What Steps are Used to Kill Bacteria Like E. coli, Salmonella, or Listeria?
Kill Steps in U.S. Food Production and Manufacturing – Top Ten Methods
In food production and manufacturing, “kill steps” are critical control processes used to eliminate or reduce foodborne pathogens (like Salmonella, Listeria, or E. coli Bacteria) to safe levels. These steps are essential in preventing foodborne illnesses and ensuring the safety of food products. Below is an overview of the most common kill steps used in the United States:
1. Heat Treatments
Heat is one of the most widely used methods to kill pathogens in food processing. It can be applied in various forms, such as:
- Pasteurization: Used for products like milk, juice, and eggs, pasteurization involves heating to specific temperatures (e.g., 161°F/72°C for 15 seconds in high-temperature short-time (HTST) pasteurization) to destroy harmful microorganisms.
- Sterilization: Common in canned foods, sterilization uses higher temperatures (above 250°F/121°C) to destroy all microorganisms, including spores.
- Cooking: In processed meats, poultry, and ready-to-eat foods, proper cooking ensures the destruction of pathogens like Salmonella, E. coli, and Listeria monocytogenes.
- Boiling: A large number of foods are boiled in homes or restaurants prior to serving – the high temperature makes it difficult, if not impossible, for most bacterial pathogens to survive.
2. Freezing
While freezing doesn’t kill all pathogens, it can inhibit their growth. Freezing is particularly effective when combined with other methods, such as blanching vegetables before freezing to reduce microbial loads. One notable exception in Listeria, which has even been linked to a number of ice cream outbreaks in recent years!
3. High-Pressure Processing (HPP)
HPP uses extremely high pressures (up to 87,000 psi) to kill pathogens in foods like deli meats, juices, and ready-to-eat products. This method is effective for preserving flavor and nutrients while ensuring safety.
4. Irradiation
Food irradiation uses ionizing radiation to eliminate pathogens, extend shelf life, and prevent spoilage. It is often used for spices, dried herbs, fresh produce, and some meat products. The process does not make food radioactive and is endorsed by regulatory bodies like the FDA and WHO.
5. Chemical Treatments
Chemicals are used to reduce microbial contamination, especially in fresh produce and poultry processing:
- Chlorine washes: Common for sanitizing fruits, vegetables, and poultry.
- Organic acids: Lactic acid and citric acid are applied to meat carcasses and produce to lower microbial loads.
- Ozone treatment: Ozone gas or ozonated water kills pathogens on produce and seafood.
6. Drying and Dehydration
Drying reduces water activity in foods, making it inhospitable for microorganisms to grow. Dehydrated foods like jerky, powdered milk, and spices rely on this method to ensure safety and stability.
7. Fermentation
Fermentation lowers pH and introduces beneficial bacteria that outcompete harmful microorganisms. Foods like yogurt, pickles, and fermented sausages rely on this natural process as an additional kill step.
8. Ultraviolet (UV) Light
UV light is used to sanitize surfaces, liquids, and even air in food processing facilities. It’s particularly effective in reducing microbial loads on fruits, vegetables, and juices.
9. Filtration
For liquids like water, wine, and juice, filtration systems remove microbial contaminants without using heat or chemicals. Techniques such as microfiltration and ultrafiltration are employed.
10. Smoking
Smoking adds flavor to foods like meat and fish while also acting as a microbial control step. Smoke contains compounds that inhibit bacterial growth.
Regulatory Oversight and Best Practices
In the U.S., kill steps are monitored and regulated by agencies such as the USDA, FDA, and EPA. Hazard Analysis and Critical Control Points (HACCP) programs ensure food manufacturers identify and control hazards at every stage of production, with kill steps forming an integral part of these systems.
Effective implementation of kill steps not only protects public health but also ensures compliance with food safety standards, safeguarding the reputation of food producers and manufacturers.
