Characteristics of acid and pepsin solubilized collagens from Nile tilapia (Oreochromis niloticus) scale
In Thailand, the production of tilapia is about 140,000 tons, which is the sixth tilapia production in the world. From the processing, the scale was generated as waste. To produce a value-added product, the production of collagen from tilapia scale could be an alternative. Generally, collagen from fish scale possesses a less fishy odor and flavor than that from fish bone and skin. From the results, the fish scale is an interesting alternative source for collagen extraction. The objectives of this study were to extract collagen from Nile tilapia (Oreochromis niloticus) scale from the production of frozen tilapia fillet as well as to study its properties. Extraction of acid (ASC) and pepsin soluble collagens (PSC) from Nile tilapia scale, as well as the determination of their yield, amino acid compositions, SDS-PAGE patterns, FTIR spectra, thermal denaturation temperature (Tmax) and zeta potential, was conducted. ASC and PSC had a yield of 0.77 and 0.71% based on dry basis), respectively. The major amino acid found in both collagens was glycine (322-332 residues/1000 residues). Also, they had a high amount of imino acid (199-205 residues/1000 residues). Based on SDS-PAGE pattern, both collagens were classified as type I collagen ((α1)2α2-heterotrimer). The similar FTIR spectra of both collagens were found. Their amide peaks had no shift in wavenumber. ASC and PSC had Tmax of 36.15 and 34.70 °C, respectively. From zeta potential analysis, ASC and PSC had the zero of net chart at pH 5.09 and 5.84, respectively. Based on the characteristics of the collagen, the scale could be an alternative source for collagen production, however their yield should be improved to serve as a potential source for further application.