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Zouari N.,University of Sfax | Zouari N.,Institute Superieur Of Biologie Appliquee Of Medenine | Fakhfakh N.,University of Sfax | Zouari S.,Institute des Regions Arides | And 5 more authors.
International Journal of Food Sciences and Nutrition | Year: 2011

Volatile and lipid chemical compositions, and nutritional and antioxidant properties of Malva aegyptiaca, an edible wild plant largely distributed in North Africa, were investigated. Forty-nine compounds of volatiles were identified showing large qualitative and quantitative differences during three phenological stages. The flowering stage was characterized by the presence of a high number of terpenic compounds, among them dillapiole was found to be the major one (55.15%). The nutrient composition of leaves and fruits was investigated in the present work. Fruits' lipidic fraction was characterized by its high level of linoleic acid (n-6) (36.17%). Interestingly, leaves' lipidic fraction was characterized by its very high content of camphor (43.69%) and by its relatively high content of linoleinic acid (n-3) (14.69%). Furthermore, our results showed that the phenolic contents varied from 352 to 404 mg gallic acid equivalent/g ethanolic and acetonic extracts, respectively. These extracts revealed interesting antioxidant activities including free radical scavenging activity (EC 50 = 0.38-0.57 mg/ml) and reducing power (EC 50 = 0.12-0.18 mg/ml). © 2011 Informa UK, Ltd.

Zouari N.,University of Sfax | Zouari N.,Institute Superieur Of Biologie Appliquee Of Medenine | Ayadi M.A.,University of Sfax | Hadj-Taieb S.,University of Sfax | And 2 more authors.
International Journal of Food Properties | Year: 2012

A 10-point simplex lattice design was used to investigate the effect of varying the ratios of whey powder, ι-carrageenan, and fat, and their interactions on instrumental texture and sensory properties of mechanically separated turkey meat sausages. Regression models have been developed and contour plots were drawn in order to better understand the global tendency of measured responses. Whey powder had a more notable influence than that of -carrageenan on all textural parameters as whey powder proportion increased. At a higher proportion (8 g/100 g sausage), whey powder improved essentially hardness, gel stress, and chewiness of extra low-fat sausage (formulation 3, 4.2±0.3 g of fat/100 g sausage). Environmental scanning electron microscopy of the corresponding sausage showed a compact microstructure characterized by large network connections. Sensory evaluation also indicated that whey powder increased the flavor, the firmness, and the sliceability scores of mechanically separated turkey meat sausage, in comparison to the high-fat standard sausage (formulation 1, 13.2±0.2 g of fat/100 g sausage). Copyright © Taylor & Francis Group, LLC.

Hammadi M.,Arid Lands Institute | Atigui M.,Arid Lands Institute | Ayadi M.,Institute Superieur Of Biologie Appliquee Of Medenine | Barmat A.,Arid Lands Institute | And 3 more authors.
Journal of Camel Practice and Research | Year: 2010

Six healthy Maghrebi dairy camels at mid lactation were used in 2 trials to assess the camel training period for machine milking, and the short time effects of machine milking vs. hand milking on some milk production parameters and physicochemical characteristics in milk. Before the study, dams were reared in oasis intensive system and hand-milked twice. In trial 1 which lasted for 2 weeks, camels were trained for machine milking. In trial 2, camels were monitored during 2 successive weeks; on the first week they were hand-milked and on the second week, they were machine milked. Trial 1. Over days of training, the animals became less hostile and the total time between entering and exiting did not exceed 15 min. The lag time, after oxytocin injection, did not change and averaged 29.6 ± 3.0 s. Nevertheless, milking time increased with the change of the milk production and averaged 7.5 ± 0.4 min and 9.4 ± 0.6 min, during the first and the second week, respectively. On the 2 nd day of machine milking, daily milk yield decreased slightly (-6%) compared to the day (-2) before the start, of machine milking. This production increased to 7.48 ± 0.52 1 on day 13 of training. On the second week of the training period, no difference was observed between the daily milk yields. During training camels for machine milking, total milk solids, protein and ash contents did not vary. Milk fat was the most affected component, it decreased from 36.8 ± 2.4 g/1 2 days before the start of machine milking until 28.7 ± 1.8 g/1 in day 10 of training period and returned to its initial value on day 13. Trial 2: Daily milk yield was 38% higher in machine than hand milking system. Milk secretion rate differed between the 2 milking systems. In the morning (8:00) as well in the afternoon (16:00), lag time was half shorter in machine milking (36.0 ± 6.9 s) than in hand milking (58.0 ± 4.0 s). However, milking time was longer in machine than in hand milking and ranged from 4.2 to 4.8 min and 2.6 to 3.2 min, respectively. Physical parameters of milk had higher values in machine than in hand milking system. However, in the morning, milk density was comparable between the 2 milking systems.

