César Kapseu

Extraction and purification of beta-amylase from stems of Abrus precatorius by three phase partitioning

The stems of Abrus precatorius were used to extract a beta-amylase enriched fraction. A three phase partitioning method and a Doehlert design with 3 variables (ratio of crude extract/t-butanol, the ammonium sulphate saturation and pH) were used. The data was fitted in a second-order polynomial model and the parameters were optimized to enrich beta-amylase. Experimental responses for the modulation were recovery of activity and the purification factor. The optimal conditions were: a ratio of crude extract/t-butanol of 0.87 (v/v), saturation in ammonium sulphate of 49.46% (w/v) and a pH of 5.2. An activity recovery of 156.2% and a purification factor of 10.17 were found. The enriched enzyme was identified as a beta-amylase and its molecular weight was 60.1kDa. Km and Vmax values were 79.37mg/ml and 5.13U/ml, respectively and the highest activity was registered at a temperature of 70°C and a pH between 6 and 6.5. A significant stabilization of the beta-amylase was observed up to 65°C.

Etude des conditions d’extraction de l’huile par pressage des amandes de Ricinodendron heudelotii (Bail.) Pierre ex Pax

Resume Les conditions d’extraction de l’huile par pressage des amandes de Ricinodendron heudelotii (Bail.) apres fragilisation ont ete realisees. La fragilisation des amandes est faite par voie humide et par voie seche a diverses temperatures (50, 70 et 90 °C) et a des temps de sejour variables (5, 10, 15, 20, 30 et 60 min). Les resultats montrent que le pretraitement a 90 °C pendant 60 min donne la plus grande friabilite aussi bien par voie seche que par voie humide soient 60,86% et 58,13% respectivement. Le chauffage et le broyage des amandes ameliorent de maniere significative (p

Variation of the Physical Properties of Sheanut (Vitellaria Paradoxa Gaertn.) Kernels during Convective Drying

The effect of moisture content and drying temperature of Vitellaria paradoxa Gaertn kernels on some of its physical properties was investigated. The kernels which were harvested at a moisture content of about 60% (wet basis) and hence prone to high post harvest losses from two ecological zones of Cameroon (Bangoua in West province and Tchabal in Adamawa province) were dried in a forced convection dryer at 40oC, for 6, 20, 48, 72 and 96 hours to give moisture contents ranging from 10 to 60% wet basis. Ten trees from each of the zones were carefully selected to serve as sources for the ripe kernel bearing shea fruits that were used as samples for this study. For each parameter studied, a sample population of 30 kernels selected at random per tree was used. The results obtained revealed that there was a significant difference in the physical properties of the kernels from different trees irrespective of the locality. The bulk density, true density, sphericity and porosity varied non-linearly with the moisture content. Kernels with larger masses showed a different variation pattern of bulk density and porosity with moisture content compared to the lighter kernels. The variation of the bulk density, sphericity, porosity of sheanut kernels with moisture content and temperature was satisfactorily modelled with empirical equations. The samples underwent considerable shrinkage (up to 35%) during the drying process. Three empirical models were used to describe the shrinkage behaviour of the kernels and it is proposed that these models could be incorporated in drying models.

FATTY ACIDS AND TRIGLYCERIDES OF Canarium schweinfurtthii Engl. FRUIT

ABSTRACT The present paper reports data on the fatty acids of Canarium schweinfurtthii Engl, as well as triglyceride and unsaponifiable matter content of fruit pulp. This fruit is consumed as such or after cooking in hot water by some cameroonian populations. Qualitatively, the pulp, shell, membrane and kernel contain predominantly (more than 96%) the same seven fatty acids. However, the content of each fatty acid varies between the different parts. Pulp oil is mainly composed in decreasing order of palmitic, oleic and linoleic acids. Shell oil is rich in stearic acid (20%) and in addition contains non negligible amounts of lauric and myristic acids; the principal fatty acids are palmitic, oleic, stearic and linoleic acids. The principal fatty acids of membrane and kernel oils are oleic, linoleic and palmitic acids. Membrane oil contains a high proportion of linoleic acid whereas kernel has a greater percentage of oleic acid. Pulp oil contains 14 triglycerides of which 4 account for more than 70%, namely:...

Analysis of cottonseed oil and its fractions by differential scanning calorimetry

Abstract This siudy yielded thermograms for cottonseed oil between 25 and 110 °C and quantified the variation of the enthalpy and specific heat versus temperature of this oil and its fractions. The method used differential scanning calorimetric analysis. The enthalpy is a linear function of temperature while the specific heat of the cottonseed oil and its fractions varies very little between 25 and 110 °C. This work showed that the thermodynamic properties of the solid and liquid fractions are similar over the range of temperature covered.

