原料乳生产中生物性风险来源分析与追溯

通过一年四季对哈尔滨市内原料奶产地的水、土壤、牛粪便、牛体涂抹等进行大量采样分析和调查,针对采集样品中11种病原菌进行的生化鉴定分析结果表明,该地区原料奶中的特征病原菌为金黄色葡萄球菌.井主要对原料乳中和其他来源样品的金黄色葡萄球菌进行了基因比对分析,确定了原料奶中该菌的主要来源,提出了相应有效的减少其污染的方法.     

原料乳及牧场环境中的微生物多样性及嗜冷菌污染源分析

原料乳中嗜冷菌超标会产生较高水平的耐热蛋白酶和脂肪酶,这两种酶是导致产品进入货架期后出现质量问题的重要原因。为探究牧场奶牛生活环境以及原料乳在流转过程中不同环节的微生物多样性,找出牧场中嗜冷菌的污染来源,本研究选取河北地区某规模化奶牛养殖场,采集TMR饲料、牛舍垫土、头三把奶、头三把奶之后的常规乳以及储奶罐中的原料乳等样品,利用宏基因组测序技术对所有样品的菌群结构、嗜冷菌种类及丰度进行分析。结果表明:在门水平上,主要微生物为变形菌门、厚壁菌门、放线菌门,在属水平上主要是无形体属、链球菌属、肠球菌属、短螺菌属、芽孢杆菌属、假单胞菌。此外对样品中的关键嗜冷菌(假单胞菌)进行分析,牛舍垫土的多样性最丰富的,包含了牧场中常规乳及储奶罐中乳假单胞菌种类的99.63%和96.39%,说明牛舍垫土是各类假单胞菌潜在的污染源。     

应用RT-PCR技术定量检测发酵乳中Lactobacillus plantarum活菌数

根据发酵乳中常见乳酸菌种的16S rRNA基因序列设计了L.plantarum的种属特异性引物,应用该引物对植物乳杆菌的模式菌株L.plantarum ATCC14917、L.plantarum非同源性对照菌株及采自西藏地区的自然发酵乳样品进行了种属特异性PCR检测,并以样品RNA转录的cDNA为模板,对检出含有L.plantarum的发酵乳样品进行了Real-Time PCR定量检测。通过Real-Time PCR图谱分析,准确地检测出了该样品中L.plantarum活菌数的含量为6.6lgcfu/mL。结果表明该方法能够简便、快速地检测出发酵乳中是否含有L.plantarum,并能够对其活菌数进行准确地定量,对发酵乳的生产和监管提供了重要的理论和实践依据。     

基于高通量测序技术比较不同来源原料乳中的细菌特征

本文采用二代高通量测序技术研究北京、河北、内蒙古、天津四地区不同季节原料乳样品中的细菌多样性并对其进行功能预测。收集四地区不同季节原料乳样品23份,提取基因组DNA后使用Illumina Mi Seq测序平台对细菌16S rRNA的V3-V4"可变区"进行测序,结合数据库对原料乳中微生物群落分布、相对丰度和细菌功能基因代谢途径进行分析。原料乳中的细菌可分为33门732属,其中变形菌门(Proteobacteria),厚壁菌门(Firmicutes),拟杆菌门(Bacteroidetes)和放线菌门(Actinobacteria)为主要菌门,平均相对丰度占微生物总数的99.37%。优势菌属为假单胞菌属(Pseudomonas)和不动杆菌属(Acinetobacter),平均相对丰度之和为60.55%。不同地区、不同季节原料乳微生物群落的结构组成和相对丰度存在差异,且假单胞菌属和气单胞菌属的相对丰度在不同季节原料乳中存在显著性差异(p0.05)。氨基酸代谢、碳水化合物代谢和膜运输为原料乳细菌主要的代谢途径。     

单分子实时测序技术研究不同来源原料乳中群落组成及多样性

目的 采用三代单分子实时测序法(single molecule real time sequencing,SMRT)研究北京和内蒙古两地原料乳中的细菌群落组成及多样性,解析其携带污染菌的差异,为原料乳质量及风险评估提供基础数据.方法 收集北京和内蒙古两地春夏季和秋冬季的原料乳样品20份,采用SMRT技术对其进行基于16...     

