浮游态和生物被膜态致病菌的光动力灭菌研究进展

光动力灭菌是一种新兴的致病菌杀灭技术。它通过光源激发光敏剂,产生活性氧自由基,多靶点作用于细菌细胞膜和DNA,造成氧化损伤并最终导致细菌死亡。传统灭菌方式在应用于食品工业时面临诸多问题,如导致耐药性细菌的出现,难以杀灭生物被膜态细菌,造成食品营养和风味流失,应用成本过高等。光动力灭菌作为非热杀菌技术,不会引发食品的感官变化和营养流失,所需设备简单,不易引发细菌耐药性,并且对细菌（浮游态和生物被膜态）、真菌、甚至孢子都有较好的杀灭作用,近年来受到广泛关注。本文概述光动力灭菌的原理和传统杀菌方法的局限性,重点阐述光动力灭菌在杀灭浮游态细菌和生物被膜态细菌中的应用和研究进展。     

不同包装条件下冷却肉品质变化及腐败菌相研究

为寻找冷却猪肉合理的包装方式,延长货架期,将猪后腿肉分别进行托盘包装、真空包装、高氧气调包装（20%CO₂+80%O₂）和低氧气调包装（65%CO₂+35%O₂）处理,并以无包装组为对照,测定样品在4℃贮藏过程中挥发性盐基氮（TVB-N）值、色差值a*、丙二醛（MDA）值、微生物菌落（菌落总数、假单胞菌菌落数和热杀索丝菌菌落数）和感官评分。结果表明:无包装和托盘包装冷却猪肉货架期不超过4 d,高氧气调包装（20%CO₂+80%O₂）货架期为6 d,真空包装和低氧气调包装（65%CO₂+35%O₂）货架期长达9 d。真空和气调包装均有利于延长冷藏猪肉货架期,但真空包装使肉呈暗红色。气调包装中O₂和CO₂的含量影响肉的品质,高氧气调包装有利于好氧菌假单胞菌和热杀索丝菌的生长繁殖,同时促进脂质氧化,但可以很好维持肉色,低氧气调包装（65%CO₂+35%O₂）可以抑制细菌的生长和脂肪氧化。综合各项评判结果,得到最佳包装方式为低氧包装（65%CO₂+35%O₂）。      

国内外鱼和鱼制品的气调保鲜研究

气调保鲜包装能抑制微生物的生长和氧化反应,从而延长食品货架期。延长的能力取决于食品种类、脂肪含量、原细菌数、混合气体的组成、气体和食品的体积比,最重要的是储藏温度。鱼制品的货架期受微生物活性的限制,有些高脂鱼或超低温储藏的鱼制品受微生物作用的影响很小。另外,MAP制品的微生物安全是首要考虑。     

A review of modified atmosphere packaging of fish and fishery products – significance of microbial growth, activities and safety

Modified atmosphere packaging (MAP) extends shelf-life of most fishery products by inhibiting bacterial growth and oxidative reactions. The achievable extension of shelf-life depends on species, fat content, initial microbial population, gas mixture, the ratio of gas volume to product volume, and most importantly, storage temperature. The shelf-life of fishery products is usually limited by microbial activity, although for some fatty fishes or at superchilled storage, it can be limited by nonmicrobial activity. Packaging of fishery products under modified atmospheres (MA) increases shelf-life compared with those packaged under air, but confers little or no additional shelf-life increase compared with vacuum packaging. The specific spoilage organism (SSO) of MA packaged cod at 0 °C has been found to be Photobacterium phosphoreum . Whether or not this bacterium is the general SSO for all marine temperate fishes at different storage temperatures and under various CO₂/N₂/O₂ mixtures needs to be resolved. Without proper control of storage temperature, the benefits of MAP may be lost. Higher temperatures inevitably lead to less dissolved CO₂ in the product and consequently loss of inhibitory effect, which may result in higher microbial and enzymatic activity, and uncertainties concerning the microbial safety, as food-borne pathogens might be present in the product.     

