二氧化氯采前处理对红富士苹果的保鲜

研究采前使用二氧化氯(ClO2)处理在红富士苹果冷藏条件下的防腐保鲜效果,探讨ClO2对红富士苹果的防腐保鲜效果机理。分别用质量浓度0、20、50、80mg/L ClO2溶液采前处理“红富士”苹果,定期测定果实采后生理指标,并在贮藏末期观察统计其腐烂指数。适宜质量浓度的ClO2采前处理对果实表面的菌落清除效果较好,可有效抑制冷藏期间果实硬度和可滴定酸含量的下降,降低苹果呼吸速率、乙烯释放速率和腐烂指数,无明显抑制果实质量减少的作用,提高了过氧化物酶(peroxidase,POD)和苯丙氨酸解氨酶(phenylalanine ammonialyase,PAL)的活性。通过不同质量浓度处理效果的比较,确定适宜的ClO2处理质量浓度为50mg/L,此处理条件对红富士苹果具有明显的防腐保鲜效果,可有效延长贮藏期。     

采前喷施二氧化氯处理对蓝莓保鲜效果的影响

为了解采前喷施ClO2采后自发气调包装近冰温贮藏下蓝莓果实生理生化的影响及贮藏保鲜机理,分别采用0、20、40、60 mg/L ClO2对蓝莓果实进行采前喷施,采后分装于带孔聚乙烯塑料盒内,再用PE保鲜膜封装,贮藏在-1±0.1℃。贮藏期间,分别测定蓝莓果实表面菌落数、风味指数、腐烂率、失重率、可溶性固形物、软果率、呼吸速率、可滴定酸、花色苷、多酚、pH等理化特性和与组织损伤和自由基清除相关的多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)等酶的活性。研究显示:适宜浓度ClO2采前喷施可有效清除果实表面微生物,显著降低可溶性固形物含量、失重率和腐烂率增加、抑制果实软化、降低呼吸速率,提高果实中POD和PAL酶活性,并维持PPO酶在较低水平。不同浓度对比分析发现,"粉蓝"蓝莓果实采前喷施40 mg/L ClO2,能显著增加保鲜效果,从而有效延长贮藏期。     

适宜后熟对猕猴桃果实冷藏后货架品质的影响

该文以‘贵长’猕猴桃为试材,研究适宜后熟对其冷藏后货架品质的影响。结果表明,猕猴桃果实采收后于阴凉处散去田间热,然后转入(4±0.5)℃贮藏,冷藏后货架成熟时果实呼吸速率、乙烯释放速率显著增加,抗氧化物质含量低,超氧阴离子(O-2)和H 2O 2快速积累,活性氧代谢失衡,从而导致其在冷藏40 d后货架时全部腐烂。猕猴桃果实后熟至可溶性固形物9.5%时再转入(4±0.5)℃贮藏,可有效抑制其冷藏后货架时呼吸速率和乙烯释放速率,减少果实营养物质损耗,维持果实抗氧化物含量和活性氧代谢平衡,进而降低果实的腐烂率,延长冷藏期。然而,猕猴桃果实后熟至可溶性固形物含量14.5%再冷藏则加速猕猴桃果实腐烂。因此,适宜后熟通过抑制乙烯释放速率、提高抗氧化物酶活性、维持活性氧代谢平衡来维持其冷藏后货架品质,为猕猴桃贮藏保鲜技术开发奠定了理论基础。     

电子束辐照对猕猴桃品质及抗性系统的影响

以‘海沃德’猕猴桃为试材，人工接种灰葡萄孢菌（Botrytis cinerea）后采用高能电子束辐照处理，于0～1 ℃、相对湿度90%～95%条件下贮藏，每15 d取一次样，测定电子束辐照处理后果实冷藏期理化指标及抗性酶活力等指标，探究电子束辐照对猕猴桃贮藏品质的影响及对灰霉病的抑制效果，为电子束辐照猕猴桃防腐保鲜技术提供理论依据。结果表明，与对照组相比，电子束辐照处理能有效降低质量损失率，保持果实的可溶性固形物质量分数，抑制可滴定酸质量分数的下降，0.4 kGy辐照组类黄酮含量最高峰峰值升高25.52%；与对照组相比，电子束辐照组过氧化物酶、苯丙氨酸解氨酶和β-1,3-葡聚糖酶活力最高峰峰值升高，且0.8、1.2 kGy辐照组β-1,3-葡聚糖酶活力峰值首次出现的时间提前30 d，丙二醛含量提高，表明电子束辐照会引起轻微的果肉细胞膜脂质过氧化，其中以0.4 kGy辐照的果实品质变化小，诱导的果实抗性较强，说明适宜剂量的电子束辐照可以作为提升猕猴桃保鲜效果和抑制腐烂损耗的有效手段。     

1-MCP结合ClO_2固体缓释剂处理对番茄贮藏的保鲜效果

以绿熟番茄果实为试材,研究了室温[(20²5)℃]和低温[(10±1)℃]贮藏条件下,1-MCP、ClO2和1-MCP+ClO2处理对果实的保鲜效果。结果表明:2种贮藏条件下,3种处理均能延缓番茄果实转色,降低番茄腐烂,抑制呼吸强度,推迟呼吸跃变的到来,延缓番茄果实硬度的下降;在一定程度上抑制了多聚半乳精醛酸酶(PG)的活性,减缓原果胶向可溶性果胶的转变。从整体情况看,1-MCP+ClO2处理组的保鲜效果优于1-MCP和ClO2单独处理组;且低温加1-MCP+ClO2处理对番茄的贮藏保鲜效果最好,贮藏45 d时其腐烂率比对照组低54%、果实硬度仅下降了0.22 kg/cm2、可溶性固形物含量和原果胶含量分别比对照组高0.35%、0.2 g/100 g。     

