How to identify whether eggs are fresh or not

Identifying whether eggs are fresh can be comprehensively judged through five methods: observing appearance, checking odor, water float test, shaking and listening to sound, and light penetration test.

1. Observe appearance

The surface of fresh eggs is rough with frost like powder, and the eggshell has no cracks and uniform color. Eggs stored for a long time may have smooth and shiny eggshells, and may have dark spots or mold spots. If there are visible cracks or damages on the surface of the eggshell, bacteria can easily invade and cause spoilage.

2. Check odor

Normal fresh eggs have no obvious odor after opening, the yolk is raised in a hemispherical shape, and the egg white is thick and layered. Rotten eggs emit a putrid odor of hydrogen sulfide, with flattened yolk that easily disperses and thin, cloudy egg white. If eggs stored in refrigeration have abnormal sour taste, they should be discarded immediately.

3. Water Floatation Test

Place eggs in a container of clean water. Fresh eggs will lie flat and sink to the bottom, while eggs stored for a week will tilt and suspend. Fully floating eggs have spoiled. The principle is that during the storage of eggs, the air chamber increases and buoyancy is enhanced. The water temperature should be maintained at around 20 degrees Celsius during testing.

4. Shake and Listen

Hold the egg and gently shake it, and the fresh egg makes almost no sound. Eggs stored for a long time will produce shaking sounds due to water evaporation, and spoiled eggs will have a noticeable liquid shaking sensation when shaken. This method requires comprehensive judgment in conjunction with other detection methods.

5. Light transmittance test

Use strong light to irradiate the eggs in a dark room. Fresh eggs should have uniform light transmittance, and the air chamber should be less than 5 millimeters and fixed in position. The old egg chamber expands, and the shadow of the yolk is obvious. The illumination method can clearly observe the position and protein status of the egg yolk, which is commonly used in professional egg product testing.

Eggs should be refrigerated and kept dry for daily storage. Placing them with the air chamber facing upwards can delay spoilage. When purchasing, choose products from legitimate channels and pay attention to checking the production date. Eggs are nutritious but prone to the growth of Salmonella. It is recommended to heat them thoroughly before consumption. Elderly people, pregnant women, and those with low immunity should pay more attention to food hygiene and safety. If the eggshell becomes sticky or the contents change color abnormally, it should be immediately stopped from consumption.