How to judge the quality of eggs

Judging the quality of eggs can be achieved through methods such as observing appearance, shaking and listening to sound, light penetration testing, water float testing, and olfactory identification. Fresh eggs usually have rough and crack free eggshells, no sound when shaken, uniform light transmission, sink to the bottom of the water, and no odor.

1. Observe the appearance

The surface of fresh egg shells is rough with fine particles, uniform in color without luster, and without cracks or stains. The eggshell of aged eggs is smooth and shiny, and may have dark spots or mold spots. If there are visible cracks in the eggshell, bacteria may have invaded and caused spoilage.

2. Shaking and Listening

Hold the egg and gently shake it. The fresh egg liquid is thick and almost silent, while the spoiled egg will emit obvious water sound due to the expansion of the air chamber and protein liquefaction. But this method requires some experience, excessive shaking may damage the egg membrane structure.

3. Light penetration test

In a dark environment, shine a flashlight on the blunt end of the egg. The fresh egg chamber should be less than 5 millimeters, the yolk contour should be blurred and centered, and the protein layering should be clear. Scattered yellow eggs show obvious shadow movement, while moldy eggs may have irregular black spots.

4. Water Floatation Test

Place eggs in 10% concentrated saline solution. Fresh eggs will sink to the bottom of the cup due to their high density. Eggs stored for 1-2 weeks will have their blunt ends slightly raised, while completely floating eggs will have spoiled. This method determines freshness based on the size of the air chamber, but attention should be paid to the accuracy of the saltwater concentration.

5. Smell discrimination

After cracking the egg, fresh eggs have a slight fishy smell, thick and layered protein, and full and raised yolk. Rotten eggs emit a putrid odor of hydrogen sulfide, with thin and cloudy protein and flattened yolk that easily disperses. The appearance of gray ring-shaped iron sulfide after cooking also indicates that it is not fresh. When storing eggs, they should be placed with the blunt end facing up in the refrigerator compartment, and the temperature should be maintained at around 4 ℃ to keep them fresh for 3-5 weeks. Pay attention to the production date when purchasing, and it is recommended to consume loose eggs within two weeks. If the eggshell is found to be sticky, has an abnormal odor, or mixes with egg yolk protein after opening, it should be discarded immediately. Eggs are nutritious but susceptible to Salmonella contamination. Elderly people, pregnant women, and children should ensure that they are fully cooked before consumption.