MALDI-TOF-MS对原料乳中产β-内酰胺酶菌株的鉴定

为研究原料乳中产β-内酰胺酶细菌的来源,通过杯碟法检测原料乳中的β-内酰胺酶,并鉴定出原料乳中有金黄色酿脓葡萄球菌;随后,通过对原料乳产地的空气、牛体臀部、牛体腹部、牛体乳房、榨乳罩杯、输乳管路外侧、盛装原料奶的空贮罐等进行了大量细菌采集和分离,并采用基质辅助激光解析电离飞行时间质谱(Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry technology,MALDI-TOF-MS)技术对分离出的菌株进行鉴定。结果表明,牛体乳房5号菌与原料乳中检测出的产β-内酰胺酶的菌株相似,均为金黄色酿脓葡萄球菌,由此推断原料乳中的金黄色酿脓葡萄球菌可能来源于牛体乳房。     

微生物发酵法制备高纯度水苏糖的研究

以草石蚕为原料,探讨了黑曲霉、米曲霉、干酪乳杆菌、瑞士乳杆菌、鼠李糖乳杆菌对草石蚕提取液中水苏糖保留率和蔗糖降解率的影响,筛选出最佳单菌发酵菌株;根据单菌对果糖、葡萄糖、蔗糖、水苏糖等的利用规律,进行混菌组合发酵,分析、优化混菌发酵工艺。接种量最优的混菌发酵组合为0.01%黑曲霉和0.01%乳杆菌,发酵36h,精制纯化后的样品水苏糖含量高达78.13%。     

研究变化规律 科学有效地控制乳制品微生物污染

正乳和乳制品从生产、贮存、运输到销售,需要涉及很多环节,如果控制不当,就会引起微生物污染,进而导致产品质量不合格。本文通过调查阿勒泰某乳制品厂原料乳和乳制品菌落总数变化规律,旨在帮助牧民采取相应措施保证原料乳的质量,并为企业制定合理的措施来控制乳及乳制品的质量安全。一、材料与方法1.材料。(1)样品来源:①原料乳样品来源。对阿勒泰某乳品企业三种不同规模的牛场原料乳进行采样     

婴儿配方乳粉原辅料中细菌的分离鉴定北大核心CSCD

利用传统可培养方法对采集自婴儿配方乳粉加工厂的14类、42份原辅料样品进行细菌的分离,并采用16S rDNA基因测序技术对分离的细菌进行分子鉴定。结果表明:乳糖、氯化钾、维生素、低聚果糖、棕榈油和乳铁蛋白共6类原辅料中没有发现细菌,其他8类原辅料中共分离出36株细菌,包含了6个属10个种。原料乳和乳清粉是主要的细菌分离来源,共分离到11株和8株细菌,分别占总分离菌株的30.6%和22.2%。肺炎克雷伯菌和格氏乳球菌是优势菌株,共占总分离菌株的52.7%。     

保康鲊广椒中乳酸菌的分离鉴定及其发酵特性的评价

对湖北保康地区鲊广椒中的乳酸菌进行分离鉴定,并对其在玉米碜和红辣椒为原料的基质中的发酵特性进行评价。结果表明:分离出的20 株乳酸菌菌株,共鉴定为短乳杆菌(Lactobacillus brevis)、食品乳杆菌(L. alimentarius)、面包乳杆菌(L. crustorum)和植物乳杆菌(L. plantarum)4 个种,其中15 株为植物乳杆菌。对比自然发酵的鲊广椒,电子鼻传感器W1C、W3C和W5C对多数植物乳杆菌制备样品的响应值明显偏大,同时酸味、鲜味和丰度亦有明显的提升。通过主成分分析发现,使用L. plantarum HBUAS52327和L. plantarum HBUAS52332纯种发酵的鲊广椒具有优良的品质。由此可见,保康地区鲊广椒中乳酸菌以植物乳杆菌为主,且添加植物乳杆菌进行纯种发酵可提升鲊广椒的品质。     

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