Heat Resistance of Escherichia coli and Salmonella enterica in Ground Beef and Chicken

• Author / Creator

  Webster, Jordan B

• Escherichia coli and Salmonella are contaminants in meat products and pose a risk for foodborne illness. Thermal lethality is the traditional method for controlling pathogens in meat products. It is recommended that ground beef and poultry products be cooked to internal temperatures of 71°C and 74°C, respectively. However, E. coli and Salmonella have a wide variance in resistance to heat. The aim of the current research was to determine the heat resistance of heat-resistant and heat-sensitive E. coli and Salmonella in ground beef and chicken and to determine the influence of the presence of a seasoning binder on heat resistance in meat products. Ground beef with and without 5.6% seasoning binder was inoculated and heated at temperatures between 55 and 70°C for different times. A linear regression model was used to calculate the D- and z-values. Seasoning binder increased the decimal reduction times (D-values) of heat-resistant E. coli AW1.7 but not of heat-resistant S. enterica ATCC 43845 in ground beef. To determine inactivation in patties, ground beef with and without 5.6% seasoning binder was inoculated with heat-resistant and heat-sensitive E. coli and Salmonella. When cooked to an internal temperature of 71°C, the presence of seasoning binder did not increase survival of heat-resistant or heat-sensitive E. coli and Salmonella in ground beef patties. Cooking ground beef patties to an internal temperature of 74°C achieved greater than 5-log (CFU/g) reduction of heat resistant E. coli AW1.7. The addition of 5.6% seasoning binder increased the survival of a cocktail of verotoxigenic E. coli inoculated in ground beef patties cooked to an internal temperature of 71°C. The cocktail was only reduced 2.8 log (CFU/g) in ground beef patties cooked to 71°C. To determine thermal inactivation in chicken nuggets, ground chicken was inoculated with heat-resistant and heat-sensitive E. coli and Salmonella, formed into chicken nuggets, heated and frozen. After being cooked to an internal temperature of 74°C cell counts of heat-resistant E. coli and Salmonella were reduced less than 3-log (CFU/g) and heat-sensitive E. coli were reduced by greater than 5-log (CFU/g). In conclusion, recommended cooking guidelines are not sufficient to prevent the survival of heat-resistant E. coli and Salmonella. The results of this study can be used by producers to help to assess their process and predict the survival of heat resistant organisms in ground beef and chicken products.

• Subjects / Keywords

  • Escherichia coli
  • Ground beef
  • Chicken
  • Heat resistance
  • Salmonella enterica

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3R78643V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.