Geophagia: Benefits and potential toxicity to human—A review

Geophagy is the habit of consuming clay soil such as chalk or kaolin. Though it is globally practiced, the safety of those involved is yet to be fully established. It is thought to be highly prevalent in pregnant women because of its antinausea or therapeutic effects. This practice is also thought to be provoked by some nutritional needs, but in modern society its etiology is obscure. The mineralogical and chemical compositions of clay may vary from one region to another and even in all form of rocks clay constitutes. Published articles in geophagy indicate lack of adequate investigations into the toxicity of geophagy, though it is globally practiced and more prevalent in Africa (as a continent) or in Africans migrants. Some studies have helped to identify some minerals that are toxic to human if ingested. In most cases, the potential toxicity emphasized by these studies is based on the detection of the presence of these nuisance elements in the geophagic materials. Scientifically, a lot has been done in the light of detection of toxic matter, but more investigations on metabolic studies are still necessary. The variability of clay content with respect to source motivated this review on geophagy and its potential toxicity to human. This review is aimed at bringing out findings that would enable a better understanding of the toxicity potential of geophagy across context and taxa

Optimisation des paramètres de production et de conservation de la farine de Taro (Colocasia esculenta)

L étude de l optimisation des paramètres de production et de conservation de la farine de taro (Colocasia esculenta) a permis de mieux comprendre le processus cuisson des tubercules et de conservation des farines. Les études de cuisson des tubercules de six variétés ont montré que la variété Ibo coco est celle qui cuit vite eu égard à ses bonnes propriétés thermiques. La cuisson des tubercules dans l eau du robinet est la meilleure technique de cuisson comparativement aux cuissons, à la vapeur, dans les solutions acides de citron et de tamarin. Les études de détermination des conditions optimales de séchage et conservation de la farine de taro, en utilisant un vieillissement accéléré à 10 et 20 jours de stockage à 45C à des activité en eau de 0,07 ; 0,11 ; 0,23 ; 0,33 ; 0,53 ont permis de montrer que le vieillissement après 10 jours de stockage était suffisant pour les analyses. De plus l application du modèle BET lors des mesures des isothermes de sorption, a permis de déterminer les teneurs en eau mono moléculaires théorique et expérimentale. Les farines produites à la teneur en eau mono moléculaire, donnent une pâte ayant des caractéristiques texturales proches de celles de la pâte traditionnelle. Toutefois, la conservation de ces farines à différentes fractions particulaires (75, 150 et 250 m) montre que les petites fractions particulaires (75 m) absorbent plus vite de l eau que les autres fractions particulaires et sont de ce fait plus susceptibles à la détériorationStudy on optimization of production and storage parameters of the taro (Colocasia esculenta) flour permitted to better understanding the cooking process of taro tubers and storage of taro flours. Studies of cooking of six varieties of tubers showed that the variety Ibo coco had high rate of cooking, due to his good thermal properties. The cooking of tubers in the faucet water is the best technique of cooking compared to, steam cooking, lemon and tammarin cooking. Studies of determination of the optimal conditions of drying and storage of the taro flour, using an accelerated ageing to 10 and 20 days of storage at 45C to the activity in water of 0,07; 0,11; 0,23; 0,33; 0,53, showed that the ageing after 10 day of storage was sufficient for analyses. Besides the use of the BET model on sorption isotherms, permitted to obtain values of theorical and experimental monolayer water. Flours produced at this monolayer water, give dough with the textural characteristics near of those of traditional dough. However, the storage of these flours with different particle sizes (75, 150 and 250 m) shown that the small particle size (75 m) absorb water quickly than other flours, and they are more susceptible to the deteriorationNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Genotypic and phenotypic diversity among Bacillus species isolated from Mbuja, a Cameroonian traditional fermented condiment

Dichotomous keys based on morphological, cultural and biochemical tests have long been used to identify Bacillus species. The analysis of 16S rDNA is suggested to be used for identification that is more exact. The present study was carried out to compare a conventional phenotypic method with the analysis of the 16S rRNA and gyrB gene for better identification, to determine their phylogenetic relationships and to contribute to selecting starter cultures for Mbuja production. Twenty-six (26) Bacillus strains isolated from 12 samples of Mbuja formerly identified by phenotyping as representatives of eight species (licheniformis, polymyxa, laterosporus, cereus, circulans, subtilis, pumilus and brevis) were studied. Results of genotypic analyses were not concurrent with previous phenotypic identification. Bacillus from different species were able to cluster together to form phylogenetic groups. An insight of these groups revealed important genetic diversity between strains from the same species. Bacillus subtilis and close relatives were the most abundant and presented appreciable biochemical traits. This group could therefore be considered for starter selection.Keywords: Mbuja, Bacillus sp., phenotyping, genotyping, starterAfrican Journal of Biotechnology Vol. 12(12), pp. 1335-134