Fates of Seeded Escherichia coli O157:H7 and Salmonella on Selected Fresh Culinary Herbs during Refrigerated Storage

Abstract

The fates of seeded Escherichia coli O157:H7 and Salmonella on selected fresh culinary herbs were evaluated at a refrigerated temperature (4 degrees C). Fresh herbs, including cilantro, oregano, basil, chive, parsley, and rosemary, were inoculated with six-strain mixtures of E. coli O157:H7 and Salmonella, and the microbial populations were monitored at 1, 5, 11, 16, 19, and 24 days. For both pathogens, a significant decrease in the population (P < 0.0001) occurred within the first 5 days of storage (< 0.8 log). Both pathogens remained the highest on cilantro and the lowest on rosemary (P < 0.0001). Storage time had a significant effect on the survival of E. coli O157:H7; populations declined as storage time progressed. Although storage of cilantro, basil, and chive was terminated after 19 days because of deteriorated quality, significant numbers of both pathogens were recovered from the remaining fresh herbs after 24 days of storage. The results showed that both bacteria were extremely persistent on all test herbs under the test conditions. The results also reinforce the concept that, once contaminated, bacterial pathogens can persist on fresh herbs throughout a normal distribution time.

Survival of Salmonella on Basil Plants and in Pesto

“…These findings lend support to recent studies that looked at herb contamination by Salmonella (14) and E. coli 0157 (16). Similarly, Hsu et al (13) found that E. coli 0157:H7 and Salmonella survived on fresh herbs, including basil. The phyllosphere of plants is a harsh environment for enteric pathogenic bacteria, and it is expected that there will be a reduction in numbers (15).…”

Growth potential of Salmonella spp. and Listeria monocytogenes in nine types of ready-to-eat vegetables stored at variable temperature conditions during shelf-life

“…and/or L. monocytogenes has been studied in several vegetables such as broad leafy endives (Carlin et al, 1995), lettuces (Koseki and Isobe, 2005a,b), carrots (Finn and Upton, 1997), cabbage (Finn and Upton, 1997), peppers and tomatoes , herbs (Hsu et al, 2006), spinach (Pirovani et al, 2000), and radish (Islam et al, 2004) but not in RTE collard greens, watercress, arugula and mix for yakisoba. Therefore, the current study reports for the first time the growth potential of Salmonella and L. monocytogenes in these RTE vegetables.…”

Survival of Salmonella and Escherichia coli O157:H7 on Strawberries, Basil, and Other Leafy Greens during Storage

“…Foodborne outbreaks occurred with strawberries and basil after transport and storage, suggesting survival of E. coli 0157:H7 or Salmonella on both commodities, even in adverse environ ments. Although survival of these pathogens has been studied on leafy greens, such as spinach (45,54), escarole (1,54), and especially, on fresh-cut iceberg or romaine lettuce (11,20,22,58,61), and growth models are available for iceberg lettuce (37,47) to predict growth of E. coli under temperature abuse, limited information is available about the survival of E. coli 0157:H7 and Salmonella on basil leaves during storage (29,35). Moreover, no information about the survival of Salmonella or E. coli 0157:H7 on basil leaves during storage at 15°C is available, which is the recom mended temperature to maintain quality during storage.…”