Etude comparative du ramollissement des fruits de l’aiélé (Canarium schweinfurthii Engl.) par voie humide et par voie sèche

Abstract A comparative study of the softening of aiele ( Canarium schweinfurthii Engl.) fruits collected from five different locations in Cameroon have been carried out. The fruits were processed in water at 45 °C during 10–60 min, or in a dryer directly on grills, or in the dryer in opened or closed glass jars at 45 °C. Physicochemical characteristics were investigated during the softening. The optimum softening times varied between 40 and 60 min with 80–100% of the fruits softened into water or by direct drying. 120 min were necessary to obtain 60–100% of softened fruits in closed or opened jars. The softening rate (% of softened fruits per minute) exhibited a maximum that was observed after 30 and 60 min at 45 °C in water or in the dried methods respectively. Depending from the locations, losses in weight of fruits varied from 0.56% to 1.62% by direct drying, from 1.96% to 4.76% in opened jars, and from 0.04% to 0.58% in closed jars. Contrary, fruits softened in water showed a gain of weight of the fruit pulp varying between 1.30% and 3.21%. There was no significant difference between the total lipids, iodine and acid values of oils obtained by solvent extraction from crude and softened fruits.

Contribution à la réduction des pertes à la sucrerie — Raffinerie de canne

Abstract The production of sugar from cane involves losses, mainly at the crystallisation stage. This study aims at reducing them. The analysis of the products which circulate, and the setting of the preservation equations helps to establish the mass-balance of the process. It appears that losses are found in the molasses, the bagasses and the foams. This study shows that the devices and stages at which more losses are incurred are, in decreasing order of importance: refinery, A jet, purifying and C jet. Solutions are proposed to reduce these losses.

Ethno-Botanical data on KAPOK (Ceiba pentandraGaertn.), MAHOGANY (Khaya senegalensis), and NEEM (Azadirachta indica A. Juss.) from the Far-North Region of Cameroon

In this study, questionnaires were used in the Extreme North Region of Cameroon in order to gather information on the oilseeds Ceiba, Khaya and Azadirachta. These oilseeds are part of the biodiversity of the area and this paper brings more knowledge on the virtues of the tree as experienced by the local population. Data gathered here will serve much in the study and valorization of the oilseeds. Results of the inquiry show that Ceiba, Khaya and Azadirachta, have a wide range of medicinal uses and applications. Keywords— Azadirachta indica A. Juss., Ceiba pentandra Gaertn., Khaya senegalensis, oilseed,

Indirect solar drying kinetics of sheanut (Vitellaria Paradoxa Gaertn.) kernels

An indirect solar dryer was tested for drying sheanut kernels. The influence of tray distance from heat source, airspeed and particle size on drying kinetics was investigated. Optimum drying air parameters obtained in the dryer were airspeeds of 1 and 1.4 m/s and a temperature of 40°C–45°C. Sheanut kernel slices dried entirely in the falling rate period. Drying rate decreased with increase in particle size. The effect of particle size on the drying rate suggested that, the drying process was controlled by internal mass transfer mechanisms. Drying kinetics was modelled with characteristic drying curve and diffusive models. Effective moisture diffusivities of sheanut kernel slices calculated without shrinkage were greater than those calculated with the incorporation of shrinkage by a value of about 50%. Acid and peroxide values indicated that butter from the dryer could be classified either as Category 1 or 2 irrespective of the drying conditions to which the kernels were subjected.

Élaboration et caractérisation des sources solides de diffusion sur silicium par la méthode sol-gel pour la réalisation de l'émetteur d'une cellule solaire

Elaboration and characterization of solid diffusion sources on silicon wafers by solgel method for realization of a solar cell emittera presente etude a pour but de decrire les pecheries, les acteurs, les prises par unite d’effort, les captures et les productions de crabes nageurs Callinectes amnicola , De Rochebrune (Crustace - Decapode – Portunidae) du complexe lagunaire de Grand-Lahou. Pour ce faire, trois enqueteurs de terrain et deux enqueteurs superviseurs enregistraient quotidiennement les debarquements des crabes nageurs dans trois sites Tioko (2001 a 2003), Lauzoua et Lahou Pkanda (2006 a 2009). Trois types d’engins a savoir les balances, les nasses et les filets fixes a pieux sont utilises par 142 pecheurs dans le complexe lagunaire de Grand-Lahou pour pecher les crabes nageurs. Ces engins, dont les plus importants numeriquement sont les filets fixes et sont implantes principalement a Tioko dans la lagune de Mackey loin de la passe et capturent essentiellement les crabes femelles. Les deux autres engins ont ete introduits selon les temoignages des populations riveraines recemment et sont utilises dans les eaux calmes et les mangroves. La production des crabes nageurs a fortement baisse car elle est passee de 878 tonnes en 2006 a 852 tonnes en 2009 a cause de la pression exercee sur la ressource. Enfin, la production moyenne annuelle estimee a 823 tonnes /an est faible comparativement aux productions annuelles de la lagune Ebrie et de la lagune Aby et cela est lie a la forte pression exercee par la peche et la fermeture progressive de la passe qui influence directement le cycle hydrologique lagunaire et par ricochet le recrutement des crabes nageurs de la lagune de Grand-lahou. Mots-cles : crustaces, decapodes, portunidae, crabes nageurs, callinectes amnicola, lagune de Grand-Lahou, Cote d’Ivoire.