绿茶游离氨基酸总量近红外光谱定量分析模型优化

Optimization on Quantitative Analysis Models of Free Amino Acids Content in Green Tea by Near Infrared Spectroscopy

采集158份绿茶样品并对其进行光谱扫描,分别采用主成分回归、偏最小二乘、改进偏最小二乘3种定量校正方法,对原始光谱分别进行4种不同的预处理,运用正交试验设计,建立了绿茶中游离氨基酸总量优化定标模型,利用目标函数法对模型进行评定,并对模型的适用性进行了验证。试验结果为:SNV+Detrend,1,1,4,4的光谱预处理下,采用改进偏最小二乘法进行定标建立的模型最优,其目标函数值f为94.25%,验证相对标准差eRSD为6.39%(<10%)。结果表明:采用正交试验设计能够综合考查不同的校正方法和光谱预处理对模型的影响,利用近红外光谱分析法能够实现绿茶中游离氨基酸总量的定量、快速检测。

158 samples of comminuted green tea were scanned by the near infrared spectroscopy analyzers. Using orthogonal experimental design, the calibration models of free amino acids content in green tea were gained with the correction methods of PCR, PLS and MPLS under different spectral data preprocessing methods separately. The models were evaluated by the objective function method. The optimal correction methods and spectral data preprocessing methods were determined, and the applicability of the models was validated. The experimental result is that using MPLS could get the optimal model. And its spectral data preprocessing method is SNV ＋ Detrend, 1, 1, 4, 4. Its objective function value is 94.25 % ; the relative standard deviation of validation is 6.39 % （less than 10% ）. The results showed that using orthogonal experiment design could comprehensively evaluate the different correction methods and spectral data preprocessing methods on the models, and NIRS could achieve quantitative and fast detection of free amino acids content in green tea.