Related Experiment Videos
Heat inactivation of Mycobacterium paratuberculosis in raw milk: are current pasteurization conditions effective?
J R Stabel1, E M Steadham, C A Bolin
1National Animal Disease Center, U.S. Department of Agriculture, Ames, Iowa 50010, USA. jstabel@nadc.ars.usda.gov
Abstract:
Currently, it is not known whether commercial pasteurization effectively kills Mycobacterium paratuberculosis in contaminated raw milk. Results from holder test tube experiments indicated that a residual population of viable bacteria remained after treatment at 65, 72, 74, or 76 degrees C for 0 to 30 min. Use of a laboratory-scale pasteurizer unit demonstrated that treatment of raw milk at 72 degrees C for 15 s effectively killed all M. paratuberculosis.
Insights
Commercial pasteurization may not eliminate Mycobacterium paratuberculosis in raw milk. However, laboratory tests show that a 15-second treatment at 72°C effectively kills this bacteria in milk.
Area of Science:
- Food safety science
- Microbiology
- Veterinary public health
Background:
- Mycobacterium paratuberculosis (MAP) is a pathogen found in raw milk.
- The efficacy of commercial pasteurization against MAP is not well-established.
- MAP is linked to Johne's disease in cattle and potentially Crohn's disease in humans.
Purpose of the Study:
- To determine if standard commercial pasteurization effectively eliminates Mycobacterium paratuberculosis from raw milk.
- To evaluate the impact of different temperatures and holding times on MAP survival.
- To assess the effectiveness of a specific laboratory-scale pasteurization process.
Main Methods:
- Holder pasteurization tests were conducted using contaminated raw milk at temperatures ranging from 65°C to 76°C for 0 to 30 minutes.
- A laboratory-scale pasteurizer was used to treat raw milk with Mycobacterium paratuberculosis.
- Bacterial viability was assessed after each treatment condition.
Main Results:
- Residual populations of viable Mycobacterium paratuberculosis were detected after holder pasteurization treatments at various temperatures and durations.
- Laboratory-scale pasteurization at 72°C for 15 seconds demonstrated complete inactivation of Mycobacterium paratuberculosis.
- This suggests that specific pasteurization parameters are crucial for effective bacterial kill.
Conclusions:
- Standard holder pasteurization may not be sufficient to eliminate Mycobacterium paratuberculosis from raw milk.
- Optimized pasteurization parameters, such as 72°C for 15 seconds, are effective in killing Mycobacterium paratuberculosis.
- Further research into commercial pasteurization efficacy against MAP is warranted to ensure milk safety.