Gorai M.,Institute Superieur Of Biologie Appliquee Of Medenine | El Aloui W.,Institute des Regions Arides | Yang X.,CAS Institute of Botany | Neffati M.,Institute des Regions Arides
Plant and Soil | Year: 2014

Aims: Seeds of Henophyton deserti (Brassicaceae), an endemic saharan shrub in south Tunisia, produce a pectinaceous mucilage layer that can imbibe a large amount of water when wetted. The aim of this study was to explore the role of mucilage in seed germination of this shrub under heterogeneous stressful environments. Methods: Germination of both intact and demucilaged seeds was tested over wide ranges of temperature, and in iso-osmotic solutions of NaCl and PEG. Recovery of germination after NaCl and Polyethylene Glycol (PEG)-6000 treatment was also tested. The effect of mucilage on water uptake was measured and the structure of the seed investigated. Results: A considerable proportion of seed mass (30 %) is made up of mucilage, which is extremely hydrophilic and able to increase seed mass by 550 % over dry seeds. Mucilage water uptake appears to be unaffected by salt concentration, while higher concentrations of PEG inhibit mucilage hydration. Mucilage decreases germination specifically at 10 °C and this effect can be interpreted in relation to oxygen uptake. High concentrations of NaCl and PEG decrease both germination percentage and rate, with some greater tolerance at 15 °C and 20 °C versus 25 °C. Recovery was higher from higher concentrations of NaCl and PEG and lower temperatures, with a clear inhibitory effect of mucilage. Conclusions: The study has shown that the mucilage of H. deserti may act as a physical barrier for regulating diffusion of water and oxygen to the inner tissue of the seed and thereby prevent germination under unsuitable conditions. © 2013 Springer Science+Business Media Dordrecht.

Lefi E.,Institute Superieur Of Biologie Appliquee Of Medenine | Conesa M.A.,University of the Balearic Islands | Cifre J.,University of the Balearic Islands | Gulias J.,University of the Balearic Islands | Medrano H.,University of the Balearic Islands
Crop and Pasture Science | Year: 2012

Soil water availability is one of the main factors determining plant growth and forage production. The effects of soil water deficit on the development of two woody Mediterranean Medicago species, M. arborea and M. citrina were studied. A field experiment was carried out in the University of the Balearic Islands (Spain), under irrigated and drought conditions on both non-defoliated plants (NDP) and defoliated plants (DP). Under drought, all studied parameters for NDP were affected by water stress in summer, though there were no significant differences between species for shoot biomass (B). However, M. citrina maintained significantly higher leaf biomass than M. arborea, which represents a great part of B. On the contrary, M. arborea plants suffered total leaf senescence in summer, and B was totally composed of woody parts. For DP, springautumn was a favourable period for plant growth and development, under both water regimes. In well irrigated M. citrina plants, and compared with M. arborea, the capacity of regrowth was higher, and leaf area was similar for NDP and for DP. During summer, the regrowth was sensitive to the extreme temperatures. In drought conditions, the capacity of regrowth was relatively favoured in spring but completely inhibited in summer for both species. © CSIRO 2012.

Guerfel M.,Institute Superieur Of Biologie Appliquee Of Medenine | Ouni Y.,Center de Biotechnologie de la Technopole de Borj-Cedria | Boujnah D.,Institute Of Lolivier | Zarrouk M.,Center de Biotechnologie de la Technopole de Borj-Cedria
Trees - Structure and Function | Year: 2010

Water relations are a key factor limiting olive production. In this study, effects of plating density on physiological aspects and productivity of 'Chemlali' olive trees were analyzed under rain-fed conditions in four planting densities (156, 100, 69 and 51 trees ha-1), in an experimental olive orchard located in the center of Tunisia. Seasonal changes in leaf relative water content (RWC), leaf water potential, stomatal conductance (gs), CO2 assimilation rate and tree production were studied. Accompanying the changes in leaf water status, all the monitored trees reduced leaf stomatal conductance (gs) and photosynthetic rate (A) throughout the summer drought, mirroring the increase in soil moisture deficit and vapor pressure deficit. However, the decrease in gas exchange was much more pronounced in high planting densities than in low ones. Our results confirm that the increase of tree-to-tree water competition with planting density was significant in the dry climate of Tunisia. Thus, planting density is critical when planting new olive orchards in arid regions. © 2010 Springer-Verlag.

Zouari N.,University of Sfax | Zouari N.,Institute Superieur Of Biologie Appliquee Of Medenine | Abid M.,University of Sfax | Fakhfakh N.,University of Sfax | And 4 more authors.
International Journal of Food Sciences and Nutrition | Year: 2011

The effects of semolina enrichment with blue-green algae (Arthrospira platensis) at three different levels (1, 2 and 3 g/100 g of semolina) on the colour, cooking properties, firmness, free radical scavenging activity and sensory characteristics of pasta are reported. Microalgae addition resulted in higher swelling index and lower cooking loss than the control sample. A significant increase in pasta firmness was evidenced with an increase of added microalgae due to structural reinforcement. In addition to colouring, the use of A. platensis (2 g/100 g of semolina) can enhance the sensory quality and nutraceutical potential as evaluated by free radical scavenging activity of pasta. © 2011 Informa UK, Ltd.

