基于紫外光谱的食用油酸值检测

为实现食用油酸值的快速准确检测，利用游离脂肪酸与邻苯二甲酰亚胺钾快速反应生成邻苯二甲酰亚胺以及邻苯二甲酰亚胺在紫外光谱290 nm波长处有特征吸收峰的原理，建立食用油酸值检测模型，不同酸值的验证样品及盲样对模型进行验证，并与滴定法进行比较分析。结果表明：模型预测酸值与滴定法所得酸值结果非常相近，决定系数（R2）均大于0.99，表明模型预测效果好且不受油脂种类的影响；模型预测酸值相对误差范围为0.22%～6.87%，相对标准偏差为1.34%，说明该模型具有较高的准确度和精确度。因此，利用紫外光谱对食用油酸值检测的方法是可行的。

Detection of Acid Value in Edible Oils Based on Ultraviolet Spectroscopy

An ultraviolet (UV) spectrophotometric method for determining acid value (AV) of edible oils was developed
based on the stoichiometric reaction of free fatty acid with K-phthalimide to produce phthalimide showing characteristic
absorption at 290 nm. The presented prediction equations for phthalimide were validated with known and unkown samples,
and analyzed in comparison with the national standard method (iodimetry). The comparable results of AV were obtained
by both methods with determination coefficients (R2) above 0.99, indicating that the models had good prediction efficiency
which was independent of the type of oil investigated. The relative errors and relative standard deviation (RSD) for the
model-predicted values were 0.22%–6.87% and 1.34%, respectively. In conclusion, the spectrophotometric method was
characterized by good precision and accuracy. Therefore, this method is feasible for rapid determination of acid value in
edible oils.