K12A全自动凯氏定氮仪测定核桃蛋白质含量

Study on Determination of Walnuts Protein by K12A Automatic Kjeldahl Apparatus

建立一种使用全自动凯氏定氮仪测定核桃中蛋白质测定的方法,通过核桃与硫酸和催化剂一同加热消解,使蛋白质分解,分解的氨与硫酸结合生成硫酸铵,然后碱化蒸馏使氨游离,用硼酸吸收后再以盐酸标准溶液滴定,根据酸的消耗量乘以换算系数,即为蛋白质含量。结果表明,采用K12A全自动凯氏定氮仪测定(NH4)2SO4标准品氮回收率在99.8%~99.9%,测定核桃蛋白质含量平均为15.8266%,相对标准偏差为0.3020%(n=6)。该方法具有准确、快速、简便、低耗、稳定的优点,相对偏差小,是核桃中蛋白质测定的首选方法。

This article established a method for determining protein in walnuts by automatic kjeldahl apparatus.Walnuts were heated and digested with sulfuric acid and a catalyst to decompose the protein.The decomposed ammonia combined with sulfuric acid to produce ammonium sulfate which was distillated to make ammonia free.Ammonia was absorbed with boric acid and then titrated with hydrochloric acid standard solution.According to the consumption of acid multiplied by the conversion factor,the protein content was calculated.The results showed that the nitrogen recovery rate of(NH4)2SO4 standard product measured by K12A automatic kjeldahl apparatus was between 99.8% and 99.9%.And the average protein content of walnuts was 15.8266%,and the relative standard deviation was 0.3020%(n=6).It showed that this method was the preferred method for protein determination in walnut for the advantages of accuracy,speed,simplicity,low consumption,and stability.