Changes in appearance and natural microflora on iceberg lettuce treated in warm, chlorinated water and then stored at refrigeration temperature

Li, Y.; Brackett, Robert E.; Shewfelt, Robert L.; Beuchat, Larry R.

doi:10.1006/fmic.2001.0401

Cited by 108 publications

(68 citation statements)

References 34 publications

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“…Enhanced growth may result from reduction in numbers of competitive background micro-organisms that might otherwise compete with L. monocytogenes. Li et al (2001b) observed that populations of mesophilic aerobic microorganisms, psychrotrophs and Enterobacteriaceae were reduced on lettuce subjected to the same treatments as those used in the present study. Tissue fluid and residual water from treatments may also enhance the rate of growth of L. monocytogenes.…”

Section: Discussionsupporting

confidence: 70%

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: Discussionsupporting

confidence: 70%

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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“…As a consequence, several innovative approaches have been explored for the decontamination of minimally processed vegetables. The bulk of them have been devoted to eliminate pathogens (Beuchat, 2000;Parish et al, 2003), and little research has appeared on spoilage microorganisms and the effect of these methods on the sensory attributes of the minimally processed vegetables and their nutritional value and shelf-life (Allende & Artes, 2003a, 2003bLi, Brackett, Shewfelt, & Beuchat, 2001). …”

Section: Microbiology Of Minimally Processed Vegetablesmentioning

confidence: 99%

Extending and measuring the quality of fresh-cut fruit and vegetables: a review

Rico¹,

Martín‐Diana²,

Baviera

et al. 2007

Trends in Food Science & Technology

857

524

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“…Detection in food and water samples is difficult, because innocuous microorganisms may be present at high levels and may mask small numbers of potentially hazardous EHEC cells. For example, leaf surfaces average 10 7 to 10 8 epiphytic bacteria/ cm 2 in the field, creating a potential problem for pathogen detection in fruits and vegetables, especially because microbial populations typically increase during storage (12,13). Consequently, public health organizations worldwide use an initial enrichment step to minimize competitors and to increase the number of any target cells.…”

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confidence: 99%

Improved Laboratory Enrichment for Enterohemorrhagic Escherichia coli by Exposure to Extremely Acidic Conditions

Grant

2004

Appl Environ Microbiol

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Analysis of food samples for E. coli O157:H7 using the standard U.S. Food and Drug Administration procedure is frequently complicated by overgrowth of nontarget microorganisms. A new procedure was developed for enrichment of enterohemorrhagic E. coli (EHEC) which utilizes exposure to pH 2.00 for 2 h. This procedure yielded larger populations of EHEC than the standard method by factors ranging from 2.7 to 7.7 and, when age-stressed cultures were used, by factors ranging from 2.7 to 11.5. Cultures of competing enterics were more effectively inhibited by the new enrichment protocol as well.

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Changes in appearance and natural microflora on iceberg lettuce treated in warm, chlorinated water and then stored at refrigeration temperature

Cited by 108 publications

References 34 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

Extending and measuring the quality of fresh-cut fruit and vegetables: a review

Improved Laboratory Enrichment for Enterohemorrhagic Escherichia coli by Exposure to Extremely Acidic Conditions

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