Collagen raw materials can be broadly divided into three main categories:
Cowhide
The earliest source was cowhide, with a molecular weight of about 300,000–500,000.
Pork skin
Later, pork skin was developed, with a molecular weight of about 100,000–300,000.
Fish skin
Recently, fish skin or fish scales from aquatic products have been used, with a molecular weight of about 10,000–30,000 (the molecular weight is proportional to molecular size).
The best raw material is fish skin or fish scales, as they are free from zoonotic virus concerns and can be processed using biotechnology into functional peptides, making them the most promising collagen source for future development.