Studies On Differentiation Of Milks With Different Origins And Milk Authentication Using LC And LC-MS Fingerprints

Liquid chromatography and liquid chromatography-mass spectrometric fingerprinting combined with chemometric data analysis were used to differentiate milks with different origins,and to differentiate milk and non-milk proteins in this study.The geographical and seasonal variations,milks and non-milk proteins were differentiated by ultraperformance non-targeted liquid chromatography(UPLC)amino acid fingerprints combined with chemometrics analyses.Principal component analysis(PCA)and partial least-squares-discriminant analysis(PLS-DA)were used by MATLAB.Gel electrophoresis was used for identifying non-milk proteins in adulterated milk system.The results showed that the correct classification rate for milks of different geographical conditions was 83.3%,and for seasonal variation at Shanghai and Suzhou cities and Shandong province were 72.7% and 91.7%,respectively,and for differentiating milks and non-milk proteins were 100% using amino acid fingerprints.The correct classification rate for milks of different geographical conditions and milk authentication were both 100%.The detection limit of SDS-PAGE of adulteration of pea-milk system was 2%;while soybean-milk system was 4%.In summary,UPLC-MS peptide fingerprints showed better ability to differentiate geographical variations of milks,comparing to UPLC amino acid fingerprints;both of them could applied for milk quality control.Gel electrophoresis was fast,intuitive,low cost,and could be used in identification of adulterated milk system.