壳聚糖涂膜常温保鲜草莓的试验研究

以壳聚糖涂膜对草莓进行常温保鲜试验,结果表明:以1.25%壳聚糖涂膜的草莓其VC、总酸、总糖、可溶性固形物含量最高,腐烂指数、呼吸强度、失重率最低,贮藏效果最好。     

羧甲基壳聚糖在草莓保鲜中的应用效果研究

羧甲基壳聚糖是壳聚糖的一种水溶性衍生物,具有良好的成膜性、抗菌性。以不同含量的水溶性羧甲基壳聚糖(CMCTS)溶液,对草莓进行涂膜保鲜处理,考察在低温贮藏条件下草莓果实的失重率、可溶性固形物、总酸和VC的变化。结果表明,1.5%CMCTS溶液在4℃、湿度70%~80%条件下可有效降低草莓果实的失重率,并能有效保持可溶性固形物、总酸和VC的含量,有效改善和提高草莓的贮藏保鲜品质,在一定程度上延长草莓的货架期,且各项保鲜指标优于壳聚糖保鲜。     

几种常用保鲜方法对草莓保鲜效果的研究

通过对6种(冷激、氯化钙、植酸、过氧乙酸、低温、壳聚糖涂膜)常用草莓保鲜方法的比较试验,分析各种保鲜方法对草莓贮藏期的失重率、腐烂率、VC含量、可溶性糖含量、可滴定酸含量及可溶性固形物含量的影响效应。研究结果表明,各处理均能明显减缓草莓果实的VC、可溶性糖、可滴定酸和可溶性固形物含量的下降,抑制草莓腐烂和失水,对草莓保鲜有一定的效果。其中冷激处理综合保鲜效果较优,且操作简单,成本较低,最适合普通农户贮藏保鲜草莓。     

存放方式对壳聚糖涂膜草莓保鲜效果的影响

[目的]研究提高壳聚糖保鲜草莓的效果。[方法]以新鲜草莓为材料,用不同浓度的壳聚糖溶液涂膜并进行密封与未密封处理。通过测定不同存放时间后草莓腐烂率、失重率、可溶性固形物含量、可滴定酸含量、VC含量的变化来探讨不同浓度壳聚糖涂膜后存放方式对草莓保鲜效果的影响。[结果]1.0%壳聚糖涂膜密封存放最有利于草莓保鲜,其抑制草莓腐烂率、失重率的下降,延缓了可溶性固形物含量、可滴定酸含量、VC含量下降的效果明显好于其他处理。[结论]壳聚糖涂膜后采用密封存放可提高对草莓的保鲜效果。      

存放方式对壳聚糖涂膜草莓保鲜效果的影响

[目的]研究提高壳聚糖保鲜草莓的效果。[方法]以新鲜草莓为材料,用不同浓度的壳聚糖溶液涂膜并进行密封与未密封处理。通过测定不同存放时间后草莓腐烂率、失重率、可溶性固形物含量、可滴定酸含量、VC含量的变化来探讨不同浓度壳聚糖涂膜后存放方式对草莓保鲜效果的影响。[结果]1.0%壳聚糖涂膜密封存放最有利于草莓保鲜,其抑制草莓腐烂率、失重率的下降,延缓了可溶性固形物含量、可滴定酸含量、VC含量下降的效果明显好于其他处理。[结论]壳聚糖涂膜后采用密封存放可提高对草莓的保鲜效果。     

壳聚糖处理番茄的保鲜效果研究

将变色期番茄果实浸入浓度为1．5％、2．0％、2．5％的壳聚糖溶液中30s,在常温下贮藏;35d,研究壳聚糖对番茄果实的保鲜效果。结果表明,壳聚糖溶液涂膜处理番茄果实,可延迟果实呼吸跃变,降低呼吸强度;缩小可溶性固形物含量变化幅度;延缓果实硬度、VC、总酸度下降速度;减小失重率,推迟果实腐烂时间,降低腐烂率,从而较好地保持番茄果实的贮藏品质。其中以浓度为2．0％的壳聚糖溶液涂膜保鲜效果最好。     

不同浓度壳聚糖处理对辣椒保鲜效果的影响

利用浓度为1.0%、1.5%、2.0%的壳聚糖溶液对辣椒果实进行涂膜处理,常温袋装贮藏,定期测定其理化指标,研究壳聚糖对辣椒果实的保鲜效果。结果表明,壳聚糖溶液涂膜处理能降低辣椒红果率、失重率、腐烂指数,减少可溶性固形物、VC的损失,能够保持辣椒果实贮藏品质,其中浓度为1.5%的壳聚糖溶液涂膜处理效果较好。     

壳聚糖复合涂膜常温保鲜草莓的研究

采用菌丝生长速率法筛选出对草莓采后主要病原菌抑制效果最佳的中草药复合物,并将其与涂膜剂壳聚糖、助剂抗坏血酸(VC)、抗氧化剂植酸复配成复合保鲜剂,通过正交实验确定了各组分的最佳浓度配比:复合中草药提取物0.3%(丁香、蛇床子、补骨脂的质量比为1:1:1)、壳聚糖1.25%、VC1.25%、植酸0.05%。草莓经此复合保鲜液处理后,显著降低了常温贮藏期间的失重率、腐烂率,延缓了可溶性固形物、VC和可滴定酸含量的下降,且各项保鲜指标均优于1.25%壳聚糖的单独涂膜处理。     

壳聚糖涂膜保鲜金柑的研究

用不同浓度的壳聚糖作为涂膜剂对金柑进行涂膜处理,在室温条件下贮藏保鲜.测定了果实失重率、Vc、可溶性固形物、可滴定酸、总糖、呼吸强度和过氧化氢酶活性等指标的变化,并与未经涂膜的进行对比,以试验比较壳聚糖涂膜保鲜对延长金柑货架期的可行性及其效果.并根据不同浓度的涂膜效果,来确定最佳的壳聚糖涂膜浓度.实验结果表明:壳聚糖涂膜保鲜效果明显优于未经涂膜的对照组,其中以浓度为0.8%壳聚糖保鲜效果最佳.     

壳聚糖复合涂膜常温保鲜草莓的研究

采用菌丝生长速率法筛选出对草莓采后主要病原菌抑制效果最佳的中草药复合物,并将其与涂膜剂壳聚糖、助剂抗坏血酸(VC)、抗氧化剂植酸复配成复合保鲜剂,通过正交实验确定了各组分的最佳浓度配比:复合中草药提取物0.3%(丁香、蛇床子、补骨脂的质量比为1:1:1)、壳聚糖1.25%、VC1.25%、植酸0.05%。草莓经此复合保鲜液处理后,显著降低了常温贮藏期间的失重率、腐烂率,延缓了可溶性固形物、VC和可滴定酸含量的下降,且各项保鲜指标均优于1.25%壳聚糖的单独涂膜处理。      

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