含油食品酸价检测不确定度的评定

目的:酸价是反映食品中的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,通过酸价检测不确定度评定,更科学的评价酸价检测的准确性、科学性和公平性。方法: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:自动电位滴定仪法检测某含油食品酸价C=6.4mg/g,U=0.2mg/g,K=2,显著性不确定度为NaOH标准滴定液浓度；指示剂滴定法酸价C=6.3mg/g,U=0.3mg/g,K=2,显著性不确定度为NaOH标准滴定液浓度最大、A类不确定度次之、滴定体积再之,且三者显著性差不多,扩展不确定度大于电位法。通过不确定度评定和显著性分析,可以有针对性的找到降低或控制检测误差的方法,提高检测结果准确性。

Evaluation of uncertainty in acid value detection of oil-containing food

objective:Acid value is an important index reflecting the degree of rancidity of oil in food,It is also one of the items that must be tested in edible oil or oily food,By evaluating the uncertainty of acid value detection,More scientific evaluation of the accuracy of acid value detection, scientific and fair.Method:Acid value was determined by cold solvent indicator titration and cold solvent automatic potential titration,The mathematical model is established, the sources of uncertainty are analyzed, the components of uncertainty are evaluated, the combined uncertainty and the extended uncertainty are evaluated.Results:Acid value of oil-containing food was detected by automatic potentiometric titration C=6.4mg/g,U=0.2mg/g,K=2,The significant uncertainty was the concentration of NaOH standard titrate.Acid value of indicator titration method C=6.3mg/g,U=0.3mg/g,K=2,The Uncertainty of NaOH standard titrate concentration was the highest,The uncertainty of Class A is second,Titrate the volume again,And the three are about the same,The extended uncertainty is larger than that of the potentiometric method.Through evaluation of uncertainty and significance analysis,The method of reducing or controlling detection error can be found pertinently to improve the accuracy of detection results.