Abstract: Gelatin was extracted from salmon skin (hereinafter refers to as the gelatin) by acid leaching and water extraction.Then the gelatin were hydrolyzed enzymatically to prepare collagen peptides.More than 91.5% of the collagen peptides has a molecular weight of less than 1 000 Da.Five fractions from collagen peptides named S1,S2,S3,S4,S5 in decreasing order of molecular weight were separated by sephadex G-15.The study in vitro shows that when RH was 81%,the moisture absorption is a decreasing sequence as S5>S4>glycerol>collagen peptides>S3>S2>S1≈hyaluronic acid>the gelatin.The moisturizing effect shows a tendency of S5≈S4>S3>S2>glycerol>collagen peptides>S1>hyaluronic acid>the gelatin.When RH was 43%,the moisture absorption is a decreasing sequence as S5>glycerol>S4>collagen peptides≈S3>hyaluronic acid>S2>S1>the gelatin.The moisturizing effect is S5>S4>glycerol>S3≈collagen peptides>hyaluronic acid≈S2>S1>the gelatin.The skin test results show that collagen peptides from salmon skin significantly increase skin hydration and effectively decrease transepidermal water loss (TEWL),which is superior to that of the gelatin from salmon skin.

Key words: moisturizing cosmetic additive, collagen peptides, moisture absorption, moisturizing effect