海蜇胶原蛋白的制备及理化性质研究
Preparation and physicochemical properties of the jellyfish collagen

以海蜇加工下脚料为原料，建立在中低温条件下，以柠檬酸为提取剂的胶原蛋白制备工艺，并对海蜇胶原蛋白的理化性质进行分析. 结果表明，海蜇胶原蛋白的最佳酶法提取工艺条件为：提取温度15℃、柠檬酸浓度0.05mol·L-1、胃蛋白酶添加量1.5%、料液比1∶2.0（w∶V）和提取时间8h，在该条件下胶原蛋白提取率为97.41%. SDS-PAGE分析结果表明，其可能结构为[α1]3；胶原蛋白中，甘氨酸、脯氨酸和羟脯氨酸分别占总氨基酸的25.16%、7.62%和9.32%；傅里叶红外光谱分析表明，其保留了完整的三螺旋结构；黏度及溶解性特征显示，其等电点pI值在6~9之间；在pH值≤1和≥10范围，结构趋于不稳定，热变性温度为22.7℃，在大于1.0mg·mL-1的NaCl溶液中基本析出.
To analyze the physicochemical properties of jellyfish collagen，the leftover jellyfish was used as raw material，and treated with preparation technology. The preparation technology for collagen was based on the low-temperature condition and citric acid which worked as an extraction agent. The optimum enzymatic extraction condition was: temperature 15℃，0.05mol·L-1 citric acid concentration，1.5% (mass fraction，the following are the same as) pepsin addition，1∶2.0 (w∶V) solid-liquid ratio and 8h extraction time. The jellyfish collagen extraction yield of 97.41% under this condition. By performing purified collagen on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)，the result demonstrated that collagen as Type I marine collagen in which three α1 chains each other. In collagen，glycine (Gly)，proline (Pro) and hydroxyproline (Hyp) account for 25.16%，7.62% and 9.32% of the total amino acids，respectively. Fourier transform infrared spectroscopy(FTIR) data of the collagen revealed that stable triple-helical structure was existence. Meanwhile，the viscosity and solubility of purified collagen were measured to evaluate the pI value of collagen about 6 to 9. When the pH value is less than or equal to 1 and above 10 range，structure tended to be unstable，thermal denaturation temperature 22.7℃. According to the experimental results，collagen would precipitate completely in NaCl solution when its mass concentration was above 1.0mg·mL-1