为了快速、准确地检测掺杂牛奶,采用基于核隐变量正交投影(K-OPLS)法分析了掺杂牛奶的光谱.选用高斯函数作为核函数,内部交叉验证均方根(RMSECV)最小值作为评价指标,优选了核函数中的核宽度σ以及Y正交成分数.配置含四环素牛奶(0.01~0.3 gL-1)、三聚氰胺牛奶(0.01~~0.3 gL-1)和葡萄糖牛奶(0.01~~0.3 gL-1)各36个,采集纯牛奶及掺杂牛奶样品的红外光谱,采用K (PLS建立各掺杂牛奶与纯牛奶的判别模型.利用这些模型对未知样品进行判别,结果显示对掺杂四环素、三聚氰胺、葡萄糖牛奶的判别正确率分别为100%、100%、95.8%o.建立了同时判别3种掺杂牛奶与纯牛奶的K-OPLS模型,该模型对未知样品的判别正确率为93.1%;同时,与偏最小二乘判别PLS-DA方法的预测结果进行了比较,结果表明:K-OPLS建模方法对于复杂的牛奶体系具有较好的预测能力.
To detect adulterated milk rapidly and accurately,the discrimination models for adulterated milk were established based on the method of Kernel Orthogonal Projection to Latent Structure (K-OPLS).By using the Gaussian radial basis function as the kernel function and the minimum value of Root Mean Square Errors of Cross-validation (RMSECV)as an evaluation index,the width of the Gaussian kernel,the minimum value of the RMSECV,and the number of Y-orthogonal components (scalar) were selected in a optimization.36 samples with different concentrations of tetracycline (0.01 -0.3 gL-1),melamine (0.01-0.3 gL-1) and glucose (0.01-0.3 gL-1) in milk were prepared,respectively.Then the infrared absorption spectra of all samples were measured.K-OPLS models for tetracycline-tainted milk,melamine-tainted milk and glucose-tainted milk were constructed.The resuits show that its classification accuracy for tetracycline-tainted milk,melamine-tainted milk and glucose-tainted milk are 100%,100%,95.8%,respectively.The K-OPLS model was used to classify the above three kinds of adulterated milk and pure milk and its classification accuracy for unknown samples is 93.1%.Compared with Partial Least Square Discriminant Analysis (PLS-DA),K-OPLS methods show higher accuracy.The results indicate that the K-OPLS model has good prediction ability for complex milk systems.