南美白对虾感染真菌毒素后的微生物菌相变化

为探明在养殖过程中受T-2毒素、黄曲霉毒素B1、赭曲霉毒素A和呕吐毒素污染的南美白对虾,经贮藏后微生物菌相结构变化的特征,采用食品安全国家标准(GB 47892-2010)对菌落总数测定的方法,计算染毒对虾中的菌落总数,同时从染毒的南美白对虾中分离筛选和鉴定出不同属的微生物,并与未染毒对虾中的微生物数量、种类及其变化趋势进行比较。实验结果表明:染毒对虾肌肉微生物种类在贮存第1~8 d和第16~20 d间,菌落种类保持在2~4种和4~7种,菌群总数呈先下降后上升再下降的趋势。从未染毒对虾和染毒对虾样品中共分离出7株菌,经16S rDNA进行测序,分别鉴定为考克氏菌属、金黄杆菌属、希瓦氏菌属、弯曲芽孢杆菌属、假单胞菌属、细杆菌属和微小杆菌属,每株样品菌种匹配率均在97%以上,其中对水产品的腐败能力较强的金黄杆菌属、希瓦氏菌属和假单胞菌属在染毒对虾中检出,空白组只检出希瓦氏菌属。真菌毒素使对虾肌肉产生变化,导致对虾肌肉品质下降,从而形成适合腐败能力强细菌的生长环境,产生新的菌种。     

冷却猪肉中腐败微生物鉴定及其消长规律的研究

目的对冷却猪肉中腐败微生物进行鉴定,研究其在0～4℃条件下贮藏时的消长规律。方法采用选择性培养基对冷却猪肉中的腐败微生物进行分离培养,利用Biolog微生物自动鉴定系统对菌株进行鉴定。结果共鉴定出11株具有代表性的细菌:肠杆菌4株,假单胞菌1株,热杀索丝菌1株,不动杆菌1株,乳酸菌2株,葡萄球菌2株。冷却猪肉中腐败微生物初始菌相结构为:热杀索丝菌54.9%,肠杆菌科8.7%,假单胞菌属3.6%,乳酸菌属29.5%,葡萄球菌/微球菌0.6%,霉菌/酵母菌2.7%。在0～4℃条件下贮藏时,热杀索丝菌、肠杆菌科和假单胞菌属是冷却猪肉中的优势腐败菌,假单胞菌属和肠杆菌科在菌相结构中的比例增长最高,特别是假单胞菌属的数量增长最快。结论鉴定出了冷却猪肉中的主要腐败微生物,确定了其初始菌相和优势腐败菌。     

冷藏鲈鱼片优势腐败菌的分离鉴定及致腐能力分析

为研究冷藏鲈鱼贮藏末期的优势腐败菌及其致腐能力,采用选择性培养基获得鲈鱼贮藏末期的特定菌落,结合感官分析确定所筛菌株中的优势腐败菌。通过多次划线分离获得纯菌株,结合菌落形态观察、传统生理生化试验与16S rDNA技术,确定所筛菌株属种,并将所鉴定的优势腐败菌接种至无菌鲈鱼样品上,在4℃条件下贮藏,测定不同贮藏时间段的挥发性盐基氮(TVB-N)与菌落总数,以TVB-N产量因子(YTVB-N)衡量各腐败菌的致腐能力。结果得出,筛选获得的5株菌株中,有假单胞菌属P1(WCS374)1株,草莓假单胞菌P2(P121)与P3(B-727)2株、希瓦式菌属S1与S2(OS185)2株。其致腐能力排序为S1S2P2P3P1,其中腐败希瓦式菌属细菌S1的致腐能力最强。由产量因子分析表明,草莓假单胞菌P2的致腐能力强于一般假单胞菌属细菌P1与P3。经综合比较,鲈鱼鱼肉中希瓦式菌属细菌的致腐能力强于假单胞菌属细菌。     

