低场核磁技术结合化学计量学法快速检测掺假牛奶

Rapid detection of adulterated milk by low-field nuclear magnetic resonance combined with chemometric method

应用低场核磁共振技术结合主成分分析法(PCA)、偏最小二乘判别法(PLS-DA)、线性判别法(LDA)对掺水、食盐、尿素和蔗糖的牛奶及纯牛奶进行测定。结果表明:在主成分得分图中,不同掺假牛奶随掺假物质的掺假比例呈一定规律性分布,并得到了很好的区分。利用PLS-DA和LDA方法建立不同掺假牛奶的判别模型,对掺水、掺尿素牛奶的判别准确率均为100%,掺食盐牛奶的判别准确率分别为83.33%和100%,掺蔗糖牛奶的判别准确率分别为73.33%和76.67%。可见PCA法、PLS-DA法、LDA法可用于快速处理分析低场核磁共振数据,并且LDA法鉴别准确率最高。

Low field nuclear magnetic resonance（ NMR） technique was used in this study to detect adulterated milk（ mixed with water,salt,urea and sucrose） and pure milk,combining with principal component analysis method（ PCA）,partial least squares discriminant analysis（ PLS-DA）and linear discriminant analysis（ LDA） The results showed that adulterated milks showed a certain regularity distribution with adulterant proportion in the PCA score plot,and was easy to identify. PLS-DA and LDA were used to establish the discriminant models for all adulterated milks.The accuracy discrimination rates using these two methods to detect milk adulterated with water and urea both were 100%,However,when the two methods were utilizied to investigate the milk mixted with salt or,sucrose respectively,the accuracy discrimination rates were 83. 33% and 100%,or 73. 33% and 76. 67%. Thus,PCA,PLS-DA and LDA could be used for the rapidly analysing data of low field NMR,and LDA showed the highest identification accuracy.