Mass spectrometry differentiation of sciadonic acid isomers and estimate of long-chain polyunsaturated fatty acid intake from fresh and processed duck eggs

Sciadonic acid, or 20:3(5Z,11Z,14Z), is an unusual polyunsaturated fatty acid (PUFA) found in certain gymnosperm nuts and marine invertebrates. However, no study has detected it in commonly consumed food items. This study analyzed the fatty acid compositions of fresh, salted, and preserved duck eggs thoroughly via gas chromatography coupled with covalent adduct chemical ionization mass spectrometry (GC/CACI-MS). A multiple reaction monitoring method was developed to specifically characterize three 20:3 isomers found in duck eggs. Sciadonic acid was quantified at 0.13 % and 0.07 % (wt/wt of total fatty acids) in fresh and processed duck eggs, respectively. The major n-3 PUFA is DHA, with average concentrations of 1.44 %, 0.79 %, and 0.98 % in fresh, preserved, and salted duck eggs, respectively. For an average Chinese individual, the daily intake of DHA and total long-chain n-3 PUFA from all types of duck eggs is estimated to be 7.6 mg/day and 10.6 mg/day, respectively.