The basic principle of the processing of leather eggs is that proteins are denatured and coagulate when they encounter alkali. When the egg white and yolk encounter a certain concentration of NaOH, changes occur due to the destruction of the protein molecular structure. The protein portion forms a gel with elasticity, and the yolk portion forms a coagulum from protein denaturation and fat saponification reactions.

From a macroscopic point of view: the coagulation process of the skin egg is manifested in four stages of clearing, coagulation, discoloration and maturation. It generally includes two methods: immersion coagulation method and direct coagulation method.

The main chemical composition of the eggs:

The main chemical composition of the eggs is protein, which contains sulfur, and over time, the yolk will decompose into amino acids, and release hydrogen sulfide. The yolk itself contains many minerals, such as iron, copper, zinc, manganese, etc., hydrogen sulfide can react with these minerals to generate sulfide, so the yolk is greenish-black is the production of these sulfides.

At the same time, the yolks of puffy eggs have a lot of protein decomposition into amino acids, so the yolks of puffy eggs taste much fresher than the yolks of ordinary eggs.

After the processing of the pine eggs than duck eggs contain more minerals, fat and total calories but slightly lower, it can stimulate the digestive organs, enhance appetite, promote digestion and absorption of nutrients, neutralize the stomach acid, cooling, lowering blood pressure.

The above references? Baidu Encyclopedia-Skinned Eggs