一种抗猪链球菌细菌素的生物学特性研究

为了开发新型天然抗菌物质,本研究以猪粪便中分离出的一株产抗猪链球菌细菌素产生菌屎肠球菌LPL420P06为试材,对其产生的细菌素进行了理化特性研究。结果表明,该细菌素具有良好的热稳定性,在90℃、30min热处理的条件下仍能保持90%以上的活性;易被胰蛋白酶、蛋白酶K、木瓜蛋白酶、中性蛋白酶失活,表明该细菌素是一类蛋白类物质;在pH5～9范围内37℃、4h处理,活性保持稳定;抑菌谱实验结果表明,该细菌素不仅对单增李斯特氏菌、金黄色葡萄球菌、猪链球菌等多种革兰氏阳性病原菌有明显的抑制作用,而且对沙门氏菌、大肠杆菌等部分革兰氏阴性菌有不同程度的抑制作用,显示出该细菌素具有很好的开发应用前景。     

西藏干酪源植物乳杆菌产细菌素的分离纯化及特性研究

从西藏干酪中分离筛选出1株能够产生抑菌活性物质的乳酸菌,该菌的发酵上清液在排除有机酸、过氧化氢的影响后仍有显著抑菌活性,然而,用胃蛋白酶、蛋白酶K和胰蛋白酶处理后抑菌活性丧失,说明该菌的代谢产物中起抑菌作用的物质具有蛋白质性质,初步确定是一种细菌素。结合形态学观察、生理生化分析及16S rDNA鉴定结果,确定该菌为植物乳杆菌,命名为ZFM804。细菌素经大孔树脂(XAD-16)层析、强阳离子交换层析、RP-HPLC三步法初步纯化。经SDS-PAGE分析该细菌素分子质量约为15 ku。理化性质分析表明该细菌素具有良好的酸碱稳定性:在pH 3~11范围内都具有抑菌活性;良好的热稳定性:100 ℃处理30 min仍有明显抑菌活性,同时可被人体内蛋白酶降解。抑菌谱测定结果表明,ZFM804植物乳杆菌素对革兰氏阳性菌和革兰氏阴性菌都有抑制作用,是一种广谱细菌素。     

唾液乳杆菌LH1F所产细菌素的纯化及其生物学特性研究

本文对唾液乳杆菌(Lactobacillus Salivarius)LH1F发酵液中的抑菌物质的特性进行了研究,在排除菌体细胞、有机酸、过氧化氢干扰及经胰蛋白酶、胃蛋白酶处理后,确定抑菌成分为肽类细菌素,然后经过60%硫酸按盐析及超滤初步纯化后,对其生物学特性进行了研究。结果表明,唾液乳杆菌LH1F所产的细菌素具有良好的热稳定性,121℃处理30 min仍保留75.5%的抑菌活性;在p H2.0~p H5.0条件下稳定;对胃蛋白酶、胰蛋白酶和蛋白酶K敏感;该细菌素具有较广的抑菌谱,对供试的多种革兰氏阳性菌(G+)及革兰氏阴性菌(G-)具有明显的抑制作用,为作为天然食品防腐剂的进一步研究奠定基础。     

戊糖乳杆菌素pentocin LPEM818的初步纯化及特性研究

对戊糖乳杆菌(Lactobacillus pentosus)LPEM818所产戊糖乳杆菌素(pentocin)LPEM818进行了初步纯化,并对其生物学特性进行了研究。结果表明,采用80%硫酸铵沉淀和Sephadex G-25凝胶层析分离纯化后,细菌素的纯化倍数为11.09倍,回收率为6.4%;该细菌素在pH 2.0～8.0条件下稳定,121℃加热15 min保留84.52%的抑菌活性;对胰蛋白酶和蛋白酶K敏感;该细菌素的作用方式为杀菌;对供试的部分革兰氏阳性菌(G+)和革兰氏阴性菌(G-)具有较强抑制作用,因其抑菌谱较广,对多数致病菌和食品腐败菌有较好抑菌作用,所以具有作为食品生物防腐剂的潜在应用价值。     

1株乳酸菌所产类细菌素Lactobacillin SD-22的初步研究

自泡菜中分离的329株乳酸菌中筛选出1株具有较广抑菌活性的菌株SD-22,经鉴定为短乳杆菌(Lac- tobacillus brevis)。在排除酸性产物和过氧化氢的干扰后,SD-22菌株发酵液对金黄色葡萄球菌(Staphyloccocus aureus),枯草芽孢杆菌(Bacillus subtilis),蜡状芽孢杆菌(Bacillus cereus)等革兰氏阳性菌和大肠杆菌(Esche- richia coli),鼠伤寒沙门氏菌(Salmonella typhimuniuns)等革兰氏阴性菌具有较好的抑制作用,而且对部分真菌也有抑制作用;经胰蛋白酶、胃蛋白酶和蛋白酶K处理后发酵液抑菌活性略有下降,表明该活性物质为非蛋白成分或起抑菌作用的非单一物质。该活性物质不同于一般细菌素,属于类细菌素,命名为LactobacillinSD-22。它具有很好的热稳定性,在酸性条件下稳定且活性高,对蛋白酶敏感性低,且具有较广的抗菌谱。     

