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本研究利用实验室保存的7株常见乳酸菌进行抑制大肠杆菌O157∶H7实验,其中4株乳酸菌对大肠杆菌O157∶H7有明显抑制效果,分别为嗜酸乳杆菌(SL1)、鼠李糖乳杆菌(SL2)、干酪乳杆菌(SL3)、植物乳杆菌(SL4)。将4株乳酸菌混合后不但抑菌效果强于4株任意单独菌株,其发酵滤液pH相比4株单独菌株下降速度最快,且pH最低。说明混合后的乳酸菌产酸能力也明显增强。将SL1、SL2、SL3、SL4通过排列组合(C(n,m))可分成11组混合菌液,然后通过牛津杯抑菌方法进行抑菌实验,结果显示乳酸菌组合(SL2、SL3、SL4)具有最佳抑菌效果。再将SL2、SL3、SL4按正交设计方案以不同比例的接种量混合成复合菌剂进行抑菌实验,结果表明:乳酸菌组合(SL2、SL3、SL4)以3∶1∶3比例制备复合菌剂时,对大肠杆菌O157∶H7的抑制效果最好。 相似文献
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近年来,因食源性致病菌造成的食品中毒正在不断增加,严重威胁了人类的健康,大肠杆菌（E.coli） O157∶H7由于其低感染剂量和高致病性等特点引起了研究人员和世界卫生组织的高度重视。因此精准快速的检测食品中的E.coli O157∶H7对食品安全问题有着重要的意义,是预防和控制食源性疾病传播的重要技术,为此本文对E.coli O157∶H7的常规检测方法、免疫学法、分子生物学法和其他方法进行论述,介绍了这些方法的优缺点,对各种方法进行了整体比较,以期为有关工作者在选择检测方法或研发新方法提供参考。 相似文献
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研究了甘草提取液对豆腐干中大肠杆菌(E.coli)O157∶H7的抑菌作用以及对豆腐干在10℃下的贮藏保鲜作用。根据响应面法优化的最佳工艺条件得到甘草提取液,用于大肠杆菌O157∶H7的抑菌研究,通过理化指标和感官评价研究对豆腐干的保鲜作用。结果表明提取的最佳条件为提取温度77.80℃,提取时间7.58 h,料液比1∶9.61(g/mL),5%甘草提取液使大肠杆菌O157∶H7在豆腐干中的停滞期达5.8 d,同时能延缓豆腐干的pH值和可滴定酸度、失水率、感官品质等变化。甘草提取液对大肠杆菌O157∶H7有较好的抑制作用,对豆腐干有一定的保鲜作用。 相似文献
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食品中出血性大肠杆菌O157:H7检验方法的建立 总被引：2，自引：0，他引：2
Ｏ157:Ｈ7大肠杆菌是出血性大肠埃希氏菌 (Ｅｎｔｅｒｏ -ｈｅｍｏｒｒｈａｇｉｃ.ｃｏｌｉＥＨＥＣ)的一个常见的血清型。自1982年美国首次发生由Ｏ157:Ｈ7大肠杆菌引起的食物中毒小型爆发以来 ,欧美各国、日本相继有本菌所致疫情爆发的报道。已知Ｏ157:Ｈ7是一种以食物传播为主要传播途径的人畜共患疾病的病原菌 ,生食受污染的食品或饮用水可引发感染 ,有时可导致大规模爆发流行。我国同样存在Ｏ157:Ｈ7引发食物中毒的隐患 ,建立统一的食品中Ｏ157:Ｈ7检验方法迫在眉睫。为此 ,我们参考日本厚生省及ＵＳＤＡ检验方法 ,[2 ,5] 建立了适用于… 相似文献
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Contaminated leafy green vegetables have been linked to several outbreaks of human gastrointestinal infections. Antimicrobial interventions that are adoptable by the fresh produce industry for control of pathogen contamination are in great demand. This study was undertaken to evaluate the efficacy of sustained active packaging on control of Escherichia coli O157:H7 and total aerobic bacteria on lettuce. Commercial Iceberg lettuce was inoculated with a 3‐strain mixture of E. coli O157:H7 at 102 or 104 CFU/g. The contaminated lettuce and un‐inoculated controls were placed respectively in 5 different active packaging structures. Traditional, nonactive packaging structure was included as controls. Packaged lettuce was stored at 4, 10, or 22 °C for 3 wk and sampled weekly for the population of E. coli O157:H7 and total aerobic bacteria. Results showed that packaging structures with ClO2 generator, CO2 generator, or one of the O2 scavengers effectively controlled the growth of E. coli O157:H7 and total aerobic bacteria under all storage conditions. Packaging structure with the ClO2 generator was most effective and no E. coli O157:H7 was detected in samples packaged in this structure except for those that were inoculated with 4 log CFU/g of E. coli O157:H7 and stored at 22 °C. Packaging structures with an oxygen scavenger and the allyl isothiocyanate generator were mostly ineffective in control of the growth of the bacteria on Iceberg lettuce. The research suggests that some of the packaging structures evaluated in the study can be used to control the presence of foodborne pathogens on leafy green vegetables. 相似文献
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Claire L. Hudson;Shirley A. Micallef; 《Journal of Food Safety》2024,44(5):e13169
Romaine lettuce is susceptible to Escherichia coli O157:H7 contamination. We evaluated strain and pre- and postharvest lettuce product differences in E. coli O157:H7 subpopulation distribution on romaine lettuce at two relative humidity (RH) levels. Plants of romaine lettuce cultivar 'Carlsbad' harvested and processed 'Carlsbad' leaves, and store-bought ready-to-eat romaine lettuce were inoculated with E. coli O157:H7 reference strain EDL933 and romaine lettuce outbreak strain 2705C. Using four processing methods, we determined pathogen cell fractions representing All (entire population), Epiphytic (loosely attached cells), Strongly Attached + Internal (excluding loosely attached cells), and Internal (excluding epiphytic cells) subpopulations. Preharvest, 80% RH favored subpopulations in each cell fraction, compared to 40% RH (p < 0.01 for both strains) and yielded 92%–100% internalization incidence of E. coli O157:H7, compared to 50%–57% at 40% RH. Levels of internal EDL933 cells were also 1.1 log higher than 2705C cells from plants kept at 80% RH (p < 0.001). While EDL933 had lower measures of Strongly Attached + Internal cells compared to All and Epiphytic fractions (p < 0.01), 2705C yielded no difference. Taken together, data suggest that the lettuce outbreak strain had a higher propensity for strong attachment to leaves and EDL933 internalized more successfully. Moreover, the Strongly Attached + Internal fractions of both strains were lower on preharvest 'Carlsbad' compared to 'Carlsbad' processed leaves (p < 0.01), suggesting that E. coli O157:H7 attached less strongly to preharvest plants than postharvest cut and stored leaves of the same variety. Our study uncovers important factors influencing cultivar- and strain-specific differences in association and internalization of enteric pathogens on leafy greens. 相似文献
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Abstract: The objective of this study was to evaluate the efficacy of slightly acidic electrolyzed (SAEO) water in killing or removing Escherichia coli O157:H7 on iceberg lettuce and tomatoes by washing and chilling treatment simulating protocols used in food service kitchens. Whole lettuce leaves and tomatoes were spot‐inoculated with 100 μL of a mixture of 5 strains of E. coli O157:H7. Washing lettuce with SAEO water for 15 s reduced the pathogen by 1.4 to 1.6 log CFU/leaf, but the treatments did not completely inactivate the pathogen in the wash solution. Increasing the washing time to 30 s increased the reductions to 1.7 to 2.3 log CFU/leaf. Sequential washing in SAEO water for 15 s and then chilling in SAEO water for 15 min also increased the reductions to 2.0 to 2.4 log CFU/leaf, and no cell survived in chilling solution after treatment. Washing tomatoes with SAEO water for 8 s reduced E. coli O157:H7 by 5.4 to 6.3 log CFU/tomato. The reductions were increased to 6.6 to 7.6 log CFU/tomato by increasing the washing time to 15 s. Results suggested that application of SAEO water to wash and chill lettuce and tomatoes in food service kitchens could minimize cross‐contamination and reduce the risk of E. coli O157:H7 present on the produce. Practical Application: SAEO water is equally or slightly better than acidic electrolyzed (AEO) water for inactivation of bacteria on lettuce and tomato surfaces. In addition, SAEO water may have the advantages over AEO water on its stability, no chlorine smell, and low corrosiveness. Therefore, SAEO water may have potential for produce wash to enhance food safety. 相似文献
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Hyun-Gyun Yuk Mee-Young Yoo Jae-Won Yoon Kwang-Deog Moon Douglas L. Marshall Deog-Hwan Oh 《Journal of food science》2006,71(3):M83-M87
ABSTRACT: This study was conducted to determine the effects of ozonated water (1, 3, and 5 ppm) alone with different exposure times (0.5,1,3, or5min), and combinations of 3 ppm ozone with 1% organic acids (acetic, citric, or lactic acids) during 1-min exposure for inactivating Escherichia coli O157:H7 and Listeria monocytogenes on lettuce and to observe the regrowth of these pathogenic bacteria on treated lettuce during storage for 10 d at 15°C. Results showed that 5 ppm ozone treatment for 5 min gave 1.09-log and 0.94-log reductions of E. coli O157:H7 and L. monocytogenes , respectively, indicating insignificant reductions compared with 3 ppm ozone treatment for 5 min. Treatment with 3 ppm ozone combined with 1 % citric acid for 1 min immersing resulted in 2.31 - and 1.84-log reductions ( P < 0.05), respectively. During storage at 15°C for 10 d after combined treatment and packaging, populations of E. coli O157:H7 and L. monocytogenes increased to approximately 9.0-log colony forming unit (CFU) /g, indicating that this treatment did not have a residual antimicrobial effect during storage. Although the storage study did not show control of these pathogens, the combined ozone-organic acid treatment was more effective in reducing population levels of these pathogens on lettuce than individual treatments. 相似文献
