Effect of Roasting Temperature and Time on the Chemical Composition and Oxidative Stability of Argan (Argania spinosa L.) Oils

Abstract

The effect of roasting on the chemical composition and oxidative stability of oils extracted from argan (Argania spinosa L. Skeels) kernel is studied, observing changes in the characteristics of oils from unroasted and roasted kernels. Argan kernels are roasted at different temperatures (150, 175, and 200 °C) and times (10, 30, and 50 min), in an electric air roaster, prior to oil extraction using the Abencor system. Phosphorus content (PC) of oils increases significantly when roasting temperature and time increases. Roasting facilitates the transfer of phenolic compounds to argan oil. However, only minor changes in characteristics such as peroxide value and carotenoid content of argan oils occurs when roasting temperature and time are raised. The amount of γ‐tocopherol still remains over 85% of the total tocopherols after roasting at the harshest conditions (200 °C, 50 min). However, the content of each tocopherol (α, γ, and δ) gradually decreases when roasting temperature and time increases, certainly due to their thermal degradation. The oxidative stability of argan oil improves when the roasting temperature and time rise. Simultaneously, significant augmentations (p < 0.05) are observed in the specific extinction coefficients in oils prepared at high roasting temperature. The color intensity of oils increases markedly over 175 °C roasting temperature.Practical Applications: This research shows the importance of roasting for producing edible argan oils since its composition, quality and stability are influenced by the conditions of this process. Energy transfer by convection avoids the direct heat of the flame onto the argan kernel and allows the possibility that less polycyclic aromatic hydrocarbons (PAHs) are formed. Furthermore, roasting parameters (temperature and time) should be quantitatively controlled to obtain a desired quality of edible argan oils. These results may help to improve roasting processing for edible argan oil extraction.The effect of roasting temperature and time has been studied with a view to obtain oils of high quality in relation to their physicochemical properties. In the extraction process of edible argan oil, the kernel roasting is the key step that improves the quality and stability of the product.