Study On Preparation Of The Collagen Form The Skin Of The Cod

In this paper，the cod skin as the test material, the extraction method of collagenfrom the skin of cod, processing method before extract and its identification wasstudied.The purpose was to find out the high rate of extraction process, to obtain type Icollagen in high purity, to provide a theoretical basis for the development of newfunctional food and low to high values of cod skin, which is the waste of aquaticproducts processing waste.1. The study of processing method of cod skin before extractionDegreasing and removing non-collagen and fat treatment on cod skin was studiedwith the non-collagen content and collagen in the supernatant as asse-ssment indexes.The results showed that the processing conditions of the removal of non-collagen in thehighest and lowest collagen loss was: at12℃, the cod skin was soaked with7.5%NaCland0.02mol/L NaOH and stirred18h with the magnetic stirrer at the same time, themeasured removing non-collagen rate can be88.94%, collagen loss rate can be3.82%.Then the cod skin is stirred5times by10%n-butyl alcohol with the magnetic stirrer,treating time is1h at a time, the measured degreasing rate can be88.36%. The processconditions can have good effect on removing non-collagen and fat.2. The study of extraction of collagen from skin of cod（1） The cod skin as test material, using acid extraction method and enzymeextraction method to extract collagen was studied respectively with extraction rate ofcollagen as assessment indexes.Acid extraction test used acetic acid, lactic acid and citricacid to extract collagen and chose the most suitable kind of acids to conduct specificresearch on acid extraction process. The results showed that the optimum extractionconditions of acid extraction was: acetic acid was the most suitable extraction acid, whenthe concentration of acetic acid was0.47mol/L, the liquid-solid ratio was1:33, extractiontime was90.2h, the measured average extraction rate of acid-soluble collagen （ASC） canbe37.36%. Enzymatic extraction test used pepsin, papain, protamex and alkalineprotease to extract collagen and chose the most suitable kind of enzymes to conductspecific research on enzyme-extraction process. The results showed that the optimumextraction conditions of enzymatic extraction was: pepsin was the most suitable enzyme,when the amount of enzyme was850u/g, the liquid-solid ratio was1:31, the extractiontime was17.6h, and the measured average extraction rate of pepsin-soluble collagen （PSC） can be55.96%.（2） The solution of acid extraction and enzymatic extraction was purified by saltingout method and dialysis method. The ASC and PSC and standard typeⅠ collagen wascontrasted and analysised, using HPLC method to test the samples purity. The resultshowed that the HPLC atlas of ASC and PSC and standard type Ⅰc ollagen wasconsistent,indicating ASC and PSC were type Ⅰc ollagen. The results showed that The purity of ASCand PSC was97.81%and94.64%respectively by contrasting the peak area of ASC andPSC with typeⅠ collagen.3. The identification and analysis of collagen from skin of codThe Characterization of ASC and PSC was identified and compared with thestandard of typeⅠ collagen. The analysis of amino acids can show that the distribution ofamino acids of ASC and PSC of the cod skin consistent with the characteristics oftypeⅠ collagen.SDS-PAGE tests showed that ASC and PSC both contained5band,which were the β₁,β2,α₁,α₂subunit （may contained α₃subunit）.The extracting collagenmolecular weight was about220KDa and contained no impurity band by comparing withelectrophoresis band of the standard type Ⅰc ollagen which proved that the ASC and PSCwere typeⅠ collagen and reached the electrophoretic purity. FT-IR testing was used toidentify extracting collagen, FT-IR information can fully showed that ASC and PSC stillkept natural triple-helical domains completely. The denaturation temperature of ASC andPSC were26.8℃and25.6℃respectively by using ubbelohde viscometer method. Itsthermal stability is better than others, so it is convenient for post processing, storage andtransportation. It proved that the collagen extracted from cod skin was type Ⅰcollagenwith high quality, which has a high degree of thermal stability.