MIB
Professeur
Activité scientifique
Profil chercheur
Enseignant-chercheur à l’Université de Yaoundé I. Grade : Professeur.
Publications scientifiques
Edzili Awono Antoine Thierry, Ifeanyi Famous Ossamulu, Maimuna A. Habib, Dogo Eustace, Hadiza Lami Muhammad, Jean Justin Essia Ngang et 1 autre(s)
Food Control
Nkoudou Ze Nardis, Ze Abada Loïc, B. Olivier, Jean Justin Essia Ngang
AGRIVITA Journal of Agricultural Science
<p>The global increase in cassava bacterial blight disease (CBB) caused by <em>Xanthomonas axonopodis</em> pv. <em>manihotis</em> (Xam) has been leading to the investigation of new strategies to tackle this problem. This study aimed to evaluate the antibacterial potential of 30 soil <em>Streptomyces</em> strains by initial screening against Xam, isolated from infected cassava leaves. The isolates demonstrating the strongest inhibitory effects were selected to extract their methanolic secondary metabolites following practical antibacterial biocontrol assessment. This was done by treating infected cassava plants with the methanolic extracts and monitoring for 14 days. The results showed that, among the 30 soil streptomyces strains, two isolates, encoded BEL_12 and KER_2, exhibited strong inhibitory effects. Their methanolic extracts showed inhibitory activity against Xam, with minimum inhibitory concentration (MIC) values of 32 µg/ml for BEL_12 and 2 µg/ml for KER_2. The CBB incidence on cassava leaves KER_2 and BEL_12 methanolic extracts was 24% and 88%, respectively. This study demonstrated the remarkable potential of Cameroonian soil <em>Streptomyces</em> spp. to produce bioactive compounds that suppress CBB and lay the basis for developing sustainable, eco-friendly biocontrol agents to reduce reliance on chemical pesticides in affected regions.</p>
Nardis Nkoudou Ze, Godwe Joel, Didier Olivier Bébiné Biédi, Bilkissou Njapndounké, Jean Justin Essia Ngang
SSRN Electronic Journal
Nardis Nkoudou Ze, Didier Olivier Bébiné Biédi, Jean Justin Essia Ngang
SSRN Electronic Journal
Didier Olivier Bébiné Biédi, Neisha BELINGA ATANGANA, Nardis Nkoudou Ze, Bilkissou Njapndounké, Eliane Flore EYENGA, Jean Justin Essia Ngang
SSRN Electronic Journal
Fabrice Ezo’o Mengo, Jean Paul Assam Assam, Sylvain Leroy Sado Kamdem, Jean Justin Essia Ngang
American journal of microbiological research
Introduction: In Cameroon, many medicinal plants are used to treat typhoid fever. However, studies have shown that some of these plants can induce resistance to antibiotics used against Salmonella Typhi (S. Typhi). The mechanisms by which this resistance is acquired are not clear. This article aims to determine the mechanisms of antibiotic resistance acquisition in S. Typhi strains exposed to medicinal plant extracts. Methods: Two plant extracts, Enantia chlorantha and Irvingia gabonensis, were used to induce antibiotic resistance in S. Typhi. The antibiotics tested were: Ciprofloxacin, Amoxicillin, Chloramphenicol, Gentamicin, and Cotrimoxazole. Five genes were searched for by PCR in the genome of S. Typhi samples obtained after exposure to plant extracts. These were: blaTEM and blaSHV, coding for resistance to β-lactam antibiotics; sul1, coding for resistance to sulfonamides; floR, coding for resistance to phenicols; and int1, coding for resistance to multiple antibiotics. Results: The results demonstrated that, S. Typhi exposed to the plant extracts Enantia chlorantha and Irvingia gabonensis exhibited the presence of genes sul1, floR, and int1. However, the absence of these genes in the unexposed control strain indicated that plant extracts are able to induce antibiotic resistance through genetic mutation. The blaSHV gene was not detected in any of the S. Typhi samples, in contrast to the blaTEM gene, which was present in all samples, including the control. Conclusion: Mechanisms other than genetic mutations need to be assessed to better understand how medicinal plants induce antibiotic resistance.
