自动凯氏定氮仪测定食品中蛋白质消化条件的改进

Improvement of digestion condition in determination of protein in food by automatic kjeldahl apparatus

中文关键词:  自动凯氏定氮仪  蛋白质  消化条件

英文关键词:automatic kjeldahl apparatus  protein  digestive conditions

中文摘要:

      目的 优化自动凯氏定氮仪测定食品中蛋白质含量的消化条件。方法 选择3种不同类别的食品分别进行测量, 研究样品量、催化剂配比(K2SO4用量/CuSO4用量, 以克计, 以下同)、浓硫酸用量、消化时间和消化温度对蛋白质测定的影响。结果 实验得出最佳消化条件为: 大米样品量0.8 g, 催化剂配比6/0.4, 浓硫酸用量12.00 mL, 420 ℃消化80 min; 香肠样品量0.8 g, 催化剂配比6/0.2, 浓硫酸用量10.00 mL, 420 ℃消化 90 min; 纯牛奶样品量1.00 mL, 催化剂配比6/0.2, 浓硫酸用量10.00 mL, 420 ℃消化70 min。平行测定结果的相对标准偏差分别为0.21%、0.29%、0.50%, 加标回收率均在99%以上。结论 采用优化消化条件后的自动凯氏定氮仪测定食品中蛋白质含量精密度高, 稳定性好, 测定结果准确可靠, 满足日常检测要求。

英文摘要:

      Objective To optimize the digestion condition of determination of protein content in food by automatic kjeldahl apparatus. Method Totally 3 different categories of food were measured in terms of sample amount, catalyst proportion (K2SO4 dosage/CuSO4 dosage, in grams, the following is the same as), sulfuric acid amount, digestion time and digestion temperature to analyze their respective effect on the protein determination. Results The optimal digestion conditions were: as to rice, the sample weight was 0.8 g, catalyst proportion was 6/0.4, added amount of sulfuric acid 12.00 mL, digestion time was 80 min at a temperature of 420 ℃; as to sausage, the sample weight was 0.8 g, catalyst proportion was 6/0.2, added amount of sulfuric acid 10.00 mL, digestion time was 90 min at a temperature of 420 ℃; as to pure milk, the sample volum was 1.00 mL, catalyst proportion was 6/0.2, added amount of sulfuric acid 10.00 mL, digestion time was 70 min at a temperature of 420 ℃. The relative standard deviations were 0.21%, 0.29%, and 0.50%, and the recoveries were all above 99%. Conclusion The optimized method has good precision and stability, and with accurate and reliable measurement, which can meet the requirements of routine testing.