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Tomato is a nutrient-rich but highly perishable fruit. In order to delay the rapid ripening and degradation of fruits and reduce postharvest losses, response surface methodology (RSM) was used as the optimizing method to formulate edible coating based on pineapple peel extract and Arabic gum of twenty concentrations of pineapple (0.5–0.83 kg/l) and 20 concentrations of Arabic gum (5–15%, w/v). Tomatoes were soaked for 10–30 min in any of the coating solution. Five parameters including ripening rate, chlorophyll a content, firmness, total flavonoid content, and titratable acidity of tomatoes were evaluated after 8 days of storage at 24 ± 0.5°C and 82 ± 1.5% relative humidity. Results showed that the experimental data could be adequately fitted into a second-order polynomial model with coefficient of determination (R2) ranging from 0.775 to 0.976 for all the variables studied. The optimum concentrations were predicted as 0.70 kg/l pineapple peel extract and 17.04% with 18.72 min optimum time. Under these conditions, predicted values of response variables are as follows: ripening rate (RR) 40.75, chlorophyll a (Chl a) 8.11, firmness (Fir) 4.00, total flavonoid content (TFC) 43.51, and titratable acidity (TA) 0.30. It is concluded that RSM can be used to optimize pineapple peel extract and Arabic gum-based edible coating formulation to extend the shelf life or delay the ripening process of tomato fruit at ambient conditions.

The valorisation of the large scale production of bananas in the producing countries depends on the safeguarding of the quality during exports throughout the world. The objective of the present study was to extend the shelf life of bananas by elucidating some physical and physiological phenomena that accompany the ripening process. To achieve this, bananas were treated by soaking in solutions of tween 20 for 10 minutes and calcium chloride at 2, 4, 6 and 8% for 30 minutes. The following parameters were evaluated generally in the peel and pulp as a function of time during ripening: green life, firmness of bananas, water content, Brix index, pigments, antioxidant compounds such as ascorbic acid and flavonoids, activity of two enzymes, chlorophyllase and pectin-methylesterase. The green life was 25 days for bananas treated with tween 20 at 4% calcium chloride and almost 15 days for controls. Firmness was lower in bananas treated with tween 20 at 6 and 8% calcium chloride as well as in control bananas. While the Brix index was higher in the latter, photosynthetic pigment contents such as chlorophylls a and b were lower over time. Lycopene, β-carotene and ascorbic acid contents increased significantly during ripening. Flavonoid content in the skin varied less during the sampling period. However, a regression of the latter was noted in the pulp. The enzymatic activity of both chlorophyllase and pectin-methylesterase was increasing during the whole experiment. The effect of the treatments on the majority of the evaluated parameters was elucidated. Although it was not always statistically significant. The treatments with tween 20 at 2 and 4% calcium chloride were the best, certainly because of an adequate integration of calcium chloride in the tissues. On the other hand, the 6 and 8% treatments showed an unexpected result, similar to the control. The integration of a high calcium content would lead to a tearing of the tissues and consequently to a disorganisation of the membrane, resulting in a faster ripening.

Mango is one of the main fruits grown in Chad. However, it is prone to high post-harvest losses due to lack of adequate distribution networks, appropriate harvesting and conservation methods. The objective of this study was to test the effectiveness of coatings based on extracts of Allium sativum (garlic), Zingiber officinale (ginger) and Spirulina platensis (spirulina) on their conservation. Shelf life, weight loss, firmness, pH and total soluble solids content of mangoes were evaluated. The coated mangoes had excellent brillance compared to control mangoes. The coatings based on the extracts of A. sativum, S. platensis and Z. officinale increased respectively the means shelf life of mangoes to 18, 19 and 24 days. Weight losses were 21% for control mangoes while they were 13% for mangoes coated using mixture containing extracts of A. sativum and S. platensis and 11% for mangoes coated with Z. officinale. Coatings based on extracts of Z. officinale and S. platensis had statistically comparable effects on the firmness of mangoes but significantly higher than those of A. sativum extracts and controls after the 10th day. pH values and total soluble solids content (TSSC) values of control mangoes were significantly higher than those of coated mangoes. On day 10 after treatment, chlorophylls were absent from the peel of control mangoes whereas they were still present in the peel of coated mangoes. The mangoes coated with extract of Z. officinale reached a shelf life of 24 days. This shelf life was significantly higher than that of mangoes coated with other types of extracts and control mangoes. The coating with Z. officinale extract slowed considerably the ripening of mangoes. It can be recommended for conservation of mangoes in fresh.

