1. Pick up the preserved eggs and observe. Expired preserved eggs have poor elasticity, the entire egg body is soft, the yolk inside is soft and large, and the protein is sticky and slippery.

2. Judging from the appearance, the expired Songhua eggs are not shiny, and the albumen on the outside has not turned dark green, and there are small dewdrop-like bubbles on the albumen.

3. Smell the eggs. Bacteria will enter the broken shell of the egg. After cutting the egg, black liquid will flow out of the yolk, which is obviously deteriorated and accompanied by a strong odor.

4. After washing the preserved eggs, use the light transillumination of fresh eggs to observe the color, solidification state, air chamber size, etc. of the eggs. Expired preserved eggs are not solidified, are watery, and have large air chambers.