电子鼻检测复合果汁饮料中的脂环酸芽孢杆菌

脂环酸芽孢杆菌是果汁加工中的一种重要腐败菌。因其具有嗜酸、耐热的特性,故巴斯灭菌不能除去此菌。该菌芽孢萌发、繁殖,产生类似药水的强烈异味,导致果汁腐败变质。本文从一种玉米蜜桃复合果汁饮料中分离筛选出1株嗜酸、耐热芽孢杆菌,经16S r DNA鉴定为脂环酸芽孢杆菌。采用FOX 4000电子鼻结合主成分分析(PCA),可快速、准确区分正常产品和异常样品(已污染脂环酸芽孢杆菌)。其中第一主成分累积方差贡献率为95.80%,异常样品与正常样品之间的模式判别指数大于79%。以正常产品为基础建立统计质量控制模型(SQC),被检异常产品位于置信区间之外。GC-MS分析结果表明,异常产品中3种挥发性物质含量高于正常产品,9种物质含量低于正常产品。结合挥发性物质的气味特征和活度分析,导致产品有异味的主要物质为邻乙氧基苯酚和愈创木酚,其含量高达51.79 mg/L和35.62 mg/L。本试验结果说明电子鼻技术可很好地用于检测果汁中的脂环酸芽孢杆菌。     

酸土脂环酸芽孢杆菌对玉米果汁饮料挥发性成分及色度的影响

从市售异味玉米果汁饮料中分离、筛选嗜酸耐热菌,对其进行分子生物学鉴定,并研究分离菌株对玉米果汁饮料挥发性成分和色度的影响。结果表明,市售异味玉米果汁饮料中分离筛选出一株嗜酸耐热芽孢杆菌,该菌最适生长温度为45~50℃,最适pH为3.5~4.0,16S rDNA测序鉴定为酸土脂环酸芽孢杆菌。将分离菌株接种于正常样品于45℃培养30 d,气相色谱-质谱联用技术(Gas Chromatograph-Mass Spectrometer,GC-MS)分析表明,正常样品和接种样品挥发性成分的种类相似,但在关键性气味物质的含量上有显著差异。接种样品中14种挥发性物质含量极显著高于正常样品,其中愈创木酚和邻乙氧基苯酚具有类似草药、消毒水等异味,且两种物质在接种样品中气味活度分别高达1696.58和398.40,为酸土脂环酸芽孢杆菌污染该饮料产生的特征性异味物质。色差分析表明接种样品L值显著高于正常样品,表明污染饮料产生异味的同时产品白度增加。     

基于电子舌技术检测商业果汁中脂环酸芽孢杆菌

采用法国Alpha M.O.S.公司生产的α-Astree Ⅱ型电子舌对7 种市售果汁饮料及其接种脂环酸芽孢杆菌样品进行测定,所得数据应用主成分分析法进行辨别分析。2 种含乳类果汁饮料未能被区分开,其他5 种样品均可区分。将电子舌可区分的6 种果汁饮料接种两株脂环酸芽孢杆菌并在45 ℃条件下培养30 d,所有接种处理中均可检出脂环酸芽孢杆菌。3 种浑浊型饮料的检出量较多,大于103 CFU/mL。3 种澄清型饮料的检出量较少,小于103 CFU/mL。应用电子舌技术可将6 种接种脂环酸芽孢杆菌DSM 3922的果汁饮料与对照组区分开,4 种接种脂环酸芽孢杆菌XC-6的果汁饮料与对照组区分开,2 种接种脂环酸芽孢杆菌XC-6的混合果汁饮料和橙汁饮料同对照组未能被区分。     

