Food Science and Technology Department


First Advisor

Byron Chaves

Date of this Version

Summer 7-12-2023


Raziya Sadat, " Evaluating Salmonella Cross Contamination In Raw Chicken Thighs In Simulated Post-Chill Tanks" (2023). Dissertations, Thesis, & Student Research in Food Science and Technology. University of Nebraska-Lincoln


A Thesis Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Food Science & Technology, Under the Supervision of Professor Byron D. Chaves. Lincoln, Nebraska: July 2023

Copyright © 2023 Raziya Sadat


Salmonella contamination poses a significant risk to food safety, particularly in poultry products and public health. This study aims to investigate the effectiveness of peracetic acid (PAA) treatment in mitigating Salmonella cross-contamination in chicken thighs within simulated post-chill tanks, considering different inoculum concentrations and organic matter (OM) levels.

The experiment involved the use of five distinct Salmonella serovars to inoculate chicken thighs, which were categorized into two groups: higher inoculation level (ca. 7 log CFU/mL) and lower inoculation level (ca, 4 log CFU/mL). These groups underwent treatment with four different solutions, including 540 ppm PAA with 1.5% OM, 540 ppm PAA with 3% OM, pre-chilled distilled water with 1.5% OM, and pre-chilled distilled water with 3% OM. Each treatment included immersion of one inoculated thigh and five non-inoculated thighs in separate tubs for 30 seconds, allowing for the assessment of cross-contamination potential. Microbiological analysis was conducted, and non-inoculated chicken thigh samples that tested negative for Salmonella were further subjected to incubation at 37 °C for 24 h for the identification of low levels of the bacteria that may have been initially undetectable. Simulated post-chill water quality parameters, including pH, chemical oxygen demand (COD), and total nitrogen (TN), were characterized before and after each treatment cycle.

The results demonstrated the significant (P < 0.05) reduction in bacterial contamination achieved through PAA treatment compared to distilled chilled water for both highly and lowly inoculated chicken thigh samples. The efficacy of PAA against Salmonella was unaffected by the presence of OM at varying concentrations. Moreover, the study confirms the occurrence of cross-contamination during the immersion process in post-chill tanks, underscoring the necessity of implementing preventive measures throughout poultry processing. Additionally, the treatment led to notable changes in the chemical composition of the samples, evident through increased levels of chemical oxygen demand (COD), total nitrogen (TN), and pH. These findings underscore the importance of comprehensive preventive measures within the industry and provide valuable insights into the efficacy of PAA treatment for Salmonella cross-contamination.

Advisor: Byron D. Chaves