Visual and Physical Signs of Contamination
You cannot reliably tell if an egg has salmonella by looking at the shell alone, because the bacterium can be present inside a normal-looking egg or on the surface. The United States Department of Agriculture states that eggs may appear clean and uncracked while still carrying the pathogen, and visual cues such as color, texture, or slight stains do not indicate safety. The best way to reduce risk is to buy refrigerated eggs from reputable producers and retailers and to avoid eggs with cracked or dirty shells, as cracks can allow bacteria to enter the interior. For more information on egg safety standards and inspection procedures, you can refer to the official USDA Egg Safety guidelines at https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/egg-safety.
Testing, Regulation, and Industry Practices
In the United States, commercial egg farms follow FDA Egg Safety Rules that require measures to prevent salmonella contamination, including refrigeration, sanitation, and rodent control. The Egg Safety Center, operated by the United Egg Producers, provides data on industry practices and outbreak tracking, noting that on-farm controls and pasteurization have significantly reduced salmonella cases linked to eggs over the past decade. For consumers, the most practical step is to purchase pasteurized eggs for recipes that call for raw or lightly cooked eggs, as pasteurization kills salmonella without cooking the egg. Additional details on federal egg safety regulations and compliance can be found in the FDA's Egg Safety Rule overview at https://www.fda.gov/food/eggs/egg-safety.
Cooking, Storage, and Risk Reduction
Safe Cooking Temperatures and Timing
Cooking eggs until both the yolk and white are firm, reaching an internal temperature of 160°F (71°C), kills salmonella, according to the Centers for Disease Control and Prevention. Recipes that use raw or undercooked eggs, such as homemade mayonnaise, Caesar dressing, or certain desserts, carry a higher risk unless pasteurized eggs are used. The CDC advises that people at higher risk for severe illness, including older adults, pregnant individuals, and those with weakened immune systems, should avoid consuming raw or undercooked eggs altogether.
Storage Best Practices
Refrigerate eggs at 40°F (4°C) or colder within two hours of cooking or purchase, and store them in their original carton on an interior shelf rather than in the door. The FDA notes that proper refrigeration slows bacterial growth and that eggs should be discarded if left at room temperature for more than two hours. Hard-boiled eggs should be refrigerated within two hours of cooking and consumed within one week for optimal safety. For more on proper storage and handling, visit the FDA's guidance on egg storage at https://www.fda.gov/food/eggs/egg-safety.