Search

To understand the salinity tolerance mechanism in faba bean contrasting pair to salinity (cv. Chourouk as sensitive and cv. Najeh as tolerant), we evaluated the effect of high salt concentration (150 mM NaCl) on the photosynthetic, physiological, and biochemical parameters at short and long term of treatment (1 and 6 days, respectively) in the seedling stage. In general, the salinity affects the growth of plants. High salinity decreased all studied parameters, especially transpiration rate (E), stomatol conductance (gs), net CO2 assimilation (A), and substomatal CO2 concentration (Ci), and dramatic changes was registered in cv. Chourouk compared to cv. Najeh. Chlorophyll contents were also affected by salinity, especially in the sensitive variety. In addition, the synthesis of osmolytes (proline) was determinate, to understand whether the osmotic adjustment is a mechanism used by cv. Najeh to tolerate salt stress. Our research suggests that cv. Najeh should be introduced in a crossbreeding program as an elite salt-tolerant germplasm.

The aim of this study was to evaluate the effect of the addition of biochar (0, 2, 5, and 8% designed by C, B2, B5, and B8, respectively) on the single and interactive effects of salinity and drought treatments on the growth of vicia faba plants in alkaline soil. 21 morphological, physiological, and photosynthetic parameters were evaluated. The amendment of biochar, carbon-rich material developed from combustion of biomass under no or limited oxygen supply, in alkaline soil under salinity stress performed positive effects on internal concentration of CO2 (+ 96.16% at B8), transpiration rate (+ 83.79% at B5), stomatal conductance (+ 30% at B2), and net CO2 assimilation (+ 37.84% at B2). Under drought stress, the addition of biochar had no effect on internal concentration of CO2 and the water use efficiency. Under combined conditions, the maximum increase (+ 40%) of internal concentration of CO2 was registered at B5. Also, addition of 2% of biochar (B2) can increase the transpiration rate to + 116%. Biochar was alleviating the effect of combined stress on vicia faba leaves by ameliorating the stomatal conductance to + 58.73% at B2. We, also, noticed that net CO2 assimilation rate increase with the increase of biochar concentration. On the other hand, biochar addition did not have effect on lengths of shoot, roots, and total plants and fresh biomass, spad value, and leaf number. However, the amendment of biochar has slightly ameliorated the electrolyte leakage, protein content, and foliar surface. The pH and the EC of initial and final treatment were also evaluated. The statistical analysis demonstrates that addition of 2% (B2) of biochar can significantly mitigate the negative effect of single effect of salinity and combined salinity drought in alkaline soil. On the other hand, the addition of 5% (B5) of biochar can alleviate the individual effect of drought compared to their respective controls. This result confirms the positive effect of biochar addition in alkaline soils. Thus, a better understanding of biochar addition on physiological basis for faba bean growth under drought and salinity stress in alkaline soil will be beneficial for sustainable agriculture.

In this study, we examined the behavior of six faba bean (Vicia faba L.) genotypes under salinity conditions at the seedling stage. The evaluation was assessed using 21 morphological, physiological, and photosynthetic traits under control, moderate, and severe salinity conditions. The principal component analysis (PCA) was used to identify genotypes of contrasting behavior in response to salt stress and to characterize the important traits for salt tolerance. The result of PCA analysis showed that the genotypes displayed different behavior under the saline conditions. The most discriminating quantitative characters were related to plant biomass production and photosynthesis, especially the mass of fresh root, number of leaves, water-use efficiency, and the substomatal CO2 concentration. The analysis of all parameters by PCA permits us to distinguish cv. Najeh as the most tolerant genotype for salinity conditions and cv. Chourouk as the most sensitive one. These results would be of pertinent tools in faba bean breeding programs.

