首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
《Food Control》2007,18(11):1383-1390
Shredded carrots were inoculated with Escherichia coli O157:H7, Salmonella or Listeria monocytogenes and washed for 1 or 2 min with chlorine (Cl; 200 ppm), peroxyacetic acid (PA; 40 ppm) or acidified sodium chlorite (ASC; 100, 200, 500 ppm) under simulated commercial processing conditions. After washed, the carrots were spin dried, packaged and stored at 5 °C for up to 10 days. Bacterial enumeration was significantly (P  0.05) reduced by 1, 1.5 and 2.5 log CFU/g after washing with ASC 100, 250 and 500 ppm, respectively. All sanitizers reduced pathogen load below that of tap water wash and unwashed controls. During storage at 5 °C the bacterial load of all treatments increased gradually, but to different extent in different treatments. ASC inhibited bacterial growth more effectively than the other sanitizers and also maintained the lowest pathogen counts (<1 log CFU/g) during storage. Organic matter in the process water significantly (P  0.05) reduced the antibacterial efficacy of Cl, but not that of PA or ASC. Therefore, ASC shows the potential to be used as a commercial sanitizer for washing shredded carrots.  相似文献   

2.
In this study, the efficacy of hydrogen peroxide vapor (HPV) for reducing Salmonella Typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes on lettuce was investigated as well as its effect on lettuce quality. Lettuce was inoculated with a cocktail containing three strains of each pathogen then treated with vaporized hydrogen peroxide for 0, 2, 4, 6, 8 and 10 min. The concentrations of hydrogen peroxide used were 0, 1, 3, 5 and 10%. With increasing treatment time and hydrogen peroxide concentration, HPV treatment showed significant (P < 0.05) reduction compared to the control (0%, treated with vaporized distilled water). In particular, vaporized 10% hydrogen peroxide treatment for 10 min was the most effective combination for reducing the three pathogens on lettuce. The reduction levels of S. Typhimurium, E. coli O157:H7 and L. monocytogenes on lettuce were 3.12, 3.15 and 2.95 log10 CFU/g, respectively. Furthermore, there were no significant (P > 0.05) quality changes (color and texture) of lettuce among all tested samples, and hydrogen peroxide residues were not detected after 36 h storage time in any of the treated samples. These results suggest that HPV treatment could be an alternative method for reducing S. Typhimurium, E. coli O157:H7 and L. monocytogenes on fresh produce.  相似文献   

3.
This study was designed to determine the presences of two environmental pathogens in two dairy factories in Sakarya, Turkey. A total of 264 environmental samples, raw milk and cheese samples were taken at four different seasons. According to the results, Listeria monocytogenes or Escherichia coli O157:H7 was isolated from 26 or 2.7% of the samples collected from both factories, respectively. None of the cheese or curd samples were found to be positive for Listeria or E. coli O157:H7. However, 50% of raw milk samples contained Listeria innocua. Listeria was mostly isolated from the swap samples taken from the drains or the floors in processing or packaging areas. However, E. coli was also isolated from the swap samples taken from the workers’ hands and gloves as well as the drains and the floor. Only one raw milk sample contained E. coli O157:H7. A higher prevalence of both pathogens was observed in the summer months than in the other months.  相似文献   

4.
Combined non-thermal treatment with chlorine dioxide (ClO2) gas, ultraviolet-C (UV-C) light, and fumaric acid was performed to inactivate Listeria monocytogenes and Escherichia coli O157:H7 inoculated on plums. Plums were treated with ClO2 gas (15 and 30 ppmv), fumaric acid (0.1, 0.3, and 0.5%), and by UV-C irradiation (3, 5, and 10 kJ/m2). The single treatments with 15 or 30 ppmv ClO2 gas, 0.5% fumaric acid, and 10 kJ/m2 UV-C decreased the population of L. monocytogenes by 1.78, 2.00, 1.65, and 1.62 log CFU/g, respectively, and the population of E. coli O157:H7 by 1.73, 1.81, 1.34, and 2.07 log CFU/g, respectively. In addition, combined treatments reduced the populations of the pathogenic bacteria more than each treatment alone. In particular, the combined treatment with ClO2 gas (30 ppmv) for 20 min, fumaric acid (0.5%), and UV-C (10 kJ/m2) decreased the populations of L. monocytogenes and E. coli O157:H7 by 6.26 and 5.48 log CFU/g, respectively. These results suggest that combined treatment with ClO2 gas, UV-C light, and fumaric acid may be a useful hurdle technology to enhance the microbiological safety of plums.  相似文献   