Postharvest conservation of tomatoes is a major current challenge for growers and traders. Edible coatings constitute a pertinent alternative to existing conservation methods.; Results: Control tomatoes were fully ripe 3 days after harvesting, whereas fruits dipped in solutions containing extracts from cocoa pods (T1), cocoa leaves (T2) or coffee hulls (T3) reached full ripeness 14 days after treatment (DAT). Fruits treated by dipping in a solution containing an extract from coffee leaves (T4) were fully ripe 21 DAT. The visual assessment was confirmed by alterations in the level of chlorophyll a. Treatments induced a significant inhibition of chlorophyll a breakdown, especially during the first week after their application, T4 being the most efficacious. Weight loss increased significantly throughout the experimental period and was accelerated by treatments. Some quality-related parameters of ripe tomato fruits were in most cases not significantly influenced by treatments. In a few cases, however, there were improvements in quality traits of ripe fruits. On 21 DAT, T4 induced significant increases in levels of β-carotene and 6-methyl-3,5-heptadien-2-ol, whereas T2 led, especially, to higher levels of volatile compounds.; Conclusion: Edible coatings based on extracts from coffee or cocoa leaves induced improvements in the shelf life and quality of tomato fruits. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

Objectif: Le Tchad produit plus de 14 variétés de mangues, de caractéristiques physiques cependant peu connus. L’étude avait pour objectif de déterminer les caractères physiques de ces variétés de mangues afin de contribuer à leur vulgarisation et valorisation.Méthodologie et résultats: Les données physiques ont été collectées sur chaque fruit de mangue dans un échantillon constitué de 15 fruits mûrs d’une variété, récoltés sur trois manguiers dans un verger. L’ensemble des fruits ont été récoltés dans 12 vergers repartis dans les quatre régions d’étude. Cette étude a montré que les variétés de mangues Davis haden, Smith, Eldon, Kent et Coeur de Boeuf cultivées au Tchad et particulièrement dans la région du Logone Occidental avaient les meilleurs paramètres physiques notamment la masse, le volume, l’indice de calibre, la masse de la pulpe et le rendement de la pulpe. Par contre les variétés locales (Bangui, Kassaï et Mangotine) avaient les paramètres les plus modestes excepté la variété Maïduguri, qui est classée parmi les variétés moyennes avec José Tchad, Julie Kassawa, Keitt, Palmer et Valencia, mais toutefois avait la meilleure qualité commerciale (proportion de la pulpe : 83,26±2,36%). Les variétés locales avaient néanmoins une fermeté plus élevée (2,33±0,38 à 2,46±0,33) par rapport aux variétés améliorées (2,11±0,29 à 2,39±0,23). Toutes ces variétés de mangues étaient de forme allongée et avaient un poids spécifique proche de celui de l’eau à l’état mûr (0,99±0,01 à 1,12±1,02). Chez toutes ces variétés de mangue, une corrélation positive parfaite (r = 1) a été trouvée entre la masse de la mangue et la masse de la pulpe.Conclusions et applications des résultats: Il ressort de cette étude qu’il y a une importante variabilité des caractéristiques morphologiques et physiques entre les variétés et qu’ils sont milieu-dépendants. Les variétés améliorées se distinguent nettement des variétés locales par l’importance de ces paramètres. Les résultats obtenus permettraient d’apprécier les potentialités adaptatives des variétés de mangues et fourniraient des informations nécessaires aux différents acteurs de la filière mangue en vue de rationaliser le choix des variétés de mangues. Ils pourraient permettre notamment le tri des fruits mûrs des non mûrs car les fruits mûrs ont un poids spécifique proche de l’unité, donc flottable sur l’eau. Enfin, ces résultats montrent que la variabilité des paramètres étudiés résulterait d’une diversité fonctionnelle des mangues cultivées au Tchad.Mots clés: Variétés de mangues, caractères physiques, diversité fonctionnelle, Tchad et régions de cultureEnglish Title: Variability of physical characteristics of mangoes cultivated in Chad: characterization of the functional diversityEnglish AbstractObjective: Chad produces more