The volatile profiles of Tunisian virgin olive oils were established by solid phase micro-extraction (SPME) and gas chromatography (GC), using flame ionisation and mass spectrometer detectors. Terpenes compounds were identified and characterized. Limonene, the main terpene compound extracted by SPME, characterized the studied olive oil. Significant differences in the proportions of terpenes constituents from oils of different maturity index were detected. The results demonstrated that the accumulation of the terpenes compounds in the studied oils obtained from different ripeness stage was strictly connected with the ripeness stage.

Faba bean (Vicia faba L.) is an important pulse crop in the Mediterranean region. Salinity is one of the most devastating abiotic stresses that alter the growth and development of plants and affect the crop yield, especially in arid and semi-arid area such as Tunisia. To surmount the damaging effect of salinity, it is important to develop tolerant cultivars of faba bean. In this study, we examined the behavior of four faba bean cultivars in response to salinity stress. Plants were grown in hydroponics at 0, 75 and 150 mM of NaCl, and 16 morphological, photosynthetic and physiological parameters were assessed. Our data showed a significant genotypic variation for salt tolerance in faba bean among the studied cultivars. All measured parameters were affected by salinity at moderate salt concentration (75 mM), while there was a more pronounced reduction of all parameters at severe salt concentration (150 mM). The statistics analysis revealed that photosynthetic and biomass parameters were the least altered in cv. ‘Najeh’. Based on the results, cv. ‘Najeh’ can be considered to be a tolerant cultivar and to attract great interest in future breeding programs for modern cultivar improvement.

Durum wheat is an important crop, whose grain is used for the production of pasta, bread, couscous, bulgur, and other products. The end-use of wheat is heavily determined by the grain’s characteristics, which depend on the wheat variety, the environmental effects, and genotype–environment interactions. In Tunisia, ancient durum wheat varieties disappeared and they were replaced by other new breeding programs. Modern Tunisian durum wheat varieties were collected from different zones throughout the country. The wheat varieties were evaluated for various chemical and technological quality parameters. Results of quality characteristics of the examined wheat grains showed a strong influence of the growing zone on almost all analytical parameters. These differences between wheat varieties may be ascribed to the differences between the genotype–environment interaction such as soil, climate, and the use of fertilizers, etc.

Sterols, which comprise a major portion of the unsaponifiable matter, are found in almost all fats and oils and are also characteristic of the purity of vegetable oils. Recently, some works have proposed that sterol profiles can be used to classify virgin olive oils according to their fruit variety. Throughout this work, the mean values of each sterol compound of olive oils extracted from several cultivars were submitted to Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) in a discriminatory fashion. Results confirm that phytosterols can differentiate between varieties, hybrids and oleasters. Always the two first principal components were sufficient to explain the variability between olive cultivars. The PCA shows a clear discrimination between all studied samples. Therefore, the composition of sterols was found to be sufficient for the olive oil discrimination, characterization and adulteration with lower priced oils.

The aim of the present investigation is to discriminate seven selected wild olive trees by studying their sterol and triterpenic dialcohol compositions with those of VOOs obtained from Chemlali and Chetoui olive cultivars, all growing in the in the same pedoclimatic conditions. The main sterol found in all the samples is β Sitosterol, followed by Δ5-avenasterol These two major sterols are strongly and negatively correlated, and there is a clear differentiation between cultivars. Thus, MAT22 oleaster shows the highest value for β-sitosterol (87.18%), whereas SB12 oleaster is characterised by the lowest percentage of β-sitosterol (71%) and the highest one of Δ5-avenasterol (21.73%). For the remaining varieties, the levels of b-sitosterol and Δ-5-avenasterol are within the range of 74–86% and 4–17%, respectively. Two triterpenic dialcohols (erythrodiol and uvaol), were also detected besides the sterolic components. Sterol content of oils was below the upper legal limit of 4% in all nalysed samples, with a range from 1.05% to 3.40%. The statistical analyses (PCA and HCA) can explain the variability of the oil composition according to the cultivar. We note a good discrimination between varieties according to sterol and triterpenic dialcohol data. These components seem to be an effective tool to discriminate between the oleasters.

