Application Of Stable Isotopes In The Identification And Traceability Of Eggs

Isotope ratio mass spectrometry（IRMS）methods play a very important role in food authenticity and origin control.The purpose of this study was to reveal the relationship between the isotopic composition of eggs and egg rearing methods and the environment.The main conclusions areas follows:This study established the method of simultaneous determination of δ¹³C and δ¹⁵N value by elemental analyzer series stable isotope ratio mass spectrometry（EA-IRMS）,and also establish a method to determine the δD in egg white and δ¹⁸O in water by TCEA-IRMS.Above method has good accuracy and repeatability.Separated egg components（egg white,egg yolk,egg shell membrane）,andmeasured δ¹⁵N and δ¹³C of each component of eggs.Carbon and nitrogen isotopic compositions are different in egg white,egg yolks and eggshell membrane.(δ¹³C :EM>EY>EW,815N:EW>EY>EM).But δ¹³C values between each components are linearly related.δ¹⁵N values between each components also have linear relationship.Feed composition directly affects the stable carbon isotopic composition of egg white.With feed increased proportion of C4 plant maize,813C value of egg whites gradually biased positive,There has a good linear relationship between the proportion of com in the feed and the δ¹³C value of egg white,and R2 is 0.9456,and nitrogen isotope affected by the fertilizer application and nutrient levels of the feed.Explore the stable isotope characteristics of different rearing eggs（free-range and caged）,the data display that,due to the different types of feed,the composition of the stable isotopes of two eggs also have some differences,In which free-range eggs 815N more biased to the positive value than the caged eggs,Preliminary results indicate that the application of stable isotope techniques to distinguish between different rearing methods eggs,further identification of laying hens rearing methods is feasible.The δ¹⁸O value of Egg white and 8D value of drinking water has a good linear relationship(δD egg = 3.9148 × δ¹⁸O drinking-73.62,R2=0.7906),8D values of egg white 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 eggs.Meanwhile investigate the dominant crops and breeding habits of the country,Combined with carbon and nitrogen stable isotopes to assist traceability.