天然抑菌剂对贵州糟辣椒“生花”菌株及常见食源菌的抑菌活性及应用

选取6种天然抑菌成分,考察其对引起贵州糟辣椒"生花"主要微生物及有害食源菌的体外抑菌性能及最小抑菌浓度(MIC),并将不同剂量复合配比的天然抑菌剂添加至糟辣椒制品中,追踪贮藏期间菌落总数和总酸含量的变化。结果表明,不同种类的天然抑菌成分对供试菌的抑菌效果和MIC存在较大差异,植物源抑菌成分对供试菌的抑菌效果优于曲酸和乳酸链球菌素,其中山苍子油、大蒜油的抑菌效果较好,对部分供试菌的MIC达到0.312μL/m L。最佳复合天然抑菌剂为山苍子油0.2%、大蒜油0.025%及生姜油0.025%,其对糟辣椒的抑菌效果和持续性及维持总酸稳定性的能力最优,糟辣椒贮藏180 d时,菌落总数降低了58.7倍,总酸含量降低0.22%。该研究在保证糟辣椒食用安全的前提下达到了较长的保质期,可为糟辣椒的绿色保质技术提供理论基础。

几种自动细菌鉴定系统鉴定食源性致病菌的准确性和重现性的评价(下)

2 结 果 各自动细菌鉴定系统检测致病菌的敏感性和特异性总结列于表3。表中数据表示鉴定结果在可接受的置信度水平时各系统检测致病菌的敏感性和特异性。不同自动细菌鉴定系统检测标准阳性株和标准阴性株的重现性结果列于表4。表中数值表示在相同置信度水平上检测结果相同的重复检测的百分比。

PCR荧光技术在阪崎肠杆菌检测中的应用

本文就婴幼儿配方奶粉中食源性致病菌阪崎肠杆菌的分类、来源、特性、致病性以及减少婴幼儿配方奶粉中阪崎肠杆菌的措施进行了介绍和综述。着重介绍了阪崎肠杆菌国内外检测标准、技术和检测仪器;综述了国际通行的保证食品安全的荧光PCR食源菌检测标准、仪器和方法;论述了荧光PCR法检测阪崎肠杆菌的政策要求、技术标准、实验技术、检测步骤以及荧光PCR实验室建设要点。

Bio-control of Some Food-Borne Pathogenic Bacteria by Bacteriophage

In recent years, researchers tended to bring new alternative to biological protective systems used in conservation of food and production of safe food. Use of bacteriophage against to pathogen bacteria in food was the most hopeful system in these methods about bio-control. Controls of bacteriophage for each pathogen species and subspecies and determination of phage-host originality are important because efficient bio-control was achieved. Researches concentrated on some food-borne pathogen bacteria such as E. coli O157：H7, Campylobacter, Salmonella and Listeria. In a consequence of these studies made as in vitro and in vivo, first commercial production of phage which will be used in foods was made in Netherlands. Also, it has been informed that use of phage is cost-efficient alternative as compared with other preservatives. This review, discussed application of bacteriophages as bio-control agents in food and advantages and disadvantages about uses of bacteriophages by taking into account antimicrobial characteristics of them.

Influence of Ultrasonic on Broken Effect of Foodborne Polluting Strains

[ Objective] The aim was to study on influence of ultrasonic on broken effect of foodborne polluting strains. [Method ] Escherichia coli, Staphylococcus aureus, and Aspergillus niger in different concentrations were tested in different ultrasonic powers and times for the broken effects.[ Result ] Eschedchia coil and Staphylococcus aureus were more sensitive to ultrasonication and the broken rates were as high as 96%. Aspergillus niger, however, was not so sensitive and the broken rate was only about 40%. The optimum parameters, including ultrasonic power, ultrasonic time and OD, of Escherichia coli were 600 W, 14 rain and 0.997, of Staphylococcus aureus were 600 W, 15 min and 1.440, and of Aspergillus ni- ger were 700 W, 20 min and 0.893, respectively. [ Conclusion] The research provided references for application of ultrasonic technology in food sterilization.

