The young collagen which is present in the body, which
is obtained through biosynthesis, is soluble in aqueous
buffers. Therefore, only this form is responsible for maintaining
adequate water content in the skin. Skin aging is
caused by the progressive transformation of soluble collagen
in the insoluble form of collagen through cross-linking
reactions and the constitution of proteins, which have
less capacity to retain water. Collagen’s ability to swell in
acid solutions and its susceptibility to enzymes decreases
with age. During our life the stiffness of fibers increases,
ultimately leading to their fragility as a result of
decline in tensile strength. Changes of the chemical and
physical properties of collagen fibers that occur in the aging
process are very noticeable. The clearest symptom of the
aging process of the skin is that it is wrinkled, dry and loses
its elasticity [6].