60Coγ-射线及电子束辐照对冷鲜鸡菌群多样性的影响

为探明γ-射线与电子束辐照对冷鲜鸡微生物含量和微生物群落多样性的影响,采用2.5 kGy剂量的γ-射线和电子束辐照处理真空包装冷鲜鸡,对其贮藏期内菌落总数、群落结构进行测定分析。结果表明,两种射线均能显著(P<0.05)降低冷鲜鸡菌落总数;高通量测序后得到了9门,62属的菌群结构,在门水平上,变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、梭杆菌门(Fusobacteria)、拟杆菌门(Bacteroidetes)为优势菌群;在属水平上,贮藏0 d时,对照组内环丝菌属(Brochothrix)、希瓦氏菌属(Shewanella)、不动细菌属(Acinetobacter)为优势菌群;贮藏5 d时,对照组内希瓦氏菌属(Shewanella)、γ-射线组内嗜冷菌属(Psychrobacter)、电子束处理组内希瓦氏菌属(Shewanella)为优势菌群;贮藏10 d时,对照组内嗜冷菌属(Psychrobacter)、γ-射线组不动细菌属(Acinetobacter)、电子束处理组内希瓦氏菌属(Shewanella)为优势菌群;贮藏15 d时,对照组内嗜冷菌属(Psychrobacter)、γ-射线组希瓦氏菌属(Shewanella)、电子束处理组内希瓦氏菌属(Shewanella)成为优势菌群。由此可知,γ-射线与电子束辐照均对冷鲜鸡微生物数量和群落结构产生显著(P<0.05)影响。     

镇江肴肉中腐败菌的初步分离鉴定

分离镇江肴肉中腐败菌,并对主要菌株进行鉴定,为研究特定腐败菌的腐败原理,延长产品的保质期打下基础.利用纯培养的方法,根据细菌的菌落形态、菌落颜色、革兰氏染色等特征,从市售冷藏镇江水晶肴蹄中选取菌落形态差别比较明显的8株菌株,通过16S rDNA序列进行分类研究,确定各细菌所属种.试验结果表明:T-1为假单胞菌属的荧光假单胞菌(Pseudomonas fluorescens),T-2为希瓦氏菌属的渡罗的海希瓦氏菌(Shewanella baltica),T-3、P-1、P-2、V-1、V-2、V-3为拉乌尔菌属的解鸟氨酸拉鸟尔菌(Raoultella ornithi-nolytica)[从前的解鸟氨酸克雷伯氏茼(Klebsiella ornithinolytica)].     

小肠结肠炎耶尔森氏菌在冷鲜鸡肉上的生长

将小肠结肠炎耶尔森氏菌接种到无该菌污染的冷鲜鸡肉上,测定接种前后于4℃贮藏的冷鲜鸡肉在第0、2、4、6、8、10天时的理化指标和微生物指标,包括p H值、挥发性盐基氮值(Total Volalite Base Nitrogen,TVBN)、菌落总数、嗜冷菌总数以及耶氏菌总数,并综合感官评价结果分析各指标间的相关性。最后通过结合16S r DNA基因序列分析及PCR扩增方法鉴定冷鲜鸡肉在贮藏过程中的菌相组成变化。实验结果表明:接种前后,冷鲜鸡肉的TVB-N值、菌落总数、嗜冷菌总数、耶氏菌总数都随贮藏时间延长而增大;p H值呈波动上升再下降趋势;感官评定分数一直下降;货架期由8 d缩短到6 d。从菌相鉴定结果中发现,假单胞菌属、希瓦氏菌属在贮藏过程中一直处于优势地位,且在贮藏后期检出了罕见的哈夫尼亚菌属。     

对新捕获与流通过程中大黄鱼新鲜度与细菌种群的研究

对大黄鱼栖息水域海水的卫生状况和新捕获、批发及零售大黄鱼的新鲜度进行评价,同时对细菌种群进行定性和定量研究.结果表明,23份海水样品中,粪大肠菌群达标率为95.7%.新捕获、流通环节中的大黄鱼新鲜度总体呈下降趋势,TVBN、菌落总数和假单胞菌数呈上升趋势.细菌种群结果显示,新捕获、流通环节的样品中革兰氏阴性菌为优势菌群,分别占75.4%、72.8%和87.5%.新捕获鱼细菌种类繁多,共检出20种细菌,主要由肠细菌科、假单胞菌属、腐败希瓦氏菌和嗜麦芽窄食单胞、玫瑰小球菌等组成;流通环节样品细菌种群逐渐变得简单,分别检出17种和11种细菌,其中不动细菌属、假单胞菌属、腐败希瓦氏菌、嗜冷杆菌等所占比例较高.     

