How to determine if a raw egg is spoiled

The determination of whether raw eggs have spoiled can be comprehensively evaluated through methods such as observing appearance, shaking and listening to sound, water float testing, smelling odors, and egg beating inspection.

1. Observe the appearance

The fresh egg shell is rough with frost like powder, and the surface pores are obvious. Rotten egg shells may have moldy spots, cracks, or a sticky texture. Be alert when the eggshell color becomes abnormally dark or green mold spots appear. Eggs stored for too long will have a decrease in surface glossiness, and the eggshell will become thinner and more fragile. If suspicious substances are found attached to eggshells, they should be discarded immediately.

2. Shake and listen

Hold the egg and gently shake it, the fresh egg mixture is thick and almost silent. Rotten eggs produce noticeable sound of water due to protein breakdown, and make a shaking sound when the yolk membrane ruptures. When shaking, feeling the liquid inside vigorously shaking or hearing a clicking collision sound usually indicates that the egg yolk has turned yellow. This method requires comprehensive judgment in conjunction with other detection methods.

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 blunt end chamber of the egg expands with storage time, and the buoyancy increases significantly when the chamber diameter exceeds 1.5 centimeters. If the egg is suspended upright on the water surface during testing, it indicates that it has been stored for a long time but has not completely spoiled. This method is sensitive to humidity in the storage environment and needs to be validated in conjunction with other methods.

4. Smell

Fresh eggs only have a slight fishy smell when opened, while spoiled eggs will emit a noticeable sulfide odor. When beating eggs, if the protein is thin and appears pink or green, or if the yolk is flat and easy to spread, it indicates spoilage. Even if the severely spoiled eggs are not opened, they still have a rotten smell when smelled. After being refrigerated for more than 5 weeks, eggs should be consumed with caution even if they look normal.

5. Egg Beating Inspection

Transfer the eggs into a clean container, with fresh egg yolks protruding in a hemispherical shape and clear protein boundaries. The spoiled egg yolk is flat and easily broken, and the protein is cloudy or has blood streaks. Black spots on the surface of egg yolks or fluorescent protein are not edible. If the eggs immediately turn yellow or mix with protein after hatching, it indicates a serious decrease in freshness. This method is the most direct but can damage the eggs, so it is recommended to use it last. When storing eggs, the refrigeration temperature should be kept below 4 ℃ to avoid mixing with strongly scented foods. Pay attention to the production date when purchasing, as regular eggs have a refrigeration shelf life of about 3-5 weeks. Before cooking, be sure to heat thoroughly until the egg whites and yolks are completely solidified, and avoid consuming soft boiled eggs. Eggs with suspicious spoilage characteristics should be discarded and not consumed at risk. Regularly cleaning the refrigerator egg rack and maintaining a dry environment can effectively extend the shelf life of eggs.