采后O_3处理对使用CPPU猕猴桃贮藏品质及其抗性酶活性的影响

为探究臭氧(ozone,O_3)对膨大剂(N-2-氯-4-吡啶基苯-N’-苯基脲,CPPU)处理秦美猕猴桃果实贮藏期间其品质劣变的抑制效果,本文以生长期使用了20 mg/L CPPU的秦美猕猴桃果实为试验材料,在0±1℃条件下贮藏。研究了10、40和70 mg/m~3 O_3处理对贮藏期间秦美猕猴桃果实的品质指标、乙烯释放量、呼吸强度以及抗性酶活性的影响。试验结果表明40 mg/m~3 O_3可以减缓CPPU处理的秦美猕猴桃品质的下降趋势,减轻了可滴定酸、Vc含量的下降,保持了较好的硬度,减缓了可溶性固形物含量的上升;抑制了乙烯释放量和呼吸强度,减少果实软化;并增加了苯丙氨酸解氨酶(Phenylalanine ammonia lyase,PAL)、β-1,3-葡聚糖酶(β-1,3-glucanase,GLU)、几丁质酶(Chitinase,CHI)的活性,从而减少了秦美猕猴桃果实的腐烂率。O_3处理能有效减轻CPPU处理对秦美猕猴桃果实产生的负面影响并延长贮藏时间。     

三氧化氯对"秦美"猕猴桃保鲜及贮藏品质的影响

以"秦美"猕猴桃为材料,研究了二氧化氯对其保鲜及贮藏品质的影响.将猕猴桃分别浸入0、20、40、80、100mg/L的二氧化氯溶液中10min,沥干后贮存于温度为1～2℃,相对湿度为90%～95%的机械冷库中,以后每月取样,对其硬度、可溶性固形物、呼吸速率、乙烯释放速率、可溶性糖、可滴定酸、Vc含量等指标进行测定.结果表明,适宜浓度的二氧化氯处理可延缓猕猴桃果实硬度的下降,抑制乙烯的释放速率,并保持了可溶性糖、可滴定酸和Vc的含量,同时也对猕猴桃果实贮藏后期的腐烂有明显的抑制作用,延缓了果实的衰老,从而延长了其货架期.综合考虑,认为80mg/L的二氧化氯处理10min对"秦美"猕猴桃的保鲜效果最为理想.     

CPPU、1-MCP处理对猕猴桃贮藏品质的影响

以陕西"秦美"猕猴桃为试材,在(0±0.5)℃贮藏条件下,研究对照果、N-2-氯-4-吡啶基苯-N'-苯基脲(CPPU)处理果、1-甲基环丙烯(1-MCP)处理果、CPPU+1-MCP处理果的呼吸强度、乙烯释放量、硬度、感官等指标的变化。结果表明:5 mg/L CPPU处理能有效促进猕猴桃果实乙烯的释放、硬度的下降和有机酸的分解,增加果实的软化率和烂果率,长时间贮藏降低果实的感官品质,因此5 mg/L CPPU不宜用于秦美猕猴桃的贮藏。1.0μL/L 1-MCP处理能延缓冷藏期果实呼吸高峰的出现,抑制乙烯的释放和可滴定酸的下降,显著抑制果实硬度降低,减少果实的腐烂率和软化率,但会使其口味变酸,影响其食用价值。CPPU或1-MCP处理均对SSC没有影响。CPPU+1-MCP处理能延缓呼吸高峰的出现,抑制乙烯的释放以及硬度和可滴定酸的降低,能降低CPPU处理果的腐烂率,因此实际生产中可用于CPPU处理果的保鲜,但其会降低果实的感官品质。总之,1-MCP处理果的保鲜效果最好,同时1-MCP处理会抵消CPPU处理的负效应,延长CPPU处理果的贮藏期,从而为猕猴桃贮藏的保鲜技术提供理论基础。     

1-MCP结合ClO2处理对冰温贮藏红提葡萄生理品质的影响

以红提葡萄为试材,通过对不同处理方式果实在贮藏期间品质和生理生化指标的变化规律分析,探讨冰温贮藏条件下,1-MCP和ClO2处理对果实的保鲜效果。结果表明:1-MCP+ClO2处理结合了1-MCP、ClO2处理的优点,减轻了葡萄贮藏过程中因腐烂造成的损失,对果实可滴定酸(TA)、可溶性固形物(TSS)和VC含量的保留有积极作用,良好的保持了葡萄的品质和营养成分;抑制了葡萄呼吸和乙烯生成速率,减缓了细胞膜透性和丙二醛(MDA)含量的增长速度,增强过氧化物酶(POD)和超氧化物歧化酶(SOD)的活性,有效延缓了葡萄在贮藏过程中的衰老进程。     

1- 甲基环丙烯复合焦亚硫酸钠处理对厚皮甜瓜的保鲜效果

以陕西省阎良区厚皮甜瓜为试材,采用1-甲基环丙烯(1-MCP)、焦亚硫酸钠(Na2S2O5)以及二者结合的处理方法,研究厚皮甜瓜采后生理变化及贮藏品质。结果表明：1-MCP结合Na2S2O5处理能明显延缓厚皮甜瓜硬度下降,抑制可溶性固形物含量快速上升,有效少果实腐烂,同时抑制苯丙氨酸解氨酶和过氧化物酶的活性,使过氧化氢酶和超氧化物岐化酶活性处于较高水平。在这种处理方式下,贮藏80d后,果实腐烂指数0.37、商品果率80%。1-MCP结合Na2S2O5复合处理对厚皮甜瓜具有很好的保鲜效果。     

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.     

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.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the