Liu, Stephen Inbaraj, and Chen’s (2007) method was used, with minor modification.
Before saponification and the formation of methyl ester in the soybean oil, the reaction vessel was filled with N2 in order to prevent the formation of isomers of polyunsaturated oils (Park & Goins, 1994). Heptadecanoic acid methyl ester (5 mg/mL) was used as the internal standard for the GC analysis.