Comparative study on characteristics and in vitro fibril formation ability of acid and pepsin soluble collagen from the skin of catla (Catla catla) and rohu (Labeo rohita).

Catla (Catla catla) and Rohu (Labeo rohita) are the major carp fish produced by freshwater aquaculture in India. Processing of these carp fish generates potentially large quantities of by-products (waste) from non-edible fish parts by fish-processing factories and fish shops. The paper focuses on the extraction of the acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the skin of carp fish and subsequently their characteristics and in vitro fibril-forming ability. The extracted collagens are characterized as type I collagen based on the electrophoretic pattern. The denaturation temperature for all the collagens extracted was found to be 30.69-35.19°C by differential scanning calorimetry (DSC) analysis. The extracted collagens exhibited higher solubility at low concentration of NaCl (0-0.4M). All the ASC and PSC displayed different degrees of fibril-forming abilities and the scanning electron microscopy (SEM) analysis confirmed their well-defined fibril morphologies. The degree of collagen fibril formation was significantly (p≤0.05) higher (78%) in rohu skin collagen than catla skin collagen (36%). In general, the characteristics of two carp skin collagens were unique as evidenced by the electrophoretic, DSC, SEM and fibril-forming patterns. Overall, the results indicated the feasibility of using the carp skin as a good alternative source of realistic high-quality collagen.