基于近红外光谱红茶中胭脂红色素的判别

Discrimination of carmine pigment in tea water based on near infrared spectroscopy

将近红外光谱技术与偏最小二乘判别法相结合,建立了掺胭脂红色素茶水的判别模型。试验分别对38个未添加色素的茶水和38个掺不同浓度胭脂红(所掺胭脂红浓度区间为0.1~10.0μg/mL)茶水在4 000~15 000 cm^(-1)区间进行近红外光谱采集,并对数据进行去噪处理。在此基础上,分别在7个不同的波数区间建立了偏最小二乘判别模型,并进行对比分析,认为:不同波数区间建模对掺胭脂红色素茶水的预判模型有着较大的影响。结果表明:在4 000~11 000 cm^(-1)区间建模,能取得较好的判别结果。所建的模型对校正集样品的判别正确率为100%,对预测集未知样品的判别正确率为96.15%。

The discrimination models of tea water adulterated with carmine pigment were constructed combined with the technology of near-infrared(NIR)spectroscopy and partial least squares discriminant analysis(PLS-DA).Firstly,38 unadulterated tea water samples,and 38 tea water samples adulterated with carmine pigment(0.1~10.0μg/mL)were prepared respectively.The NIR spectra of all samples were collected and pretreated with de-noising method in the range of 4 000~15 000 cm-1.Based on the de-noising pretreatment of spectral data,7 different wave-number ranges were selected to construct PLS-DA models for discriminating adulterated tea water samples.It is pointed out that the wave-number interval selection has great influence on predictive ability of PLS-DA model.The results show that good discriminant model can be obtained in the range of 4 000~11 000 cm-1.The classification accuracies of the constructed PLS-DA model were 100%and 96.15%for calibration set and prediction set respectively.