浅谈啤酒生产的微生物控制

长期以来 ,啤酒的酿造生产一直受到微生物污染的威胁 ,病害微生物会造成啤酒酸败、变质及混浊。因此微生物控制在啤酒生产中是一项非常重要的工作 ,要想保证产品的酿造质量 ,必须从控制微生物污染开始。微生物 (主要指细菌 )是一群微小的、无处不在的生物 ,它存在于我们周围的空气和水中 ,因此啤酒在生产中的任何一个阶段都有可能受到它的污染。控制微生物污染主要是工艺卫生的管理 ,找出污染源 ,然后采取有效的措施进行管理。首先是酿制啤酒的原料。如果水分偏高 ,存放环境恶劣 ,例如仓库潮湿 ,温度高 ,通风不良 ,都容易造成大米、麦芽发霉…     

啤酒发酵中的微生物管理技术

啤酒生产中的关键技术之一就是微生物的发酵过程 ,包括啤酒酵母的繁殖和发酵 ,同时又不可避免地引起一些其它微生物如细菌、野生酵母的污染过程。这两种不同作用的微生物直接影响着啤酒的口味、质量指标及卫生质量 ,甚至产量。因此 ,啤酒发酵的微生物管理是啤酒生产的核心 ,作为啤酒生产企业的微生物管理人员能够很好地掌握各环节微生物作用特点 ,有效地指导生产 ,则是非常重要的。以下是我们在微生物管理方面的一点体会。1　啤酒酵母的管理使用什么样的啤酒酵母进行发酵这很重要。要想控制其它微生物对啤酒的影响 ,必须使用繁殖速度快、发…     

啤酒微生物检测培养基的选择探讨

对啤酒生产企业来讲选择合适的检测培养基,保证微生物检测的准确性,对提高啤酒生产质量具有重要意义。本文对啤酒微生物检测培养基选择方法进行了探讨,以期为确定合适的微生物检测培养基提供参考。     

隔离器饲育SPF鸡微生物质量控制方法的建立

目的建立隔离器饲育SPF鸡生产管理方式,探讨并建立其微生物质量控制方法。方法对引进的SPF鸡种蛋进行孵化后,将种鸡置于隔离器中进行饲养,在种鸡10、20、40周龄时采取鸡血清进行微生物质量监测,检验当前SPF鸡生产管理和微生物质量控制方法的有效性。结果隔离器饲育SPF鸡初期由于对孵化环节控制不严出现了微生物污染现象。在对孵化环节操作管理改进后,隔离器饲育SPF鸡的微生物状况得到控制。结论通过加强各个环节消毒,隔离器饲育环境能够保证SPF鸡的微生物质量。适当控制隔离器内SPF鸡的密度不仅有利于SPF鸡的繁育和种蛋回收,而且有利于环境微生物的控制。     

食品微生物检验技术及未来发展趋势研究

近些年来随着人们生活水平的提高,人们对于食品安全问题的关注度越来越高,许多违规操作生产的食品厂家纷纷被勒令停产或者取缔。世界卫生组织(WHO)对于食品的微生物污染问题高度关注,食品检验技术中的微生物检验成为重要技术之一,能够有效的控制由于微生物含量或种类不合格导致的食品安全问题。本文主要通过分析食品微生物检验技术中涉及到的检验项目以及相关检测技术进行分析,并对微生物检验技术的发展前景做了展望。     

制药企业环境菌库建立的探讨

建立制药企业环境菌库。连续4年从药品生产洁净区环境和操作人员表面、制药用水系统、合并血浆、产品和原/辅料中收集微生物，对微生物进行分离纯化，采用生化鉴定、基因测序分析系统对微生物进行鉴定,再采取适当的方法加以保存，建立企业的环境菌库。通过对4年的微生物数据进行整理和分析，环境菌库共收集了111种微生物，保存了176株微生物，建立了企业环境菌库。建立企业环境菌库，可为开展微生物污染控制、消毒效果评价、污染事件调查和微生物污染溯源提供数据和技术支持。     

