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Survival and growth of Listeria monocytogenes on romaine lettuce as influenced by crisping and misting
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Guo, Mengqi. Survival and growth of Listeria monocytogenes on romaine lettuce as influenced by crisping and misting. Retrieved from https://doi.org/doi:10.7282/T35D8V96

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TitleSurvival and growth of Listeria monocytogenes on romaine lettuce as influenced by crisping and misting
NameGuo, Mengqi (author); Matthews, Karl (chair); Schaffner, Donald W. (internal member); Chikindas, Michael (internal member); Rutgers University; Graduate School - New Brunswick
Date Created2017
Other Date2017-01 (degree)
SubjectFood Science, Listeria monocytogenes, Lettuce--Microbiology
Extent1 online resource (ix, 54 p. : ill.)
DescriptionListeria monocytogenes is a foodborne pathogen of particular concern for manufacturers of refrigerated fresh produce because of its wide distribution in the environment and its ability to grow at refrigeration temperature. Approximately, two-thirds of supermarkets implement crisping and misting to enhance product appearance and quality. Based on the FDA food code, water used for soaking, submersion, hydrating, or crisping does not need to contain chemical sanitizers. When product is submerged in water, cross-contamination may occur. Therefore, the impact of crisping in water with and without sanitizer was investigated. The study was coupled with determining the influence of misting on growth and survival of L. monocytogenes. Romaine lettuce was inoculated with L. monocytogenes cocktail to achieve initial population of ca. 5.5 log CFU/g, heads were submerged in tap water or tap water containing electrolyzed water for 5 min and then held at 5 oC for 2 h to crisp. Half of the crisped lettuce heads were placed in a refrigerated commercial display cabinet and misted for 24 h. Lettuce was then transferred to a refrigerator (5 oC and 15 oC) and held for 7 days. The population of L. monocytogenes and psychrotrophic bacteria was determined at day 0, 1, 4, and 7 for each treatment and temperature. The results showed that crisping in electrolyzed water significantly reduced (P<0.05) the population of L. monocytogenes by 2.93 log compared to tap water alone (1.32 log reduction). An additional 1 log reduction in population of L. monocytogenes occurred after 24 h misting. The population of L. monocytogenes remained relatively constant during 7 days of refrigerated storage. There was no significant difference in population of L. monocytogenes on lettuce held at 5oC or 15oC. Crisping and misting treatments reduced the population of psychrotrophic bacteria on lettuce. The psychrotrophic bacteria population was greater on lettuce held at 15oC, reaching 6.99-7.54 log CFU/g after 7 days. Results of the present study suggest that crisping treatment, especially with electrolyzed water sanitizer significantly reduced the population of L. monocytogenes on romaine lettuce. Misting also had a negative effect on the survival and growth of L. monocytogenes. Based on the methods used in the present study, the practice of crisping with a commercial sanitizer and misting may enhance the microbial safety of commodities sold at retail supermarkets.
NoteM.S.
NoteIncludes bibliographical references
Noteby Mengqi Guo
Genretheses, ETD graduate
Persistent URLhttps://doi.org/doi:10.7282/T35D8V96
Languageeng
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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