abstract
Collagen (also known as collagen) is a structural protein of extracellular matrix, which is called "collagen" in English and evolved from Greek. It is a white polysaccharide protein containing a small amount of galactose and glucose. It is the main component of extracellular matrix (ECM), accounting for about 85% of collagen fiber solids. Collagen is a common macromolecular protein in animals, which mainly exists in connective tissues (bone, cartilage, skin, tendon, toughness, etc.). ), accounting for 25% ~ 30% of protein of mammals, equivalent to 6% of body weight. In many marine organisms, such as fish skin, the content of protein is as high as 80%. It plays a role in supporting, protecting, combining and forming boundaries between the body and organs. In addition to biomechanics, it also has the functions of signal transduction, growth factor and cytokine transport.
Animal tissues from livestock and poultry have always been the main way for people to obtain natural collagen and collagen peptides. However, due to the occurrence of mad cow disease (BSE), foot-and-mouth disease (FMD), avian influenza and other diseases, people questioned the safety of collagen from terrestrial mammals and its products. Besides, in areas where people believe in Islam, the application of collagen from livestock is limited. It gradually turned to marine life to develop collagen. Although the European Food Safety Agency (EFSA) has confirmed that even collagen from animal bones is safe, there is no possibility of being infected with mad cow disease and other related diseases.
Due to the difference of amino acid composition and crosslinking degree, the rich collagen contained in aquatic animals, especially their processing wastes-skins, bones and scales, has many advantages that livestock collagen does not have, such as certain gelation, high dispersibility, low viscosity, water absorption, water holding capacity and emulsification. In addition, it was found that collagen from marine animals was obviously superior to collagen from land animals in low antigenicity, low allergenicity and denaturation. Therefore, aquatic collagen may gradually replace terrestrial collagen.
There are many types of collagen, and the common ones are type I, type II, type III, type V and type VII. Collagen is widely used in food, medicine, tissue engineering, cosmetics and other fields because of its good biocompatibility, biodegradability and biological activity, such as low antigenicity, easy absorption in the body, promoting cell survival and growth, and promoting platelet aggregation. It can be used not only as health food, beauty products and packaging materials, but also as food additives for the improvement of meat products, frozen foods, beverages, cakes and dairy products. In the medical field, collagen can be made into collagen sponge, collagen membrane, artificial skin, immobilized enzyme carrier and capsule because of its low immunogenicity, fiber re-formation, strong mechanical properties and biodegradability. The traditional collagen health care product "Ejiao" in China is mainly made of donkey skin (in fact, the collagen contained in donkey skin), which has a high nourishing and health care function and is known as one of the three treasures of traditional Chinese medicine.