Simultaneous production of raw starch degrading highly thermostable a-amylase and lactic acid by Lactobacillus fermentum 04BBA19

The widely used thermostable amylases were produced long time ago from Bacillus genus. Although, lactic acid bacteria (LAB) fermentation presents several advantages including the reduction of growth of pathogenic microorganisms, no study has yet reported thermostable amylases from lactic acid bacteria. An amylolytic LAB, Lactobacillus fermentum (04BBA19) isolated from starchy wastes of a soil sample from the western region of Cameroon was studied for amylase and lactic acid production. The bacterium exhibited maximal amylase and lactic acid production at temperature of 45°C, and within pH range of 4.0 to 6.5. Upon the optimization of various environmental and cultural conditions the yield of amylase and lactic acid reached 732.3±0.4 U/ml and 53.2±0.7 g/L respectively in fermented broth after 48 h of culture. The enzyme was identified as α-amylase, with a very high thermostability revealed by the retention of 100% of original activity after pre-incubation for 30 min at 80°C. The stability was improved significantly with the addition of 0.1% (w/v) CaCl2.2H2O; the half life of the enzyme in these conditions was 6 h at 80°C. Owing to its aptitude to exhibit a simultaneous production of thermostable amylase and lactic acid, L. fermentum (04BBA19) appeared as a potential candidate for the making of high density gruel from starchy material.Key words: Lactic acid bacteria, thermostable a-amylase, lactic acid, fermentation, high density gruel

Parameters influencing the size of chitosan-TPP nano- and microparticles

Chitosan nanoparticles, produced by ionic gelation, are among the most intensely studied nanosystems for drug delivery. However, a lack of inter-laboratory reproducibility and a poor physicochemical understanding of the process of particle formation have been slowing their potential market applications. To address these shortcomings, the current study presents a systematic analysis of the main polymer factors affecting the nanoparticle formation driven by an initial screening using systematic statistical Design of Experiments (DoE). In summary, we found that for a given chitosan to TPP molar ratio, the average hydrodynamic diameter of the particles formed is strongly dependent on the initial chitosan concentration. The degree of acetylation of the chitosan was found to be the second most important factor involved in the system's ability to form particles. Interestingly, viscosimetry studies indicated that the particle formation and the average hydrodynamic diameter of the particles formed were highly dependent on the presence or absence of salts in the medium. In conclusion, we found that by controlling two simple factors of the polymer solution, namely its initial concentration and its solvent environment, it is feasible to control in a reproducible manner the production and characteristics of chitosan particles ranging in size from nano- to micrometres

Partial purification and characterization of alpha-amylases from Abrus precatorius, Burnatia enneandra and Cadaba farinosa

Leaves of Abrus precatorius, tubers of Burnatia enneandra and stems of Cadaba farinosa are used in savannah regions of Cameroon in traditional food processing, particularly in sweetening and liquefaction of gruels. α-amylase was extracted and partially purified from these plants using conventional methods of protein purification including ammonium sulfate fractionation and two steps of gel filtration. Purification achieved 58, 61 and 46 fold respectively for A. precatorius, B. enneandra and C. farinosa. The purified enzymes were then characterized in terms of molecular weight, optimum pH and stability, optimum temperature and stability, Km, Vmax and metals ions effects. The optimum pH of enzymes varied from 6.0 for amylases from B. enneandra and C. farinosa, to 7.0 for amylase from A. precatorius; while the optimum temperature was 60°C for amylases from A. precatorius and B. enneandra, and 65°c for amylase from C. farinosa. The three enzymes displayed, respectively for A. precatorius, B enneandra and C farinosa, a molecular weight of 60, 65 and 48.5 kDa, Km for hydrolyzing soluble starch of 3.25, 1.81 and 3.18 mg/ml, and strong individual activation by Ca2+, Co2+ and Fe3+. Li2+ appeared as a common activator for all the amylases, while Ag+, Hg2 +, Zn2+ and Cu2+ act as common inhibitors

Valorisation of crude earth as sustainable building material: a case of international cooperation in the Logone Valley (Chad-Cameroon)

Deforestation is one of the most dramatic threats to environmental equilibrium and food safety in many regions of the world, and particularly in sub-Saharan Africa. It is enhanced by many kinds of human activities, among which is the earth brick-firing process that needs large amounts of wood for attaining and maintaining temperatures required during this process. In order to reduce deforestation, the present study investigated from different points of view the potential of crude earth to be used as building material, taking as a case study the Logone Valley located at the border between Chad and Cameroon. First, an on-site investigation was made to verify the state-of-the-art of brick production technologies and to evaluate their impact on the environment. Subsequently, morphological and geotechnical analyses on soil samples collected from different sites of the Logone Valley were carried out, to evaluate their suitability to brick production. Finally, a pilot plant for crude earthen brick production was set, particularly based on a new press designed for this purpose

Séchage des amandes de karité et qualité du beurre: impact du séchage traditionnel au soleil

Drying of Shea Kernels and Butter Quality: Impact of Traditional Sun Drying. The objective of this study was to determine the effect of the conditions of direct sun exposure of the kernels from Butyrospermum parkii (shea) on the quality of the butter and to define the best conditions of drying. The influence of the thickness of kernels and of time was determined, according to the central composite experimental design, in comparison with the extraction yield, the acid and peroxide values, the melting properties and the composition of unsaponifiable matter of butter. The maximum butter yield is obtained with kernels content 10 to 15% of residual water. The cutting up of kernels makes easier the vaporizing of water but, also increases acidity and reduces contents of unsaponifiable, triterpenic alcohols and sterols successive in an increase of interface between enzymes and molecules. While, a long exposure is favourable to the appearance of peroxides which destabilize not stable compounds with high melting point. So, an exposure during 5 - 8 days of kernels cut up in slices with more than 12 mm of thickness represents the best conditions of drying