[show abstract][hide abstract] ABSTRACT: One hundred and fifty accessions belong to six wild olive populations from Tunisia were analyzed using fruit pomological traits and oil chemical characteristics. Analysis of variance revealed significant differences among olive accessions for the main studied parameters, indicating a high degree of variability among oleasters. Cluster analysis revealed no clear relationships between accessions according to their geographical origin. Among the screened oleasters, three stand out for their interesting oil parameters, as compared to traditional varieties with high oleic and low linoleic acid contents, high triolein level, large total phenol content, high oxidative stability and high oil content. ZI2 had the highest values of oleic acid (78.5%), whereas H3 was noteworthy for its higher content of phenolic compounds (435.3 mg/kg). Accordingly, oil from H3 presented the highest oxidative stability (83.5 h). A significant relationship was observed between phenolic compounds and oxidative stability.PRACTICAL APPLICATIONSThe identification of new cultivars and their oil composition is a key point in the improvement of olive oil production. This is the first study of chemical composition of virgin olive oils from wild olives. The paper is a study on the quality characteristics of olive oils obtained from wild olive trees growing in Tunisia to define new cultivars well adapted to Tunisian environment and yielding high quality oils. Although the study was carried out in Tunisia, it might be applied to other countries with wild olive trees, in order to contrast productivity and oil quality with those resulting from native cultivars and transplanted foreign varieties.
[show abstract][hide abstract] ABSTRACT: In this study, eighteen olive varieties, originating from Spain, France, Italy, Greece and Algeria, and maintained at the olive experimental station of Boughrara (arid region of Tunisia) were evaluated for their oil yield and fatty acid composition. The analysis of variance revealed significant differences among varieties for all traits (p < 0.01). The Hierarchical Cluster Analysis (HCA) classified the varieties into three main groups. The first group included a subgroup which is composed of seven olive varieties (Cornezuelo, Verdial de Vélez-Málaga, Leccino, Coratina, Koroneiki, Lechín de Granada and Changlot Real) characterized by high oil yield with high oleic, low palmitic and linoleic acid contents. The fatty acid compositions of the oils from these varieties comply with international standards and show more beneficial characteristics than the oil obtained from Chemlali: the most abundant olive cultivar in Tunisia. Finally, the main fatty acids (palmitic (C16:0), oleic (C18:1) and linoleic (C18:2)) of nine of the studied virgin olive oils were compared to those sampled from their traditional areas. Except for Koroneiki and Olivière oils which showed an unchanged fatty acid composition and for Cornezuelo oil in which the level of oleic acid raised and the level of linoleic acid decreased, most of oils showed a decrease in oleic acid rates and an increase in palmitic and linoleic acid percentages as compared to those from their original sites.
En este estudio, dieciocho variedades de aceituna procedentes de España, de Francia, de Italia, de Grecia y de Argelia, cultivadas en la estación experimental del olivo de Boughrara (región árida de Túnez), fueron evaluadas para el rendimiento en aceite y la composición de ácidos grasos. El análisis de la varianza mostró diferencias significativas entre todas las variedades (p < 0.01). El análisis de “clusters” jerárquico clasificó las variedades en tres grandes grupos. El primer grupo incluía un subgrupo compuesto por siete variedades de aceituna Changlot Real, Koroneiki, Verdial de Vélez- Málaga, Coratina, Lechín de Granada, Cornezuelo y Leccino, que se caracterizan por su alto rendimiento en aceite, alto contenido en oleico y bajo contenido en ácidos palmítico y linoleico. Las composiciones de ácidos grasos de aceites provenientes de estas variedades se conforman con estándares internacionales y son mejores si las comparamos con la de Chemlali (el cultivo más abundante en Túnez). Finalmente, los ácidos grasos mayoritarios (palmítico (C16:0), oleico (C18:1) y linoleico (C18:2)) de nueve de los aceites de oliva virgen estudiados fueron comparados con los de las mismas variedades cultivadas en sus áreas originarias. A excepción de los aceites Koroneiki y Olivière que mostraron una composición de ácidos grasos inalterable y del aceite Cornezuelo en el que se observó un aumento del nivel de ácido oleico y un descenso del nivel de ácido linoleico, la mayoría de los aceites mostró disminución de ácido oleico y aumento de los porcentajes de ácido palmítico y linoleico, comparándolos con los obtenidos de las aceitunas cultivadas en su lugares de origen.