5.
Y.J. Kim  M.H. Kim  K.B. Song 《Food Control》2009,20(11):1002-1005
The combined effect of aqueous chlorine dioxide (ClO2) and fumaric acid as a chemical treatment to inactivate pre-existing microorganisms was evaluated using broccoli sprouts. Broccoli sprouts were treated with distilled water, 50 ppm ClO2, 0.5% fumaric acid, and a combination of 0.5% fumaric acid and 50 ppm ClO2. Treatment with 50 ppm ClO2 and 0.5% fumaric acid reduced the initial populations of total aerobic bacteria, yeasts and molds, and coliforms in broccoli sprouts by 2.70, 2.46, and 1.71 log CFU/g, respectively. In addition, the combined treatment of 50 ppm ClO2 and 0.5% fumaric acid reduced the initial populations of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes inoculated on broccoli sprouts by 2.39, 2.74, and 2.65 log CFU/g, respectively, compared to the control. These results suggest that the combination of aqueous ClO2 and fumaric acid can be useful as a hurdle for extending the shelf life of broccoli sprouts during storage.  相似文献   

6.
Kimchi, a traditional Korean food, is fermented by lactic acid producing bacteria. Among the many types of kimchi, soongchimchae is a typical type of kimchi that combines fermented vegetables and meat. We aimed to investigate the survival of Escherichia coli O157:H7 and Listeria monocytogenes during the fermentation of kimchi supplemented with pork meat. Regardless of whether it was assessed in cabbage kimchi or radish kimchi, in which pH levels differ, the population of E. coli O157:H7 gradually decreased during the fermentation at 4 °C and was no longer detected in cabbage samples after 14 post-fermentation days (PFDs). The pH of cabbage kimchi and radish kimchi were 5.8 and 6.0, respectively, at 0 PFDs, changing to 3.9 and 4.1 at 15 PFDs. Although the population of L. monocytogenes gradually decreased, L. monocytogenes did not survive in cabbage kimchi or radish kimchi after 15 PFDs. Compared with radish kimchi, the pH of cabbage kimchi dropped rapidly during the early fermentation period and reached a pH of 3.9 at 15 PFDs. We observed that pH changes during fermentation were associated with a reduction in foodborne bacterial pathogens. Antimicrobial factors and inhibitory mechanisms against foodborne bacteria need to be investigated in the different types of kimchi.  相似文献   

