Changes in Populations of Listeria monocytogenes Inoculated on Packaged Fresh-Cut Vegetables

Farber, J. M.; Wang, S. L.; Cai, Ying; Zhang, S.

doi:10.4315/0362-028x-61.2.192

Cited by 108 publications

(45 citation statements)

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“…Beuchat and Brackett (1990), in contrast, reported that populations of L. monocytogenes on unwashed, shredded lettuce were essentially unchanged throughout 15 days of storage at 5°C. Other researchers have reported that L. monocytogenes grows at refrigeration temperature on fresh-cut vegetables (Garcia-Gimeno and Zurera-Cosano 1997;Farber et al 1998), endive (Carlin et al 1996) and shredded cabbage (Kallander et al 1991).…”

Section: Discussionmentioning

confidence: 99%

Mild heat treatment of lettuce enhances growth of Listeria monocytogenes during subsequent storage at 5oC or 15oC

Brackett

Chen

et al. 2002

J Appl Microbiol

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Aims: The objective of this study was to determine the influence of mild heat treatment, storage temperature and storage time on the survival and growth of Listeria monocytogenes inoculated onto cut iceberg lettuce leaves. Methods and Results: Before or after inoculation with L. monocytogenes, cut iceberg lettuce leaves were dipped in water (20 or 50°C), containing or not 20 mg l -1 chlorine, for 90 s, then stored at 5°C for up to 18 days or 15°C for up to 7 days. The presence of 20 mg l -1 chlorine in the treatment water did not significantly (a ¼ 0AE05) affect populations of the pathogen, regardless of other test parameters. The population of L. monocytogenes on lettuce treated at 50°C steadily increased throughout storage at 5°C for up to 18 days. At day 10 and thereafter, populations were 1AE7-2AE3 log 10 cfu g -1 higher on lettuce treated at 50°C after inoculation compared with untreated lettuce or lettuce treated at 20°C, regardless of chlorine treatment. The population of L. monocytogenes increased rapidly on lettuce stored at 15°C. At 2 and 4 days, significantly higher populations were detected on lettuce that had been treated at 50°C, compared with respective samples that had been treated at 20°C, regardless of inoculation before or after treatment, or the presence of 20 mg l -1 chlorine in the treatment water. Conclusions:The results clearly demonstrated that mild heat treatment of cut lettuce leaves enhances the growth of L. monocytogenes during subsequent storage at 5 or 15°C. Significance and Impact of the Study: Mild heat treatment of cut lettuce may result in a prolonged shelf life as a result of delaying the development of brown discoloration. However, heat treatment also facilitates the growth of L. monocytogenes during storage at refrigeration temperature, thereby increasing the potential risk of causing listeriosis.

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Section: Discussionmentioning

confidence: 99%

Mild heat treatment of lettuce enhances growth of Listeria monocytogenes during subsequent storage at 5oC or 15oC

Brackett

Chen

et al. 2002

J Appl Microbiol

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“…The capacity of this organism to grow in a freshcut produce environment, including cabbage, has been well documented (4,8,10,16,25). We used a differential display method that compared the transcription of L. monocytogenes in two different environments: growth on plant tissue and growth in minimal medium.…”

Section: Discussionmentioning

confidence: 99%

Identification of Genes Induced in Listeria monocytogenes during Growth and Attachment to Cut Cabbage, Using Differential Display

Palumbo

Kaneko²,

Nguyen

et al. 2005

Appl Environ Microbiol

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The food-borne pathogen Listeria monocytogenes is a ubiquitous soil bacterium with the potential to contaminate fresh produce during cultivation and postharvest processing. In order to identify potential mechanisms by which L. monocytogenes may successfully attach to and colonize fresh produce, gene expression in L. monocytogenes cells inoculated onto fresh-cut cabbage was compared to gene expression in cells grown under control conditions. Differential display of reverse transcriptase PCR fragments amplified with a set of 81 arbitrary primers allowed the isolation and identification of 32 L. monocytogenes gene fragments that were observed to be more highly expressed under cabbage-associated conditions. Genes involved in carbohydrate, amino acid, and nucleic acid metabolism, motility and cell division, and transport were identified, as were a number of open reading frames (ORFs) encoding putative proteins with no known functions. Site-directed mutations in two ORFs encoding potential cell surface-associated proteins and a third ORF encoding a putative regulatory protein had no effect on the mutants' capacity to attach to fresh-cut cabbage. Although this study did not show clearly the impact of the differentially expressed genes on growth on cabbage, it is a first step in identifying some of the genetic factors that are potentially involved.Contamination of fresh-cut produce by Listeria monocytogenes is a great concern for both consumers and food processors. In the United States, there are approximately 2,500 cases of listeriosis per year, which result in about 500 deaths (21). The disease is systemic and can result in severe complications, such as septicemia, liver failure, meningitis, and abortion, in susceptible individuals (29). This gram-positive, facultatively intracellular pathogen is a saprophyte in its natural soil and agricultural niche, from which it can contaminate both plants and animals (5, 33). L. monocytogenes also grows well in food processing environments due to its ability to grow at refrigeration temperatures and its ability to survive within biofilms that can resist sanitation procedures. These abilities allow postharvest contamination of food (14).The first recognized instance of human listeriosis due to food contamination was a 1981 outbreak caused by contaminated coleslaw, which resulted in 41 cases and 18 deaths. The contamination was traced to a cabbage field on a farm known to have had cases of ovine listeriosis (30). An understanding of the physiology of L. monocytogenes when it is in association with plants may lead to better methods of eliminating it from the food supply. Toward that end, we set out to study the gene expression of L. monocytogenes in a fresh-cut cabbage system. We compared cDNA from L. monocytogenes grown in medium to cDNA from L. monocytogenes grown with cut cabbage, using a differential display method following reverse transcriptase PCR (RT-PCR), to identify genes that were upregulated when L. monocytogenes was grown in association with cabbage and in cabbage-assoc...

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“…Farber et al, 1998;Aureli et al 2000;Farber et al, 2000;Pingulkar et al, 2001). Figure 2 presents the empirical histogram of the 287 calculated TTE.…”

Section: Evaluation Of Sanitary Consequencesmentioning

confidence: 99%

Time–temperature profiles of chilled ready-to-eat foods in school catering and probabilistic analysis of Listeria monocytogenes growth

Rosset

Cornu

Noël

et al. 2004

International Journal of Food Microbiology

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Changes in Populations of Listeria monocytogenes Inoculated on Packaged Fresh-Cut Vegetables

Cited by 108 publications

References 0 publications

Mild heat treatment of lettuce enhances growth of Listeria monocytogenes during subsequent storage at 5oC or 15oC

Mild heat treatment of lettuce enhances growth of Listeria monocytogenes during subsequent storage at 5oC or 15oC

Identification of Genes Induced in Listeria monocytogenes during Growth and Attachment to Cut Cabbage, Using Differential Display

Time–temperature profiles of chilled ready-to-eat foods in school catering and probabilistic analysis of Listeria monocytogenes growth

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