Antioxidant activity, tocopherols and polyphenols of acornoil obtained from Quercus species grown in Algeria

• Published in: Food research international 2018-12, Vol.114, p.208-213
• Main Authors: Makhlouf, Fatima Z., Squeo, Giacomo, Barkat, Malika, Trani, Antonio, Caponio, Francesco
• Format: Article
• Language: English
• Subjects: Antioxidants; Carotenoids; LC-MS/MS; Phenolic compounds; Quercus; Vegetable oil; Vitamin E
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2018.08.010

Among the unusual vegetable fats, acorn oil has interesting nutritional and functional properties. Few studies are present in literature on acorn oil characterization and antioxidant activity evaluation while no studies are present regarding the analysis of the phenolic profile. The present study aims at investigating the content of hydrophilic and lipophilic phenolic compounds and pigments, as well as antioxidant properties and quality of the oil extracted from three Quercus species grown in Algeria. Oil yield, expressed as dry weight, was in the range 7.05–8.40%. Tocopherols contents were remarkable for the three species (539–676 mg kg−1), with (β + γ)-tocopherols being the most abundant. Oils had also significant amounts of carotenoids (42–66 mg kg−1) and similar polyphenol patterns, but with a wide quantitative variability between species (195–436 mg kg−1). Twenty phenolic compounds were detected, 12 of which were tentatively identified. All of them were hydrolysable tannins derivatives (gallotannin or ellagitannin). Oils methanolic extracts had remarkable antioxidant activity; up to 3.34 and 3.79 μmol TE g−1 oil (DPPH and ABTS test, respectively). Quercus oil is a potential source of natural antioxidants, and it could be used as a new functional oil. [Display omitted] •Algerian Quercus oils showed high phenolic content and antioxidant activity.•Acorn oils were rich in tocopherols, with β- and γ- being the most abundant.•Twenty phenolic compounds were detected through LC-MS/MS.•Identified phenolics belonged to the class of hydrolysable tannins derivatives.•Pigments pattern could make acorn oils very stable to photo-oxidation.