利用主成分权重重置实现牛奶成分浓度快速检测中近红外光谱的净化去噪

Purification and Noise Elimination of Near Infrared Spectrum in Rapid Detection of Milk Components Concentration by Using Principal Component Weight Resetting

为了利用近红外光谱技术对牛奶中脂肪、蛋白质和乳糖的浓度进行快速检测,提出了基于直方图规定化和模糊层次分析法的近红外光谱主成分权重重置预处理方法。针对牛奶样品的光谱进行主成分分析,确定光谱数据中的最佳主成分数,得到了各主成分的得分和权重。采用直方图规定化的数学统计思想实现二维光谱矩阵的滤波及净化去噪,利用模糊层次分析方法对有效主成分信息的权重进行重置映射,滤掉无关的主成分干扰信息,建立权重重置后的光谱。在此基础上,对预处理后的光谱数据进行脂肪、蛋白质和乳糖的偏最小二乘回归1(PLS1)建模,得到脂肪的相关系数为0.980,预测均方根误差为0.158×10^(-2) g·mL^(-1);蛋白质的相关系数为0.997,实际预测偏差为0.050×10^(-2) g·mL^(-1);乳糖的相关系数为0.985,实际预测偏差为0.152×10^(-2) g·mL^(-1)。由模型预测结果可知,基于直方图规定化和模糊层次分析法的近红外光谱主成分权重重置预处理方法比常规预处理方法具有更好的滤波和去噪效果,说明将直方图规定化和模糊层次分析法相结合对牛奶近红外光谱进行预处理具有可行性。

In order to use the near infrared spectroscopy to rapidly detect the concentrations of fat,protein and lactose in the milk,apreprocessing method of weight resetting for near infrared spectroscopy based on histogram normalization and fuzzy analytic hierarchy process is proposed.The principal component analysis is conducted for the spectrum of milk samples,the best principal component number in the spectral data is determined,and the scores and weights of the principal components are obtained.Filtering and purification and noise elimination of twodimensional spectral matrix are realized by using the mathematical statistic idea of histogram normalization.The fuzzy analytic hierarchy process is used to reset the weight of the active principal component information,and the irrelevant interference information of principal component is filtered out,thereby,the spectrum is reconstructed.On this basis,partial least squares 1（PLS1）regression models of fats,proteins and lactose are built after spectral data preprocessing,getting the correlation coefficient of fat is 0.980 and predicted root mean square error is0.158×10^-2 g·mL^-1;the correlation coefficient of protein is 0.997 and predicted root mean square error is 0.050×10^-2 g·mL^-1;the correlation coefficient of lactose is 0.985 and predicted root mean square error is 0.152×10^-2 g·mL^-1.Through the model prediction results,we can see that this pretreatment method has better filtering and noise eliminationeffect than the conventional pretreatment method.It is feasible to pretreat the near infrared spectrum of milk by combining histogram normalization and fuzzy analytic hierarchy process.