1, look at the appearance. Observe whether its appearance is complete, damaged or mildewed. After high-quality preserved eggs are peeled, their protein is dark brown transparent body, which has certain toughness; Contaminated preserved eggs are light green, with poor toughness and easy loosening. Such preserved eggs must not be eaten.

2. shake it. The color of spoiled preserved eggs is poor, and protein changes color; The air chamber is large, and there are many dew bubbles, and there is a sense of water swinging or light floating after shaking.

3. smell the smell. Cut the preserved egg, and the deteriorated yolk has a black liquid flowing out, with a light or heavy smell or musty smell. The whole preserved egg without deterioration is solidified, not sticky, clean and elastic, translucent and brown, with loose patterns and textures; When the egg is cut vertically, you can see that the yolk is light brown or light yellow with a thin center.