Songhua Eggs the earliest place of origin is Weishan, Weishan Lake Brand Songhua Skin Eggs, which according to historical records has a history of more than 500 years from the beginning of the Ming Dynasty, and is still an important place of origin of Songhua Eggs.

Pine eggs may have evolved from the salted duck eggs recorded in the Northern Wei Dynasty's "Qimin Essentials". A clear record of leather eggs, Ming Xiaozong seventeen years (1504) into the book, "Zhuyu shanfang miscellaneous parts".

Sponge eggs production principle:

Sponge eggs use the egg in alkaline solution, can make the protein gel properties, so that it becomes elastic solid. However, the skin egg production if the recipe is poorly controlled, will make the protein in the alkaline solution instead of hydrolysis, protein denaturation for protein, it can not be eaten.

If there is a crack in the shell or the recipe is not well controlled, the hydrogen sulfide inside the egg will also spill out and turn it into a golden yellow color. Normal eggs are dark green, fluffy and elastic.