Graduate Thesis Or Dissertation
 

Important Considerations for Food Process Validations : Strain Selection, Contamination Level, and Relevant Treatment Conditions

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/qr46r3635

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  • Reports of foodborne outbreaks have increased in the last decade, posing a public health risk to consumers. In an attempt to mitigate this risk, the newly established Food Safety and Modernization Act (FSMA) takes a preventive rather than reactive approach to food safety. Under FSMA, producers are required to validate preventive control processes as part of their Hazard Analysis Risk-Based Preventive Controls (HARPC) plan. Process validation studies are used to validate preventive controls on a product, process, and strain-specific level. When designing a validation study, careful consideration of strain selection, inoculation level, method of inoculation, and conditions specific and relevant to normal processing should be taken. This thesis was designed to evaluate a common but unsubstantiated assay used in strain selection for process validations, and analyze the impact of inoculation level, naturally contaminated product, and process-relevant treatment conditions on process validations. The initial study provided a review of data available in literature regarding expression of the rdar (red, dry, and rough) morphotype and its potential use as a screening tool for strain selection in food process validations. Additionally, an optimized assay method was developed and proposed. This optimized assay was used to characterize the morphotype of over 200 previously unreported Salmonella and Shiga-toxin producing E. coli isolates, the results of which are included. Available data correlating the rdar morphotype to increased resistances relevant to food processing were discussed, as well as gaps in literature that should be filled prior to using the rdar assay as a screening method for increased resistance to processing treatments in process validations. The second study evaluated the efficacy of peroxyacetic acid at reducing low levels of Salmonella spp. on inoculated or naturally contaminated in-shell Oregon hazelnuts. Taking a novel approach to food process validation studies, this study investigated the impact of low level contamination, natural and artificial contamination, and industry relevant treatment conditions on process efficacy. Hazelnuts inoculated at low levels were submerged with little agitation in either water or peroxyacetic acid for one minute and analyzed for presence or absence of Salmonella. Achieving significantly less reduction than similar studies in literature, these factors may be important to consider when designing a process validation study.
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file details PearsonEvaH2016.pdf 2017-08-14 Público Descargar