How to Know if Eggs Don't Have Salmonella: A Guide to Safe Egg Practices

October 22, 2025 •

4 min read

While many believe a simple visual or sniff test can confirm an egg's safety, the unfortunate reality is that you cannot see, smell, or taste Salmonella bacteria. This makes knowing if eggs don't have Salmonella impossible without laboratory testing, emphasizing the need for proper handling and cooking practices.

Quick Summary

This guide explains why at-home methods are ineffective for detecting Salmonella in eggs. It details essential food safety protocols for buying, storing, and cooking eggs properly to minimize your risk of infection.

Key Points

Undetectable Threat: Salmonella is invisible, odorless, and tasteless, making it impossible to detect in eggs using your senses.
Cooking is Key: The only reliable method to kill Salmonella is to cook eggs thoroughly until both the yolk and white are firm.
Assume Raw Eggs Are Contaminated: Treat all raw eggs with caution by washing hands and surfaces after handling to prevent cross-contamination.
Pasteurized Eggs for Raw Dishes: For recipes like hollandaise or homemade mayonnaise that use raw eggs, use pasteurized eggs for safety.
Proper Storage is Essential: Always refrigerate eggs at 40°F or colder in their original carton to limit bacterial growth and maintain freshness.
Discard Damaged Eggs: Never use eggs with cracked or dirty shells, as they can provide an entry point for bacteria.

The Unseen Threat: Why You Can't Detect Salmonella

One of the most important facts about food safety is that harmful bacteria, including Salmonella, do not cause food to look, smell, or taste bad. This means that even an egg that appears and smells perfectly fresh can potentially harbor these dangerous microorganisms. Salmonella bacteria can contaminate an egg in two primary ways: from the hen's reproductive tract before the shell is even formed, or from fecal matter on the outside of the shell. Grocery store eggs are typically washed to remove exterior contaminants, but the internal risk remains for a small percentage of eggs. Therefore, relying on your senses is not a reliable method for determining if eggs are free from Salmonella.

Essential Steps for Safe Egg Handling

Since detection is not a practical option for the consumer, prevention is the only effective strategy. Following proper food safety guidelines from the moment you purchase eggs is crucial.

Buy Refrigerated Eggs: Always purchase eggs from a refrigerated case at the grocery store. Check the carton to ensure eggs are clean and the shells are not cracked before buying.
Refrigerate Immediately: Once home, store eggs promptly in a clean refrigerator at 40°F (4°C) or below. Keeping eggs in their original carton helps protect them from absorbing odors and maintains freshness. The best place to store them is on a shelf, not the door, where temperatures fluctuate.
Prevent Cross-Contamination: Treat raw eggs with the same caution as raw meat. After handling eggs, wash your hands and any utensils, equipment, or surfaces that came into contact with them using hot, soapy water.
Handle Cracked or Dirty Eggs: Never use eggs that are cracked or dirty. Cracks create an entry point for bacteria. If you have backyard chickens, simply brush off dirt, but never wash them, as water can facilitate bacterial movement into the egg.

The Role of Thorough Cooking

The most reliable method for destroying Salmonella bacteria is cooking. To ensure eggs are safe to eat, they must be cooked to a specific internal temperature.

Firm Up Your Eggs: Cook eggs until both the yolk and the white are firm. Runny yolks or whites should be avoided, especially for at-risk individuals. Scrambled eggs should not be runny.
Check the Temperature: For egg-containing casseroles or other dishes, cook to an internal temperature of 160°F (71°C). Using a food thermometer can help ensure accuracy.
Use Pasteurized Eggs for Raw Dishes: If a recipe calls for raw or lightly cooked eggs, such as homemade Caesar salad dressing, mayonnaise, or hollandaise sauce, use pasteurized eggs or egg products. This heat-treatment process eliminates harmful bacteria beforehand.

Debunking Common Egg Tests

Many people rely on traditional methods to check egg freshness, but these are often confused with safety checks. It's important to understand the difference.

The Float Test

When an egg is placed in a bowl of water, its buoyancy indicates its freshness, not whether it is contaminated with Salmonella. A fresh egg will sink and lay on its side, while an older egg, which has developed a larger air cell over time, will stand on one end or float. A floating egg may be old, but if it has been stored correctly and doesn't smell bad when cracked, it may still be edible if cooked thoroughly.

The Sniff Test

A strong, sulfurous smell after cracking an egg is a definite sign that it has spoiled and should be discarded. However, the absence of a bad smell does not guarantee the absence of Salmonella, as this particular bacteria is odorless. It is crucial not to confuse spoilage bacteria, which cause a foul odor, with pathogenic bacteria like Salmonella.

Comparison: Freshness vs. Safety Tests


Test Method	Indication	Relevance to Salmonella	How it Works
Float Test	Age of the egg	None; indicates freshness, not safety.	An egg's air cell expands as it ages, making it more buoyant.
Sniff Test	Spoilage due to general bacteria	None; Salmonella is odorless.	A putrid smell indicates decomposition, not necessarily pathogenic contamination.
Visual Inspection	Cracks, sliminess, discoloration	Indirectly related; these issues can be entry points for bacteria, but a clean egg isn't guaranteed safe.	Discoloration or slime can indicate bacterial or mold growth, but not specifically Salmonella.
Thorough Cooking	Elimination of bacteria	Directly related; kills Salmonella and other harmful bacteria.	Heating an egg to a firm yolk and white destroys any bacteria present.
Pasteurization	Pre-treated for safety	Directly related; process kills Salmonella.	Eggs are heated to a specific temperature for a set time to kill bacteria.

Conclusion: Prioritize Prevention, Not Detection

In the end, you cannot rely on a float test, sniff test, or visual inspection to determine if eggs are free of Salmonella. The bacteria are invisible and odorless, making at-home detection impossible. The only effective strategy is to assume any raw egg could be contaminated and to take precautionary measures. By purchasing refrigerated eggs, storing them properly, preventing cross-contamination, and cooking them thoroughly, you can drastically reduce your risk of illness. For recipes requiring raw or undercooked eggs, using pasteurized eggs is the safest choice.

For more information on food safety, visit the FoodSafety.gov website.

Frequently Asked Questions

No, the float test indicates an egg's age, not the presence of Salmonella. A floating egg is older due to a larger air pocket, but cooking it thoroughly can still make it safe to eat.

A bad, sulfurous smell indicates a spoiled egg due to other types of bacteria, not necessarily Salmonella. Salmonella is odorless, so the lack of a foul smell does not guarantee safety.

Keep eggs refrigerated at 40°F (4°C) or below, discard any cracked or dirty eggs, and wash your hands, utensils, and surfaces after handling raw eggs to prevent cross-contamination.

The safest way is to cook eggs until both the white and the yolk are firm. For dishes like casseroles, cook to an internal temperature of 160°F (71°C).

Yes, pasteurized eggs have been treated with heat to kill Salmonella and are the safest option for recipes that call for raw or lightly cooked eggs.

Common symptoms include diarrhea, fever, stomach cramps, nausea, and vomiting, which usually appear 6 to 72 hours after exposure and last for 4 to 7 days.

Yes, it is possible for an egg with a clean, uncracked shell to be contaminated with Salmonella from the hen's reproductive tract before the shell was formed. This is why proper cooking is always necessary.