7.
Acid solutions are increasingly being used for decontaminating meat surfaces. On the surfaces of acid-treated meat, the population of microorganism is reduced due to the low pH of acids, and the subsequent growth of the microorganism is reduced due to the residual acids on meat surfaces. Microbial cells on meat surfaces subjected to acid treatments may cross-contaminate untreated meat surfaces, e.g., microorganisms on the surfaces of acid-treated cooked ham cross contaminate the untreated surfaces during slicing. The objective of this study was to examine this scenario in determining the subsequent growth of acid-treated Listeria monocytogenes and Escherichia coli O157:H7 on the surfaces of untreated meat. Cells of multiple-strain L. monocytogenes or E. coli O157:H7 were exposed to HCl solutions of pH 3, 4, or 5 and deionized water at room temperature for 24 h. The acid or deionized water-treated cells were inoculated separately onto cooked ham. Samples inoculated with L. monocytogenes were stored at 4 and 8 °C and samples inoculated with E. coli O157:H7 were stored at 10 and 12 °C. Populations of the pathogens on ham were enumerated during storage, and the lag phase durations (LPD, h) and growth rates (GR, log CFU/h) of the pathogens were determined. The populations of L. monocytogenes and E. coli O157:H7 in pH 5, 4, and 3 solutions were 1.2–3.1 and 0.6–2.4 log CFU/ml, respectively, lower than those in deionized water, indicating an increased acid stress on both microorganisms at lower pHs. L. monocytogenes subjected to pH 3 and pH 4 stresses and E. coli O157:H7 subjected to pH 3 stress exhibited significantly (p < 0.05) extended LPDs and reduced GRs on cooked ham. The growth of L. monocytogenes on ham was more readily reduced by acid stress than that of E. coli O157:H7. This study showed that acid treatments reduced the viability of L. monocytogenes and E. coli O157:H7and the acid stress reduced their subsequent growth ability on untreated ham. Therefore, cross-contamination of L. monocytogenes or E. coli O157:H7 cells from acid-treated meat surfaces onto untreated meat surfaces may not impose increased risk to the product.  相似文献   

8.
《Food Control》2007,18(5):548-553
This study evaluated the effects of ozonated water (1, 3, and 5 ppm) alone with different exposure times (0.5, 1, 3, or 5 min), and combinations of 3 ppm ozone with 1% organic acids (acetic, citric, or lactic acids) during 5-min exposure for control of Escherichia coli O157:H7 and Listeria monocytogenes on enoki mushroom and to observe the regrowth of these pathogenic bacteria on treated enoki mushroom during storage for 10 days at 15 °C. Results showed that ozone treatment gave less than 1.0- and 0.5-log count reductions on E. coli O157:H7 and L. monocytogenes, respectively. Efficacy was improved with combined 3 ppm ozone and 1% citric acid treatment, resulting in 2.26- and 1.32-log count reductions, respectively. During storage at 15 °C (10 days) after combined treatment and packaging, populations of E. coli O157:H7 and L. monocytogenes increased to more than 8.0 log cfu/g, indicating that the combined 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 than individual treatments in reducing initial population levels of these pathogens on enoki mushroom.  相似文献   

9.
Beef jerky is a convenient, ready-to-eat meat product, but requires processing lethality steps to ensure the safety of the product. Previous outbreaks involving various jerky products have highlighted the risks associated with jerky and the importance of utilizing pathogen interventions during processing. In this study, two alternative interventions were evaluated for reducing pathogen populations during jerky processing. Results demonstrated that high pressure processing (HPP; two treatments of 550 MPa, 60 s) could produce significant (p < 0.05), but variable reductions (6.83 and 4.45 log10 CFU/strip) of Salmonella spp. and Escherichia coli O157:H7, respectively, on resulting beef jerky. HPP treatments, however, produced minor reductions (p < 0.05) of Gram-positive pathogens, resulting in reductions of 1.28 and 1.32 log10 CFU/strip of Listeria monocytogenes and Staphylococcus aureus, respectively. Alternatively, boiling water (100 ± 2 °C) treatments (20–30 s) used after marination and prior to dehydration, reduced Salmonella spp., E. coli O157:H7, L. monocytogenes, and S. aureus populations >5.0 log10 CFU/strip in resulting beef jerky. Thus, 20 or 30 s boiling water (100 ± 2 °C) treatments could be effective interventions for commercial jerky processors or home food preservers. Future validation of these processes in-plant could provide processors and regulators with alternative strategies for safe and shelf-stable jerky products.  相似文献   

