柠檬酸提取贝肉中镉及其提取液中氨基酸组成分析

Extraction of cadmium from shellfish homogenate by citric acid and analysis of amino acids composition

以马氏珠母贝匀浆液为原料,利用柠檬酸络合提取马氏珠母贝匀浆液中的重金属镉,考查柠檬酸溶液浓度、溶液pH、料液比和反应时间对镉提取率的影响,优化镉的提取条件,并分析提取液中氨基酸组成,通过化学评分和必需氨基酸指数对其蛋白质的营养价值进行评价。结果表明,柠檬酸对马氏珠母贝匀浆液中的镉具有很好的提取效果,在最佳提取条件下,即柠檬酸溶液的浓度为0.08mol/L、pH 4.0、料液比1∶10(m∶V)、提取时间4h,柠檬酸对马氏珠母贝匀浆液镉的提取率达到92.2%。马氏珠母贝肉脱镉后所得的柠檬酸提取液中总氨基酸含量为2 940mg/100g,必需氨基酸占总氨基酸的百分含量为51.7%,蛋白质的EAAI为78.06;马氏珠母贝肉总氨基酸含量为13 120.0mg/100g,必需氨基酸占总氨基酸的百分含量为32.4%,蛋白质的EAAI为69.98,表明马氏珠母贝肉以及柠檬酸提取液均富含蛋白质、必需氨基酸,且必需氨基酸组成比较均衡。

Pinctada rnartensii homogenate was used as raw material and Gadmium（Cd） was extracted from the homogenate by citric acid using complexation. The effects were studied of the concentration of citric acid, pH value of the solution, ratio of material to solution and reaction time on the extraction rate of Cd. The extraction conditions of Cd from Pinctada martensii homogenate were optimized. Fur- thermore, amino acids composition in extracted liquid was analyzed and the nutritional values of proteins in it were evaluated by methods of chemical score（CS） and essential amino acids index（EAAI）. The results showed that citric acid had proved to be very effective for the extraction of Cd from Pinctada martensii homogenate. The condi- tions to obtain the highest extraction rate by citric acid were 0.08 mol/L of citric acid, pH 4.0, 1： 10 of material to solution and 4 h. Under these optimal conditions, extraction rate of Cd from Pinctada martensii homngenate reazhed up to 92.2%. The content of total amino acids in the extracted liquid which was ohtained after the removal of Cd from Pinctaaa martensii homogenate was 2 940 mg/100 g, and the percentage of essential amino acids in total amino acids was 57.7%, EAAI of proteins was 78.06. The content of total amino acids in shellfish was 13 120.0 mg/100 g, and the per centage of essential amino acids in total amino acids was 32. 4 %, EAAI of proteins was 69. 98. Therefore, the results indicated that shellfish and extracted liquid were rich in proteins and essential ami- no acids. Moreover, the essential araino acids compositions of shell fish and extracted liquid were in counterpoise relatively.