Christian Mertz

Cirad - La recherche agronomique pour le développement, Montpelhièr, Languedoc-Roussillon, France

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Publications (11)13.21 Total impact

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    ABSTRACT: Description du produit : Parmi les catégories des jus de fruits, les purs jus de fruits, 100 % purs jus sont inexistants sur le marché national ; ce qui confère à notre produit son caractère innovant. C’est un 100 % pur et naturel jus ou rien ni ajouté, rien n’est enlevé. Caractéristiques : les « purs jus de fruits, 100 % purs jus, obtenus par un pressage douceur (dans les 24 heures suivant la cueillette) de l’orange sanguine rigoureusement sélectionnée sans adjonction d’aucune sorte : sans colorant, sans conservateur ajouté (ni naturel, ni synthétique), sans eau additionnée ni sucre (une orange sanguine pressée pure 100 % et rien d’autre) et pour lesquels seule une adjonction de vitamine C et un traitement de stabilisation (pasteurisation) est autorisée. Notre produit est caractérisé par une DLC (date limite de consommation) de 21 à 30 jours. Impact du produit : un produit innovant qui valorise la production agricole locale et nationale, en réduisant l’importation de la matière première et surtout qui remplit les verres du consommateur des bienfaits nutritionnels des fruits frais. Utilisateurs potentiels : Enfants, nourrissons, personnes âgées, femmes enceintes.
    Le Salon National de la valorisation des résultats de la recherche des PNR • 8-9 Avril 2014 • Palais des Conventions, Oran, Algérie, Oran (Algérie); 04/2014
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    ABSTRACT: The aim of the present study was to assess the effects of sorghum bioprocessing into Gowè on iron bioavailability and antioxidant properties of the final products. Gowé is an African sour beverage whose process combines malting and fermenting of sorghum grains. The effects of the durations of germination and fermentation on the phytochemicals were evaluated using a central composite design. The antioxidant capacity and iron bioavailability of the derived flour were also evaluated. During the germination process, the tannin content of the grain decreased from 429.5 to 174.1 mg/100 g DM, while the total phenolic content increased from 300.3 to 371.5 mg GAE/100 g DM. The phenolic acid contents of the flour were significantly modified as a result of the durations of germination and fermentation. Both germination and fermentation enhanced the antioxidant capacity of sorghum flour and antioxidant characteristics were significantly correlated with the levels of total phenolics, tannins and phenolic acids. Phytate content of sorghum grain decreased drastically from 1003 to 369.1 mg/100 g DM when the duration of germination or fermentation increased. This was associated with an increase in the bioavailability of iron.
    Journal of Agricultural and Food Chemistry 02/2013; · 2.91 Impact Factor
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    ABSTRACT: Carotenoids are compounds synthesized in plants, bacteria and fungi, closely associated to the chlorophyll to perform photosynthesis. A spectacular evolutionary achievement allowed the aphid to produce carotenoids obviously by lateral transfer of genes from fungi. We have recently documented that these molecules are involved in photo conditioning of metabolism such ATP synthesis in this insect model. The carotenoid synthesis in aphid was directly determined in living insects without extraction procedure by Raman imaging technique and the analysis was compared between insects raised in distinct environments. In contrast with the Raman spectrum that provides information on molecular motifs recognition (conjugated double bonds) but does not discriminate between isomers and ester forms, the mass spectrometry technology allowed us to analyze finely the variations in carotenoid composition. In parallel to these spectral analysis and chemistry determination, series of dosage of ATP were performed in order to correlate carotenoid synthesis and metabolism in aphid.
