Protein denatures and solidifies when it meets alkali. When protein and egg yolk meet a certain concentration of NaOH, the molecular structure of protein is destroyed and changed. Protein part forms elastic gel, and yolk part forms solidified body through protein denaturation and fat saponification. Macroscopically, the solidification process of preserved eggs can be divided into four stages: thawing, solidification, discoloration and maturity. Generally, it includes soaking and mud wrapping method and direct mud wrapping method.

Introduction of preserved eggs in Songhua River

1. After preserved eggs were stored for a period of time, the interior of duck eggs changed. Egg white condenses into jelly and becomes translucent black, with many pale yellow patterns on it, which are very similar to the needle-like leaves of pine trees, so it is also called preserved eggs. Preserved egg is an egg processed food invented by Han people in China, and it is a unique food in China. It has a special taste, which can stimulate appetite.

2. Precautions: Preserved eggs should not be eaten with turtles, plums and brown sugar. Usage and dosage: Jiang Mo and vinegar should be used to detoxify preserved eggs; Preserved eggs are best eaten after being cooked. Preserved eggs also contain lead, so children should eat less. It should not be stored in the refrigerator for a long time.

3. How to eat: directly dip in seasonings, such as soy sauce, sauce paste, Chili sauce and so on. Mix ginger slices or beer directly. Make into various dishes, such as preserved eggs and tofu, sweet and sour preserved eggs, three-color eggs, preserved egg lean porridge, emerald preserved egg soup, etc.

4. Preservation method: It can be preserved for a long time when the eggshell is intact. But once the eggshell is cracked and damaged, it stinks for three days at high temperature and worms for seven days. Don't be careless. So remember to put it in a cold place. This method is the way to preserve preserved eggs. Preserved eggs can reach a stable and collision-free state after being cooked, and can be stored at room temperature. They can't be refrigerated or frozen for a long time, which is easy to destroy the taste of food. They only need to be refrigerated briefly before eating.

5. Selection method: preserved eggs, brown protein crystal clear, top grade. If there is a white line like snowflake, it is the best preserved egg, so it is named Songhua preserved egg. The looser the pattern, the better the quality. However, the center of yolk can be divided into two types: center and solid, depending on the curing time. Deteriorated preserved eggs have light green protein, yellow yolk and more markings on the eggshell surface.