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Dabbou S.,Dentistry Faculty | Dabbou S.,Higher Institute of Biotechnology of Monastir | Chehab H.,Institute Of Lolivier Of Sousse | Taticchi A.,University of Perugia | And 2 more authors.
Chemistry and Biodiversity | Year: 2015

The quality indices and chemical composition of Coratina olive oil produced in the northern region of Tunisia were evaluated, to determine the effect of three different irrigation regimes of the trees on the olive oils. The olives were sampled at two different stages of maturity, the oils were extracted, and standard methods were used to analyze the composition and quality of the oils. The fatty-acid contents and quality parameters were only slightly affected by the irrigation regime. The contents of palmitic, oleic, and linoleic acids were above 12, 72, and 8%, respectively, for the second harvest, regardless of the irrigation level of the olive trees. Parameters such as the α-tocopherol content and the phenolic profile were found to be significantly affected by the harvesting time; however, inconsistent changes were observed for the irrigation regimes, especially for the oil of the second harvest. It was shown that the irrigation conditions of the olive trees as well as the harvesting time of the fruits gave rise to a diverse range of olive oils in Tunisia. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Dabbou S.,University of Monastir | Brahmi F.,University of Monastir | Selvaggini R.,University of Perugia | Chehab H.,Institute Of Lolivier Of Sousse | And 3 more authors.
International Journal of Food Science and Technology | Year: 2011

Nowadays, a significant increase in intensively and irrigated managed olive orchards has occurred in Tunisia in the hope to increase the olive production. Aromatic profile with sensory analysis were considered in virgin olive oils from Arbequina, Coratina and Koroneiki cultivars grown intensively under three irrigation treatments (T1, T2 and T3 equivalent to 50%, 75% and 100% ETc.). Results showed that the aromatic quality depends first on the irrigation level applied and second on the cultivar. From sensory analysis, hay-like and greasy were the principal off-flavour detected. As the amount of supplied water increased, volatiles showed different behaviours depending on cultivar and the most important changes occurred in the release of the three alcohols ((E)-2-penten-1-ol, 1-hexanol, (E)-2-hexen-1-ol and phenylethyl alcohol) and hexanal. The most effective by irrigation regimes in separating cultivars were (E)-2-hexenal, (Z)-2-penten-1-ol, (E)-2-hexen-1-ol, fruity, bitter and pungent sensory descriptors. In conclusion, the data obtained herein proved the heavy influence of the cultivar in comparison with irrigation regimes. © 2011 The Authors. International Journal of Food Science and Technology © 2011 Institute of Food Science and Technology.

Dabbou S.,University of Monastir | Chehab H.,Institute Of Lolivier Of Sousse | Brahmi F.,University of Monastir | Taticchi A.,University of Perugia | And 2 more authors.
International Journal of Food Science and Technology | Year: 2011

The impact of different irrigation regimes based on two ripeness index, on the quantity and quality of virgin olive oil from the introduced olive cultivar Olea europaea L. Koroneiki grown at a high-density olive orchard in northern Tunisia, was assessed. Olive trees were subjected to three treatments (T1, T2 and T3) that received a seasonal water amount equivalent to 50%, 75% and 100% of the estimated local evaporative demand by a drip irrigation system and olives were collected in two different ripeness index. The olive oil content decreased when the water applied was increased but rose during ripening. The quality indexes and fatty acid composition were less affected by the irrigation schedule but most significantly by the maturity of olives. Moreover, phenol contents increased according to fruit ripening whereas no clear cut differences or consistent effects were observed by irrigation. α-tocopherol decreased slightly in the oils as ripening progressed while insignificant differences between the irrigation treatments studied were obtained. Consequently, a restitution of 75% of crop evapotranspiration (ETc.) was sufficient to achieve good minor compounds; however, higher water volumes (100% ETc.) gave little additional α-tocopherol and phenols increases. © 2011 The Authors. International Journal of Food Science and Technology.

Mechri B.,University of Monastir | Tekaya M.,University of Monastir | Cheheb H.,Institute Of Lolivier Of Sousse | Hammami M.,University of Monastir
Journal of Chromatographic Science | Year: 2015

This study reports a method for the analysis of mannitol, sorbitol and myo-inositol in olive tree roots and rhizospheric soil with gas chromatography. The analytical method consists of extraction with a mixture of dichloromethane:methanol (2:1, v/v) for soil samples and a mixture of ethanol:water (80:20) for root samples, silylation using pyridine, hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS). The recovery of mannitol sorbitol and myo-inositol (for extraction and analysis in dichloromethane:methanol and ethanol:water) was acceptable and ranged from 100.3 to 114.7%. The time of analysis was <24 min. Among identified polyols extracted from rhizosphere and roots of olive plants, mannitol was the major compound. A marked increase in mannitol content occurred in rhizosphere and roots of water-stressed plants, suggesting a much broader role of mannitol in stress response based on its ability to act as a compatible solute. © The Author 2015. Published by Oxford University Press. All rights reserved.

Dabbou S.,University of Monastir | Chehab H.,Institute Of Lolivier Of Sousse | Faten B.,University of Monastir | Esposto S.,University of Perugia | And 5 more authors.
Agricultural Water Management | Year: 2010

This study investigated the effect of irrigation amount on the concentration of phenolic compounds in olive (Olea europaea L., cv. Arbequina) oil obtained from an intensively-managed orchard in a semi-arid area with a Mediterranean climate in Tunisia. Different irrigation treatments 50% Etc, 75% Etc and 100% Etc were applied to the olive orchard. Oil quality, evaluated using the parameters established to determine the quality level of virgin olive oils (acidity, K232, K270 and peroxide index) was slightly affected by irrigation. However, results showed that irrigation positively affected both fruit and oil quality. In fact, the least irrigation regime (T1), showed a significantly higher content of oleic acid (70.08%), whereas olive oils from more irrigated trees (T2 and T3) had higher contents of palmitic acid (11.64% and 13.14%, respectively) and lower of linoleic acid (approximately 12.7%). However, content of phenolic compounds (hydrophilic and lypophilic), in the oils extracted, strongly differed. In fact, different irrigation regimes applied not only affected the total amount of phenols which were proportional to irrigation (193.2 and 271.87 mg kg-1 for T1 and T3, respectively) except for T2 but also their HPLC profiles. Contrarily to phenols, insignificant differences were observed in the concentration of α-tocopherol between the irrigation treatments studied. © 2010 Elsevier B.V. All rights reserved.

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