建立洁净区微生物数据库与无菌药品GMP生产过程控制的探讨

目的 建立洁净区微生物数据库,为追溯洁净区微生物污染来源提供依据,为无菌药品生产过程控制提供有力指导.方法 对乙型脑炎减毒活疫苗生产车间洁净区环境和操作人员进行微生物负载检测,并对该车间注射用水、纯化水系统样品进行微生物限度检测,鉴别研究相应分离菌,建立洁净区微生物数据库.同时对乙型脑炎减毒活疫苗中间产品进行无菌检查检测,并对阳性结果分离菌进行鉴别分析.然后根据建立的洁净区微生物数据库对阳性结果举例进行溯源探讨分析.结果 洁净区环境和人员主要存在里拉/藤黄微球菌、人葡萄球菌、表皮葡萄球菌以及科氏葡萄球菌科氏亚种等革兰阳性菌和蜡样芽胞杆菌等,水系统中则主要存在少动鞘氨醇单胞菌和铫子芽胞杆菌等.中间产品无菌阳性结果主要存在里拉/藤黄微球菌、蜡样芽胞杆菌以及奇异变形菌等,经调查分析,分别为操作过程中经环境偶然带入或试验动物操作不慎带入.结论 建立洁净区微生物数据库是追溯产品微生物污染来源的有效方法,能够为无菌药品GMP生产过程制定有效的控制措施提供依据,并使其更有针对性.     

微生物硫循环网络的研究进展

硫元素是所有生物的基本组成成分,是生物体必需的营养元素之一。硫氧化还原微生物的数量多、分布广、代谢途径多样化,硫化合物之间的平衡依赖于微生物代谢网络中的各种硫转化反应与代谢过程。此外,硫循环与碳、氮循环紧密相关,对地球生态循环起到了至关重要的作用。本文综述了近期微生物硫循环网络的研究进展,包括所涉及的主要微生物、硫循环的生物化学途径、硫循环的环境意义和工业应用潜能等,深入了解自然和人工生态系统中存在的硫循环过程,可为控制工农业生产中硫元素的增减与利用提供理论基础与应用方案。     

天然白桦树液中污染微生物的分离与控制

本文以天然白桦树液为材料,对其污染微生物进行了分离培养和初步鉴定,从而基本搞清了污染微生物的种类与数量。发现,天然桦树原汁及其饮料中有数量不同的细菌、酵母菌、霉菌及放线菌的污染。其中,霉菌居多,酵母、细菌次之,放线菌最少。 在弄清污染微生物分布的基础上,作者研究比较了几种控制灭活微生物的方法。其中pH2.0的酸性处理未能灭活全部污染微生物,而采用90℃加热杀菌的办法以及膜板过滤技术均可达到理想的结果。 作者还根据试验结果分析探讨了微生物控制中pH值、温度、水份和环境等与微生物生长繁殖存活间的关系。从而为如何研究和解决饮料中微生物污染问题提供了有用的资料和可行的方法。     

微生物醌指纹法在环境微生物群体组成研究中的应用

微生物醌是能量代谢过程的电子传递体,不同的微生物含有不同种类和分子结构的醌。因此,环境样品中微生物醌的组成,即醌指纹可在一定程度上反映微生物的群体结构。本简要介绍了微生物醌的分析方法,并利用醌指纹对活性污泥中的微生物群体组成进行了解析。     

利用固化技术生产麦花啤

麦花啤是一种发酵饮料,深受广大消费者欢迎,但是旧生产工艺是自然发酵,即不能保证产品质量,而且又由于杂菌污染,而导致爆瓶,甚至伤人,后果严重,用固化酵母新技术生产麦花啤,完全克服了上述问题,结果十分令人满意。     

