不同贮存年限陈皮的太赫兹光谱和成像的差异分析

The Differences in the Dried Tangerine Peels Stored for Different Years Revealed by Terahertz Spectroscopy and Imaging

本研究利用太赫兹光谱与成像技术及统计分析方法对5种不同贮存年限(3、5、10、15和20年)的陈皮进行了差异性表征和年限鉴别。结果表明,不同贮存年限陈皮样品的太赫兹光谱信息参数(包括吸收系数、折射率、复介电常数虚部和介质损耗角正切值)和太赫兹频域图像对比度均存在明显的差异和较为一致的变化趋势,3~15年陈皮的各参数值随贮存年限的增加而递减,15~20年陈皮的各参数值随年限增加而渐增;对0.6~1.8THz范围内的各光谱参数进行统计学分析及独立样本t检验,提取变化规律具有一致性且差异显著(p<0.05)的光谱参数数据,建立了基于主成分分析-支持向量机(PCA-SVM)的高效陈皮贮存年限预测模型,其年限预测准确度可达94%以上。该结果表明了太赫兹技术在表征不同陈皮差异及鉴定贮存年限上的可行性和优越性。

In the study, five kinds of dried tangerine peels stored for different years(3, 5, 10, 15 and 20 years) were subjected to differential characterization and identification of storage years by terahertz spectroscopy and imaging technique and statistical analysis method. The results showed that significant differences and consistent changing trends were found in the terahertz spectral parameters(including the absorption coefficient, refractive index, complex dielectric constant imaginary part and dielectric loss tangent value) as well as the contrast of terahertz frequency-domain images among the different dried tangerine peel samples: decreasing gradually with an increase of storage year for those stored for 3~15 years, whilst increasing gradually with an increase of storage year for those stored for 15~20 years. Moreover, statistical analysis and independent sample t-test were carried out for each of the terahertz spectral parameters in the range of 0.6~1.8 THz, and the spectral parameter data with high consistency and significant difference(p<0.05) were extracted to establish a highly efficient prediction model for storage years of dried tangerine peels based on the principal component analysis-support vector machine(PCA-SVM). The accuracy of the model reached over 94%. This result indicates the feasibility and superiority of the terahertz technology in the characterization of the differences between tangerine peels and in the identification of storage years for dried tangerine peels.