Assessment of fatty acid composition as tool to evaluate the purity of avocado oil sold in the US marketplace.

Recent publications indicate that avocado oils partially or completely substituted with other edible oils of lower commercial value may be present in the US marketplace. The conclusions reported in these publications were based primarily on the analysis of the fatty acid and sterol composition of oils purchased from retail stores across the US. In June 2022, the US Pharmacopeia published the first standard of identity for avocado oil, permitting the assessment of avocado oil purity based on the comparison with a reference fatty acid and sterol composition. In this study, the fatty acid composition of avocado oils sold in the US marketplace was studied using mono-dimensional and two-dimensional gas chromatography with online reduction (GC-ORxGC). The content of principal and minor fatty acids was critically evaluated to assess which ones may be more suitable to detect the undeclared presence of other food oils. The identity and occurrence of minor fatty acids in avocado oil were further confirmed by fractionating selected samples by silver ion liquid chromatography prior to GC analysis. The purity of the avocado oil samples collected from the US marketplace was finally assessed by comparison with the US Pharmacopeia standard of identity.