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Association of foodborne pathogens with Capsicum annuum fruit and evaluation of the fruit for antimicrobial compounds

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dc.contributor.authorHuff, Karleigh Roseen
dc.contributor.committeechairBoyer, Renee R.en
dc.contributor.committeememberWilliams, Robert C.en
dc.contributor.committeememberO'Keefe, Sean F.en
dc.contributor.committeememberDenbow, Cynthia J.en
dc.contributor.departmentFood Science and Technologyen
dc.date.accessioned2017-04-06T15:43:49Zen
dc.date.adate2011-09-27en
dc.date.available2017-04-06T15:43:49Zen
dc.date.issued2011-09-07en
dc.date.rdate2016-09-30en
dc.date.sdate2011-09-20en
dc.description.abstractHot peppers are gaining popularity in the United States as both a vegetable and a spice. In 2008, jalapeño peppers were involved in a multistate outbreak of Salmonella Saintpaul. This is the first outbreak implicating jalapeño as a vehicle for foodborne illness. Hot peppers contain many compounds thought to possess antimicrobial characteristics. This research was conducted to provide more information on the interactions of pathogenic bacteria and jalapeño peppers, as well as to identify properties of Capsicum annuum that affect bacterial survival, growth, and inhibition. Behavior of pathogens associated with jalapeños was investigated by inoculating jalapeño fruits with a cocktail of Listeria monocytogenes, Salmonella enterica, or Escherichia coli O157:H7 on the intact external surface, injured external surface, or intact internal cavity and storing the jalapeños at 7°C or 12°C. Intact external jalapeñosurfaces did not support the growth of the bacteria tested under storage conditions of 7°C. However, L. monocytogenes populations remained detectable throughout the 2 week study. At 7°C, pathogenic bacteria were able to survive but not grow on injured and internally inoculated jalapeño, but populations increased at 12°C (p=0.05). The most supportive growth environment for the pathogenic bacteria was the internal cavity of jalapeño held at 12°C. This study demonstrated the importance of intact uninjured produce and proper storage temperatures for food microbial safety. Inhibitory properties of jalapeños were studied by making extracts from fresh jalapeño peppers to test for antimicrobial activity. A disk diffusion assay determined that the extracts were capable of inhibiting the growth of the pathogenic bacteria tested. Listeria monocytogenes was especially sensitive to the extracts. jalapeño extracts were fractionated using HPLC and used for inhibition assays using disk diffusion and growth curve generation. Two fractions stimulated bacterial growth (p=0.05), while two other fractions inhibited bacterial growth. The inhibitory fractions were separated further using HPLC and tested for antimicrobial activity. Fraction E1 suppressed the growth of L. monocytogenes. HPLC-MS analysis revealed that Fraction E1 contained compounds known as capsianosides. To prove that inhibition is caused by capsianoside(s) and determine minimum inhibitory concentrations, a method to isolate the pure compound should be developed.en
dc.description.degreePh. D.en
dc.identifier.otheretd-09202011-130409en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-09202011-130409/en
dc.identifier.urihttp://hdl.handle.net/10919/77213en
dc.language.isoen_USen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectbacterial growth curveen
dc.subjectfoodborne pathogenic bacteriaen
dc.subjectliquid chromatographyen
dc.subjectgrowth and survivalen
dc.subjectCapsicum annuumen
dc.titleAssociation of foodborne pathogens with Capsicum annuum fruit and evaluation of the fruit for antimicrobial compoundsen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineFood Science and Technologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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