Rapid determination of metallic additives in century eggs by microwave plasma‐atomic emission spectrometer and microwave‐assisted digestion

Century eggs (also known as pídàn) are a widely used preserved food product in Taiwanese cuisine. Due to their peculiar appearance, pungent odor, and unusual texture, several consumers have raised concerns. Actually, some metallic additives are employed to control the quality of gelation of protein during the production of century eggs. Therefore, a method involving microwave plasma‐atomic emission spectrometer and microwave‐assisted digestion was proposed in this study. In addition, to clarify distribution information of metallic additives in century eggs, detailed analyses based on the egg structure were adopted. The linearities for Fe and Zn were obtained in the range of 0.1–5, and 0.02–1 mg L−1 for Cu and Pb. The method detection limits for test metals were 0.06–0.036 mg L−1. The measured values for the RM EGGS‐1 sample agreed reasonably well with the reference values, demonstrating that the developed method is practical for routine analysis with lower instrument procurement/running cost. The analytical results for century eggs collected from local markets revealed diverse distributions of metal ions in different parts. Remarkably, this method can readily identify the metallic additives used during the production processes even in the presence of complicated matrices. Because metallic additives are widely employed to control protein gelation during the production of century eggs, quantitative information regarding these additives is crucial for ensuring the safe consumption of century eggs. The developed methodology can not only identify such additives during the production processes but also clearly indicate the distribution of metal ions in century eggs.