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Aouadi D.,National Agricultural Research Institute of Tunisia INRAT | Aouadi D.,University of Carthage | Zorghi L.,Research Unit of Macromolecular Biochemistry and Genetics | Neffati M.,Arid Regions Institute IRA | Ben Salem H.,International Center for Agricultural Research in the Dry Areas
Journal of Animal and Feed Sciences | Year: 2015

The foliage of woody plants, Artemisia herba alba (ART), Eucalyptus globulus (EUC), Pistacia lentiscus (PIS), Rosmarinus officinalis (ROS) and Thymus capitatus (THY), growing in central Tunisia was analysed for contents of nutrients and phytocompounds, including essential oils (EOs) and tannins. PIS and THY were highest in neutral detergent fibre and condensed tannins, respectively. EUC had the highest levels of total phenols, total tannins and oxalates. The concentration of EOs was highest in ROS and THY (26.59 ml · kg-1 dry matter (DM) vs 14.14 ml · kg-1 of DM, respectively). The EOs profiles differed among all the plant species. ROS and EUC EOs were composed mainly of 1,8-cineole (27.86% and 50.19%, respectively) while ART's EOs were dominated by camphor (16.28%) and chrysanthenone (14.78%). Carvacrol (44.24%) was the chemotype of THY EOs. The major compound of PIS EOs was α-pinene (12.82%). Biological assay showed that tannins affect the nutritive value of these plants. With the exception of THY, the association of polyethylene glycol to substrates incubated in calibrated syringes resulted in a major increase of gas production (+21% to +136%). Differences in the profiles of EOs extracted from the five woody species suggest that these EOs could differ in their impact on digestion and performance of ruminants. © 2015, Polish Academy of Science. All rights reserved. Source

Fiori L.,University of Trento | Lavelli V.,University of Milan | Duba K.S.,University of Trento | Sri Harsha P.S.C.,University of Milan | And 2 more authors.
Journal of Supercritical Fluids | Year: 2014

The current study focuses on the recovery of grape seed oil by supercritical CO2 extraction. Grape seeds from six grape cultivars were extracted in two subsequent harvesting years, and the resulting oils were characterized for the relative amount of: (a) lipid classes; (b) lipid acyl chains; and (c) tocopherols and tocotrienols. Comparative extractions were performed by utilizing n-hexane as solvent and by mechanical pressure. A well-established modeling approach was applied to evaluate the mass transfer parameters affecting the kinetics of supercritical CO2 extraction: with these parameters, process scale-up can be addressed. The results reported in this study testify the potentiality of grape seed oil as a source of unsaturated fatty acids and tocols. Moreover, they offer a clear picture of the similarities and differences among oils from different grape cultivars and obtained through different extraction techniques. © 2014 Elsevier B.V. Source

Duba K.S.,University of Trento | Casazza A.A.,University of Genoa | Mohamed H.B.,National Agricultural Research Institute of Tunisia INRAT | Perego P.,University of Genoa | Fiori L.,University of Trento
Food and Bioproducts Processing | Year: 2015

Polyphenols were extracted from grape skins and defatted grape seeds (cultivar: Pinot Nero) by using subcritical water in a semi-continuous mode. Extractions were performed at a pressure of 10 MPa, at three different temperatures (80, 100 and 120 °C) and with two water flows. For both skins and defatted seeds, total polyphenol (TP) yield significantly increased with temperature: for skins from 44.3 ± 0.4 to 77 ± 3 mg/g, while for defatted seeds from 44 ± 2 to 124 ± 1 mg/g when the temperature increased from 80 to 120 °C. Importantly, TP yield decreased with flow rate at constant temperature. The extraction kinetics was simulated by a simple model from literature. The model adjustable parameters were calculated by best fitting procedures with experimental data: the model fitted the experimental kinetics curves in a satisfactory way, providing reference values for the adjustable parameters. The present research outlines the potentialities of using subcritical water for extracting valuable polyphenols from food processing by-products, and the effect of the operating conditions. Moreover, it proves that a very simple model from literature allows the interpretation of the extraction curves on the base of mass transfer and partition coefficients. © 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Source

Mohamed H.B.,National Agricultural Research Institute of Tunisia INRAT | Zrig A.,Gabes University | Geuns J.M.C.,Catholic University of Leuven | Khemira H.,Gabes University | Khemira H.,Jazan University
Australian Journal of Crop Science | Year: 2014

To assess the efficacy of near lethal heat stress for endodormancy release of Superior Seedless grapevine buds, single-node cuttings were soaked for 1 h in hot water (50°C) and then forced for one month. The effects of hot water treatment (HWT) on budburst, metabolic changes of carbohydrates, proline, free polyamines PAs (putrescine (Put), spermidine (Spd) and spermine (Spm)) and antioxidant enzymes' activity were investigated in bud under forcing conditions. Near-lethal heat stress caused a transient increase in starch hydrolysis, leading to an abrupt accumulation of soluble sugars, especially sucrose concentration during the first 3 days after treatment. This accumulation of soluble sugars coincided with a brief stimulation of the antioxidant system represented by ascorbate peroxidase (APX; EC, peroxidase (POD; EC as well as an increase in the concentration of proline and free polyamines, especially putrescine (Put) and spermidine (Spd). These changes, which occurred immediately upon treatment, appear to be related with a process leading to endodormancy release. These results support the argument that a temporary and acute oxidative stress is involved in the mechanism leading to dormancy release and budbreak. Furthermore, it is possible that the stimulation of both peroxidases' activity and proline biosynthesis activated the pentose phosphate pathway (PPP) which helped the bud to overcome endodormancy. After this initial period and towards budbreak initiation, there was a rapid decline in the concentration of soluble sugars, proline and Put, while, Spm and Spd became abundant. Such post stress changes appear to be associated with the reactivation of growth leading to an earlier and more vigorous budbreak. The metabolic response to HWT was compared to those observed after bud chilling or the application of restbreaking agents such as hydrogen cyanamide (HC). The similarity in the response to these various stimuli suggests the presence of common regulatory pathways involved in bud dormancy release and subsequent sprouting. Source

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