[show abstract][hide abstract] ABSTRACT: Fruits from three Tunisian cultivars of Olea europea L. grown in the southeast of Tunisia were harvested at the maturity stage of ripeness and immediately processed with a laboratory mill. There are as yet no data on the chemical composition of virgin olive oils from the southeast of Tunisia, an area characterized by an arid condition of growth for olive trees. Our results showed significant differences in the analytical parameters examined for the three cultivars such as fatty acid composition, total phenols and o-diphenols, and the content of chlorophylls and carotenoids, confirming the importance of genetic factors in the chemical characteristics of the oil. Headspace solid-phase microextraction (HS-SPME) was applied to the analysis of volatile compounds of virgin olive oils. Forty-eight compounds were isolated and characterized by GC-RI and GC-MS, representing 94.1–98.1% of the total amount. (E)-Hex-2-enal, the main compound extracted by SPME, characterized the olive oil headspace for all samples. So, it was clearly shown that there were qualitative and quantitative differences in the proportion of volatile constituents from oils of the various cultivars.
European Journal of Lipid Science and Technology 01/2008; 110(1):81 - 88. · 2.27 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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 1522 mg/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.
[show abstract][hide abstract] ABSTRACT: The chemical composition of virgin olive oil may be influenced by genotype and different agronomic (i.e. fruit ripeness degree, water supply) and technological factors. This article reports the evaluation of the influence of the olive ripening stage on the quality indices, the major and the minor components and the oxidative stability of the two main monovarietal Tunisian cultivars (cvv. Chétoui and Chemlali) virgin olive oils. Moreover, the olives cv. Chétoui were tested in a rain-fed control and an irrigation regime. The oils sampled at five different ripeness stages were submitted to liquid chromatographic determination (HPLC-DAD/MSD) of their quali-quantitative phenolic and tocopherolic profiles. Moreover, the triacylglycerol and fatty acid compositions, and minor components such as squalene, pigments and their relation with the oil oxidative stability were evaluated. The tested oils showed very good correlation between the oxidative stability and the concentrations of total phenols, practically secoiridoids and α-tocopherol.
[show abstract][hide abstract] ABSTRACT: A study on the characterization of virgin olive oils from wild olives ( Olea europaea L. subsp. oleaster ) was conducted in order to define new cultivars which are welladapted to the Tunisian environment and yield high quality oils. The study was done during the crop years 2003/04, 2004/05 and 2005/06. The main analytical parameters of the oils were evaluated: fatty acid compositions, chlorophylls, carotenoids, tocopherols and phenolic compounds as well as their relationship with oxidative stability. The fatty acid composition of all the wild olive trees tested produced virgin olive oil which complies with commercial standards, as well as for their appreciable amounts of tocopherols and phenolic compounds. Tocopherol analysis by HPLC revealed the presence of Î±, Î², Î³ and Î´ tocopherols in all the studied olive oils. Total tocopherol content was significantly influenced by the varietal factor. It ranged from 310 (SB12) to 780 mg/kg (H3). As for total tocopherols, the amount of each tocopherol varied according to genotype. Î± tocopherol is the most prominent, whereas Î², Î³ and Î´ tocopherols are less represented. Results showed a clear influence of total phenols and o-diphenols on virgin olive oil stability (R = 0.905, 0.963 P <10â3, respectively), and a much lower contribution of tocopherols (R = 0.568) and acidic composition (R = 0,563).