真空包装冷藏大菱鲆鱼片的货架期及其优势腐败菌群体感应检测

本研究以真空包装冷藏大菱鲆鱼片为研究对象,通过感官、微生物和化学指标评价其货架期,利用16Sr DNA方法对其贮藏初期和末期的微生物分布进行鉴定,并采用报告菌株法检测大菱鲆鱼片贮藏过程中两种类型群体感应信号分子(AHLs和AI-2)的产生情况,检测其优势腐败菌的群体感应类型。结果显示,大菱鲆鱼片在真空包装冷藏环境下可以贮藏9 d,此时细菌总数达6.87 logCFU/g,挥发性盐基氮含量为28.70 mg/100 g。对比初始和末期微生物种类变化,真空包装大菱鲆鱼片冷藏过程中的优势腐败菌主要为希瓦氏菌,其次为肠杆菌科细菌。群体感应信号分子AHLs和AI-2含量随贮藏时间延长而增加。贮藏末期分离的希瓦氏菌均能分泌AI-2信号分子,分泌能力因菌株而异。利用基因手段可从希瓦氏菌中扩增到AI-2的分泌基因lux S,表明lux S在产AI-2菌株中具有一定保守性,可能参与希瓦氏菌的腐败进程。     

不同时期鲳鱼冷藏期间优势腐败菌的多样性变化

目的：比较分析不同时期冷藏鲳鱼（Pampus argenteus）贮藏期间的感官品质、pH值、微生物指标与主要微生物菌群的变化规律。方法：冷藏（4±1） ℃条件下,以感官评定、pH值与菌落总数为品质评价指标,采用聚合酶链式反应（polymerase chain reaction,PCR）扩增结合生理生化鉴定法分别对冬、春两个时期的鲳鱼进行优势腐败菌的变化规律研究。将经细菌培养与分离纯化得到单菌落按其形态特征进行分类,再通过生理生化鉴定与革兰氏染色,初步得到菌落种类,对单菌落进行DNA提取与PCR扩增并测序。结果：冬季样品获得12 种菌株,春季样品获得9 种菌株。贮藏末期时,冬季样品中优势腐败菌的种类与比例分别为嗜冷杆菌（Psychrobacter spp.）21.51%、草莓假单胞菌（Pseudomonas fragi）16.13%、荧光假单胞菌（Pseudomonas fluorescens）52.68%与热杀索丝菌（Brochothrix thermosphacta）9.68%;春季样品为草莓假单胞菌（Pseudomonas fragi）8.62%、荧光假单胞菌（Pseudomonas fluorescens）64.66%与腐败希瓦氏菌（Shewanella putrefaciens）26.72%。结论：冬、春时期中冷藏鲳鱼贮藏期间优势腐败菌的种类基本一致,以革兰氏阴性菌为主,但在细菌种类与比例上存在差异,冬季样品的微生物种类较春季丰富。贮藏期间,随着荧光假单胞菌所占比例的增加,使腐败希瓦氏菌的生长受到明显抑制。     

冷鲜牛肉贮藏中菌群结构及优势菌致腐性的分析

为探究牛肉在0?℃冷藏下微生物菌群变化和优势腐败菌,采用培养依赖的16S rRNA结合高通量测序技术分析牛肉样品的微生物多样性变化。通过定期测定接种牛肉汁的生长、感官、蛋白酶活性、pH值和挥发性盐基氮（total volatile basic nitrogen,TVB-N）值,分析分离株的致腐特征。结果表明,牛肉冷藏中感官品质保持良好,15?d出现异味,18?d有腐臭味。而样品中菌落总数第3天快速上升,15?d菌落总数为8.73（lg（CFU/g））,之后呈现稳定,假单胞菌（Pseudomonas spp.）、热死环丝菌（Brochothrix thermosphacta）、肠杆菌（Enterobacter）和乳酸菌4 种分离培养基中细菌与菌落总数增长趋势相似,其中假单胞菌增长最快,肠杆菌数和乳酸菌数生长最慢。两种菌群鉴定结果显示,冷鲜牛肉初始微生物构成复杂,包括热死环丝菌、不动杆菌属（Acinetobacter spp.）、气单胞菌属（Aeromonas spp.）和假单胞菌等多种菌属构成,而腐败末期菌群构成趋于单一,假单胞菌和热死环丝菌为优势腐败菌,特别是莓实假单胞菌（P. fragi）。将腐败分离株10?株假单胞菌、4?株热死环丝菌和1?株蜂房哈夫尼菌（Hafnia alve）接种于冷藏的牛肉汁,发现假单胞菌和蜂房哈夫尼菌的接种组感官评分、pH值和TVB-N值高于热死环丝菌,且假单胞菌有较强的蛋白酶活性。研究表明,结合感官和微生物评价冷鲜牛肉贮藏期为15?d,且菌群多样性下降,假单胞菌和热死环丝菌是优势腐败菌,其中假单胞菌致腐性较强。     

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.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status