Survival of Escherichia coli O157:H7 and Salmonella enterica serovars Typhimurium in iceberg lettuce and the antimicrobial effect of rice vinegar against E. coli O157:H7.
The microbiological safety of fresh produce is a significant concern of consumers and industry. After applying at an inoculated level (about 10(6) CFUg(-1)) of E. coli O157:H7 and Salmonella enterica serovars Typhimurium on shredded iceberg lettuce and water samples individually, they were stored at 4 degrees C for 14 days and 22 degrees C for 7 days to monitor the growth and survival of pathogens. The results showed that at the end of 4 degrees C storage, populations of two pathogens in lettuce and water decreased approximately 1 log CFUg(-1). However, microbial levels on shredded lettuce increased 3 logs within 3 days at 22 degrees C. Vinegar (acetic acid) had been used to reduce populations of foodborne pathogens in foods; hence, the antimicrobial effect of rice vinegar on the survival of E. coli O157:H7 in inoculated lettuce (10(4) and 10(7) CFUg(-1)) is examined in this study. Results were observed that the treatment of inoculated lettuce (10(7) CFUg(-1)) with commercial vinegar containing 5% acetic acid (pH 3.0) for 5 min would reduce 3 logs population at 25 degrees C. Less than a 1-log decrease in bacterial numbers was recovered during 5 min exposure to 0.5% (pH 3.26) acetic acid.
Chang
Ju-Mei
JM
Department of Health, Central Region Laboratory, Bureau of Food and Drug Analysis, Executive Yuan, Taichung, Taiwan, ROC.
Fang
Tony J
TJ
D019342:Acetic Acid / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development*; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D018545:Lactuca / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D012486:Salmonella typhimurium / Q000187:drug effects / Q000254:growth & development*; D013997:Time Factors
D000900:Anti-Bacterial Agents; D019342:Acetic Acid