散养与笼养鸡蛋中稳定碳氮同位素特征研究

建立了元素分析-稳定同位素比值质谱（EA-IRMS）联用测定鸡蛋各组分的碳氮稳定同位素组成的方法，并初步探究了散养与笼养蛋鸡生产的鸡蛋的碳氮稳定同位素分布特征。结果表明：利用该方法测定鸡蛋各组分（蛋清、蛋黄、蛋壳膜）的碳氮同位素组成具有良好的重复性，SD值均不高于0.2‰（n=6）；鸡蛋各组分的碳氮同位素组成存在差异，各组分δ¹³C值从大到小的顺序依次为蛋壳膜＞蛋清＞蛋黄，各组分δ¹⁵N值从大到小的顺序依次为蛋黄＞蛋清＞蛋壳膜，与δ¹³C值的变化规律相反；各组分δ¹³C值之间呈线性相关（R²分别为0.768，0.761，0.640），各组分δ¹⁵N值之间也呈线性相关（R²分别为0.862，0.875，0.711）。对比散养和笼养生产的鸡蛋，散养鸡蛋蛋清中δ¹³C和δ¹⁵N值的分布范围分别为-18.00‰~-14.97‰，3.02‰~4.37‰；笼养鸡蛋蛋清中δ¹³C和δ¹⁵N值的分布范围分别为-18.96‰~-15.98‰，1.66‰~2.68‰。可见，结合δ¹³C和δ¹⁵N值，能够有效地区分散养与笼养鸡蛋。

Study on Stable Carbon and Nitrogen Isotope Characteristics of Cage-Free Eggs and Caged Eggs

A method of elemental analysis-stable isotope ratio mass spectrometry (EA-IRMS) was established for determination of the components of carbon and nitrogen stable isotope of EW （egg white）, EY (egg yolks) and EM (eggshell membrane). And carbon and nitrogen stable isotope distribution characteristics of free-range eggs and caged eggs were explored preliminary. The results show that the method has good repeatability in determination of carbon and nitrogen isotopic composition of EW, EY and EM, and SD values are less than 0.2‰ (n=6). Carbon and nitrogen isotopic compositions are different in egg white, egg yolks and eggshell membrane (δ¹³C: EM >EY>EW,δ¹⁵N: EW>EY>EM). Butδ¹³C values of each components are linearly related (R² are 0.768, 0.768, 0.761 for EW, EY and EM, respectively), andδ¹⁵N values for each components also have linear relationship (R² are 0.862, 0.862, 0.875).δ¹³C andδ¹⁵N values of free-range eggs (EW) are from -18.00‰ to -14.97‰ and from 3.02‰ to 4.37‰, respectively, and that of caged eggs(EW) are from -18.96‰ to -15.98‰ and from 1.66‰ to 2.68‰, respectively. Combined withδ¹³C andδ¹⁵N values can better distinguish caged eggs and free-range eggs.