利用细胞质导入法选育嗜杀啤酒酵母

利用细胞质导入(Cytoduction)法中的核融合缺陷细胞融合技术,在对酿酒酵母(Saccharomyces cerevisiae)D518菌株不做任何遗传标记,将嗜杀酵母5045菌株的嗜杀质粒转移到受体菌D518中,获得了具有两亲株优良性状的融合子KD102菌株。对融合子分析表明:融合子遗传性状稳定,不仅含有供体菌5045的嗜杀质粒,而且受体菌D518的核基因被原封不动地保留下来,为异质体细胞(Heteroplasmon)。将融合子KD102菌株用于小型、中型及生产性酿酒试验,结果表明,具有与亲株D518同样的酿造特性。在发酵过程中,能抑制野生酵母污染,净化发酵体系。对于保证啤酒纯种酿造及提高成品酒的生物稳定性具有明显效果。     

Role of Plasmids in Lactobacillus brevis BSO 464 Hop Tolerance and Beer Spoilage

Specific isolates of lactic acid bacteria (LAB) can grow in the harsh beer environment, thus posing a threat to brew quality and the economic success of breweries worldwide. Plasmid-localized genes, such as horA, horC, and hitA, have been suggested to confer hop tolerance, a trait required for LAB survival in beer. The presence and expression of these genes among LAB, however, do not universally correlate with the ability to grow in beer. Genome sequencing of the virulent beer spoilage organism Lactobacillus brevis BSO 464 revealed the presence of eight plasmids, with plasmids 1, 2, and 3 containing horA, horC, and hitA, respectively. To investigate the roles that these and the other five plasmids play in L. brevis BSO 464 growth in beer, plasmid curing with novobiocin was used to derive 10 plasmid variants. Multiplex PCRs were utilized to determine the presence or absence of each plasmid, and how plasmid loss affected hop tolerance and growth in degassed (noncarbonated) beer was assessed. Loss of three of the eight plasmids was found to affect hop tolerance and growth in beer. Loss of plasmid 2 (horC and 28 other genes) had the most dramatic effect, with loss of plasmid 4 (120 genes) and plasmid 8 (47 genes) having significant, but smaller, impacts. These results support the contention that genes on mobile genetic elements are essential for bacterial growth in beer and that beer spoilage ability is not dependent solely on the three previously described hop tolerance genes or on the chromosome of a beer spoilage LAB isolate.     

Hopped Beer: The Case For Cultivation

The history of hops, hopped beer, and hop cultivation is unclear and ambiguous. An assessment of the available literature reveals many contradictions, especially regarding the first use of hops in beer and the earliest incidence of hop cultivation. Historically, hops were used for a variety of purposes; now their primary use is as a preservative and flavoring in beer. Hop cultivation is poorly documented, but was certainly undertaken by the 10th century, most probably in response to the demand generated by beer-brewing. After comparing the literature and investigating source material, a chronology of hop use in beer and hop cultivation is proposed.     

Effect of Beer Ingestion on the Plasma Concentrations and Urinary Excretion of Purine Bases: One-Month Study

To investigate the effect of long-term beer ingestion on the plasma concentrations and urinary excretion of purine bases, 5 healthy males participated in the present study, during which they ingested beer every evening for 30 days. Blood and 24-hour urine samples were collected in the morning one day before and 14 and 30 days after the initiation of the beer ingestion. During the beer ingestion period, the plasma concentration and the urinary excretion of uric acid were increased significantly, while uric acid clearance was not decreased. Further, purine ingestion was not significantly different throughout the study. These results suggest that production of uric acid by ethanol ingestion was the main contributor to the increased plasma uric acid. Therefore, patients with gout should be encouraged to avoid drinking large amounts of beer on a daily basis.     

The use of chitooligosaccharide in beer brewing for protection against beer-spoilage bacteria and its influence on beer performance

Objectives

To identify a biological preservative that can protect beer from microbial contamination, which often results in the production of turbidity and off-flavor.