than 14 varieties of mangoes; however, their physicals characteristics are little known. The aim of the study was to determine the physical characteristics of these varieties of mangoes in order to contribute to their popularization and valorization.Methodology and results: Physical data were collected from each mango fruit in a sample of 15 ripe fruits of one variety harvested from three mango trees in an orchard. All fruits were harvested from 12 orchards in the four study regions. This study showed that Davis haden, Smith, Eldon, Kent and Coeur de Boeuf mango varieties cultivated in Chad and particularly in the region of Logone Occidental had the best physical parameters including mass, volume, index of caliber, the mass of the pulp and the pulp yield. On the other hand, the local varieties (Bangui, Kassaï and Mangotine) had the most modest parameters except the variety Maïduguri, which is classified among the medium varieties group with José Tchad, Julie Kassawa, Keitt, Palmer and Valencia, but nevertheless possessed the best commercial quality (pulp proportion: 83.26 ± 2.36%). Local varieties had higher firmness (2.33 ± 0.38 to 2.46 ± 0.33) than improved varieties (2.11 ± 0.29 to 2.39 ± 0.23). All these varieties of mangoes grown in Chad were elongated and had at ripe stage a specific weight nearly to 1 (0.99 ± 0.01 to 1.12 ± 1.02). In all these varieties of mango, a perfect positive correlation (r = 1) was found between the mass of the mango and the mass of the pulp.Conclusions and applications of the results: This study showed that there is a great variability of morphological and phycical characteristics between varieties and that they are milieu-dependent. The improved varieties were clearly distinguishable from local varieties by the importance of morphological and physical parameters. The results obtained would allow an appreciation of the adaptive potential of mango varieties and provide the necessary informations to the various actors in the mango sector in order to rationalize the choice of mango varieties. They could in particular allow the sorting of mature and ripe fruits because the ripe fruits have a specific weight nearly to unit, therefore floatable on water. Finally, these results indicated that the variability of parameters studied could be a result of a funtional diversity of mango varieties cultivated in Chad.Keywords: Mango varieties, physical characters, functional diversity, Chad and cultivation regions

It is generally accepted that plastids play a major role in the synthesis of fatty acids. However, the degree of importance of the chloroplast integrity is not yet well established. In order to determine the effects of alterations in the chloroplast ultrastructure on this process Phaseolus aureus seedlings, species very sensitive to phase-shifts between light and temperature, were grown under control (12/12 h, 32/10 degrees C, light/dark) or inverse (12/12h, 10/32 degrees C, light/dark) conditions. Leaf sections were examined with an electron microscope and the fatty acid contents in the leaves and hypocotyls analyzed using a gas chromatograph. The electron microscopy of chloroplasts showed that unlike normal seedling leaves, there were few thylakoid membranes and no stacking of these membranes into grana occurred in the leaves of inverse seedlings. The levels of fatty acids in the leaves of normal seedlings (e.g., alpha-linolenic acid, 25 to 70 microg g(-1)) were always higher than those found in inverse seedling leaves (e.g., alpha-linolenic acid, 10 to 26 microg g(-1)). However, in leaves of both normal and inverse seedlings rhythmic fluctuations in the levels of fatty acids with 16 to 18 carbon atoms were observed. Furthermore, the fatty acid contents in hypocotyls of both types of seedlings were almost similar throughout the duration of the experiment. These results suggested that the high network density of thylakoid membranes and their stacking in places into grana are not prerequisites for the synthesis and/or conversion of fatty acids but would rather condition an optimal biogenesis rate and that light/dark cycles might be determinant factors in the induction of rhythmic fluctuations in fatty acid levels in plant leaves.