    PROTOCOL EXCHANGE. 10/2012;
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    ABSTRACT: A singular adaptive phenotype of a parthenogenetic insect species (Acyrthosiphon pisum) was selected in cold conditions and is characterized by a remarkable apparition of a greenish colour. The aphid pigments involve carotenoid genes well defined in chloroplasts and cyanobacteria and amazingly present in the aphid genome, likely by lateral transfer during evolution. The abundant carotenoid synthesis in aphids suggests strongly that a major and unknown physiological role is related to these compounds beyond their canonical anti-oxidant properties. We report here that the capture of light energy in living aphids results in the photo induced electron transfer from excited chromophores to acceptor molecules. The redox potentials of molecules involved in this process would be compatible with the reduction of the NAD+ coenzyme. This appears as an archaic photosynthetic system consisting of photo-emitted electrons that are in fine funnelled into the mitochondrial reducing power in order to synthesize ATP molecules.
    Scientific Reports 01/2012; 2:579. · 5.08 Impact Factor
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    Séminaire d’Echange International Aux Interfaces du Développement Durable; 06/2011
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    ABSTRACT: Noni fruit (Morinda citrifolia L.) juice has been used for more than 2000 years in Polynesia as a traditional folk medicine. The aim of the present study was to finely characterize noni juice from Costa Rica and to evaluate its anti-oxidative and anti-inflammatory activities. A microfiltrated noni juice was prepared with Costarican nonis. HPLC-DAD and Electro Spray Ionization Mass Spectrometric detection (HPLC-ESI-MS) were used to identify phenolic compounds and iridoids. The anti-oxidative activity of noni juice was measured in vitro by both Oxygen Radical Absorbance Capacity (ORAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging methods. The anti-inflammatory effects of noni juice were investigated in vitro by: measuring its effect on nitric oxide and prostaglandin E2 production by activated macrophages, evaluating its inhibitory activities on cyclooxygenase (COX)-1 and -2 and in vivo on a carrageenan-induced paw oedema model in rats. Several polyphenols belonging to the coumarin, flavonoid and phenolic acid groups, and two iridoids were identified. Noni juice demonstrated a mean range free radical scavenging capacity. Furthermore, it also reduced carrageenan-induced paw oedema, directly inhibited cyclooxygenase COX-1 and COX-2 activities and inhibited the production of nitric oxide (NO) and prostaglandins E(2) (PGE(2)) in activated J774 cells, in a dose dependent manner. This study showed that noni's biological effects include: (1) anti-oxidant properties probably associated with phenolic compounds, iridoids and ascorbic acid and (2) anti-inflammatory action through NO and PGE(2) pathways that might also be strengthened by anti-oxidant effects.
    Journal of ethnopharmacology 01/2011; 133(1):108-15. · 2.32 Impact Factor
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    ABSTRACT: Free and glycosidically bound volatiles of purees from Andean blackberry (Rubus Glaucus Benth.) fruit were determined. Free volatile compounds were extracted by two techniques: solvent extraction and Solid-Phase Micro-Extraction (SPME). The glycosidically bound volatiles were isolated using Solid Phase Extraction (SPE) technique. The analysis of free volatiles and enzymatically released aglycons were performed by GC-MS. Fifty five volatile compounds were identified and quantified from solvent extraction. The major class was the carboxylic acids (68.8%), dominated by palmitic acid (16.8%) and benzoic acid (15.0%). Alcohols were highly represented (23.4%), with 2-heptanol (10.6%) and terpinen-4-ol (5.7%) being prevalent compounds of this class. Using HS-SPME, among the seventy-one identified compounds, alcohols (47.3%) including 2-heptanol (17.9%) and terpinen-4-ol (20.0%), and esters (39.8%) with ethyl and methyl benzoate (33.9 and 3.8% respectively) were the two predominant classes. β-damascenone, a potent flavour compound was detected using SPME method. Fifty-three aglycons were identified, acids (57.4%), norisoprenoids (15.4%), terpenic alcohols (10.3%) and some aliphatic and shikimic alcohols (15.0%) predominated in the glycosidically bound fraction. Acetylenic precursors of β-damascenone were present at noticeable level in the glycosidic fraction.
