术,研究贮藏前壳聚糖涂膜处理及其结合贮藏后1- 甲基环丙烯(1-MCP)熏蒸处理对货架期“牛心”李果实品质的影响。结果表明：贮藏前采用10、15、20g/L 壳聚糖溶液涂膜处理及其结合贮藏后采用1.0μl/L 1-MCP 熏蒸可以有效保持低温贮藏(2℃、4 周)后货架期(23～25℃)李果实的硬度,延缓果实VC 含量的下降和果皮色泽的转红,抑制果实腐烂的发生。壳聚糖和1-MCP 的结合处理比两者各自的处理效果都好,能进一步显著地改善李果实在货架期的品质表现,为李果实综合贮藏保鲜技术开发提供依据。     

不同浓度的1-MCP处理对鄂北冬枣低温贮藏品质的影响

以鄂北冬枣为试验材料,研究0、500、1 000、1 500 n L/L浓度的1-MCP对鄂北冬枣贮藏过程中果实品质的影响。结果表明:1-MCP冷藏处理能够明显抑制果实的腐烂,延缓果实硬度,可溶性固形物含量、VC含量及可滴定酸含量降低,并能减缓果实水分散失。综合来看,以500 n L/L处理对维持冷藏期间果实的保鲜效果较好。     

室温下1-MCP缓释剂对早金酥梨贮藏品质的影响

以早金酥梨为试材,研究其分别经1、2、4包/10 kg的1-MCP处理后,放置在(23±1)℃室温下贮藏16 d的品质变化情况。结果表明,1-MCP处理较好地保持果实中总糖、可滴定酸和VC的含量,维持果实硬度,抑制果实的呼吸强度,降低了果实的腐烂率,提高了果实的品质,以2包/10 kg的1-MCP处理效果最好。     

海藻酸钠和溶菌酶复合涂膜对马陆葡萄贮藏的保鲜效果

以海藻酸钠和溶菌酶为保鲜剂对马陆葡萄进行复合涂膜保鲜,研究不同浓度的海藻酸钠溶液对马陆葡萄贮藏保鲜效果的影响,分析比较各处理组对葡萄果实的感官品质、腐烂指数、质量损失率、硬度、呼吸强度、VC含量、可溶性固形物含量以及超氧化物歧化酶(superoxide dismutase,SOD)酶活性等生理生化指标的变化。结果表明:1%海藻酸钠和0.1%溶菌酶处理后的马陆葡萄,感官效果最好,在(4±1)℃条件贮藏25d后,果实的腐烂指数为0.17,质量损失率仅为9.34%,VC含量为3.2mg/100g,可溶性固形物含量为12.1%,呼吸强度显著低于其他处理组,保鲜效果最佳。     

二氧化氯与1-甲基环丙烯联合处理对“萨米脱”樱桃低温贮藏效果的影响

目的 探究二氧化氯(ClO2)与1-甲基环丙烯(1-methylcyclopropene, 1-MCP) 复合处理对樱桃保鲜效果的影响, 提供更好的樱桃贮藏保鲜方法。方法 以萨米脱樱桃为材料, 在低温下(4 ℃)贮藏条件下, 采用 3 μL/L 1-MCP与100 μL/L ClO2联用对樱桃进行熏蒸处理, 测定相关指标, 包括腐烂率, 硬度、可滴定酸含 量(titritable acidity, TA)、可溶性固形物含量(total soluble solid, TSS)、VC含量、总酚含量及抗氧化能力。 结果 1-MCP、ClO2单独以及复合处理都对樱桃有不同程度的保鲜效果, 其中复合处理保鲜效果最佳。贮藏至25 d, 复合处理腐烂率分别比对照、1-MCP及ClO2处理组低7%、10%和30%, 可以减缓樱桃贮藏过程中TSS、TA、VC、总酚等物质含量的下降, 有效保持果实的外观品质。复合处理还原力及DPPH清除能力方面分别比对照组高出54%和43%, 提高果实的抗氧化能力。结论 1-MCP与ClO2复合处理能够有效地保持贮 藏期间樱桃品质, 保鲜效果优于单独处理, 有较大的应用前景。     

无硫复合护色剂联合1-MCP对大枣贮藏品质改善的研究

以大枣为原料,用无硫复合护色剂联合1-甲基环丙烯（1-methylcyclopropene,1-MCP）处理,研究其在0℃下对八成熟大枣的保鲜效果。结果表明,无硫复合护色剂和1-MCP处理均可有效保持冷藏枣品质,显著降低冷藏枣的腐烂率、呼吸速率,维持较高的果肉硬度、可滴定酸含量和抗氧化酶活力（p＜0.05）。无硫复合护色剂和1-MCP联合处理对冷藏枣的保鲜效果高于二者单一处理的效果,有较好的叠加效应。无硫复合护色剂联合1-MCP处理对降低冷藏枣腐烂率、延长枣的贮藏品质有着良好效果。     

微孔保鲜膜耦合1-MCP对‘贵长’猕猴桃保鲜效果研究

以‘贵长’猕猴桃为试材,研究微孔保鲜膜耦合不同剂量1-MCP处理对采后猕猴桃果实低温贮藏品质变化及感官的影响。结果表明,微孔保鲜膜耦合不同浓度的1-MCP低温贮藏处理,能有效地抑制猕猴桃果实采后呼吸强度增加,推迟呼吸跃变峰及乙烯跃变峰的出现,抑制果实硬度、VC含量下降,延缓可溶性固形物和还原糖含量的上升速度,有效减少膜脂过氧化物(MDA)的产生,显著抑制果实的腐烂,贮藏到180 d时,经1.0μL/L 1-MCP处理的果实仍然有91%好果率,并保持了较高的SOD、POD、CAT酶活性,从而达到延缓果实后熟衰老的目的。综合分析各项指标,微孔保鲜膜耦合1-MCP处理低温贮藏对修文‘贵长’猕猴桃有良好的贮藏保鲜效果;但4种处理浓度存在差异,从保鲜效果上看,以1.0μL/L 1-MCP处理效果最好;但通过果实的感官评价数据分析,1.0μL/L 1-MCP处理果实在货架期期间软化较慢,味道偏酸,口感下降,食用品质降低,而0.75μL/L 1-MCP处理果实软化程度与口感最佳。     

1-甲基环丙烯和二氧化氯复合处理对冬枣采后生理及贮藏品质的影响

为探讨冬枣绿色保鲜新技术,研究1-甲基环丙烯(1-methylcyclopropene,1-MCP)与二氧化氯(chlorine dioxide,ClO2)单独及复合处理[3μL/L 1-MCP与100μL/L ClO2熏蒸、4℃条件下贮藏]对冬枣采后生理和贮藏特性的影响,贮藏过程中每10 d测定转色、腐烂、硬度、含水量、可溶性固形物(total soluble solids,TSS)、可滴定酸(titratable acid,TA)、维生素C(vitamin C,VC)、总酚、还原力和DPPH自由基清除率的情况。研究结果表明:1-MCP或ClO2单独处理都能有效延缓果实转色,减少果实腐烂,保持果实较高的含水量、硬度、TSS含量、TA含量、VC含量、总酚含量、还原力和DPPH自由基清除率,提高采后冬枣果实的贮藏品质。与单独1-MCP及ClO2处理相比,1-MCP复合ClO2处理的保鲜效果更佳,可作为采后冬枣保鲜的有效手段。     

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.