Partial Characterisation of Oak Acorns Oil Extracted from Moroccan Quercus Suber L.

Abstract

There is a paucity of literature on the nutritional profile of Moroccan Quercus suber L. acorns oil, and its importance has not been fully exploited to date. Therefore, this work aimed to characterise, for the first time, the Moroccan Quercus suber L. acorns oil, to compare results with those of previous works performed on the same species, as well as its characteristics with those of olive oil. The oil was extracted by using the Soxhlet apparatus. Free fatty acids, peroxide value, iodine value, refractive index, and saponification value were determined according to AOCS recommended practices. The fatty acids and sterols were analysed by GC-MS, while Tocopherol was analysed with HPLC. The percentage of the oil expressed as dry weight was 5.2-5.5%. The fatty acid composition showed that the most abundant fatty acids were oleic (64.7-67.0%), linoleic (16.6-19.2%), and palmitic (11.1-11.5%). The HPLC analysis revealed high levels of Tocopherols content (2123-3566 mg/kg oil). The amounts of γ-tocopherol, α-tocopherol, and δ-tocopherol were 1777-3052 mg/kg oil, 272-378 mg/kg oil, and 74-136 mg/kg oil, respectively. Sterol composition shows that β-sitosterol is the main component (86.9%-87.2%), followed by stigmasterol (3.8-1.4%), ∆5-avenasterol (2.9-3.0%), and campesterol (2.6-2.8%). Cholesterol, ∆7-stigmasterol, and ∆7-avenastrol were present in minimal amounts. The current results show that Moroccan Quercus suber L. acorns oil can be an excellent natural source for cosmetic and pharmaceutical product applications. Therefore, more investigations are required to understand the nutritional potentials of this oil and its bioactivity.