不同种类果汁中脂环酸芽孢杆菌及其代谢产物污染调查

为了解不同种类果汁中脂环酸芽孢杆菌及其主要代谢产物的污染情况,随机选取6种市售果汁(共24份)进行调查。采用固相微萃取(SPME)和气相色谱(GC)-质谱(MS)技术检测果汁中愈创木酚和2,6-二溴苯酚的含量,并利用YSG培养基(p H=3.7)分离果汁中的脂环酸芽孢杆菌。在24份果汁样品中,2,6-二溴苯酚检出率为0%(0/24);愈创木酚检出率为33.3%(8/24),浓度最高可达26.9μg/L;脂环酸芽孢杆菌检出率为12.5%(3/24),分离出的3株脂环酸芽孢杆菌均来自愈创木酚含量较高的橙汁样品;在未检出愈创木酚的16份果汁样品中均没有分离出脂环酸芽孢杆菌。在所检测的24份果汁样品中,部分橙汁、葡萄汁以及桃汁中检测到愈创木酚,但是只在橙汁样品中分离出了脂环酸芽孢杆菌,表明橙汁可能更容易在生产过程中被脂环酸芽孢杆菌及其代谢产物所污染。     

3 种脂环酸芽孢杆菌分离培养基的性能评价

目的：比较3 个厂家的K培养基、酵母粉淀粉葡萄糖（yeast extract starch glucose medium,YSG）培养基和耐酸耐热芽孢菌（Alicyclobacillus）培养基（Bacillus acidoterrestris medium,BAT）对脂环酸芽孢杆菌的检测效果。方法：选用标准菌株、分离株及实际样品对3 个厂家（广东环凯微生物科技有限公司（简称HK,下同）、厂家Ⅰ和厂家Ⅱ）的K培养基、YSG培养基和BAT培养基进行生长菌落数及分离效果的评估。结果：酸土脂环酸芽孢杆菌标准株和脂环酸芽孢杆菌分离株4-2在K、YSG和BAT 3 种培养基上生长的菌落数（3 个厂家培养基上的菌落数平均数）均无显著性差异（P＞0.05）;酸热脂环酸芽孢杆菌标准株和脂环酸芽孢杆菌分离株5-3在K培养基上不生长,在YSG培养基和BAT培养基上生长良好,其菌落平均数统计学上无显著性差异（P＞0.05）;对实际样品中酸土脂环酸芽孢杆菌的分离,3 个厂家的同种培养基分离率和符合率相当;对实际样品中酸热脂环酸芽孢杆菌的分离,在YSG和BAT培养基上,HK和厂家Ⅱ的分离率和符合率相当,优于厂家Ⅰ。结论：K培养基不适合所有脂环芽孢杆菌,但分离酸土脂环酸芽孢杆菌效果很好,YSG培养基和BAT培养基适合所有脂环酸芽孢杆菌。HK和厂家Ⅱ的培养基优于厂家Ⅰ。     

培养条件和果汁种类对脂环酸芽孢杆菌生长的影响

脂环酸芽孢杆菌是造成巴氏灭菌果汁腐败的重要细菌之一。鉴于目前脂环酸芽孢杆菌的培养方法尚未统一且污染特征不明确,本研究考察了pH、7种培养基和9种果汁对其生长的影响,同时采用固相微萃取(SPME)和气相色谱(GC)-质谱(MS)技术检测了该菌的主要代谢产物愈创木酚和2,6-二溴苯酚在果汁中的释放情况。结果表明,脂环酸芽孢杆菌在pH4.0时生长情况最好,pH2.5时生长较差,pH6.0~7.0时最差。AAM培养基和BAT培养基较其他5种培养基(YSG培养基、K氏培养基、SK培养基、PDB培养基和营养肉汤培养基)更适合用来培养脂环酸芽孢杆菌。脂环酸芽孢杆菌接种到9种果汁中后生长差异明显,在葡萄汁和橙汁中生长情况最好,细菌数量分别为1.5×104 CFU/mL和8.5×103 CFU/mL;在菠萝汁和西柚汁中生长缓慢,细菌数量分别为4.4×102 CFU/mL和1.9×102 CFU/mL。此外,9种果汁接种脂环酸芽孢杆菌后均未检测出2,6-二溴苯酚;但是,除葡萄汁外的8种果汁均检测出愈创木酚,浓度在8.6~23.9 μg/L之间。     

