近红外漫反射光谱无损检测乳粉蛋白质的研究

Study on Noninvasive Detection Using NIR Diffuse Reflectance Spectrum for Monitoring Protein Content in Milk Powder

利用近红外漫反射光谱技术对奶粉蛋白质含量的快速无损检测进行了研究。挑选来自国内不同地区的29种奶粉,以化学分析值作参比,采用偏最小二乘回归算法建立奶粉光谱信息和蛋白质含量的定量模型,预测均方根差(RMSEP)为0.687%。采用波长选择对模型进行优化后,波长点从1 558个减为11个,大大加快了运算速度,同时还在一定程度上提高了模型的精度。为了减小颗粒大小不均匀和粒子表面非特异性散射的影响,对光谱数据进行了标准正态变量(SNV)变换和多元散射校正(MSC),结果表明这两种方法是有效的,得到RMSEP减小了约37%。研究结果表明,近红外漫反射光谱测定奶粉中蛋白质含量实时、快速,能满足工业过程分析中的测量精度要求,为提高奶粉质量分析水平提供了新的途径。

A quick and nondestructive method using near-infrared （NIR） diffuse reflectance spectroscopy to determine the content of protein in milk powder was presented. Twenty-nine kinds of milk powder were selected from domestic different districts. Partial least square （PLS） regression was utilized to build the calibration between the spectra and the protein content with chemical analysis as a reference method. Root mean square error of prediction （RMSEP） of 0. 687% was acquired. With the application of the method of wavelength selection, the number of wavelengths was decreased greatly from 1 558 to 11. The speed was accelerated and the accuracy of the calibration was improved to some extent. In order to reduce the particle size and nonspecific scattering effect, standard normal variate （SNV） and multiplicative scatter correction （MSC） were performed. These two treatments proved useful, and the RMSEP was reduced by 37%. Our results suggested that NIR diffuse reflectance spectroscopy was fast and real-time and could meet the practical measurement accuracy as required for industrial process analysis, providing a new tool for quality control of milk powder products.