Distribution Characteiustics And Application Of The Stable Isotope Composition In Milk

Isotope ratio mass spectrometry (IRMS) methods play a very important role in food authenticity and origin control. The stable isotope composition of food is strictly connected with environmental conditions. The measurements of bioelements (hydrogen, nitrogen, carbon, oxygen, and sulfur) composition provide a very sensitive tool to food control. The aim of this study is to explore the relationship between isotopic composition of milk and its origin.The stable carbon isotope (813C) ratios of whole milk and its isolated components (casein, skim milk, and fat) were determined by elemental analysis-isotope-ratio mass spectrometry (EA-IRMS). This technique was found to be repeatable and possess good accuracy with a standard deviation of less than0.1‰(n=5). A comparison of the δ13C values of different milk samples indicates that the813C composition is impacted by the type of forage consumed by the cows. The δ13C values of milk from farms in which maize is the main roughage are higher than-17.6‰, are relatively lower when the diet contains Leymus chinensis and alfalfa. The δ13C values of commercially available milk purchased from different regions demonstrate distinct characteristics, milk samples from China and countries using advanced animal husbandry practices are significant differences.δ18O values of milk water and drinking water were determined by Gasbench-IRMS and TC/EA-IRMS, results shown that δ18O values of raw milk were higher than δ18O values of drinking water, shown good linearity (δ18ORaW milk=1.1886×δ18Odrinkingwater+3.8729, R2=0.9138).δ18O values of milk water reflects the oxygen isotope composition information of drinking water. Due to the impact of precipitation evaporation source effects, temperature effects, continent effects, latitude effects, and height effects,δ18O value of water has obvious geographical features to generally infer origin of milk.The conclusion of this research verified values of in terms of tracing the types of milk and producing areas. The accumulated data was used to lay a theoretical foundation for the application of stable isotope analysis techniques in milk traceability.