Michel Arnaud Mbock, Raceline Gounoue Kamkumo, Rohit Shukla, William Feudjou Fouatio, Patrick Valère Tsouh Fokou, Florence Tsofack Ngueguim et 10 autre(s)
Journal of Ethnopharmacology
Patrice Bonny, Julien Schaeffer, Alban Besnard, Marion Desdouits, Jean Justin Essia Ngang, Françoise S. Le Guyader
Frontiers in Microbiology
Many recent pandemics have been recognized as zoonotic viral diseases. While their origins remain frequently unknown, environmental contamination may play an important role in emergence. Thus, being able to describe the viral diversity in environmental samples contributes to understand the key issues in zoonotic transmission. This work describes the use of a metagenomic approach to assess the diversity of eukaryotic RNA viruses in river clams and identify sequences from human or potentially zoonotic viruses. Clam samples collected over 2years were first screened for the presence of norovirus to verify human contamination. Selected samples were analyzed using metagenomics, including a capture of sequences from viral families infecting vertebrates (VirCapSeq-VERT) before Illumina NovaSeq sequencing. The bioinformatics analysis included pooling of data from triplicates, quality filtering, elimination of bacterial and host sequences, and a deduplication step before de novo assembly. After taxonomic assignment, the viral fraction represented 0.8–15% of reads with most sequences (68–87%) remaining un-assigned. Yet, several mammalian RNA viruses were identified. Contigs identified as belonging to the Astroviridae were the most abundant, with some nearly complete genomes of bastrovirus identified. Picobirnaviridae sequences were related to strains infecting bats, and few others to strains infecting humans or other hosts. Hepeviridae sequences were mostly related to strains detected in sponge samples but also strains from swine samples. For Caliciviridae and Picornaviridae , most of identified sequences were related to strains infecting bats, with few sequences close to human norovirus, picornavirus, and genogroup V hepatitis A virus. Despite a need to improve the sensitivity of our method, this study describes a large diversity of RNA virus sequences from clam samples. To describe all viral contaminants in this type of food, and being able to identify the host infected by viral sequences detected, may help to understand some zoonotic transmission events and alert health authorities of possible emergence.
Tchikoua Roger, A T Edzili Awono, SANDRINE AIMÉE YOUTE FANCHE, Jean Justin Essia Ngang
Journal of Microbiology Research
Uncontrolled fermentation is a method of transformation which can expose food to risks of contamination by moulds and mycotoxins. Food contaminations represent a potential threat to the health of consumers. In the far North of Cameroun, Iassa obtained by spontaneous fermentation of Hibiscus sabdariffa grains belongs to this food category. This study was aimed at preserving the safety quality of Iassa against fungal growth during fermentation by using lactic acid bacteria (LAB). To carry out this work, moulds and LAB were first isolated from Iassa samples collected in the locality of Gamboura (Cameroon). This was followed by the production of Iassa at the laboratory which was inoculated with moulds and LAB, and the entire batch was left to ferment for 120 hours at 25°C. The antifungal activity of LAB and titratable acidity were evaluated during fermentation. The results showed that, Iassa is a favourable food to the development of moulds. High contamination of this product by moulds of the genus Aspergillus and Fusarium were observed. Generally, this contamination ranged from 2.9Log10CFU/g to 6.9Log10CFU/g. Among the isolated LAB, Lactobacillus brevis and Lactobacillus paracasei were identified as the best LAB with good antifungal activity. Lactobacillusbrevisinhibited completely the growth of Aspergillus in Iassa after 96 hours of fermentation. During this assay, a high growth of Lactobacillus brevis varying between 12.0 and 13.3 Log10CFU/g was also observed. Unlike Lactobacillus brevis, Lactobacillus paracasei produced a high quantity of acidity evaluated at 0.9%. From this work, these bacteria can be used as a LAB starter to ensure safety of the Iassa against moulds after 96 hours of fermentation.
Abel Wade, Jenna E. Achenbach, Carmina Gallardo, Tirumala Bharani K. Settypalli, Souley Abdoulkadiri, Gaston Djonwe et 7 autre(s)
The Journal of Microbiology
African swine fever (ASF) is a highly lethal haemorrhagic disease in domestic and wild swine that has acquired great importance in sub-Saharan Africa since 1997. ASF was first reported in Cameroon in 1982 and was detected only in Southern Cameroon (South, West, East, Northwest, Southwest, Littoral, and Centre regions) until February 2010 when suspected ASF outbreaks were reported in the North and Far North regions. We investigated those outbreaks by analysing samples that were collected from sick pigs between 2010 and 2018. We confirmed 428 positive samples by ELISA and real-time PCR and molecularly characterized 48 representative isolates. All the identified virus isolates were classified as ASFV genotype I based on the partial B646L gene (C-terminal end of VP72 gene) and the full E183L gene encoding p54 protein analysis. Furthermore, analysis of the central variable region (CVR) within the B602L gene demonstrated that there were 3 different variants of ASFV genotype I, with 19, 20, and 21 tetrameric tandem repeat sequences (TRSs), that were involved in the 2010-2018 outbreaks in Cameroon. Among them, only variant A (19 TRSs) was identical to the Cam/82 isolate found in the country during the first outbreaks in 1981-1982. This study demonstrated that the three variants of ASFV isolates involved in these outbreaks were similar to those of neighbouring countries, suggesting a movement of ASFV strains across borders. Designing common control measures in affected regions and providing a compensation programme for farmers will help reduce the incidence and spread of this disease.
