储藏微环境条件下小麦细胞超微结构变化及衰老机制研究

采用人工模拟储藏小麦,通过测定小麦胚细胞中的O_2~-、有毒产物MDA的含量、种子活力以及利用透射电镜观察,研究不同储藏微环境(A、B、C、D)下小麦衰老和胚细胞超微结构的变化规律。结果表明:随储藏时间延长和环境温湿度的增加,胚细胞中O_2~-和MDA含量不断增大,种子活力下降,储藏90 d后O_2~-和MDA产生速率都显著高于前期(P0.05),并且高温高湿D(35℃,85%)条件下三者变化幅度都显著高于低温低湿A(15℃,50%)条件(P0.05)。电镜观察发现:随储藏温湿度的增高,小麦胚细胞的超微结构损伤也在加剧,主要表现为:细胞形态改变;膜的完整性逐渐丧失;细胞核染色质凝聚,核仁分裂;线粒体数目减少,内外膜破损,出现空泡化等。以此探讨小麦衰老与胚细胞超微结构损伤之间的关系,以期丰富储藏小麦的衰老机制研究。     

不同溶质型桃果实采后贮藏过程中线粒体内COX活性及其基因的表达

以软溶质型桃‘雨花三号’(Prumus persica(L.)Batsch,cv.Yuhua3)和硬溶质型桃‘加纳岩’(Prumus persica(L.)Batsch,cv.Jianayan)果实为试材,研究不同溶质型桃果实采后贮藏过程中呼吸速率、乙烯释放量、细胞色素氧化酶(cytochrome c oxidase,COX)活性以及线粒体编码的COX 3种亚基(COXⅠ、COXⅡ、COXⅢ)基因表达量的变化。结果表明:‘雨花三号’桃果实贮藏过程中,硬度不断下降,且在贮藏后期伴随着呼吸高峰和乙烯释放高峰的出现;而‘加纳岩’在贮藏过程中,硬度下降较缓慢,乙烯释放量较少,呼吸速率较平稳。两种溶质型桃果实在贮藏前期,COX活性不断增加,但到贮藏后期,COX活性下降。‘雨花三号’桃果实中COX活性三种亚基基因的表达量显著低于‘加纳岩’。COX主要作用于桃果实贮藏前期,为果实后熟提供足够能量,贮藏后期表达量降低,活性受影响,机体代谢失衡,线粒体编码的COX与桃果实采后衰老之间存在一定的内在联系。     

解偶联剂DNP处理对采后龙眼果实呼吸作用和细胞膜透性的影响

研究呼吸解偶联剂2,4-二硝基苯酚(DNP)对采后龙眼果实呼吸作用和细胞膜透性的影响。龙眼果实分别用蒸馏水(对照组)和0.1 mmol/L DNP各浸泡0.5 h,晾干后用聚乙烯薄膜袋(0.015 mm厚)包装,在(28±1)℃下贮藏。定期测定贮藏期间果实呼吸速率、细胞膜透性、三磷酸腺苷(ATP)含量、呼吸末端氧化酶[细胞色素C氧化酶(COX)、多酚氧化酶(PPO)和抗坏血酸氧化酶(AAO)]活性的变化。结果表明:DNP处理导致龙眼果实果皮ATP含量快速下降,呼吸速率和COX、PPO活性快速上升,细胞膜透性增大。结论:DNP处理使细胞内能量亏缺,诱导呼吸速率的上升,提高了呼吸末端氧化酶COX、PPO活性,使龙眼果皮电子传递泄露增加,破坏了细胞膜结构完整性,从而促进细胞膜透性增大。     

储藏微环境对小麦蛋白质二级结构影响

该研究采用傅里叶变换红外光谱(FTIR)技术测定不同温湿度微环境下储藏60 d和120 d的小麦蛋白质二级结构,并运用peakfit v4.12软件分析其变化规律。结果表明:原始小麦样品其蛋白质二级结构以β–折叠和无规则卷曲为主。在四种储藏微环境条件下,随储藏时间延长,小麦蛋白质二级结构总体均呈现α–螺旋结构明显减少、β–转角转换为β–折叠和无规则卷曲的趋势,其中α–螺旋也可能参与三者转化。说明在储藏期间小麦蛋白质螺旋结构被破坏;蛋白质二级结构由反转转化为折叠,蛋白质结构趋向稳定。对比四种储藏微环境,时间相同时,储藏于15℃,50%RH下的小麦蛋白质α–螺旋结构减少最小,有利于小麦品质保持。     

不同溶质型桃果实成熟衰老过程中线粒体内细胞色素氧化酶的变化

以软溶质型桃‘雨花3号’和硬溶质型桃‘加纳岩’果实为试材,研究不同溶质型桃成熟衰老过程中细胞色素氧化酶（cytochrome c oxidase,COX）活性以及线粒体编码的COX 3 种亚基（COXⅠ、COXⅡ、COXⅢ）基因表达量的变化。结果表明：桃果实成熟前期,COX活性不断增加,成熟后期,COX活性开始下降。‘加纳岩’COX 3 种亚基基因的表达量高于‘雨花3号’,且COX 3 种亚基在桃果实成熟前期表达量较高。说明线粒体DNA编码的COX 3 种亚基主要作用于桃果实成熟前期,为果实生长代谢提供所需能量,到了后期表达量降低,活性受影响,导致果实线粒体内的活性氧积累,机体代谢失衡,呼吸速率增加,线粒体编码的COX 3 种亚基与桃果实成熟衰老之间存在一定的内在联系。     

