Author ORCID Identifier

https://orcid.org/0009-0000-2744-6705

Semester

Spring

Date of Graduation

2025

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Division of Animal and Nutritional Sciences

Committee Chair

Cangliang Shen

Committee Co-Chair

Jacek Jaczynski

Committee Member

Jacek Jaczynski

Committee Member

Nettie Freshour

Abstract

Chicken products in grocery stores are contaminated with Salmonella that is ranked number one as a foodborne pathogen, and causes about 1.35 million cases of foodborne illness, 26,500 hospitalizations, and 420 deaths annually. The objective of this study is to determine thermal kinetic parameters of Salmonella surrogate bacteria E. faecium in ground poultry as affected by different temperatures and salt concentrations. The raw chicken was sliced up into a 500 g batch with a total of 6 batches per replicate, ground up in the meat grinder followed by inoculation with E. faecium resistant to 200 ppm Nalidixic Acid. NaCl (0, 1.0, 3.0, and 5.0%) plus Na-tripolyphosphate (0.5%) solution to achieve a pump rate of 8% was added. The lab scale circulated water bath was set and pre-heated at 62, 66, 70, and 74°C followed by submerging 10 g samples of inoculated ground poultry into the water bath for 0, 15, 30, 45, 60, 70, 80, 90, 100, 110, 120, 140, 180, or 240 s. Enumeration of E. faecium was determined via plate counting after homogenized sample was diluted, and then plated on BEA agar containing 200 ppm Nalidixic Acid. Agars were incubated at 35°C for 48 hours followed by manually counting the colonies recorded as colony forming unit (CFU). At 62°C with an initial E. faecium count of 4.85-6.58 log10CFU/g and heated for 240 seconds, surrogate cell counts decreased to a range of 2.72-5.55 log10CFU/g. D-values and Z-values were calculated using the Weibull model. Survival curves suggest chicken samples containing no salt were least heat susceptible when compared to samples containing higher salt concentrations.

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