| In this paper, contents of general nutritional composition, amino acids and mineralelements of the meat and skin of farmed Chinese giant salamander （Andrias davidianusBlanchard） were analyzed and evaluated, simultaneously response surfacemethodology （RSM） was adopted to optimize the process parameters forextraction of pepsin-soluble colla gen fro m its skin, and physicochemicalproperties of the purified acid-soluble collagen （ASC） and pepsin-soluble collagen（PSC） were analyzed to provide scientific theoretical directions for its furthercomprehensive exploitation and utilization.The results indicated high protein content of （92.60±4.24） g/100g and （96.46±5.32） g/100g （dry weight）, low fat content with （6.24±1.78） g/100g and （4.02±0.62）g/100g （dry weight） in the meat and skin of farmed Chinese giant salamander,respectively. There was total of18different amino acids in the meat, including6kindsof flavor amino acids （FAA） and8kinds of essential amino acids （EAA） for humanbody, accounted for42.77%and40.72%respectively. The ratio of essential amino acidsto non-essential amino acids is68.68%, in line with the ideal model of FAO/WHO withno limited amino acids. According to amino acid score （AAS） and chemical score （CS）,the skin was rich in sulphur amino acids while the first limited amino acid and thesecond limited amino acid were Tryptophan （Trp） and Leucine （Leu） in the protein ofthe skin, respectively. In addition, Potassium （K） was the most predominant mineralelement found in the meat and skin, and the contents were （1184.96±73.84） mg/100gand （391.24±87.69） mg/100g （dry weight）, respectively. In trace elements, thecontents of zinc （Zn） and iron （Fe） were much higher.The skin of Chinese giant salamander is rich in collagen with the content of （19.00±2.66） g/100g （wet weight） and60%（dry weight）, respectively, and approximatelyaccounted for62.89%of total protein in skin. Pepsin and0.5mol/L acetic acid asenzyme and solution for extraction respectively, on the basis of single factor experiments, RSM was adopted to obtain the optimal process parameters forextraction of PSC from the skin of Chinese giant sa lamander. The results showedthe quadratic polyno mial regression model was established and the optimalconditions were as follows: pepsin amount of16.5%, solvent-to-solid ratio of15mL/g and enzyme extraction time of29h, then the extraction rate of66.99%was obtained, which tallied closely with the theoretical predicted value （67.83%）by the regression model. Additiona lly extraction rate was significantly improvedfrom28.88%to66.99%compared with control experiments. According to RSM,the effect order of the three factors on the extraction rate of colla gen from theskin were as follows: solvent-to-solid ratio first, enzyme extraction time second,and then pepsin amount. The interaction between solvent-to-solid ratio andenzyme extraction time had significant effects on the extraction rate of collage n,while others had no significant effects.Physicochemical properties of purified ASC and PSC were researched. Theresults ind icated: ASC and PSC contained two different α chains and β chainwhich is dimer of α chains, showing the patterns of type Ⅰ collagen. The highestcontent was glycine, then glutamic acid, proline and hydroxyproline in ASC and PSC,and the lowest was cystine, which was line with amino acid composition features ofcollagen. The imino acid content in ASC was lower than PSC, so the thermal stability ofPSC excelled ASC. A strong Ultraviolet absorption peak was obtained at233.0nm and232.0nm respectively, which was in accordance with the characterization of type Ⅰ.Fourier transform infrared （FT-IR） spectra showed the characteristic absorptionfrequency of ASC and PSC were similar, and amide Ⅲ, absorption peak of1454.63-1233.02cm-1for ASC and1453.15-1239.28cm-1for PSC proved integrity oftriple helix structure of collagen.The denaturation temperature range of ASC and PSCwere20-25℃,25-30℃. |
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