A fast, sensitive, accurate and robust GC-FID and confirmatory GC-MS method, was developed to simultaneously determine squalene and underivatized free plant sterols in Citrus essential oils (cEOs). The method was applied to assess the content of squalene and free plant sterols in four most commonly employed cold-pressed cEOs (bergamot, lemon, mandarin and orange). cEOs plant sterols exhibited distinctive molecular patterns, with levels ranging from 182 to 1100 mg kg-1 in lemon and bergamot essential oils, respectively. β-sitosterol was the dominant compound in all cases, with an average content of ∼650 mg kg-1 in bergamot and orange essential oils. Campesterol and brassicasterol occurred at much lower amount in all samples. Bergamot essential oil was also the richest in squalene (537 mg kg-1) compared to the other cEOs. The method developed could contribute to define compositional patterns of cEOs, thus supporting their versatile utilisation in the food and flavour industry.
Keywords: Citrus spp.; Essential oils; free plant sterols; gas chromatography; mass spectrometry.