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.