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Tung-Shi Huang Chuanling Xu Ken Walker Patricia West Shuqing Zhang Jean Weese 《Journal of food science》2006,71(4):M134-M139
ABSTRACT: The bacterial reduction of Salmonella and Escherichia coli O157:H7-inoculated apples and lettuce by ClO2 at 0, 5, 10, 20, and 40 ppm with and without 170-kHz ultrasonic treatments for 3, 6, and 10 min, respectively, have been studied. The treatments of ClO2 at 20 and 40 ppm for 3, 6, and 10 min or at 5 and 10 ppm for 6 and 10 min with 170-kHz ultrasonication caused 3.115 to 4.253 log reductions in Salmonella and 2.235 to 3.865 log reduction in E. coli O157:H7 on inoculated apples. Using combined ClO2 and ultrasonication to treat 4.48 × 104 CFU/g Salmonella and 1.07 × 105 CFU/g E. coli O157:H7-inoculated lettuce, the bacterial reductions were 2.257 to 2.972 and 1.357 to 2.264 log, respectively. The residual ClO2 decreased with increasing treatment times, over 80% of ClO2 was detected after the 3-min treatment, and more than 70% remained after the 10-min treatment time. No bacteria were recovered from the posttreatment solutions of ClO2 or ClO2 combined with ultrasonication. The temperature of the ClO2 treatment was 20.1 °C, and it increased to 40.1, 44.9, and 50.3 °C, with 170-kHz ultrasonic treatments for 3, 6, and 10 min, respectively, on apples. 相似文献
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Five strains of Escherichia coli O157:H7 with ATCC 11775 E. coli were grown in brain heart infusion (BHI) broth (pH 5.8, adjusted with citric acid) and treated with butylated hydroxyanisole (BHA), butylated hy-droxytoluene (BHT), tertiary butylhydroquinone (TBHQ), and propyl gallate (PG) individually or combined. Additives ranged from 100–400 ppm with inocula levels between 5 and 104 CFU/mL in tissue culture plates or in flasks; samples were incubated at 4°C or 37°C for 24 hr. Additive antimicrobial efficacy varied with inoculum level and incubation temperature. BHA at <200 ppm was bactericidal on all strains. Poly-hydroxyl additives (TBHQ, PG) were less effective at 4°C. BHA-BHT combinations were synergistic at 4°C. 相似文献
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近年来, 生物传感器因具有快速、简便、灵敏度高、低成本等优势被广泛应用到临床检测、环境监测等领域。该技术在食品安全领域也逐步得到重视, 尤其在病原微生物的快速检测方面。本文从免疫识别和核酸识别两方面简要介绍生物传感器技术检测食源性大肠杆菌O157:H7研究的最新进展, 对生物传感器技术存在的问题及未来的研究方向进行了总结及展望。 相似文献
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ABSTRACT: The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichia coli O157:H7 and Listeria monocytogenes on lettuce. After surface inoculation, each leaf was immersed in 1.5 L of EO or acidified chlorinated water for 1 or 3 min at 22 °C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log10 CFU per lettuce leaf for 3 min treatments, respectively (p < 0.05). However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p > 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage. 相似文献
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贮藏于4℃的家制酸奶中低浓度大肠杆菌O157:H7的存活研究 总被引：1，自引：0，他引：1
牛奶预热后分装并分别接种体积分数3%的酸奶和2.15(lg(CFU/mL))的大肠杆菌O157:H7,在45℃下发酵5h后贮藏于4℃的冰箱中。利用Pathatrix大体积循环系统中偶联了抗体的免疫磁珠特异性地捕获这些酸奶中的大肠杆菌O157:H7。免疫磁珠重悬于1%的蛋白胨水后涂布于添加了新生霉素(5mg/L)的山梨醇麦康凯固体培养基中,培养基在37℃恒温培养箱中放置24h。实验结果表明,酸奶中大肠杆菌O157:H7的数量逐渐减少,12d后才检测不到。因此乳制品加工及保存过程中,需要加强对大肠杆菌O157:H7污染的监测,以保证乳制品的安全性。 相似文献