Lesson 4: Jensen Farms Listeria Outbreak Case Study
Listeria monocytogenes -Listeria
Location and Percent of Listeria Found in Meat Plants (n=41)
- Floors-39%
- Floor Drains-39%
- Cleaning Aids-34%
- Wash Areas-24%
- Sausage Peelers-22%
- Food Contact Surfaces-20%
- Walls & Ceilings-5%
- Compressed Air-4%
Why the concern with Listeria? Work through this exercise to understand why Listeria is big concern in food safety.
This table shows the growth and survival limits of Listeria.
| Growth and Survival Limits for Listeria monocytogenes | ||||
|---|---|---|---|---|
| Parameter | Minimum | Maximum | Optimal | Can Survive (but no growth) |
| Temperature (C) | -1.5 to +3 | 46 | 30 to 37 | -18 |
| pH | 4.2 to 4.3 | 9.4 to 9.6 | 7.0 | 3.3 to 4.2 |
| Water Activity (aw) | 0.90 to 0.93 | >0.99 | 0.97 | <0.90 |
| Salt (%) | <0.5 | 12-15 | N/A | >20 |
Jensen Farms Listeria Outbreak of 2011
Another Listeria Outbreak:
2015 Blue Bell Listeria Case:
Check out the graphic and visit this web site for more information
Post-Harvest Practices Played a Role in the Listeria Outbreak in Cantaloupe
- Cantaloupe that was washed, dried, and packed on unsanitary food contact surfaces could have been contaminated with Listeria or could have collected nutrients that allowed Listeria to grow on the cantaloupe rind.
- After harvest the cantaloupes were placed in cold storage; they were not pre-cooled to remove the field heat before the cold storage.
- Warm fruit with field heat potentially created conditions that would allow the formation of condensation, which is an ideal environment for Listeria growth.
- Factors that played a role in the cantaloupe outbreak of Listeria:
Case Study-End Results
- Ultimately, lawsuits bankrupted Jensen Farms; it is no longer in existence.
- Rocky Ford Cantaloupe growers established the Rocky Ford Growers Association with a defined growing region for produce that is allowed to be called Rocky Ford Cantaloupe™.
- New efforts were directed at the prevention of Listeria.
Focused efforts on prevention of Listeria
Additional Resources-Case Study Research
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•Martin Wiedmann, Cornell University–Research on transient vs. resident pathogens in food safety–Current work in his laboratory focuses on microorganisms that cause a considerable number of foodborne deaths annually in the US, including Listeria monocytogenes and Salmonella–Pathogenesis of foodborne and zoonotic diseases can involve complex interactions between a bacterial pathogen, a variety of environments and one or multiple host species–The ability of bacterial cells to survive and compete in a variety of environments plays a key role in the pathogenesis and transmission of many foodborne diseases
definition
Pathogens that can be spread from animals to humans and vice versa.