Fatty acid determination in chicken egg yolk: A comparison of different methods

Four different methods (direct-methylation, saponification, chloroform-meth anol extraction and postextraction saponification) were compared to determi ne the fatty acids in egg yolk. About 50 mg of pooled egg yolk samples, wit h C23:0 as an internal standard, was used for all assays. No difference (P > 0.05) was observed among the four methods for C17:0, C18:0, C18:1, C20:I, C18:2n-6, and C22:6n-3 content of egg yolk. Direct saponification resulted in a lower (P < 0.05) content of C14:0, C16:1, C18:3n-3, and C20:4n-6. Fat ty acids at less than 0.5%, such as C15:0 and C14:1, were not detectable in the direct saponification method. The total saturated, monounsaturated, or polyunsaturated fatty acids did not differ (P > 0.05) among the four metho ds. Direct methylation of egg yolk resulted in lower variability than other methods and is fast and economic for determining egg fatty acid compositio n.