Extraction, purification and application of hydrolysed collagen from fish skin

Abstract

Collagen hydrolysate is a mixture of peptides which have molecular weight less than 20 kDa and are obtained from enzymatic hydrolysis of collagen or gelatin. It has extraordinary properties and bioactivities compared to collagen and gelatin, such as antioxidant, anti-freezing, anti-microbial, ultraviolet ray prevention, and stimulator for the healing hormones of arthritis. Thus, collagen hydrolysate is widely used in functional foods, cosmetics and pharmaceuticals. The procedure to produce hydrolysate collagen from fish skin begins with the process of removing non-collagen substances, then enzymatic hydrolysis, and finally purification and fragmentation of collagen hydrolysate. The removal of non-collagen agents usually employs sodium hydroxide. Depending on the chemical composition of the fish skin, sodium hydroxide concentration ranges from 0.05 M to 0.1 M, the ratio of fish skin weight to sodium hydroxide solution is 1:10 (w/v) and soaking time is from 6 to 24 hours. Currently, many studies use protease enzymes to hydrolyze collagen. Depending on the type and source of enzyme, the collagen hydrolysate products have different degrees of hydrolysis (DH). Each type of enzyme needs to be performed at its optimum catalytic conditions such as pH, enzyme/substrate (E/S) ratio, hydrolysis temperature, hydrolysis time to achieve maximum DH and desired molecular weight of the obtained peptides. For rapid and effective separation of the collagen fragments, ultrafiltration or gel filtration chromatography are usually used.