一株源于果园Alicyclobacillus的分离、鉴定及其生物学特性

目的:为了解脂环酸芽孢杆菌在果园土壤中的分布情况,对陕西果园土壤进行研究。方法:以酸化的YSG培养基分离培养脂环酸芽孢杆菌,观察菌株形态,测定生理生化特性,应用API 50CHB及API ZYM系统测定糖酵解和酶反应,以气相色谱(GC)分析脂肪酸组成,并以16S rDNA序列分析法构建系统发育树。结果:分离菌株与标准菌株的形态基本一致,酶谱有很大的相似性但糖酵解反应差异较大;16S rDNA序列分析显示,分离菌株与标准菌株属于同一属的不同种,分离菌与Alicyclobacillus contaminans的同源性达到99%。结论:采用国际通用的脂环酸芽孢杆菌的分离方法,结合API系统、脂肪酸组成分析及16S rDNA序列分析,可以快速的将分离菌鉴定到种;脂环酸芽孢杆菌在果园土壤中确有分布,可能对果汁质量造成威胁。     

接种不同优势腐败菌的冷藏猪肉中挥发性物质的研究

为研究接种不同优势腐败菌的新鲜猪肉在4℃冷藏中的变化,将梭状芽孢杆菌、韩国假单胞菌和热死环丝菌分别接种到新鲜猪肉上,采用顶空固相微萃取-气相色谱-质谱联用(HS-SPME-GC-MS)技术,研究其在储藏过程中产生的挥发性物质。实验显示,不同样品在48、96、144h贮藏时间下的挥发性成分有较大差异,随着冷藏时间的增加,烷烃类物质种类及含量均明显增加;醇类物质含量增加而醛类物质含量减少;硫氢甲烷、3-甲硫基丙烯等含硫化合物被检测出,但含量较低;酸类物质含量随贮藏时间的延长而逐渐增加;接种梭状芽孢杆菌的样品检测出了高含量的3-羟基-2-丁酮,接种热死环丝菌的样品出现高含量的3-甲基丁醇。结果表明,接菌样品与对照样品的挥发性物质总含量存在显著差异(p0.05),即上述3种菌种会对冷藏猪肉的挥发性物质总含量产生显著影响。     

基于GC/MS对1株芽孢杆菌FJAT-13831的鉴定

目的通过芽孢杆菌物质组学分析,快速地区分亲缘关系极近的芽胞杆菌种类。方法本文利用GC/MS检测了芽孢杆菌9个模式菌株和1个分离菌株FJAT-13831的胞外物质成分,并进行主成分和聚类分析。结果不同的芽孢杆菌种间胞外物质具有显著性差异,FJAT-13831的胞外物质成分与其相近种类差异很大,应是芽胞杆菌属的一个新种。结论该方法可从代谢水平上对芽孢杆菌亲缘关系相似的不同种进行区分,为芽孢杆菌的鉴定及新种判断提供一种新的技术手段。     

橙汁主要营养成分及温度处理对脂环酸芽胞杆菌生长的影响

本文研究了橙汁主要营养成分和加工中温度处理等因素对两种引起已灭菌果汁腐败的主要病原微生物酸土脂环酸芽孢杆菌(A licyclobacillus acidoterrestris)和酸热脂环酸芽孢杆菌(A licyclobacillus acidocaldarius)生长的影响.结果表明,柠檬酸、蔗糖、矿质元素(钙、镁和钾元素)等橙汁中的主要营养成分在一定浓度范围内均可以促进两种脂环酸芽孢杆菌的生长.酸热脂环酸芽孢杆菌和酸土脂环酸芽孢杆菌在蔗糖浓度分别高于25％和20％时,生长受到抑制.当环境中钾浓度高于1000mg/L时,酸土脂环酸芽孢杆菌生长的生长受到抑制.在不同橙汁含量的饮料中,橙汁原汁最适合两种脂环酸芽孢杆菌的生长,而浓缩果汁中两种菌的生长量最少.温度处理实验表明,两种脂环酸芽孢杆菌分别经(-20、4、30、50、70、90℃)处理30min后,仍能保持良好的生长状态.当菌体经121℃处理30min时,生长几乎完全受到抑制.因此.橙汁饮料及橙汁原汁更容易感染酸土脂环酸芽孢杆菌和酸热脂环酸芽孢杆菌;通过巴氏杀菌很难彻底杀灭橙汁中的脂环酸芽孢杆菌,有必要寻求新型非热杀菌方法来控制橙汁中脂环酸芽孢杆菌.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.