Abstract

This study aims at bringing to light the preservative potential of essential oils of Thymus vulgaris, Cinnamomum zeylanicum and Mentha piperita in the stabilisation of lipids against oxidation. The essential oils were extracted by hydrodistillation and chemical composition were analysed by gas chromatography coupled with mass spectrometry. In vitro antioxidant potentials of the essential oils were tested by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide (H₂O₂) methods. The effects of essential oils on palm olein during accelerated storage for 20 days were carried out using the Shaal Oven test and indices of oxidation were measured. Essential oil of T. vulgaris was the most active oil with respect to the DPPH and H₂O₂ tests. T. vulgaris and C. zeylanicum showed varying degree of inhibition to palm olein oxidation within 20 days of storage at 60°C. Essential oils of T. vulgaris and C. zeylanicum at a concentration of 300 ppm showed comparable results to that of tert-butyl hydroquinone (TBHQ) applied at the recommended dose of 200 ppm. Palm olein samples treated with the essential oils did not show rancid characteristics at the end of storage. These essential oils significantly stabilised palm olein during accelerated storage conditions and may be exploited for use as preservatives in food products.

Key words: Antioxidant, essential oils, Thymus vulgaris, Cinnamomum zeylanicum and Mentha piperita, palm olein, food preservatives.