Extraction and characterization of acid-soluble collagen from scales and skin of tilapia (Oreochromis niloticus)

Acid-soluble collagen (ASC) was extracted from scales and skin of tilapia. The yields of scale collagen (SCC) and skin collagen (SKC) were 3.2 g/100 g and 27.2 g/100 g respectively, dry weight. The SDS-PAGE profile showed all collagen samples contained [alpha 1(I)](2)alpha 2(I) component and were characterized as type I collagen. LC-MS/MS analysis confirmed the SCC and SKC to be Oreochromis niloticus type I collagen. Amino acid analysis revealed the imino acid content from the SCC and SKC samples were 207 and 197 residues/1000 amino acid residues, respectively. Based on FTIR spectra and X-ray diffraction, isolation of ASC did not affect its three dimensional structure. Zeta potential studies indicated both SCC and SKC exhibited a net zero charge at pH 6.82 and 6.42, respectively. Both ASC samples exhibited high solubility in acidic pH (1-3) and lost their solubility at NaCl concentrations below 3 g/100 mL. The data collected here indicate that SCC and SKC may be suitable for use as an alternative to land-based mammalian collagen in food, nutraceuticals and pharmaceutical industries. (C) 2015 Elsevier Ltd. All rights reserved.