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Evaluation of Surrogates for Listeria monocytogenes for High Pressure Processing (HPP) Validation Studies
Bacterial surrogates utilized in validation studies are non-pathogenic bacterial strains or species that have similar or slightly higher resistance to a processing treatment than the target pathogen. The selection of a specific microorganism deemed suitable as a surrogate is an extensive process. The principal goal of this research was to evaluate bacterial surrogates suitable for use in HPP validation studies for the pathogen, Listeria monocytogenes. This study had three parts. First was a scoping review that gathered existing literature on various non-pathogenic bacterial species or strains used in different HPP studies. The focus was then narrowed down to surrogates for L. monocytogenes. Literature gaps were identified, such as the deficiency in parallel studies conducted on the surrogate with the pathogen, diversity in the microorganisms evaluated, inadequate statistical parameters, and lack of information on the food matrices used. The second part was the screening process, in which five surrogate candidates were suspended in buffer solution and subjected to two pressure levels and holding times. Results showed that L. innocua ATCC 33090 and 51742 had similar resistance to pressure when compared to the pathogen in published data. Other surrogate candidates demonstrated higher resistance. More holding times were added to the screening process, which then established L. innocua 51742 as the most promising candidate. Its D-value in buffer solution was calculated to be 3.17 and 1.11 min for 450 and 550 MPa, respectively. The third part was validating the applicability of the surrogate in food matrix processed by HPP. L. innocua 51742 was inoculated on deli meat and HPP-treated at similar processing parameters. Data showed a higher microbial inactivation in the surrogate inoculated in deli meat compared when suspended in buffer solution. However, D-values of the surrogate for both pressure levels in the different suspension media did not differ from each other. L. innocua 51742 is closely related to and demonstrated similar pressure resistance to L. monocytogenes making it the best potential surrogate for the pathogen.
Pilapil, Anna Rose Bordora, "Evaluation of Surrogates for Listeria monocytogenes for High Pressure Processing (HPP) Validation Studies" (2022). ETD collection for University of Nebraska-Lincoln. AAI29322899.