气调包装酱卤鸭食管冷藏期间理化指标变化及优势腐败菌的分离鉴定

为研究气调包装酱卤鸭食管冷藏条件下贮藏品质的变化,将未加抑菌剂的气调包装酱卤鸭食管在冷藏（0～4 ℃）条件下贮存12 d,分别测定其pH值、水分活度、硫代巴比妥酸反应物（thiobarbituric acid reactive substance,TBARs）值、感官评分及微生物菌相等指标的变化。结果表明：随着冷藏时间的延长,气调包装酱卤鸭食管的感官品质显著降低、pH值显著下降,而TBARs值呈显著上升趋势,水分活度呈下降趋势,但下降幅度很小;将分离纯化后的腐败菌采用16S rDNA测序方法进行鉴定,发现冷藏条件下气调包装酱卤鸭食管中的优势腐败菌主要有副黄假单胞菌、特基拉芽孢杆菌、肉芽肿克雷伯氏菌和香坊肠杆菌。     

基于宏基因组学分析气调包装中华鳖贮藏期间菌相变化

研究气调包装中华鳖贮藏过程中微生物菌相变化,为中华鳖贮藏保鲜提供参考。采用宏基因组学法研究气调包装(50%CO2/50%N2,3 mL∶1 g)的中华鳖4℃贮藏过程中的菌相变化,结果表明:整个贮藏过程中,气调包装样品的群落丰富度逐渐上升,物种多样性呈先上升后下降趋势;气调包装的优势腐败菌属为希瓦氏菌属,在贮藏末期占29.68%;气调包装能有效抑制假单胞菌属、黄杆菌属等水产品中常见的腐败微生物,维持产品新鲜品质,是中华鳖包装贮藏的优良选择。     

125th Anniversary Review: Bacteria in brewing: The good,the bad and the ugly

Beer is a beverage that is produced in a multistage process, where some stages of that process are intentionally influenced by microorganisms, while at other stages of the production process microorganisms are actively discouraged. Most of the intentional microbial activity is facilitated by yeast; however bacteria also play an influential role in beer production. This paper will describe the beneficial role of bacteria in the beer production process (the Good), but will also pay due attention to the negative influences bacteria might have on the quality of beer as a commodity (the Bad), and the properties of beer that have given it the status of an inherently safe food for human consumption with regards to disease‐causing bacteria (the Ugly). Copyright © 2013 The Institute of Brewing & Distilling     

食源性细菌关键小分子信号通路研究进展

食源性细菌引起的食品腐败和生物被膜形成是食品科学领域关注的热点。研究表明这些现象与细菌群体感应（quorum sensing,QS）系统和第二信使环二鸟苷酸（cyclic di-guanosine monophosphate,c-di-GMP）系统密切相关,深入研究发现细菌可通过利用胞外自诱导物和胞内c-di-GMP分别感知细胞密度和外界刺激来调控一系列生理活性。鉴于此,本文主要围绕食品腐败和生物被膜形成关联的QS和c-di-GMP这两个系统,阐述食源性细菌关键小分子信号通路,探讨QS和c-di-GMP信号通路之间的调控网络,旨在更好地理解食品体系中细菌引起的腐败和生物被膜形成现象,提供保障食品品质与安全的控制靶点。     

食源性致病菌和腐败菌的快速检测方法研究进展

食源性致病菌和腐败菌污染一直是引发食品安全事件的重要因素。传统的检测方法虽具有较高的准确性,但需培养及生化实验,耗费时间长且操作较复杂,开发高效、快速的检测方法对保障食品安全至关重要。近年来,科学技术的进步使一些新方法、新技术逐渐被运用,比传统培养法检测时间更短、效率更高、特异性更好,具有广阔的应用前景。因此,本文综述了食源性致病菌和腐败菌快速检测方法的最新研究进展,包括纸片法、流式细胞术、阻抗法、腺苷三磷酸荧光法、光谱检测技术、分子生物学检测技术、免疫学检测法及生物传感器检测技术等,着重论述了各种方法的原理、优缺点、应用状况及发展方向,为致病菌和腐败菌引发的食品安全事件的预防及控制提供参考。     

姜黄素介导的光动力技术对副溶血性弧菌与腐败希瓦氏菌的杀灭效果

为了开发新型抗菌技术,本研究建立了一种高效的姜黄素介导的光动力技术(photodynamic technology,PDT).以水产品中常见的致病菌(副溶血性弧菌)与腐败菌(腐败希瓦氏菌)为研究对象,通过表征PDT处理前后的菌落总数、再生长能力、细菌表面形态变化、活性氧(reactive oxygen species,...     