The volatile compounds of twelve legume cultivars were evaluated by headspace-solid phase micro-extraction (HS-SPME) coupled to gas chromatography–mass spectrometry (GC-MS) from both whole seeds and their flours. The total identification percentages of the extracted volatiles were ranged between 94.2% and 99.7%. The number of aroma compounds detected was 104. Among them, 60 compounds were determined in the emission of whole legume seeds and 69 from legume flours. The volatiles were classified into seven chemical classes, i.e. monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, phenylpropanoids, apocarotenes, nitrogen/sulfur derivatives, and non-terpene derivatives. Aldehydes were considered one of the most abundant constituents in non-terpene derivatives, followed by esters, alkanes, alcohols, ketones, lactones, phenols, phenones, alkenes, and hydrocarbons. A wide difference in term of volatiles was observed between whole and crushed seeds. Multivariate data analysis (PCA) was assessed to compare among legume cultivars, which leads to the identification of relevant constituents to specific cultivar. Overall, this is the first time a multivariate analysis was used to characterize the volatile profiles of twelve legume cultivars with their flours. This study can provide useful information on the conception of legume–based ingredients combined with specific volatile characteristics in order to reduce unwanted odors and definitely for pertinent breeding programs.

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 APPLICATIONS The 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.

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.

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. Chetoui and Chemlali) virgin olive oils. Moreover, the olives cv. Che´toui 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 alfa-tocopherol.

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.

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.

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.

Chetoui and Chemlali olive fruits were stored at two different temperatures (ambient and 5°C) for different periods before oil extraction at 0, 7, 14, 21 and 28 days to investigate the effect of postharvest fruit storage on olive oil quality. Conventional analyses (acidity, peroxide value, specific extinction coefficient at 232 and 270 nm and fatty acid composition) and non conventional analyses (pigments, total phenols, oxidative stability and radical scavenging capacity) were carried out in order to evaluate the oil quality. Results showed that fruit storage at ambient temperature led to the deterioration of the oil parameter qualities such as acidity, K232 and K270 which is more rapidly in Chemlali oils than that of Chetoui cultivar. In the same way, the trend of total phenols, oxidative stability and radical scavenging capacity of the studied olive oils showed a decrease during the fruit storage at ambient temperature. This reduction was more severe in Chemlali olive oils than those of Chetoui cultivar. Storage of fruits at 5°C prevented the fast alteration that is produced in oils extracted from fruits stored at ambient temperature. Key words: Olive storage, oil quality, fatty acids, stability.

At the industrial scale, the major source of olive oil deterioration is the poor handling of the raw material during the time separating harvesting from processing. The objective of this work was to verify the effect of modified atmospheres and cold storage in relation to quality parameters of the extracted oils. Olives (cv Chétoui) intended for oil extraction, were stored for 21 days at two different temperatures (ambient temperature 14 ± 2 °C and 5 °C) and under two different modified atmospheres 21% O2 – 0% CO2 and 2% O2 – 5% CO2. Oils quality was ascertained with analytical parameters: free fatty acids, peroxide value, K232, K270 as suggested by European regulation. Oxidative stability, total phenols content, radical scavenging activity and fatty acids composition were carried out in order to measure the hydrolytic and oxidative degradation of oils. Olive oils quality parameters were significantly affected by treatments with especially a beneficial effect on primary oxidation indicators and free acidity. Most efficient treatments, with regard to oils phenolic content and involved parameters, were 21% O2 – 0% CO2 at ambient temperature (636.25 mg ca/kg) and 2% O2 – 5% CO2 under 5 °C (637.50 mg ca/kg). Those two treatments improved individually oil samples phenolic content of 25% but not at the same storage period.

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 (Chetoui 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 Chetoui 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.

The sterol profile of Tunisian virgin olive oils produced from Chetoui 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 Chetoui 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 Chetoui 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.