DOI: https://doi.org/10.55373/mjchem.v27i4.172

Keywords: Turmeric; essential oil; FTIR Spectroscopy; Chemometrics; authentication

Abstract

Turmeric essential oil (TEO) exhibits diverse biological activities that include anti-inflammatory, cytotoxic, anti-arthritis, hepatoprotective, antifungal, antibacterial, and antioxidant properties. Problem statement: Many TEOs sold on online shopping platforms do not use proper labels. So, these TEOs could harm customers if they contain adulterated essential oils. Objective: This study aimed to authenticate TEO from vegetable oils, namely soybean oil (SO), palm oil (PO), and virgin coconut oil (VCO). Method: TEO was extracted using the hydrodistillation technique. Eleven binary mixtures of TEO with vegetable oils (0-100%) were prepared, and 13 commercial TEOs were obtained from online shopping platforms. All essential oils were then analyzed using FTIR spectroscopy coupled with chemometric analysis. Findings: The extracted TEO was pale yellow with a distinctive odor, yielding 0.21% (v/w). Discriminant analysis (DA) successfully distinguished pure TEO from adulterated TEO at specific wavenumbers (TEO-SO and TEO-PO models at 2000-650 cm^–1 and TEO-VCO models at 4000-650 cm^–1). However, no commercial TEO was categorized as pure TEO using the developed DA models. For quantification purposes, the best PLS regression models for quantifying SO, PO, and VCO levels in TEO were in wavenumber ranges of 3500-2500 cm^–1, 2000-700 cm^–1, and 1500-700 cm^–1, respectively. Conclusion: FTIR spectroscopy combined with chemometrics is able to authenticate pure turmeric essential oil. The commercial turmeric essential oils were not detected as pure TEO.