The bacterium Salmonella is a common cause of foodborne illness, known as Salmonellosis, frequently associated with contaminated food products, especially those of animal origin. This illness can cause symptoms like diarrhea, fever, and abdominal cramps. While most people recover without specific treatment, it can be serious for vulnerable populations. Applying heat is the most reliable method for eliminating this pathogen from food before consumption. Safe food preparation depends on understanding the relationship between temperature and time to ensure the destruction of the bacteria.
The Temperature and Time Required for Elimination
The destruction of Salmonella is governed by the thermal death point, which is the specific temperature threshold required to inactivate the organism. This process works by destroying the bacteria’s cellular structures and DNA. Because Salmonella does not form heat-resistant spores, it is relatively easily killed by heat compared to other bacteria. The time required to eliminate Salmonella is inversely related to the temperature applied; higher temperatures require less holding time. For instance, 160°F (71°C) will kill Salmonella almost instantly, whereas 145°F (63°C) requires a sustained period of a few minutes to achieve the same level of safety.
Safe Internal Temperatures for Common Foods
Translating the thermal death point into practical food safety relies on reaching specific minimum internal temperatures for various high-risk foods. Using a calibrated food thermometer is the only way to accurately ensure the temperature has been reached throughout the entire product, especially at the thickest part. The appearance or color of food is an unreliable indicator of safety.
Poultry, including whole birds, ground poultry, and parts, must reach a minimum internal temperature of 165°F (74°C). This higher temperature ensures the destruction of pathogens, which is especially important for ground products where bacteria can be mixed throughout the meat. Ground meats like beef, pork, and lamb require 160°F (71°C). Cuts of meat like steaks, chops, and roasts can be safely cooked to 145°F (63°C), but they require a three-minute rest time after removal from the heat source. Eggs should be cooked until both the yolk and white are firm, and dishes containing eggs should reach 160°F (71°C). All leftovers must be reheated to a uniform internal temperature of 165°F (74°C).
Preventing Cross-Contamination and Reintroduction
Achieving the correct internal temperature is only one part of food safety, as measures must also be taken before and after cooking to prevent the reintroduction of Salmonella. Cross-contamination occurs when bacteria from raw food items, like meat juices, are transferred to cooked or ready-to-eat foods via improper handling, contaminated utensils, or uncleaned surfaces.
To prevent this, separate cutting boards should be designated for raw proteins and ready-to-eat produce. Never place cooked food on a plate or surface that previously held raw meat or poultry unless it has been thoroughly washed. Proper handwashing requires hands to be washed with soap and water for at least 20 seconds after handling raw ingredients. Cleaning and sanitizing all surfaces and utensils that have come into contact with raw food should be done immediately. For safe storage, perishable food should be refrigerated promptly, within two hours of cooking or purchasing, to prevent any surviving bacteria from multiplying. Refrigeration temperatures should be maintained at 40°F (4°C) or below.