10.
The goal of this study was to evaluate the efficacy of a novel antimicrobial solution made with chitosan, lauric arginate ester, and organic acids on Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and non-O157 shiga toxin-producing E. coli cocktails and to test its potential to be used as a marinade for raw beef. Fresh beef top round steaks were surface-inoculated with the pathogen cocktails at approximately 2.5 or 4.5 Log CFU/cm2, marinated with the antimicrobial solution (AMS), and then stored at 4 °C for 6, 24, and 48 h. Three commercially available marinades were used for comparison. Results revealed that AMS had the most antimicrobial effect regardless of the type or inoculation level of pathogens (P < 0.05). After 6 h, the AMS marination reduced all pathogens to levels below the limit of detection (<1 Log CFU/cm2), resulting in a 3.5 Log CFU/cm2 reduction. When AMS was diluted with autoclaved distilled water by 5 times (AMS 1:5) or 10 times (AMS 1:10), its antimicrobial efficacy was impacted by marination time, the inoculated pathogens, and the inoculation levels. This study demonstrates that the developed antimicrobial solution has a great potential to be used during marination by consumers to ensure better food safety.  相似文献   

11.
Heat, acid, and salt have been commonly used to ensure the microbial safety of foods and are often used in combinations in many food products. When combined, they can produce different results, such as additive, synergistic, and antagonistic effects. However, there has been little investigation into the effect of these combination treatments. Therefore, in this study, the effect of combined treatment of heat, acid, and salt was investigated in laboratory media. All possible paired combinations among three factors, heat (55 °C), acid (0.25% acetic acid, [v/v]) and salt (3%, [w/v]) were tested and compared with individual treatments for killing E. coli O157:H7 in laboratory media. When salt was combined with heat, there was no significant difference in reduction of E. coli O157:H7 (additive effect). However, when acid was combined with heat, there was a higher reduction of E. coli O157:H7 (synergistic effect). When salt was combined with acid treatment, salt gave protection against acid treatment (antagonistic effect), thus, there was lower reduction of E. coli O157:H7 in the combined treatment than in the single acid treatment. Depending on the combination of preserving factors, results were different.  相似文献   

12.
The bactericidal efficacy of acidic electrolyzed oxidizing water (AC-EW) (pH = 2.30, free chlorine = 38 ppm) and sterile distilled water (DW) on three pathogens (Escherichia coli O157:H7 Salmonella Typhimurium, and Listeria monocytogenes) inoculated on raw trout skin, chicken legs and beef meat surfaces was evaluated. The decontaminating effect of AC-EW and DW was tested for 0 (control), 1, 3, 5 and 10 min at 22 °C. AC-EW significantly (P < 0.05) reduced the three pathogens in the inoculated samples compared to the control and DW. The level of reduction ranged between ca.1.5–1.6 logs for E. coli O157:H7 and S. Typhimurium in the inoculated foods. However, AC-EW exhibited less bactericidal effect against L. monocytogenes (1.1–1.3 logs reduction). AC-EW elicited about 1.6–2.0 log reduction in the total mesophilic count. Similar treatment with DW reduced pathogens load by ca. 0.2–1.0 log reduction and total mesophiles by ca. 0.5–0.7 logs. No complete elimination of the three pathogens was obtained using AC-EW possibly because of the level of organic matter and blood moving from food samples to the AC-EW solution. This study demonstrates that AC-EW could considerably reduce common foodborne pathogens in fish, chicken and beef products.  相似文献   

13.
Minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations of malic acid against Listeria monocytogenes, Salmonella Enteritidis and Escherichia coli O157:H7 inoculated in apple, pear and melon juices stored at 5, 20 and 35 °C were evaluated. MICs and MBCs against L. monocytogenes, S. Enteritidis and E. coli O157:H7 were significantly affected by storage temperature, juice characteristics and type of microorganism. Malic acid was more effective at 35 and 20 °C than at 5 °C in all studied fruit juices. E. coli O157:H7 was more resistant to malic acid than S. Enteritidis and L. monocytogenes. Apple, pear and melon juices without malic acid were inhibitory to E. coli O157:H7, S. Enteritidis and L. monocytogenes at 5 °C, whereas, MBCs of 1.5% (v/v) of malic acid in apple and pear juices, and 2% (v/v) in melon juice at 5 °C were needed to reduce E. coli O157:H7, those concentrations being higher than those required to reduce S. Enteritidis and L. monocytogenes in those fruit juices. In addition, concentrations of 2%, 2.5% and 2.5% (v/v) of malic acid added to apple, pear and melon juices, respectively, were required to inactivate the three pathogens by more than 5 log cycles after 24 h of storage at 5 °C. Transmission electron microscopy showed that malic acid produced damage in the cell cytoplasm of pathogens without apparent changes in the cell membrane.  相似文献   