Results

The antimicrobial activity of a chitooligosaccharide against beer-spoilage bacteria and its effect on the fermentation performance of brewer’s yeast was studied. Chitooligosaccharide with an average 2 kDa molecular weight was the best at inhibiting all tested beer-spoilage bacteria. The application of chitooligosaccharide in the brewing process did not influence the fermentation of brewer’s yeast. The change in beer performance induced by the contamination of Lactobacillus brevis could be effectively controlled by application of chitooligosaccharide in the beer brewing process.

Conclusion

The experimental data suggested that chitooligosaccharide should be an excellent preservative to inhibit beer-spoilage bacteria in the brewing process and in the end product.

     

Brewhouse-resident microbiota are responsible for multi-stage fermentation of American coolship ale

American coolship ale (ACA) is a type of spontaneously fermented beer that employs production methods similar to traditional Belgian lambic. In spite of its growing popularity in the American craft-brewing sector, the fermentation microbiology of ACA has not been previously described, and thus the interface between production methodology and microbial community structure is unexplored. Using terminal restriction fragment length polymorphism (TRFLP), barcoded amplicon sequencing (BAS), quantitative PCR (qPCR) and culture-dependent analysis, ACA fermentations were shown to follow a consistent fermentation progression, initially dominated by Enterobacteriaceae and a range of oxidative yeasts in the first month, then ceding to Saccharomyces spp. and Lactobacillales for the following year. After one year of fermentation, Brettanomyces bruxellensis was the dominant yeast population (occasionally accompanied by minor populations of Candida spp., Pichia spp., and other yeasts) and Lactobacillales remained dominant, though various aerobic bacteria became more prevalent. This work demonstrates that ACA exhibits a conserved core microbial succession in absence of inoculation, supporting the role of a resident brewhouse microbiota. These findings establish this core microbial profile of spontaneous beer fermentations as a target for production control points and quality standards for these beers.     

Beer Consumption Increases Human Attractiveness to Malaria Mosquitoes

Background

Malaria and alcohol consumption both represent major public health problems. Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial. Our aim was to ascertain the effect of beer consumption on human attractiveness to malaria mosquitoes in semi field conditions in Burkina Faso.

Methodology/Principal Findings

We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes). Water consumption had no effect on human attractiveness to An. gambiae mosquitoes, but beer consumption increased volunteer attractiveness. Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers'' odours). The level of exhaled carbon dioxide and body temperature had no effect on human attractiveness to mosquitoes. Despite individual volunteer variation, beer consumption consistently increased attractiveness to mosquitoes.

Conclusions/Significance

These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.     

啤酒酵母代谢工程研究进展

啤酒工业上应用的啤酒酵母菌株在生产中都会存在着某些方面的缺陷。通过分析啤酒酵母某些代谢产物的代谢途径,寻找改变其代谢流量的方法,然后用分子生物学手段对其代谢流量加以改变,来调节啤酒酵母某些产物的代谢水平已经成为啤酒酵母育种的新方式。对酵母的底物利用、可操作性、控制有害副产物的产量及改善啤酒风味等方面的研究成果进行了综述。     

Studies on the Sunlight Flavour of Beer

In order to establish the mechanism of occurrence of sunlight flavour of beer in continuation of the preceding paper, humulone, lupulone, and their analogues and degradation compounds, i.e., cohumulone, adhumulone, 5-acetyl-3-methylfilicinic acid including analogues, tetrahydrohumulone, hexahydrolupulone, humulinic acid and lupuloxinic acid, were tested for the occurrence of sunlight flavour of beer.

As a result, among the above-mentioned compounds, humulone, lupulone, cohumulone, adhumulone, tetrahydrohumulone and hexahydrolupulone were found to cause the sunlight flavour, but the other compounds did not cause typical sunlight flavour. This fact shows that some specific structural components seem requisite for the occurrence of sunlight flavour of beer.

It was also revealed that isomerization caused by boiling accelerates the occurrence of the sunlight flavour of beer. Finally, the result of the experiment conducted by the gas chromatographic procedure showed that any new component is not detected by the exposure of beer to sunlight but, two components somewhat increased.