中国包装食品中钠含量分析和变化的研究

目的研究不同实验室对包装食品中钠检测的实验室变化。方法根据2000年全国包装食品消费的调查,选择7类(谷物、豆类、肉类、奶制品类、饮料类、坚果、休闲食品)14种包装食品,在全国的7家实验室进行3次钠的平行样检测,钠检测方法为国家标准方法。结果所有钠检测结果筛查合格率为78.6%。钠检测精密度为:实验室内变异系数2.46%~7.82%;除钠含量非常低的核桃仁外,实验室间6.40%~51.86%,室内和室间总和为6.88%到52.16%,平均24.64。除钠含量非常低的核桃仁外,钠检测的相对扩展不确定度由12.66%到96.16%,平均46.02%。结论不同实验室内对钠的检测符合国家标准方法的要求。如果重点考虑中高钠含量的食品,则总的实验室不确定度可以控制在50%内。应进一步提高我国实验室钠检测的总体水平,降低低钠含量食品的分析误差。

Laboratory analysis and its variety for sodium in prepackaged foods in China

Objective To observe the lab variety of sodium analysis of prepackaged from different labs of China.Methods Fourteen foods from seven kinds of foods were selected as food samples, including cereal products, bean products, meat products, dairy products, beverages, nuts, snacks, according to national prepackaged foods consumption survey results in 2000. The sodium concentrations were analyzed parallelly for three times by national standard methods in seven labs in China. Results The 78.6% results were up to grade by Grubbs, Cochran and Dixon screening methods. The accuracy of protein analysis was expressed by variety co efficiency (C.V%). The C.V% of inner labs was from 2.46% to 7.82%. Besides walnut (with very low sodium content), the C.V% of inter labs and total labs were from 6.40% to 51.86% and from 6.88% to 52.16% (average 24.60%). The relative expanded uncertainty of protein detection was from 12.66% to 96.16% (average 46.02%). Conclusion Sodium analysis in labs in China were fit for national standards. If sodium labeling were focused on middle and high sodium contents prepackaged foods, the uncertainty of analysis could be controlled in 50%. The sodium detection level of labs in China should be promoted that the analysis variety of low content food could be reduced.