14.
The effectiveness in the assurance of fresh vegetable microbiological quality of wash solutions containing 200 ppm free chlorine, 0.1 mg/ml benzalkonium chloride, 0.2% and 1% lactic acid was assessed on Escherichia coli O157:H7 and Yersinia enterocolitica contaminated lettuce and tomatoes. Y. enterocolitica reduction on tomatoes (5.08, 4.77 and 4.21 log after 0.2% lactic acid, 200 ppm chlorine and 0.1 mg/ml benzalkonium chloride treatments, respectively) were significantly higher than those for Y. enterocolitica on lettuce and E. coli O157:H7 on both vegetables. Antimicrobial treatment effects on bacterial counts and product quality after subsequent 7 day storage (4 °C and 22 °C) were determined. No pathogens were found in natural microflora of fresh vegetables.  相似文献   

15.
The wide application of nucleic acid amplification techniques and the increasing industrial interest toward rapid methods has led to the development and application of PCR based methods for the detection of microbial pathogens in food. In the present paper we describe the development of a multiplex PCR method for simultaneous detection of Salmonella enterica serovar Typhimurium, Listeria monocytogenes and Escherichia coli O157:H7 in a complex food matrix (liquid whole egg).Four different DNA extraction procedures were evaluated for their application on food and, among these, Chelex resin combined with a DNA purification step were found to better perform on the food system considered.A multiplex PCR system was developed, based on the evaluation and combination of published primer sets, and applied to the simultaneous detection of the target pathogens plus an internal amplification control, both in culture media and in a model food system.The overall system proposed, based on an overnight enrichment step followed by DNA isolation and multiplex PCR, was satisfactorily tested for its specificity and sensitivity and allowed the detection of the presence of bacterial DNA and the identification of the target pathogens down to 10 cells/25 g liquid whole egg.  相似文献   

16.
17.
Epidemiological data indicates that a large number of foodborne illnesses are attributed to cross-contamination during food preparation in the domestic kitchen. The objectives of this study were to evaluate the efficiency of household washing practices in removing Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Enteritidis on artificially contaminated lettuce and to determine the transfer rate of these three foodborne pathogens from contaminated lettuce to wash water, tomato, cabbage, and cutting boards during washing and cutting processes. Washing under the running tap water with scrubbing for 60 s was the most effective method in reducing pathogen populations by 1.86–2.60 log10 CFU/g. Also, final rinsing and scrubbing practices were found to enhance the efficiency of washing treatment. In this study, the transfer rates of S. Enteritidis, E. coli O157:H7, and L. monocytogenes from cutting board to cabbage and tomato via cutting process (17.5–31.7%) were higher (P < 0.05) than from wash water to cabbage and tomato (0.8–23.0%) during washing treatment. Overall, our findings suggest that wash water and cutting board can be potential vehicles in the dissemination of foodborne pathogens. Therefore, there is a need to promote consumer awareness for proper handling practices in the kitchen to minimise the risk of foodborne infection.  相似文献   