稻谷储藏危害真菌生长与CO2浓度的相关性

采用危害真菌孢子计数法和便携式储粮危害生物快速检测仪法,研究了稻谷储藏过程中危害真菌生长与CO2浓度的关系。选择不同水分的稻谷样品,在不同温度下储藏60 d,采用两种方法对各稻谷样品真菌生长与CO2浓度进行检测,并对检测结果进行相关性分析,其相关系数分别为,r2=0.959 1(25℃)和r2=0.943 9(30℃)。在我国南方某地,选择了3个储藏稻谷的平房仓作为实验仓,每仓设30个采样点,采样深度为0.35 m,对各采样点的真菌生长与粮堆和仓内环境中CO2浓度进行了研究,并对检测结果进行相关性分析,相关系数分别为r2=0.998 4和r2=0.988 7。研究表明,稻谷储藏过程中危害真菌的生长与CO2浓度具有良好的相关性。     

储粮真菌危害早期检测方法的研究

在传统真菌孢子计数法的基础上,为消除样品自身携带真菌孢子的干扰,通过对样品检测浓度设限,建立了一个储粮真菌危害早期检测方法——危害真菌孢子计数法。方法操作为样品用水提取,过滤,滤液于显微镜下进行真菌孢子计数。在本试验中对样品前处理条件进行了优化,最佳样品提取条件,称样量为10 g,提取时间为1 m in,滤网孔径为300目;对不同感染水平的小麦、稻谷样品进行了重复性试验(n=8),相对标准偏差(RSD%)范围在8.2%~31.4%;与平板菌落计数法比较,相关系数r2=0.847 9,显示出两者具有良好的相关性。本方法可用于储粮真菌危害的早期检测。     

解冻猪肉中优势腐败菌致腐能力研究

将解冻猪肉中的优势腐败菌(假单胞菌属、热死环丝菌和肠杆菌科)接种到灭菌肉上研究其在不同温度贮藏过程中腐败的特点。在贮藏期间每天进行感官评价,测定各腐败菌的菌落数(CFU)、挥发性盐基氮(TVB-N)、脂肪氧化值,并以产生腐臭味时的TVB-N产量因子Y(TVB-N/CFU)作为各优势腐败菌腐败能力的定量指标。研究结果表明：至贮藏期第5天时解冻猪肉已产生强烈的腐臭味,热死环丝菌菌数在4、0℃和－5℃贮藏时分别达11.28lg(CFU/g)、9.63lg(CFU/g)和6.62lg(CFU/g),而相应的TVB-N值分别达14.92、14.50mg/100g和9.10mg/100g;与之类似,假单胞菌属菌数4、0℃和－5℃贮藏时分别达9.46lg(CFU/g)、8.87lg(CFU/g)和5.37lg(CFU/g),TVB-N值分别达21.59、14.49mg/100g和8.97mg/100g。研究表明热死环丝菌和假单胞菌属导致解冻猪肉腐败能力较强。     

Monitoring Gram positive bacterial contamination in Czech breweries

Quality control procedures were monitored in a number of Czech breweries. All Gram positive bacterial contaminants found in the beer were collected and isolated. The occurrence of this contamination was recorded. Gram positive bacteria obtained from the breweries were isolated and identified by API 50 CHL. This method is generally used as a comparative method for identification of lactic acid bacteria. Pasteurised beer was inoculated with all identified bacteria in the absence of oxygen. Haze formation was checked over three months. The results show that different beer spoilage was observed on inoculating beer with isolates identified as identical.