以绿茶为研究对象, 氮含量为定量分析指标, 研究了不同分辨率(2, 4, 6, 8, 16 cm-1)对近红外光谱图及氮含量模型的影响。 结果表明: 仪器的分辨率影响光谱图的质量, 分辨率越高, 得到的信息越丰富, 但同时噪音增大; 分辨率越低, 光谱图更加平滑, 信息量减少, 当分辨率太低时光谱失真严重。 分辨率为4 cm-1时, 模型外部验证集RMSEP值为0.054 6, 明显低于其他模型, 相关系数为0.998 2, 预测性能最好; 模型预测精度也较好, STDEV和RSD分别为0.020和0.334。 分辨率4 cm-1为最优分辨率。 试验可以为近红外光谱仪采集绿茶光谱图提供参数选择依据, 提高模型的稳定性与预测性能, 促进近红外光谱检测技术在茶叶上的应用与推广。

The effect of different resolutions(2, 4, 6, 8, 16 cm-1) on the near infrared spectrogram and nitrogen content model for green tea was studied. Test results showed that instrument resolution could influence the spectra quality. The higher the resolution was, the richer the information would be, but the noise would increase. With lower resolution, spectrogram would be much more smooth, but get seriously distorted, and prediction accuracy would decrease at the same time. The partial least squares model was built after spectral pretreatment. When resolution was 4 cm-1, the RMSEP value of external validation set was 0.054 6, which was obviously lower than others. The Corr.Coeff. was 0.998 2. Its prediction performance was the best and the prediction accuracy better. STDEV and RSD were 0.020 and 0.334 respectively. Resolution 4 cm-1 for near infrared spectrometer collecting green tea samples was the optimal resolution. This research can provide a reference for parameters selection when collecting green tea spectra with near infrared spectrometer, improve the stability and prediction performance of the model and promote the application and promotion of the near infrared spectroscopy for tea.