Collagen is the generic name for the group of amino acids. Unfortunately, the name is also often misused for marketing purposes. Its properties depend on their origin and method of extraction.
For many years in cosmetology collagen was from bovine or porcine origin. Method of extraction was simple boiling the skins and bones. Collagen, a protein is resistant to high temperatures, and thus the process is completely wrong. Denatured collagen already at 30-40 degrees, not to mention cooking it in the 95st for several hours. Companies were added this boiled dead protein into the creams - not active protein with absolutely no biological function. From some time, the collagen is extracted from fish skin with technology of "cold extraction". Such collagen is native, biologically activewith a triple helix conformation, which is in a helical form. It has full biological activity. Likewise, food supplements - dry collagen can be cheaply at high temperature to give hydrolysed "cut" protein completely inactive, but can also perform the process of liofilization - freeze-drying under vacuum in -40degrees retaining its native form and its biological activity. In conclusion, unfortunately, many manufacturers use phrases like: "contains collagen" is meant hydrolyzate or denatured proteins (random coil).