En este trabajo se han caracterizado los aceites obtenidos a partir de siete acebuches previamente seleccionados entre varias poblaciones de Olea europea L. Subsp. oleaster . El estudio se llevó a cabo durante las campañas de producción 2003/04, 2004/05 y 2005/06.Varios parámetros analíticos fueron evaluados: composiciones en ácidos grasos, pigmentos, tocoferoles, fenoles; así mismo, se investigó la relación de estos parámetros con la estabilidad de los aceites. Los resultados obtenidos mostraron que todas las muestras de frutos de acebuche produjeron aceites cuya composición de ácidos grasos, tocoferoles y compuestos fenólicos cumplió las normas comerciales para aceite de oliva virgen del Comité Oleícola Internacional. El análisis de los tocoferoles con el HPLC reveló la presencia de las formas Î±, Î², Î³ y Î´ en todos los aceites de oliva estudiados. El contenido total de tocoferoles estuvo claramente influido por la variedad, oscilando entre 310 mg/kg en SB12 hasta 780 mg/kg en H3. La forma Î± de los tocoferoles fue la más importante mientras que de las formas Î², Î³ y Î´ se hallaron menores contenidos. Los resultados indicaron una clara influencia de los fenoles y de los o-difenoles en la estabilidad de los aceites vírgenes de oliva (R = 0.905, 0.963 con P < 10<sup>-3</sup>, respectivamente), y una contribución mucho más baja de los tocoferoles (R = 0.568) y de los ácidos grasos (R = 0,563).
[show abstract][hide abstract] ABSTRACT: The effects of ripening degree of olives on volatile profile of monovarietal virgin olive oils (VOO) from Tunisian and Sicilian cultivars were investigated. Fruits obtained from Tunisia (Chétoui and Chemlali) and Italy (Nocellara del Belice, Biancolilla and Cerasuola) were picked at three different stages of ripeness and then immediately processed. Moreover, the changes in volatile composition were evaluated in Chétoui variety as a function of the irrigation regime versus the rain-fed control. Using headspace–solid-phase microextraction (HS–SPME) technique coupled to GC–MS and GC–FID, the volatile compounds of the monovarietal virgin olive oils were identified and quantitatively analyzed. The proportions of different classes of volatiles of oils showed significant differences throughout the maturity process. The results suggest that adding to the genetic factor; agronomic conditions affect the volatile formation and therefore the organoleptic properties of VOO.
[show abstract][hide abstract] ABSTRACT: Characterization of virgin olive oils from two new olive cultivars obtained through controlled crossings on Meski variety was investigated. These two olive varieties have been selected among a progeny of 30 olive descendants after an evaluation of oil fatty acid composition and the content of their fruits. The study was achieved during the crop years 2001/2002 and 2002/2003. These two new cultivars (9D and 6H) had an improved oil composition compared to that of Chemlali, the dominant Tunisian olive oil variety; the latter is characterized by low rate of oleic acid and high rates of linoleic and palmitic acids. New cultivars are distinguished by: (1) good content of total phenols and oil yield; (2) a balanced fatty acid composition; and (3) a good content of OOO and a relatively low ΔECN42 as compared to that of Chemlali.
[show abstract][hide abstract] ABSTRACT: Evaluation and identification of wild olive genetic resources allowed us to select new olive varieties and to recognize Tunisian grove richness and diversity. Five new olive cultivars were previously selected among populations of wild olive plants on the basis of agronomic and chemical evaluations. Their virgin olive oils were analysed for their fatty acid composition, quality indices (Free acidity, PV and UV characteristics) and oxidative stability. They were then submitted to solid phase microextraction (SPME) and their volatile compositions were determined.Forty five compounds were isolated and characterized by GC–MS, representing 85%–98% of the total amount. The presence of some of these compounds in virgin olive oil had not been previously reported. The volatile compounds identified were mainly (E)-3-hexen-1-ol, (E)-2-hexen-1-ol, tricosane and β-selinene. Results demonstrated that the profiles of oleaster oils were distinctly different from those of European and Tunisian oils. All results indicate that there is a wide variability in the chemical and aroma characteristics of the selected oleaster virgin olive oils.
[show abstract][hide abstract] ABSTRACT: The effect of growing area on the natural antioxidant and oxidative stability of Chétoui virgin olive oil was studied. Total phenolic content, tocopherol composition, fatty acid composition and oxidative stability were analyzed. The results obtained in this study showed that Chétoui virgin olive oil composition is greatly influenced by growing environment, i.e., mainly by the climatic and pedologic factors. The cumulative rainfall appears to have a major influence on phenolic and o-diphenol content. Among studied samples, Amdoun oil had the highest total phenolic content, which exceeded 700 mg/kg. Moreover, it contained the highest amounts of o-diphenols 286.08 ± 6.74 mg/kg and total tocopherols 405.65 ± 4.17 mg/kg.The amounts of total phenols and o-diphenols showed a good correlation (P ≤ 0.001) with stability while tocopherols showed a very low relation to oxidative stability.