Master of Science (MS)
Plant Pathology and Crop Physiology
Floodwater can contain microbial contaminants such as plant and foodborne pathogens and can compromise the quality of fresh fruit and vegetables produced in Louisiana. The goal of this research was to determine the impact of flooding on microbial quality (foodborne and plant pathogens) of cantaloupe fruit produced on raised or flat beds. Cantaloupe fruit produced on 30 cm raised beds or flat ground, were flooded with a mixture of surface and well water spiked with three generic Escherichia coli strains (ATCC 23716, 25922, 11775). Mean baseline generic Escherichia coli and total coliform populations in flood water (mixture of spiked well and pond water) were 5.1±0.4 and 6.2±0.1 log10MPN/100ml respectively. There were no significant differences (p=0.7509 or p=0.4041 log10MPN/cm2 and log10MPN/100ml respectively) in generic Escherichia coli on fruits surface from raised or flat beds. Independent of bed type, total coliform populations on fruit surface were consistent (p=0.2324 or p=0.1865 log10MPN/cm2 and log10MPN/100ml respectively) over 72 hours, while generic Escherichia coli populations decreased significantly (p=<0.0001 or 0.0001 log10MPN/cm2 and log10MPN/100ml respectively). There were no significant differences in the number of fruits positive for Salmonella spp. over time (RapidChek, p=0.3916; Xylose lysine desoxycholate (XLD), p=0.0634; polymerase chain reaction (PCR), p=0.4100), and between flooded and non-flooded plot (RapidChek, p=0.3916; XLD, p=0.0634; PCR, p=0.4100). Fruits positive for L. monocytogenes did not differ significantly over time and between flooded and non-flooded plots based on listeria semi-selective agar medium (LSA, p=0.9196) and polymerase chain reaction (PCR; p=0.9289) and between flooded and non-flooded plots (LSA, p=0.5056 and PCR, p=0.4966). Independent of bed type, mean fruit rot incidence caused by Sclerotium rolfsii or Phytophthora spp. increased significantly by 17.6% (p=0.0001) and 20% (p=0.0001) respectively one week after flooding. No significant differences were detected in mean percent fruit rot incidence for Southern Blight (Sclerotium rolfsii) (p=0.4231) or Phytophthora fruit rot (Phytopthora capsici) (p=0.2657) between fruit produced on raised beds or flat ground. There is evidence that the quality of cantaloupe fruit might drop significantly with or without floods due to foodborne and plant pathogen contamination in production hence presenting a major public health risk to consumers.
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Kikway, Isaack, "Evaluation of the Microbial Quality of Cantaloupe Fruit Produced on Raised or Flat Beds Following a Flooding Event" (2017). LSU Master's Theses. 4508.
Ivey Melanie Lewis
Available for download on Saturday, February 23, 2019