Study On Extractionan And The Structural Morphous In The Processing Of Collagen From The Body Wall Of Sea Cucumber

The body wall is the edible part of sea cucumber. The body wall of sea cucumber is rich in protein, most of that is collagen protein. The quality of the sea cucumber during processing and storage depends on the construction change of the collagen protein. In this presentation, the collagen protein was extracted from the special local products of Dalian-sea cucumber (Stichopus japonicus), and the construction change of the collagen protein under different temperature was investigated.The soluble collagen (PSC) was extracted and purified by pepsin hydrolysis method from the body wall of the sea cucumber. The optimum hydrolysis condition was determined according to the collagen protein yield. The properties of PSC were studied by SDS-PAGE, UV and FTIR spectrum. The construction change of the purified collagen at different temperature (30℃,40℃,50℃,60℃,70℃,80℃,90℃,100℃,105℃,110℃,115℃,120℃) with different dealing time (10min、15min、20min、25min、30min respectively)was studied. Frozen sections of all the samples treated under the above conditions were prepared and stained. The microstructure of the elastic fibers and collagen fibers was observed and compared under optical and electronic microscope.The results showed that the water content of the raw sea cucumber was91.34%. The collagen protein content was about70.04%of crude protein. The optimum condition for extracting PSC was as below:at4℃, pepsin addition14%(w/w), dosage liquor ratio1:500, extraction time72h. Under the optimum condition, the yield of pepsin soluble collagen was73.44%. The optimum salting-out condition was0.8mol/L sodium chloride. The PSC exhibited a maximum absorbance at233nm, The UV and FTIR spectra showed that the collage was homogeneous, with an intact triple-stranded helices. The SDS-PAGE demonstrated that the purified PSC were composed of2distinct subunits,α1and α2, which formed (α1)2α2heterotrimers.The tissue structure was different between live and heated sea cucumber. The collagen fibrous bundles of raw sea cucumber were thick, presented certain directivity. Comparing with raw sea cucumber, the apertures between collagen fibrils of the heated samples were small, and the width of collagen fibrils shorten. With the increase of the temperature, the proportion of the apertures gradually increased, and the width of collagen fibrils expanded. Heating at the same temperature for different time, the structural change of the sea cucumber was great. When the temperature was over100℃, the collagen protein denatured and agglutinated.Partial denaturation of collagen was benefit for the quality and taste of the sea cucumber after reabsorbing water. After the collagen denatured, the formed gelatin always resolve along with the reabsorbing process. This dissolution will decrease the nutritional value of the sea cucumber. After reabsorbing water, it is difficult to preserves the sea cucumber. So cryopreservation is the suitable method for storage.The results of the histology studies showed that structure of he body wall changed greatly during heating and processing. This is possible related to the textural properties of the collagen in the body wall of sea cucumber. This will provide important clue for the processing of sea cucumber for industry.