Collagen is extracted from animal skin. In addition to collagen, the skin also contains protein polysaccharides such as hyaluronic acid and chondroitin sulfate, which contain a large number of polar groups and are moisturizing factors. They also have the effect of preventing the conversion of tyrosine into melanin in the skin. Therefore, collagen has pure natural moisturizing, whitening, wrinkle prevention, freckle removal, and other functions, and can be widely used in beauty products. Add a certain amount of acetic acid to cosmetic collagen to maintain its liquid state.