Study On Detection And Origin Identification Of Dairy Products Based On Stable Isotope Ratio And Trace Elements

Milk powder and milk are important sources of protein and nutrients for modern people.They are two of the most important nutritious foods for human beings.They are rich in protein,vitamins,calcium and other nutrients needed by human beings.The nutritional value of dairy products from different sources are different because of their dairy breeds and feeding environment.In order to obtain profits,the criminals are rampant in their activities such as making inferior products and adulterating merchandise.We want to know if stable isotopes and trace elements can be applied to trace the origin and adulteration of milk powder and milk,so,we detected the stable isotope and microelement contents of milk powder and milk from different regions.And discussed the feasibility of the stable isotope and microelement contents information for identification and adulteration of milk powder and milk.In this study,169 milk powder samples and 17 milk samples were collected brtween 2016 and 2017.The contents of Mn?Ni?Cu?Rb?Sr?Ba?As?Rh?Pb?Li?V?Co?Y?Cs?La?Ce?Nd in milk powder were determined by inductively coupled plasma mass spectrometry(ICP-MS).The ?13C??15N??D??18O values of milk powder,the ?13C?815N values of milk and the 815N values of exogenous nitrogen doped milk were determined by elementary analyzer-stable isotope ratio mass spectrometers(EA-IRMS),and the ?D and ?18O values of milk water were determined by GasBench-stable isotope ratio mass spectrometers(GasBench-IRMS).Combined with One-way Analysis of Variance(One-way ANOVA),Multiple Comparison Method(MCM),Principal Component Analysis(PCA),Clustering Analysis(CA),Progressive Discrimination Analyses(NSDA),the effective traceability indexes were screened,and a reliable discriminant model of origin was established.We have the following results:1.Different continents have significant difference values of ?D and ?18O,but not of ?13C and ?15N.Different countries have significant difference values of ?D and ?15N,but not of ?13C and ?18O.The content of Ni?Cu?Rb?Sr?Ba?As?Li?V?Y?Cs?La?Ce?Nd vary significantly among samples from different continents.Ni?Cu?Rb?Sr?Ba?As?Li?V?Co?Y?Cs?La?Ce?Nd content vary significantly between different countries.An Irish sample can be distinguished by using stable isotope characteristics and trace element characteristics.2.The comprehensive analysis of stable isotopes and trace elements is superior to single stable isotope or trace element discrimination in discriminating milk powder producing area.Two kinds of indexes combined with chemical measurement can distinguish milk powder origin.Stable isotopes and trace elements can be used to judge the origin of milk powder accurately,and the correct rate of discrimination is 92.1%.3.The correct discriminant rate of ?13C??15N??D??18O to the origin of milk samples in different regions is above 80%,which can accurately distinguish milk samples from Europe.4.The ?15N value of pure milk is higher than that of milk mixed with exogenous nitrogen.It is feasible to identify exogenous nitrogen in milk by ?15N.