Fabrice Ezo’o Mengo, Stéphanie Claire Tchonang, Hermann Ludovic Kemaleu, Sylvain Leroy Sado Kamdem, Jean Justin Essia Ngang
Journal of Advances in Microbiology
International audience
Gislaine Aurelie Kemegne, Pierre Mkounga, Jean Justin Essia Ngang, Sylvain Leroy Sado Kamdem, Augustin Ephrem Nkengfack
BMC Microbiology
BACKGROUND: Antimicrobial activity of anthraquinone compounds of emodine type has been reported by many authors. These compounds are found in Vismia laurentii (Clusiaceae), a plant used in traditional pharmacopoeia for treatment of microbial infections among others affections. The continuous identification of new compounds has raised the problem of the relation between the structure and antimicrobial properties. RESULTS: The yeast growth kinetics parameters were not influenced by the pH variation as it was the case for the other tested bacteria. Fungicidal activities were noted for all molecules while only few of them had bactericidal activities, mostly on Gram positive bacteria. Mathematical model establishing a quantitative relationship between physicochemical properties of molecules and their fungicidal activities were obtained for Candida albicans and showed that physicochemical properties impacting on antifungal activity were polarizability, partition coefficient, molecular weight and hydrogen bond acceptor. CONCLUSIONS: This work demonstrated that the presence of a long aliphatic chain methoxy group substituted in position two of the emodine structure increased the antibacterial properties of the studied compounds. Moreover this antimicrobial property depends on the pH of the environment, and specifically on the polarizability and number of hydrogen bond acceptors of the compound.
Guillaume Legrand Ngolong Ngea, Fabienne Guillon, Jean Justin Essia Ngang, Estelle Bonnin, Brigitte Bouchet, Luc Saulnier
Food Chemistry
Nardis Nkoudou Ze, Sylvain Leroy Sado Kamdem, Hélène Agnia, Fabrice Mengo, Jean Justin Essia Ngang
British Journal of Applied Science & Technology
International audience
Sylvain Leroy Sado Kamdem, Blaise Kuate Kamga, Jean Justin Essia Ngang, François‐Xavier Etoa
Journal of Food Processing and Preservation
Process factors influencing the production of nonpasteurized mango slice preserves were studied. The initial dipping conditions, the composition of the storage syrup and the use of Citrus aurantifolia essential oil (CEO) as a preservative were taken into account. The results obtained by applying the response surface methodology permitted us to propose the combination of dipping time, citric acid and sugar percentages of the storage solution, which provided a 99% stability probability of the nonpasteurized preserves for 4 weeks. This achievement was further ameliorated by modifying the storage solution and including CEO. The best process factors increased the shelf life up to 6 months with associated dipping in a hot solution at 55C with storage solution composed of 2% citric acid, 1% ascorbic acid, 1% calcium chloride, 17.4% sugar and 1,000 ppm CEO. The adopted mild process factors could be a good strategy for nonthermal processed fruit products. Practical Applications Production of preserves is a technology widely used for the transformation of fruits. Pasteurization, which is a key unit in most of the current processes applied, is one of the reasons of consumer's rejection of the product in terms of organoleptic acceptance. The results of this work contributes to the understanding of factors affecting the stable production of mango preserves without pasteurization and gives indications on the replacement of synthetic preservatives with the use of Citrus aurantifolia essential oil while maintaining the shelf life of the product up to 6 months.
