Physicochemical properties and radical scavenging capacities of pepsin-solubilized collagen from sea cucumber Stichopus japonicus

Pepsin-solubilized collagen (PSC) was successfully prepared from the body wall of sea cucumber Stichopus japonicus. Ultraviolet–visible and Fourier transform infrared spectroscopic analyses showed that the PSC was a high-purity collagen that maintained the intact triple-stranded helices. Physical and chemical characterization of the PSC showed a isoelectric point of 4.14, a superior moisture-absorption and retention capacities comparing to glycerol, a minimum solubility at pH 5.0 in 0.5 M acetic acid, and a sharp decrease in solubility in the presence of low concentration of NaCl. The viscosity of PSC was shown to decrease continuously as the temperature was increased. The radical scavenging activity of the PSC was characterized with two model systems: for hydroxyl radicals, the PSC was more active than vitamin C but less active than sulfourea; for 1,1-diphenyl-2-picrylhydrazyl radicals, the PSC was more active than vitamin E.