Study On Extraction,Purification And Physico-chemical Property Of Collagen From The Body Wall Of Sea Cucumber(Stichopus Japonicus)

Sea cucumber is an important aquatic economic species. The body wall, which consists of insoluble collagen, is the major edible part of sea cucumber. The changes of shape and texture of sea cucumber during processing and storage depends on the change of the collagen. So it is significant to study sea cucumber collagen for which can provide theoretical foundation and scientific basis for the development of deep-processing products and the process optimization of sea cucumber.In this paper, pepsin-solubilized collagen (PSC) and acid-solubilized collagen (ASC) of sea cucumber (Stichopus japonicus) were extracted. PSC was purified, and its physicochemical properties, antioxidant activity and angiotensin-converting enzyme (ACE)-inhibition activity were studied. Meanwhile, the extraction process of ASC was optimized through the experiment of uniform design.The experimental results indicated that PSC was purified effectively by using DEAE-52ion-exchange chromatography. The UV and FTIR spectra showed that the collagen had high purity and maintained intact triple-stranded helices. The distribution pattern of amino acid composition of PSC was similar with that of collagen Type I.The PSC obtained in this study has an isoelectric point (pI) of4.14; The solubility of PSC reached the minimum when the pH was around the pH4.0; The solubility of PSC in0.5mol/L acetic acid slowly decreased with increasing salt concentrations until a lowest point, and which was constant after that; The moisture-absorption and-retention properties of PSC was better than glycerol; The oil absorption value was92.4mL/g; The relative viscosity of PSC increased continuously along with increasing concentration, and decreased continuously along with increasing temperature.CPC had high hydroxyl radicals scavenging activity with the IC50value of0.52mg/mL which was higher than Vc but lower than sulfourea. The DPPH radicals scavenging rate of CPC was45.58%at concentration of5mg/mL, which was higher than that of VE; PSC possess stronger anti-peroxidation potency than Vc, and the content of peroxide was0.5%as PSC concentration reached5mg/mL. The ACE inhibitory activity of PSC increased with PSC concentration, and the IC50value was1.65mg/mL.The optimum extraction condition of ASC acquired by the experiment of uniform design was:acid concentration of0.5mol/L, dosage liquor ratio of1:1000, extraction time for72h. Under these conditions, the yield of ASC was7.35%. The collagen had high purity and maintained intact triple-stranded helices. The distribution pattern of amino acid composition of PSC was similar with that of collagen Type I.