18.
《Food Control》2010,21(10):1354-1359
A simple cloth-based hybridization array system (CHAS) utilizing polyester cloth as the solid phase for DNA hybridizations has been adapted as a tool for the identification of presumptive verotoxigenic Escherichia coli O157:H7 colonies isolated from foods by standard culture techniques. Key indicator genes for this organism, rfbO157, fliCH7, vt1 and vt2 (encoding the O and flagellar antigenic determinants and verotoxin genes, respectively) were amplified in a multiplex PCR incorporating digoxigenin-dUTP, followed by hybridization of the amplicons with an array of specific oligonucleotide probes immobilized on polyester cloth, and subsequent immunoenzymatic assay of the bound digoxigenin label. This system includes a simple internal amplification control (IAC) to gauge PCR inhibition based on the incorporation of a primer pair with complementary 3′ ends, resulting in the generation of a unique “primer-dimer” detectable by hybridization with a specific capture probe immobilized on polyester cloth. The CHAS provided sensitive and specific detection of the E. coli O157:H7gene markers, exhibiting the expected patterns of reactivity with a panel of various target and non-target organisms.  相似文献   

19.
《Food Control》2007,18(8):961-969
Lauricidin and lactic acid were evaluated for their effects on growth and survival of Listeria monocytogenes (L55), Salmonella enteritidis (S552) and Escherichia coli O157:H7 (E19) inoculated onto raw chicken breast. Fresh, raw chicken breasts were purchased immediately after slaughter and transported on ice to the laboratory within 20 min. Each chicken breast was decontaminated by briefly dipping in 70% ethanol and passed through a flame of a Bunsen burner and then allowed to cool. The decontaminated Chicken breast was dipped in TSB broth, at room temperature (25 °C) for 15 min, containing approximately log 9 CFU/ml of L. monocytogenes, S. enteritidis or E. coli O157:H7. Initial counts of L. monocytogenes, S. enteritidis or E. coli O157:H7 counts in chicken breast immediately after dipping in TSB broth were in the range of log 7–log 8 CFU/g. After inoculation, the chicken breasts were kept at room temperature for 20 min to allow attachment. Each inoculated chicken breast (25 °C) was dipped in 0 (control – sterile water), 0.5%, 1%, 1.5% or 2% of lauricidin (w/v) or lactic acid (v/v) for 10, 20 or 30 min and then individually placed in oxygen-permeable polyethylene bags. Breasts were subjected to microbiological analyses after treatment (day 0) and after storage for 2, 5, 7, 10 and 14 d at 4 °C. Initial counts of L. monocytogenes, S. enteritidis and E. coli O157:H7, in chicken breast treated with lauricidin decreased by 2.90, 1.31 and 2.27 log CFU/g, respectively. Lauricidin was more effective in reducing L. monocytogenes population than S. enteritidis and E. coli O157:H7 population. Dipping chicken breast in lauricidin for 30 min caused a significant reduction of L. monocytogenes, S. enteritidis and E. coli O157:H7 population compared to 10 and 20 min dipping. Initial L. monocytogenes, S. enteritidis and E. coli O157:H7 counts on chicken breast treated with lactic acid decreased by 1.97, 1.71 and 2.59 log CFU/g, respectively. Lactic acid caused a higher reduction in initial S. enteritidis and E. coli O157:H7 counts compared to lauricidin.  相似文献   

20.
This study was performed to compare the effectiveness of saturated steam (SS) and superheated steam (SHS) in the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes biofilms on polyvinyl chloride (PVC) and stainless steel. Biofilms were formed on PVC and stainless steel coupons by using a mixture of three strains each of three foodborne pathogens at 25 °C. After biofilm development, PVC and stainless steel coupons were treated with SS at 100 °C and SHS at 125, 150, 175, and 200 °C for 5, 10, 20, and 30 s on both sides. The viable cell numbers of biofilms were significantly (p < 0.05) reduced as SHS temperature and exposure time increased. For all biofilm cells, SHS treatment resulted in an additional log reduction compared to SS treatments. After exposure to 200 °C steam for 30 s or 10 s on PVC or stainless steel, respectively, the numbers of biofilm cells were reduced to below the detection limit (1.48 log). This study demonstrated that SHS treatment effectively reduced populations of biofilm cells and reduced disinfection time compared to SS treatments and further evaluated its potential as an excellent intervention for controlling microbial biofilms and enhancing safety in the food processing industry.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号