储藏微环境对小麦蛋白质二级结构影响

该研究采用傅里叶变换红外光谱(FTIR)技术测定不同温湿度微环境下储藏60 d和120 d的小麦蛋白质二级结构,并运用peakfit v4.12软件分析其变化规律。结果表明:原始小麦样品其蛋白质二级结构以β–折叠和无规则卷曲为主。在四种储藏微环境条件下,随储藏时间延长,小麦蛋白质二级结构总体均呈现α–螺旋结构明显减少、β–转角转换为β–折叠和无规则卷曲的趋势,其中α–螺旋也可能参与三者转化。说明在储藏期间小麦蛋白质螺旋结构被破坏;蛋白质二级结构由反转转化为折叠,蛋白质结构趋向稳定。对比四种储藏微环境,时间相同时,储藏于15℃,50%RH下的小麦蛋白质α–螺旋结构减少最小,有利于小麦品质保持。     

储藏微环境对小麦中蛋白质含量变化规律的影响

将小麦储藏在模拟四个小麦主产区-蒙新、华北、华中和华南等的储粮微环境条件(15℃,50%RH;20℃,65%RH;28℃,75%RH和35℃,85%RH)下,研究小麦蛋白质组分及巯基和二硫键含量的变化规律。结果表明:储藏时间对各微环境储藏小麦总蛋白质含量的影响不显著(P0.05);至储藏末期(240 d)时,三种储藏条件(20℃,65%RH;28℃,75%RH和35℃,85%RH)下小麦醇溶蛋白和巯基含量比低温低湿组(15℃,50%RH),分别减少2×10-4、1×10-4、1.2×10-3 g/g和0.13、0.55、0.75?mol/g,谷蛋白和二硫键含量分别增加5×10-4、1.3×10-3、2.4×10-3 g/g和0.22、0.27、0.42?mol/g;高温高湿(35℃,85%RH)条件下,小麦醇溶蛋白、谷蛋白、巯基和二硫键含量变化显著(P0.05),且谷蛋白/醇溶蛋白的比例升高,更易于诱导游离巯基氧化为二硫键。显然,低温低湿储粮条件,更有利于保持小麦蛋白质组分的稳定而实现小麦安全储藏。     

临界安全水分下小麦储藏过程中抗霉变特性的比较

将3种角质化率有显著差异的小麦品种增水调节至临界安全水分附近进行模拟储藏试验,结果表明,这几种小麦在水分13.5%、30℃条件下储藏28 d后,小麦籽粒上霉菌含量的增速存在较大差异,冀麦38和矮抗58的带菌量增加速率均非常显著地高于温麦6(p<0.01)。进一步的研究证明,温麦6对灰绿曲霉(Aspergillus glaucus)的生长有明显的抑制作用,在30℃、25℃、20℃和15℃的各种温度和相应的临界水分下进行储藏试验,温麦6中的灰绿曲霉生长迟后时间均达到或超过7 d;将干燥小麦置于RH 85%高湿环境下进行吸湿模拟储藏,温麦6中的灰绿曲霉生长迟后时间达14 d。因而,质地偏软的温麦6在相同的储藏条件下具有更强的抗霉变特性。     

黑果枸杞功能性成分抗氧化活性及对线粒体的保护作用研究

目的:研究黑果枸杞功能性成分(多糖、黄酮和多酚)的抗氧化活性及对线粒体的保护作用。方法:对黑果枸杞多糖、黄酮和多酚功能性成分分别进行提取,测定这三种成分对二苯代苦味酰基(DPPH)、羟自由基(·OH)以及超氧阴离子自由基(O2-·)的清除能力,以及对小鼠肝脏线粒体肿胀度和丙二醛(MDA)含量,评价黑果枸杞功能性成分抗氧化活性及对线粒体的保护作用。结果:黑果枸杞中多糖、黄酮和多酚类物质的含量分别为30.6、21.3、和49.5mg/g(以干基计,md)。黑果枸杞黄酮和多酚清除DPPH自由基、·OH和O2-·的能力强于多糖。黑果枸杞多糖,黄酮及多酚提取物对DPPH自由基的清除率分别为52.5%,72.4%,82.3%;对·OH的清除率分别为48.2%,56.6%,75.8%;对O2-·的清除率分别16.1%,40.7%,53.3%。黑果枸杞黄酮(p0.01)和多酚(p0.01)能显著抑制Fe SO4-VC引起的线粒体肿胀,黑果枸杞黄酮和多酚能显著降低线粒体MDA的含量(p0.05)。结论:黑果枸杞多糖、黄酮和多酚具有抗氧化活性,黄酮和多酚对线粒体的保护作用强于多糖。     

混合药剂对受O3伤害烟草的保护作用及生理响应

在控制条件下,喷施甲基托布津和芸苔素内酯处理后,在低温加O3胁迫下诱发烟草气候斑,调查气候斑发生情况,同时测定叶片中叶绿素含量、相对电导率、过氧化物酶(POD)活性、过氧化氧酶(CAT)活性、超氧化物歧化酶(SOD)活性、抗坏血酸过氧化物酶(APX)活性等生理指标.结果表明:喷施甲基托布津和芸苔素内酯混配药剂后,病情指数仅为清水对照的37.78%;在低温加O3胁迫下,经该混配药剂处理能维持叶片相对电导率,与25℃生长条件下没有显著差异(P>0.05),而超氰化物歧化酶(SOD)、抗坏血酸氧化酶(APX)活性均升高,比清水对照分别高232.8%、51.1%,过氧化氢酶(CAT)、过氧化物酶(POD)活性比25℃生长条件下略有下降,但比清水对照高,且有显著差异(P<0.05).     

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