Masters Theses
Date of Award
8-2020
Degree Type
Thesis
Degree Name
Master of Science
Major
Comparative and Experimental Medicine
Major Professor
Doris D'Souza
Committee Members
Stephen Kania, Niki Labbe, Xiaofei Ye
Abstract
Hepatitis A virus (HAV) is an epidemiologically relevant foodborne pathogen, more thermally resistant than most tested non-spore forming bacteria, that necessitates validation of its inactivation during food processing. Staphylococcus carnosus strain CS 300 has been evaluated as a potential HAV-surrogate. In this study, the thermal resistance of S. carnosus CS 300 grown in Tryptic Soy Broth (TSB) containing 4% NaCl, 5% NaCl, or 20% glycerol at 42°C and inoculated into spinach, macaroni and cheese, and pasta salad after growth in TSB with 20% glycerol was compared to HAV, by the linear and Weibull models. In buffer, linear model D-values of CS 300 grown in 4% NaCl ranged from 14.39±1.51 to 3.12±0.78 min for 56 to 64°C, for 5% NaCl ranged from 23.82±3.82 to 0.90±0.15 min, and for 20% glycerol ranged from 27.35±3.17 to 0.90±0.18 min at 56 to 68°C, respectively. Weibull model td=1 values in 4% NaCl ranged from 16.68±5.79 to 2.48±1.50 min for 56 to 64°C; in 5% NaCl at 56 to 68°C was 22.74±7.64 to 0.96±0.45 min; while in 20% glycerol ranged from 28.84±5.51 to 0.68±0.03 min. Increased D-values of CS 300 in spinach that ranged from 69.44±8.02 to 1.24±0.10 min for 58 to 68oC, while td=1 values of 75.63±20.87 to 0.87±0.46 min were obtained. Similarly, D-values in pasta salad ranged from 29.96±1.86 to 0.91±0.13 min for CS 300 compared to 9.67±0.41 to 1.33±0.09 min for HAV, with td=1 of 29.37±7.51 to 1.29±0.13 min for CS 300 and 10.58±4.44 to 1.42±0.62 min for HAV at 56 to 64°C, respectively. D-values for macaroni and cheese were 62.02±1.73 and 9.96±0.66 min for CS 300 compared to 2.72±0.25 and 1.29±0.32 for HAV at 60 and 64°C, with higher td=1 values for both. Comparing models, over-processing was dependent on the temperature and food matrix. Overall, increased heat-resistant S. carnosus CS 300 grown in TSB with 20% glycerol appears suitable for validation of heat-inactivation of HAV at 56, 60, and 64°C in spinach, macaroni and cheese, and pasta salad, though it loses its thermal resistance at the higher temperatures tested by both the linear and Weibull models.
Recommended Citation
Bowman, Alexander, "Staphylococcus Carnosus CS 300 Grown Under Varying Conditions at 42°C as a Potential Surrogate for Correlation of Hepatitis A Virus Inactivation in Select Foods. " Master's Thesis, University of Tennessee, 2020.
https://trace.tennessee.edu/utk_gradthes/6069
Comments
Chapter 2 to be submitted to the Journal of Food Science