Rapid isolation of high purity pepsin-soluble type I collagen from scales of red drum fish (Sciaenops ocellatus)

Pepsin-soluble collagen (PSC) was successfully extracted from the scales of red drum fish (Sciaenops ocellatus) and rapidly isolated using a hydrophilic ultrafiltration process that is far more efficient than the standard collagen isolation approach. SDS-PAGE analysis of the isolated PSC identified the product as type I collagen, with high electrophoretic purity, similar to the rat-tail collagen reference sample. FTIR confirmed the collagen's triple-helical structure, and UV determined the proper wavelength to optimize collagen detection. PSC was soluble under acidic conditions (pH 1-3) and solubility was found to decrease with increasing NaCl concentrations (0-6%). After microwave digestion, the As, Cr, Pb, and Cd contents of PSC, detected by ICP-MS, were less than the Chinese national standards. Ultrafiltration for the isolation of type I PSC was more flexible and efficient compared with conventional salt precipitation with dialysis and might meet the requirements for large-scale production in the food and nutraceutical industries. In addition, red drum fish scales might potentially serve as a significant alternative collagen source. (C) 2015 Elsevier Ltd. All rights reserved.