Lipid oxidation of argan compared to virgin olive, and cactus oils: Rancimat test for kinetic and thermodynamic analysis

Abstract

This study examined the stability and oxidation kinetics of argan oil (AO) in comparison to other reputed culinary oils worldwide, namely virgin olive oil (VOO) and cactus oil (CO). In order to provide a comprehensive comparative analysis, various parameters were assessed, including fatty acid composition, sterol and tocopherol profiles, and the Rancimat test under elevated temperatures to determine kinetic parameters. The results revealed significant variations between argan, olive, and cactus oils in terms of the physicochemical characteristics studied (p < 0.05). In terms of fatty acids, argan oil contains the highest percentage of saturated fatty acids (19.3%), while olive oil has a higher percentage of monounsaturated fatty acids (75.3%) and cactus oil is distinguished by its higher content of polyunsaturated fatty acids (62.6%). Additionally, argan and olive oils contain higher quantities of total sterols (152.5 ± 5.5 and 140.5 ± 2.5 mg/100 g, respectively) compared to cactus oil (112.5 ± 5.5 mg/100 g). Furthermore, argan and cactus oils contain significant amounts of total tocopherols, mainly γ-Tocopherol (65.5–55.4 mg/100 g), whereas olive oil is characterized by a high content of β-Tocopherol (20.5 mg/100 g). The oils were subjected to oxidation at five distinct temperatures (373, 383, 393, 403, and 413 K) using the Rancimat test. A noticeable increase in the oxidation rate was observed as the temperature increased. The natural logarithms of the kinetic rate constants exhibited a linear relationship with temperature, with the temperature coefficient varying between 6.93 × 10⁻² K⁻¹ for virgin olive oil and 7.45 × 10⁻² K⁻¹ for cactus oil. Argan oil demonstrated better oxidative stability and a significantly longer shelf life (20 months) than the other oils. These results were corroborated by kinetic measurements of oxidative stability, including reaction rate constants, the Arrhenius equation, and other thermodynamic indicators.