The Use of Str Mutations for Enhancement of Hydrogen Peroxide Formation by Lactobacillus Delbrueckii MH-IO at Refrigeration

The strains ofLactobacillus delbrueckii subsp, lactis widely used in food preservation due to ability produce high amount of hydrogen peroxide at refrigerator temperatures to inhibit food-borne pathogens and psychrophilic spoilage microorganisms. In order to improve of bio-preservation efficacy ofL. delbrueckii MH 10 mutations causing resistance to streptomycin （str） were used. Among UV-mutagenized population of L. delbruecla＇i three str mutants producing high amounts of H2O2 were selected. Sir mutants produced significant amounts of hydrogen peroxide 50-60 μg/ml in sodium phosphate buffer （0.2 M, pH 6.5） and in beef broth （BB） at 5 ℃ for 5 days submerged cultivation without of growth. Evaluation mutants antibacterialactivity at refrigeration temperatures against food-borne pathogen Escherichia coli O157：H7 revealed elimination of pathogen total number up to practically undetectable amount for 3 days. In case of solid-state cultivation on agar-based medium, disks soaked by mutant cells suspensions formed larger inhibitory zones on E. coli O157：H7 lawn for one-day cold exposition. The size of inhibition zone depends on concentration of LAB cells. Str mutants L. delbrueckii reduced initial amount 2 - 105 of E. coil O 157：H7 in ground beef up to 3 log for 3 days of solid-state cocultivation when the wild strain reduced only 2 log. The application ofL. delbrueckii mutants did not cause any changes in sensory characteristics of ground beef, moreover promotes expanding of shelf-life due to inhibition of psychrophilic spoilage microorganisms.

Analysis and Evaluation of Microbial Contamination of Raw Beef in Supermarkets in Phnom Penh

The study focused on analysis and evaluation of microbial contamination of raw beef was designed to （1） determine the presence of foodborne pathogens in raw beef; （2） compare the prevalence of microbial contamination among the three supermarkets, and （3） evaluate the sanitary quality of raw beef products. Also, six kind of microorganisms including Total Plate Count, Total Coliform and Fecal Coliform, which represented sanitary quality and E. coli, S. Aureus and B. cereus, which determined the presence of foodborne pathogens, were analyzed. The procedures used to analyse experimental samples taken from three supermarket （in every one week for three weeks） in Phnom Penh were based on Merck＇s study in 2005. The results had shown that there were no significant differences in Total Plate Counts, Total Coliform and Fecal Coliform in all samples, and they were found in unacceptable numbers in the raw beef products. However, the prevalence of foodborne pathogens including E. coli, S. aureus and B. cereus were found in acceptable numbers. Furthermore, the samples taken from the second supermarket had the highest level of microbial contamination among the three supermarkets, while the samples taken from the first supermarket had the lowest level of microbial contamination. This experimental finding demonstrated the need for sanitary improvement in the beef retails markets and strict sanitary guideline and implementation of these practices could guarantee consumers＇ health by consuming raw beefs with the lowest risk of foodborne pathogens.

Elimination of Foodborne Pathogens in Seafoods by Irradiation： Effects on the Quality and Shelf-Life

Animal originated contamination is the main problem of public health and causes human suffering all over the world. Nowadays, radiation technology is used on foods and yielded with positive results. Gamma radiation causes damage in the structure of bacterial DNA and cell walls. This irritation can lead to decrease in bacterial growth such as spoilage and pathogenic organisms （i.e, Salmonella spp., Bacillus cereus, Listeria monocytogenes, Yersinia enterocolitica, Staphylococcus aureus, Escherichia coli O 157：H7） by this means, increased quality and shelf-life can be obtained. However, for the maintaining organoleptic and nutritional quality, it is an obligation to achive the lowest levels of doses according to chemical, physical, microbiological properties of the product. Radiation energy can lead to radiolytic products from lipids, proteins and water which are the maj or components of seafoods. Another problem in seafood industry is quality losses at the retail and distribution. Time-temperature integrations are the major factors affecting the bacterial growth and enzymatic activity on the loss of seafood quality. The purpose of this review is to summarize the available information on the elimination of some food pathogens by irradition, which emphasize the effects of gamma irradiation on the quality and shelf-life of seafoods.