Caractérisation morphologique et sédimentologique de l’embouchure du fleuve Sassandra (Côte d’Ivoire)

L’embouchure du fleuve Sassandra n’est pas homogène au plan morphologique avec des profondeurs variant entre 0 et 8,5 m et qui diminuent de l’amont vers l’aval. Cependant, elles sont plus élevées au niveau des dépressions situées à proximité de la passe. Quelques roches granitiques y affleurent sous la forme de hauts fonds. Sur le plan sédimentologique, les sédiments sont constitués majoritairement de sables localisés dans les fonds de l’embouchure. Les vases s’accumulent essentiellement sur les bordures des bras. La granulométrie des sables met en évidence une prédominance de sables grossiers et de sables moyens. La quasi-totalité des sédiments de l’embouchure du fleuve Sassandra provient d’un environnement de type continental fluviatile. Une masse importante de sables se déplace par saltation. Le mode de transport des sables fins est dominé par le transport en suspension. Les sables moyens se déplacent essentiellement par saltation et le transport par charriage est le mode de transport dominant des sables grossiers. En définitive, cette étude a permis de réaliser les cartes bathymétriques et de répartition des sédiments, ainsi que la détermination de l’environnement de dépôts des sables.Mots-clés : morphologie, sédimentologie, bathymétrie, embouchure, Sassandra, Côte d’Ivoire

Biochemical characterization of juices from three wild fruit species consumed in Côte d’Ivoire "Adansonia digitata, Parkia biglobosa and Tamarindus indica"

In the context of the valorization and the development of local products in Côte d’Ivoire, this study is based on juices samples prepared from the pulp of wild fruits of Baobab (Adansonia digitata), Tomi (Tamarindus indica) and Néré (Parkia biglobosa). The physiochemical characteristics such as dry matter (desiccation, 105°C), mineral (spectrophotometer), ash, fat, fiber and protein (AOAC), Energy (coefficients), vitamins A & C (HPLC), organic acids & total polyphenols (HPLC), carbohydrate (by difference), pH and titratable acidity (titrimetry, NaOH) of pasteurized juices (75°C, 5 min) were investigated. Data showed that the juices have been characterized by low protein (0.21-0.28 %), fat (0.26-0.65 %) and ash (0.20-0.47 %) content and high level of total carbohydrates (21-30 %) and energy (85.83-124.43 Kcal/100mL). Baobab and Tomi juices were distinguished by their high acidity (103-159 meq.g / Kg) while Baobab and Néré juices were characterized by their average fiber content (4-5.30 %). The juices of Baobab, Tomi and Néré are very rich in some minerals (K and Mg) but calcium (Ca) and iron (Fe) are not bioavailable (Oxales/Ca and Oxalates/Fe > 2). The juice of baobab is rich in vit A (80 mg/100mL) and vit C (189 mg/100mL) than the others juices. Catechin was the most phenolic content (52.29-110.32 mg/100mL) where tartric acid was the most organic acid (4.02-6.82 mg/100mL) in the juices. The knowledge of the nutritional value of these juices could contribute to a better understanding of the essential role of these three wild fruits in terms of food and trade

Effect of glycerol, peanut oil and soybean lecithin contents on the properties of biodegradable film of improved cassava starches from Côte d’Ivoire

peer reviewedEdible films have been successfully used in the food packaging industry for several decades. Today natural polysaccharides, including cassava starch, are increasingly being used in the production of such biodegradable edible films and food packaging. In Côte d'Ivoire, there are improved cassava varieties whose starches have not yet been tested in the production of biodegradable films. In this study, the optical and mechanical properties and the water solubility of starchbased composite films of four improved cassava varieties with added glycerol, peanut oil and soy lecithin were determined. Starch was obtained by cold water extraction from native cassava from the varieties Bocou 1, Bocou 2, Yavo and TMS. Films preparation was made bycasting method with cassava, glycerol (25-30 %), peanut oil (5-10%) and soybean lecithin (0-5 %). Increasing the glycerol content, increased L*color value and elongation at break and decreased a*, b*, colourdifference (ΔE* ab) and tensiles trength of the composite films. Also, increasing the oil content from 5 to 10%, increased the opacity, b*, ΔE*ab, water solubility, elongation at break but decreased L*, a* and tensiles trength. Similarly, increasing the soy lecithin content from 0 to 5%, increased the opacity, L*, b* and ΔE*ab, but decreased a*, of the starch-based composite films. The results suggest an ideal formulation of 4% starch/25% glycerol/5% oil/5% soy lecithin for a film with optimum mechanical properties with low solubility

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

Effect of Edible Coating based on improved Cassava Starch on Post-Harvest quality of fresh Tomatoes (solanum lycopersicum l.)

peer reviewedComposite coatings based on improved cassava starch have the capacity to preserve the quality and extend the shelf life of fresh tomatoes. Two new edible composites coatings C1 (4% starch/25% glycerol/5% oil/5% soybean lecithin) and C2 (4% cassava starch/microcrystalline cellulose 30%/25% glycerol/5% oil/5% lecithin) were compared with the commercially available SemperfreshTM coating and no coating. Different coatings/no coating were applied to fresh tomatoes that were subsequently stored at 20 ± 2°C and 70 ± 2% relative humidity for 4 weeks. Tomatoes coated with the composite coatings C1 and C2 based on improved cassava starch showed a significant (P < 0.05) delay in changes of firmness, weight, titratable acidity, pH, total soluble solids, sugar/acidity ratio and colour development compared with both SemperfreshTM and uncoated control fruit. The results demonstrated that our assessed combination of improved cassava variety starch vegetable oil, glycerol, soy lecithin and cellulose and derivates can be used as edible coating to increase the shelf life of tomatoes stored at 20 ± 2°C up to four weeks

Stability of yam starch gels during processing

To evaluate their aptitude to be used as functional ingredients, twenty one varieties of yam starches of Côte d'Ivoire were submitted to different technological stress such as high temperature treatment, long term freezing and refrigeration, high speed shearing and acidic treatment, in comparison with commercial modified starches. The gel of "kangba " starch (D. Cayenensis-rotundata) is the most stable during thermal processing. The cultivar "Daminangba" (D. alata) which present the clearest gel (63 % of clarity) is also the most stable during refrigeration with a low syneresis (26%) at 4°C.The "Esculenta 7" cultivar (D. esculenta) shows the weakest value of syneresis at -20°C. The gel of D. dumetorum species is the strongest under acidic condition with 8% of viscosity decrease from pH 7 to pH 3, whereas the "Bodo " cultivar (D. alata) gel shows good resistance to shearing with 31% fall of viscosity from 160 rpm to 900 rpm on the RVA. The "Sopèrè", "Lopka" and Kponan cultivars (D. Cayenensis-rotundata) present the strongest viscosities in all the technological treatments