Date of Award

6-2-2025

Degree Type

Thesis

Degree Name

Master of Food and Animal Sciences (M.S.)

First Advisor

Aliyar Cyrus Fouladkhah

Abstract

Foodborne pathogens pose significant risks to public health and food safety, necessitating innovative control strategies. High-pressure processing (HPP) was evaluated as an intervention against Listeria monocytogenes in cold-smoked rainbow trout, with treatments at 500 MPa and 4.4 °C and 60.0 °C achieving up to a 5.03 log CFU/g reduction. The efficacy of nisin in suppressing Listeria monocytogenes and Listeria innocua during refrigerated storage was also examined, demonstrating significant microbial inhibition, particularly in the early storage phase, supporting its application as a hurdle technology. Additionally, the synergistic effects of HPP (400 MPa, 4 °C) and natural bioactive compounds, including lactic acid, carvacrol, malic acid, citric acid, and thymol, were assessed against Salmonella serovars in buffered and acidic environments. The combination treatments enhanced microbial inactivation, reinforcing the role of natural antimicrobials in food preservation. To address microbial risks in food processing environments, the impact of lactic acid on biofilm formation by wild-type and rifampicin-resistant Shiga toxin-producing Escherichia coli (STEC) O157:H7 and non-O157 strains on stainless steel and rubber surfaces was investigated, demonstrating its effectiveness in reducing biofilm-associated risks. These findings highlight the potential of integrating pressure-based and natural antimicrobial interventions for enhanced food safety and pathogen detection. Furthermore, with advancements in culture-independent pathogen detection, elevated hydrostatic pressure was applied to enhance DNA extraction procedures, improving the sensitivity of standard and real-time PCR assays for detecting L. monocytogenes from biotic and abiotic environments.

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