Comparison of functions of collagen,gelatin and collagen hydrolysate as skin-care cosmetic materials

The basic physicochemical properties of collagen,gelatin and collagen hydrolysate,such as the relative viscosity and intrinsic viscosity measured by Ubbelohde viscosimeter,the content of free amino groups in the samples determined by trinitrobenzenesulphonic acid(TNBS)method,moisture absorption and retention determined under various relative humidity conditions,the penetration and distribution of TRITC-labeled samples on the surface of rat skin,and biological activity(determined) by keratinocyte culture experiments,were investigated in consideration of their skin-care functions.The results showed that:1)The relative viscosity of collagen is 5 times that of gelatin and collage hydrolysate,and the intrinsic viscosity of collagen is remarkably higher.2)The contents of free amino groups in the samples are in the order of collagen(hydrolysate)gelatincollagen.3)Collagen is endowed with greater absorption capacity of water as compared to those of gelatin and collagen hydrolysate.4)All the samples could penetrate into hair follicles,but only collagen appears uniformly on the skin surface,illustrating good property of moisture retention.5)Only collagen considerably promotes growth and(proliferation) of cells,and the growth situation of cells cultured on gelatin and collagen hydrolysate is similar to that of control reference sample.Therefore,it can be concluded that,in comparison with gelatin and collagen hydrolysate,collagen has better moisture retention property and possesses higher biological activity of protecting against aging of skin.