含油食品酸价检测不确定度评定

Assessment of Uncertainty in Acid Value Detection of Oil-containing Food

酸价是反映食品中油脂酸败程度的重要指标,也是食用油或含油食品中必检项目之一。酸价检测不确定度评定可以更科学地评价酸价检测的准确性、科学性和公平性。本文采用冷溶剂指示剂滴定法与冷溶剂自动电位滴定法检测酸价,建立数学模型,分析不确定度来源,评定各不确定度分量、合成不确定度及扩展不确定度。结果表明,自动电位滴定法检测某含油食品酸价结果为6.4 mg/g,扩展不确定度为0.2 mg/g,K=2,显著性不确定度分量为NaOH标准滴定液浓度;指示剂滴定法酸价为6.3 mg/g,扩展不确定度为0.3 mg/g,K=2,显著性不确定度为NaOH标准滴定液浓度不确定度最大、A类不确定度次之、滴定体积不确定度再次之,且三者显著性相近,扩展不确定度大于电位滴定法。通过不确定度评定和显著性分析,可以有针对性地找到降低或控制检测误差的方法,提高检测结果准确性。

Acid value is an important index reflecting the rancidity degree of oil in food,it is also one of the items that must be tested in edible oil or oil-containing food.Assessment of uncertainty in acid value detection can scientifically assess the accuracy,scientificity,and fairness of acid value detection.This paper used the cold solvent indicator titration and the cold solvent automatic potentiometric titration to detect acid value,established a mathematical model,analyzed the sources of uncertainty,then assessed each uncertainty component,combined uncertainty,and extended uncertainty.The results showed that,through the automatic potentiometric titration,the acid value detection of a certain oil-containing food indicated C=6.4 mg/g,U=0.2 mg/g,K=2,and the significant uncertainty component was the concentration of NaOH standard titration solution.The acid value detected by the indicator titration indicated C=6.3 mg/g,U=0.3 mg/g,K=2.The concentration of NaOH standard titration solution had the highest significant uncertainty,followed by class A uncertainty,and the titration volume uncertainty,the three had the similar significance,and the extended uncertainty of indicator titration method was greater than that of the potentiometric method.Assessment of uncertainty and significance analysis,can find targeted methods to reduce or control detection errors and improve the accuracy of detection results.