The sterol profile of Tunisian virgin olive oils produced from Chétoui cultivar, the second main variety cultivated in the north of the country, grown under different environmental conditions, was ...established by gas chromatography using a flame ionisation detector. More than ten compounds were identified and characterised. As expected for virgin olive oil, the main sterols found in all Chétoui olive oils were β-sitosterol, Δ5-avenasterol, campesterol and stigmasterol. Cholesterol, 24-methylenecholesterol, clerosterol, campestanol, sitostanol, Δ7-stigmastenol, Δ5,24-stigmastadienol, and Δ7-avenasterol were also found in all samples, but in lower amounts. Most of these compounds are significantly affected by the geographical origin. The majority of the Chétoui virgin olive oils analysed respected EC Regulation No. 2568, and in all cases total sterol amounts were higher than the minimum limit set by legislation, ranging from 1017 to 1522mg/kg.
Two triterpenic dialcohols (erythrodiol and uvaol), were also detected besides the sterolic components. Their content was below the upper legal limit of 4% in all analysed samples, with a range from 1.2% to 3.2%. These results suggest that, besides the genetic factor, environmental conditions influence the sterolic fraction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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Chétoui olive leaf extracts: influence of the solvent type on phenolics and antioxidant activities Abaza, L., Technopole de Borj-Cédria, Hammam-Lif (Tunisia). Lab. de Caractérisation et Qualité de l'Huile d'Olive; Ben Youssef, N., Technopole de Borj-Cédria, Hammam-Lif (Tunisia). Lab. de Caractérisation et Qualité de l'Huile d'Olive; Manai, H., Technopole de Borj-Cédria, Hammam-Lif (Tunisia). Lab. de Caractérisation et Qualité de l'Huile d'Olive ...
Grasas y aceites (Sevilla),
(Ene-Mar 2011), Volume:
62, Issue:
1
Journal Article
Peer reviewed
Open access
El objetivo de este trabajo fue estudiar la influencia del disolvente usado en la extracción de los compuestos fenólicos y en las propiedades antioxidantes de los extractos obtenidos a partir de ...hojas de olivo procedente de la variedad Chétoui. La extracción se realizó a temperatura ambiente, usando cuatro disolventes: agua desionizada(ddH2O), metanol 80% (80% MeOH) , etanol 70% (70% EtOH), y acetona 80%. Los fenoles totales y los flavonoides totales se midieron usando los métodos colorimétricos con Folin-Ciocalteau y cloruro de aluminio, respectivamente. Las propiedades antioxidantes han sido determinadas por dos métodos: el DPPH y el ABTS. El contenido de fenoles totales y flavonoides de los extractos de hojas de olivo (OLEs) varió desde 16,52 hasta 24,93 mg de ácido gálico/g de materia seca y desde 6,23 hasta 21,47 mg de catequina/g de materia seca, respectivamente. Los valores de IC50 de DPPH varian de 0,17 a 0,97 mg/mL y los valores de la actividad antioxidante determinados por ABTS (capacidad antioxidante en equivalentes de trolox) se encuentran entre 629,87 y 1064,25 micromol TE/g de materia seca, respectivamente. Nuestros resultados revelaron que los disolventes de extracción tienen una influencia significativa en las propiedades antioxidantes de los extractos de hojas de oliva. El metanol se recomienda para los extractos con alto nivel de flavonoides y con actividades antioxidantes importantes. Además, se observó que la capacidad antioxidante en equivalente de trolox (TEAC) depende más de los flavonoides (r = 0,821) que de los fenoles totales (r = 0,399).
The aim of this study was to investigate the influence of the solvent type on the extraction of phenolics and the antioxidant properties of the extracts obtained from Chétoui olive leaves. Extraction was conducted at room temperature using four solvents: deionized water (ddH2O), 80% methanol (80% MeOH), 70% ethanol (70% EtOH), and 80% acetone. Total phenols and total flavonoids were measured using the Folin-Ciocalteau and aluminum chloride colorimetric methods, respectively. The antioxidant properties have been determined by two scavenging activity methods, DPPH and ABTS. The total phenol and flavonoid contents of the olive leaf extracts (OLEs) ranged from 16.52 to 24.93 mg gallic acid/g DM and from 6.23 to 21.47 mg catechin/g DM, respectively. The IC50 values of DPPH varied from 0.17 to 0.97 mg/mL and the antioxidant activity values determined by ABTS (trolox equivalent antioxidant capacity) were between 629.87 and 1064.25 micromol TE/g DM. Our results revealed that extracting solvents have a significant influence on the antioxidant properties of olive leaves and that a methanol mixture is recommended for extracts with high levels of flavonoids and important antioxidant activities. Moreover, it was noticed that the trolox equivalent antioxidant capacity (TEAC) depends more on the flavonoids (r = 0.821) than on the total phenols (r = 0.399).
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