产细菌素乳酸菌的鉴定及其特性研究

从婴儿粪便中分离获得能够产生抑菌活性物质的乳酸菌,通过排除有机酸、过氧化氢的干扰试验,该菌发酵上清液仍有明显的抑菌活性;通过蛋白酶K和胰蛋白酶试验,证明该菌株产生的抑菌活性物质具有蛋白质性质,是一种细菌素.初步提纯该细菌素,其抑菌活性较适pH范围为2～4,120℃热处理30 min后仍有70%的抑菌活性.经Trcine-SDS-PAGE试验分析该细菌素分子质量为4kDa.抑菌谱测定结果表明,该细菌素不仅对革兰氏阳性菌(单增李斯特氏菌、枯草芽孢杆菌、金黄色葡萄球菌等)有抑制作用,而且还抑制革兰氏阴性菌(大肠杆菌、沙门氏菌、恶臭假单胞菌、福氏志贺氏菌等),具有广谱的抑菌作用.通过菌落形态、生理生化特性试验和16S rRNA基因序列分析,鉴定该乳酸菌为植物乳杆菌,命名为Lactobacillus plantarum ZJ317.     

戊糖乳杆菌素C50-6的纯化及特性研究

对分离自四川传统肉制品的戊糖乳杆菌C50-6产生的戊糖乳杆菌素进行了纯化,研究其理化性质和生物学活性,结果表明:发酵液经(NH4)2SO4盐析和Toyopearl SP-650M阳离子交换层析纯化后,细菌素的回收率为21.76%,纯化倍数为39.15倍;经Tricine-SDS-PAGE和电泳条带抑菌试验测得该乳杆菌素分子质量约2 500u;该细菌素对酸和热稳定,对木瓜蛋白酶、胰蛋白酶和蛋白酶K敏感;对供试的革兰氏阳性菌、革兰氏阴性菌和少数真菌具有较强抑制作用,对多数乳酸菌无抑制作用。     

泡菜中产细菌素菌株的分离及细菌素性质的初步研究

从四川泡菜中分离得到一株产细菌素的菌株,经形态学、生理生化鉴定等试验,初步鉴定此菌株为乳酸菌。对其所产细菌素做温度、pH、蛋白酶的敏感性试验,实验结果表明,发酵上清液中的抑菌物质对胃蛋白酶、木瓜蛋白酶较敏感,菌株所产细菌素在高温(121℃20min)和酸性条件(pH 3.0～5.0)下均有较强的抑菌活性,可以较好地抑制革兰氏阳性、阴性菌,筛选得到的菌株所产细菌素是一类具有广谱抑菌活性的细菌素。     

一株乳酸乳球菌所产细菌素的生物学特性

对乳酸乳球菌KLDS4.0326所产类细菌素进行分离纯化,并对细菌素的部分生物学特性进行研究。在排除酸性产物和过氧化氢的干扰后,菌株的无细胞发酵上清液对金黄色葡萄球菌和枯草芽孢杆菌等革兰氏阳性细菌以及大肠杆菌、沙门氏菌等革兰氏阴性细菌具有显著的抑制作用;经胰蛋白酶、胃蛋白酶、木瓜蛋白酶和蛋白酶K处理后,抑菌活性降低,表明抑菌成分为蛋白类物质;该细菌素具有良好的热稳定性,在酸性条件下抑菌活性稳定,并且具有较广的抑菌谱,能够抑制多种革兰氏阳性细菌和革兰氏阴性细菌。     

一株产广谱细菌素乳酸菌的筛选与鉴定

为获得产广谱细菌素的乳酸菌,采用经典的乳酸菌筛选法及16S rRNA基因序列测定法,从传统酸白菜中分离乳酸菌并进行菌种鉴定,从蛋白酶稳定性、热稳定性、pH值稳定性和抑菌谱4个方面分析抑菌物质的生物学特性。结果表明,从传统酸白菜中分离出1株产抑菌活性物质的乳酸菌SY5,经鉴定为戊糖乳杆菌(Lactobacillus pentosus)。将发酵上清用蛋白酶K和胃蛋白酶处理后抑菌活性丧失,表明抑菌活性物质具有蛋白质性质,确定为细菌素。生物学特性分析表明,该细菌素在120℃热处理30 min后仍保留82.7%的抑菌活性,pH值范围为2～7。抑菌谱测定结果表明,该细菌素对多种革兰氏阳性菌和革兰氏阴性菌均有较好的抑制效果,具有广谱抑菌活性。     

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