Zouari N.,University of Sfax | Zouari N.,Institute Superieur Of Biologie Appliquee Of Medenine | Fakhfakh N.,University of Sfax | Zouari S.,Institute des Regions Arides | And 4 more authors.
Food and Bioproducts Processing | Year: 2011

The present study describes chemical composition, angiotensin I-converting enzyme (ACE) inhibitory, antioxidant and antimicrobial activities of the essential oil of wild growing Thymus algeriensis Boiss. et Reut. (Lamiaceae), a traditional medicinal plant which is mainly endemic in Tunisia and Algeria. The essential oil from the fresh leaves and flowers of T. algeriensis were extracted by hydrodistillation and analysed by GC and GC/MS. Fifty-seven compounds were identified accounting for 97.71% of the total oil, where oxygenated monoterpenes constituted the main chemical class (44.85%). The oil was dominated by camphor (7.82%), 4-terpineol (7.36%), α-pinene (6.75%), 1,8-cineole (5.54%) and cis-sabinene hydrate (5.29%). The T. algeriensis essential oil was found to possess an interesting inhibitory activity towards ACE with an IC50 value of 150 μg/ml. The obtained results also showed that this oil can act as radical scavengers (IC50 = 0.8 mg/ml) and displayed a lipid peroxidation inhibitory activity (IC50 = 0.5 mg/ml) as evaluated by 2,2-diphenyl-1-picrylhydrazyl and β-carotene bleaching methods, respectively. Furthermore, the oil was tested for antimicrobial activity against six bacterial strains and two fungal strains. The inhibition zones and minimal inhibitory concentration values of microbial strains were in the range of 13.5-64 mm and 1-6 μl/ml, respectively. The oil exhibited remarkable inhibitory activity against fungal and Gram-positive bacteria strains. © 2010 The Institution of Chemical Engineers.

Zouari N.,University of Sfax | Zouari N.,Institute Superieur Of Biologie Appliquee Of Medenine | Fakhfakh N.,University of Sfax | Amara-Dali W.B.,University of Sfax | And 3 more authors.
Food and Bioproducts Processing | Year: 2011

Turkey liver is an important edible meat by-product. However, it is generally unprocessed, underutilized and low-priced compared to mammalian livers. The present investigation was conducted to provide information on physicochemical composition and functional characteristics of turkey liver. Proximate composition (%) was: moisture (72.3 ± 1.2), protein (21.9 ± 0.6), fat (2.9 ± 1.6), carbohydrate (1.4 ± 0.7), and total ash (1.5 ± 0.1). Cholesterol, glycogen and total heme pigments (g/kg) in the turkey liver were 2.05 ± 0.06, 5.36 ± 0.01 and 2.3 ± 0.08, respectively. Contents in saturated, monounsaturated and polyunsaturated fatty acids (%) were 42.5, 14.6 and 32.6 respectively. Interestingly, turkey liver fat also contains 5% of camphor (oxygenated monoterpene). Mineral concentrations (mg/kg) in liver were: Na (817 ± 14), K (1390 ± 90), Ca (31.4 ± 0.3), Mg (23 ± 0.4), Fe (161 ± 5), Zn (40 ± 2) and Cu (34 ± 2). Liver proteins extracted at 5 or 10 g/l NaCl showed the highest foaming capacity (P < 0.05). Addition of xanthan (1-3 g/l) to liver proteins improved both foam formation and its stability (P < 0.05). Turkey liver also showed interesting emulsifying properties. The emulsion stability of liver proteins was more pronounced at high NaCl concentration (20 g/l). The highest emulsion stability was obtained at acidic or basic pH values (P < 0.05) and decreased at pH 6. © 2010 The Institution of Chemical Engineers.

Maraghni M.,Institute des Regions Arides | Gorai M.,Institute Superieur Of Biologie Appliquee Of Medenine | Neffati M.,Institute des Regions Arides | Van Labeke M.C.,Ghent University
Acta Physiologiae Plantarum | Year: 2014

The aim of this study was to investigate the effects of drought stress induced by polyethylene glycol-6000 in wild jujube, Ziziphus lotus. One-month-old, hydroponically grown seedlings were subjected to three treatments, i.e. normal watering (-0.2 MPa), moderate (-1.2 MPa) and severe (-2.1 MPa) drought stress for 14 days under controlled climatic conditions. Plant growth was markedly reduced with increasing osmotic stress. The shoot water potential (Ψw) and leaf relative water content followed similar patterns and significantly decreased with increasing osmolality of solutions. As a consequence of drought, contents in proline and soluble sugars were found to be more elevated in leaves than in roots. The level of lipid peroxidation in terms of malonyldialdehyde contents increased in both leaves and roots of drought-stressed plants. Wild jujube displayed higher activities of antioxidant enzymes in the roots than in the leaves. Catalase and guaiacol peroxidase activities increased significantly in drought-stressed roots, whereas ascorbate peroxidase activity showed a slight decline with no significant changes. These findings suggest that Z. lotus was able to adapt to severe drought stress by accumulation of compatible solutes and by activation of free radical-scavenging enzymes. Overall, defence mechanisms in Z. lotus against oxidative stress are organized differently in plant tissues, with higher solute accumulation in leaves and increased activity of antioxidants in roots, during drought stress. © 2013 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.

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