关键词: 近红外光谱技术, 绿茶, 全氮量, 子模型

Abstract: A calibration model of total nitrogen content in the green tea was established based on partial least square. The model demonstrated great predictive performance after the first derivative processing and smoothing, in spectrum range of 4691~3959 cm-1and 5126~4848cm-1. The correlation coefficient of predicted and chemical measurement value about the validation set was 0.9939 and the RMSEP was 0.0925%.Sub models of total nitrogen in green tea were established according to different tenderness. With the sub models, the prediction performance was improved. The prediction performance of the tenderness 3model was the best. The RMSEP and R about predicted and chemical measurement value were 0.0379% and 0.9961. The total nitrogen detection in green tea by Near Infrared Spectroscopy can achieve fast and efficient nitrogen detection and quality evaluation, and imposes minimal effects to environment. This technique has academic and realistic significance in developing the rapid measurement methods and pushing the frontier of quality testing in tea.

Key words: near infrared spectroscopy, green tea, total nitrogen content, sub-model