How to determine the freshness of eggs

The freshness of eggs can be comprehensively evaluated through five methods: observing the appearance, shaking and listening to sound, water float testing, lighting penetration, and olfactory testing.

1. Observe appearance

The surface of fresh egg shells is rough and powdery, with a layer of white frost attached, while the shell of aged eggs is smooth and shiny. The color of eggshells is not related to freshness, but eggs with cracks, mold, or obvious stains may have spoiled. Egg yolks that are centered and have blurred contours are fresher, while egg yolks that are offset or have clear contours may be stored for a longer period of time.

2. Shake and listen

Hold the egg close to your ear and gently shake it. The fresh egg makes almost no sound, and the yolk and egg white are tightly bound together. Eggs stored for a long time may produce noticeable shaking sounds due to the expansion of the air chamber, and spoiled eggs may produce water like shaking sounds. This method needs to be combined with other detection methods, and the single shaking time should not exceed 3 seconds.

3. Water Float Test

Place the eggs in a clear water container, with fresh eggs settling flat at the bottom. Store them in a tilted or upright suspension for about 1-2 weeks, and those that have completely surfaced and gone bad. The principle is that as the egg chamber is stored for a longer period of time, its buoyancy increases. The water temperature for testing should be close to room temperature to avoid using ice or hot water that may affect the results.

4. Light transmission

In a dark room, strong light is used to illuminate eggs. Fresh eggs have uniform light transmission and a light orange red color, with no obvious shadow on the yolk. The chamber of the aged egg has increased by more than 5 millimeters, and the shadow of the egg yolk has deepened or blood streaks have appeared. This method can detect black spots or turbidity caused by internal deterioration, and it is more effective to use a professional egg tester.

5. Olfactory detection

Fresh eggs have no obvious odor when opened, and the egg white is thick and layered clearly. Rotten eggs will produce a hydrogen sulfide odor, with thin and watery egg whites and flattened egg yolks that are easy to disperse. The center of cooked egg yolks may turn green or the protein may have gray spots, indicating that they have been stored for too long but have not spoiled, which does not affect their safety for consumption. When storing eggs, the temperature should be maintained at 0-4 degrees Celsius and the humidity should be 70% -80%. Placing the blunt end upwards can slow down the expansion of the air chamber. Choose packaging products with clear production dates when purchasing, and it is recommended to consume loose eggs within two weeks. Before cooking, it is necessary to conduct a freshness test, and eggs with abnormal odors or shapes should be discarded immediately. Under reasonable storage conditions, refrigerated eggs can have a shelf life of 4-5 weeks, but nutrients will slowly dissipate over time. It is recommended to prioritize consuming newly produced eggs for optimal nutritional value.