Plant genomes contain a vast number of oxygenase genes, but only very few have been functionally characterized. To devise an alternative method for the detection of novel oxygenase-catalysed reactions the effects of the cytochrome P450 oxygenase inhibitors 1-aminobenzotriazole (ABT) and tetcyclacis (TET) have been examined by metabolite profiling analysis in tomato fruit (Solanum lycopersicum). Treatment with TET resulted in significant increases in the levels of certain flavonoids, whereas ABT strongly inhibited their formation during fruit ripening. Injections of buffered solutions of ABT into tomato fruits led rather to an accumulation of 9,12,13-trihydroxy-10(E)-octadecenoic acid probably due to retarded metabolism of the hydroxylated acid, while TET completely repressed its formation. Peroxygenase, a hydroperoxide-dependent hydroxylase involved in the formation of the trihydroxy fatty acid, is strongly inhibited by TET (IC(50) 2.6 μM) as was demonstrated by studies with the recombinant tomato enzyme expressed in yeast. The data show that ABT and TET affect oxygenases differently in tomato fruit and reveal that these enzymes catalyse distinct reactions in different metabolic pathways, among which C(18)-trihydroxy fatty acid and flavonoid metabolism involve novel oxygenase-catalysed reactions. The method is suitable to identify potential substrates and products of ripening-related, putative oxygenases and can support functional analyses of recombinant enzymes.

Une enquete a ete menee au Tchad dans le but d’identifier les differentes varietes de mangues cultivees, leurs periodes de recolte, leurs methodes de culture et de conservation. Cette enquete par sondage a deux degres a ete menee selon une methode standard dans 300 exploitations d’arboriculture de mangues de quatre regions de la zone soudanienne. L’etude a permis d’identifier quatre varietes de mangue locale et dix varietes de mangue amelioree. Elle a aussi revele que plus de 95% de chefs de verger sont des hommes et 26% sont analphabetes. C’est une culture de type traditionnel et pluvial qui utilise les outils et le materiel rudimentaires. L’utilisation d’intrants chimiques est meconnue. La methode de recolte predominante consiste a cueillir les fruits matures a l’aide d’une perche terminee en crochet et cela provoque generalement l’abrasion ou le fendillement des fruits qui tombent. Ces fruits recoltes sont mis dans les sacs ou mis en tas et recouverts de paille ou de feuilles de manguiers en attendant leur murissement. Le sechage est peu repandu mais demeure la principale methode de conservation. Pour mieux produire, il est donc indispensable d’ameliorer les pratiques culturales, d’innover les methodes de recolte, de conservation, et de vulgariser les varietes ameliorees. Mots cles : Varietes de mangues, enquete, methodes culturales, methodes de recolte, methodes de conservation, Tchad.

Seedlings of Phaseolus aureus ROXB were grown under 12/12 h light/dark cycles with the light period at 32.5°C and darkness at 10°C (normal conditions N) or with light at 10°C and darkness at 32.5°C (inverse conditions, I). I-conditions affected the level of chlorophyll and carotenoids (very low), monogalactosyldiacylgycerol (low) and phosphatidylinositol (high) in the leaves. Leaves of I-seedlings showed a sharp and durable decline of relative water content during the low temperature phase. For the N-seedlings, loss of water was restricted to the end of this period. The loss of water was accompanied by visible symptoms of wilting at specific times of day. Although the pigment content remained nearly unchanged, ABA content of leaves of both N-and I-seedlings increased during water stress. Upon return to the warm period, ABA level continued to increase after the leaves had regained turgor, this ‘after stress’increase being more pronounced in the leaves of I-seedlings. Exogenous application of ABA induced a slight increase in the content of phospholipids in N- and I-leaves and a decrease in free fatty acids, whereas monogalactosyldiacylglycerol content was significantly reduced in N-leaves after application of ABA. Upon transfer of I-plants to 20°C for 12 h during the light period, pigment and chloroplastic lipid content increased rapidly whereas upon a further exposure to 10°C in light, pigments and especially monogalactosyldiacylglycerol were lost. The control of pigment and lipid metabolism and the role of ABA during chilling stress are discussed.