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Inactivation of Salmonellae in Autoclaved Ground Beef Exposed to Constantly Rising Temperatures 1.
W S Thompson1, F F Busta1, D R Thompson1
1Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, Minnesota 55108.
Journal of Food Protection
|March 1, 2019
Summary
This study monitored Salmonella inactivation in ground beef during cooking. Results indicate that controlling Clostridium perfringens during cooking also effectively controls Salmonella, validating USDA processing guidelines for precooked beef.
Area of Science:
- Food safety and microbiology
- Thermal processing of foods
- Bacterial inactivation kinetics
Background:
- Salmonella is a significant foodborne pathogen, particularly in beef products.
- Understanding bacterial inactivation under dynamic cooking conditions is crucial for public health.
- Previous research focused on constant temperatures, but real-world cooking involves rising temperatures.
Purpose of the Study:
- To determine the heat resistance of Salmonella in ground beef under simulated cooking conditions.
- To compare the thermal inactivation of a Salmonella composite with Salmonella typhimurium.
- To evaluate the adequacy of USDA processing guidelines for precooked beef roasts.
Main Methods:
- Autoclaved ground beef inoculated with a five-serotype Salmonella composite was subjected to rising temperatures (6.0, 8.5, 12.5 C/h) and constant temperatures (55-63 C).
- Survival of Salmonella typhimurium TM-1 was compared to the composite.
- Decimal reduction times (D-values) and z-values were calculated for both constant and rising temperature conditions.
Main Results:
- The D50 C for constant temperature was 30.2 min, while for rising temperatures, it ranged from 49.8 min (12.5 C/h) to 82.4 min (8.5 C/h).
- Neither Salmonella serotype nor heat treatment significantly altered heat resistance.
- Salmonella inactivation kinetics were comparable to those of Clostridium perfringens under similar conditions.
Conclusions:
- Controlling Clostridium perfringens during beef processing is likely sufficient for Salmonella control.
- The USDA processing ruling from July 18, 1978, is deemed adequate for controlling Salmonella in precooked beef roasts.
- Dynamic temperature modeling provides valuable insights into bacterial inactivation during cooking.
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