基于太赫兹光谱快速检测大豆油中的磷脂酸含量

Rapid Detection of Phosphatidic Acid Content in Soybean Oil Based on Terahertz Spectroscopy

通过在一级大豆油中添加磷脂酸制备大豆油脂样品105个,测定它们的磷脂酸的含量。采集样品的太赫兹(Terahertz,THz)光谱,与参考信号相比,太赫兹波透过样品后在时间方面均产生不同程度的延迟,太赫兹波幅值出现不同程度的降低,磷脂酸的存在增加了大豆油脂样品对太赫兹波的吸收,样品中磷脂酸含量越高,其频域谱幅值越低,样品在1.58 THz处有一个较为明显的特征吸收峰,可利用太赫兹光谱对样品中磷脂酸进行定性分析。利用一阶导数、二阶导数对经剔除异常样本后剩余的91个样品的吸收光谱进行预处理,以此作为输入变量,利用偏最小二乘(PLS)建立数学模型,模型的预测集决定系数(R^(2))为0.9980,预测集均方根误差(RMSEP)为0.0813,相对标准偏差(RSD)为8.16%,说明该方法可准确预测大豆油中磷脂酸的含量。

105 samples of soybean oil were prepared by adding phosphatidic acid to first-grade soybean oil,and the content of phosphatidic acid was determined.The terahertz spectrum of the sample was collected.Compared with the reference signal,the Terahertz(THz)wave has different degrees of delay in time after passing through the sample,and the terahertz wave amplitude has decreased to varying degrees.The presence of phosphatidic acid increases the absorption of terahertz waves in soybean oil samples.The higher the content of phosphatidic acid in the sample,the lower the frequency-domain spectral amplitude.There is a more obvious characteristic absorption peak at 1.58 THz.Qualitative analysis of phosphatidic acid in samples can be performed using terahertz spectroscopy.The first and second derivatives were used to pre-process the absorption spectra of the 91 samples remaining after excluding abnormal samples.As input variables,a mathematical model was established using Partial Least Squares(PLS).The prediction coefficient(R^(2))of the prediction set is 0.9980,the root mean square error of prediction(RMSEP)of the prediction set is 0.0813,and the relative standard deviation(RSD)is 8.16%,which can accurately predict the content of phosphatidic acid in soybean oil.