    Food Research International. 01/2011;
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    ABSTRACT: Tropical highland blackberry (Rubus adenotrichus Schltdl.) is a good source of antioxidants and contains appreciable levels of phenolic compounds, mainly ellagitannins and anthocyanins. This study examined the influence of three ripening stages on phenolic contents. Major anthocyanin pigments increased from 0.20 (red fruit) to 1.34 mg g−1 fresh weight (FW) (fully ripe fruit), whereas ellagitannins and ellagic acid derivatives dropped from 3.8 to 2.2 mg ellagic acid equivalents g−1 (FW). Flavonols also dropped from 5.1 to 2.0 mg quercetin equivalents 100 g−1 (FW). Consequently, values for total phenolic compounds ranged from 5.8 to 5.2 mg gallic acid equivalents g−1 (FW), showing no specific trend. Antioxidant activity (H-ORAC) increased from 38.29 to 64.00 μmol of Trolox equivalents g−1 (FW) during ripening. When compared with other commercial cultivars, R. adenotrichus stands out for high H-ORAC value, although comparatively it possesses low anthocyanin content and average total phenolic content.
    Food Chemistry. 01/2010;
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    ABSTRACT: The carotenoids from yellow tamarillo were determined by high-performance liquid chromatography-photodiode array detection/mass spectrometry (HPLC-PDA/MS). Xanthophylls were found as esterified with palmitic and myristic acids. All-trans-β-cryptoxanthin esters and all-trans-β-carotene were the major carotenoids of tamarillo. Changes in carotenoid and vitamin C contents after thermal pasteurization of degassed and not degassed tomato tree nectars were studied. Zeaxanthin esters appeared to be the less thermo-labile carotenoids. Carotenoids degradation was not significantly influenced by dissolved oxygen level. However, thermal treatment induced 5,8-epoxidation and cis-isomerization. Retention of ascorbic acid was total under degassed conditions while losses of dehydroascorbic acid were not affected by the initial level of dissolved oxygen.
    Food Chemistry. 01/2010;
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    ABSTRACT: Major compounds (i.e. phenolic compounds and carotenoids) were analysed in the extracts of the edible part of three tropical fruits: the Andean blackberry, the naranjilla and the tree tomato. Ellagitannins and anthocyanins were predominant in blackberries and phenolic composition can be used to differentiate the two species studied. Similar phenolic composition occurred in red and yellow tree tomato except for anthocyanins which were absent in the yellow tree tomato. Phenolic acids were detected in the naranjilla pulp. Carotenoids were analysed in the fruits. The composition in carotenoids was similar in the two varieties of tree tomato and their vitamin A activity was calculated. Carotenol fatty acid esters were predominant. β-Cryptoxanthin esters and β-carotene were the major carotenoids. The carotenoid content was high compared to literature data, providing an important high vitamin A activity. In blackberries and naranjilla, this class of compounds was found only at trace level. Finally, ORAC values were estimated in different solvent extracts and results were compared with published data in common fruits.
    Journal of Food Composition and Analysis. 01/2009;
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    ABSTRACT: High-performance liquid chromatography with diode array (LC-DAD) and electrospray ionization mass spectrometric detection (ESI-MS) was used to analyze phenolic compounds of two blackberry species ( Rubus glaucus Benth. and Rubus adenotrichus Schlech.) growing in South America. UV-visible spectrophotometry was a valuable tool for identifying the class of phenolic compound, whereas MS and MS ( n ) fragmentation data were useful for their structural characterization. Ellagitannins were the major compounds, with sanguiin H-6 and lambertianin C being the predominant ones. The anthocyanin composition as well as the presence or absence of kaempferol glycosides can be used to distinguish the Rubus species studied. Flavonol hexoside-malonates were identified in both berries. Hydroxycinnamic acids were minor compounds and found as ferulic, caffeic, and p-coumaric acid esters. Similar contents were obtained by analysis of soluble ellagitannins and ellagic acid glycosides as ellagic acid equivalents and by analysis of ellagic acid equivalents released after acid hydrolysis.
    Journal of Agricultural and Food Chemistry 11/2007; 55(21):8616-24. · 2.91 Impact Factor