Jean Justin Essia Ngang, Maximilienne Ascension Nyegue, FOE C. NDOYE, ALEX D. TCHUENCHIEU KAMGAIN, Sylvain Leroy Sado Kamdem, Rosalba Lanciotti et 2 autre(s)
Journal of Food Protection
Blaise Pascal Bougnom, Onana Boyomo, D. Nwaga, Jean Justin Essia Ngang, F. X. Etoa
Sustainable development and biodiversity
Djoulde Roger DARMAN, Jean Justin Essia Ngang, F. X. Etoa
Notulae Botanicae Horti Agrobotanici Cluj-Napoca
This work aims at developing an alcoholic drink from water melon fruit in order to reabsorb the water melon surpluses and to reduce the pressure made on cereals (sorghum and corn) for the manufacture of artisanal alcoholic drinks. Antioxidant effect of polyphenols, was studied, total polyphenols, ethanol, methanol and total acids content of red water melon wines were determined and compared to a product used in human therapeutic; an extract of the Ginkgo biloba, one local sorghum beer, palm wine and few industrial wines. Results indicate that water melon based alcoholic drinks present an ethyl alcohol content varying from 8±1% to 13±1%, a total acidity from 1.2±0.1 g/l to 1.7±0.0 g/l. The newly produce water melon based wines present high content of polyphenols, and strong antioxidant capacity compare to the Ginkgo-biloba, sorghum beer and the tree other samples wines. A reasonable consumption of 240 ml/day of water melon wines represents a polyphenol contribution of 403 mg/day and an anti capacity oxidizing respectively of 4.25 or 2.4 mmol/day versus 0.18 mmol/day for the Ginkgo biloba extract.
Roger D Djoulde, François‐Xavier Etoa, Jean Justin Essia Ngang, C. M. F. Mbofung
Resume Les processus de transformation artisanale du manioc pour l’alimentation humaine passe dans la plupart des cas, par une etape de fermentation spontanee non controlee. Ceci a pour consequence une mauvaise qualite des derives. Afin d’ameliorer ces procedes artisanaux, et par la les qualites nutritionnelle, toxicologique et hygienique des derives du manioc consommes sous les tropiques, une centaine de microorganismes ont ete isoles des cossettes de manioc fermente, ceci dans l’optique d’elaborer un ferment destine a la fermentation du manioc. Parmi ces souches, 80% produisent des amylases; 66,66% de la linamarase; 26,6% de la pectinemethylesterase; 3,33% de la pectate lyase et 26,6% de la pectine lyase. La plupart des microorganismes ont indique des reelles potentialites a produire les enzymes importantes pour la bioconversion de la pulpe du manioc. Ces microorganismes ont ete selectionnes pour la mise au point d’un ferment de rouissage du manioc. Summary Screening for Properties of some Strains of Lactobacilli with Potentials Applications as Starter Culture for Cassava Fermentation
Léopold Ngoune Tatsadjieu, Jean Justin Essia Ngang, M.B. Ngassoum, F. X. Etoa
Fitoterapia
Jean Justin Essia Ngang, E. Wolniewicz, F. Letourneau, Pierre Villa
Biotechnology Letters
E. Wolniewicz, Jean Justin Essia Ngang, F. Letourneau, Pierre Villa
Biotechnology Letters
Jean Justin Essia Ngang, F. Letourneau, E. Wolniewicz, Pierre Villa
Applied Microbiology and Biotechnology
Jean Justin Essia Ngang, F. Letourneau, Pierre Villa
Applied Microbiology and Biotechnology
Michel Arnaud Mbock, Raceline Gounoue Kamkumo, Naveed Iqbal, William Feudjou Fouatio, Rohit Shukla, Anshuman Chandra et 12 autre(s)
Fitoterapia
Since the last decades, Detarium microcarpum have been used and studied due to the significant properties to threat various ailments. It is therefore crucial to ascertain the safety properties of is phytoconstituents. The present study was taken up to investigate the oral acute toxicity, 28 days repeated oral sub-acute toxicity study of D. microcarpum root bark extract in Albino Wistar rats, molecular docking, and molecular dynamic simulation. Based on acute oral toxicity, the LD 50 value of the extract was considered “non-toxic” up to a 5000 mg/kg b.w. The regular administration of the extract post 28-day treatment was also qualified as safe based on the body and organ weight, hematological, biochemical, and histopathological results in the sub-acute toxicity assay. The majority of the previous identified and isolated compounds passed the ADMET analysis, and the molecular docking identified 1,7-dihydroxy-6-methylxanthone (15) as the top one candidate with an effective binding affinity of −8.1, and − 7.5 (kcal/mol), for P450 and UGT2B7 proteins respectively. This compound was then further assessed using MD simulation, which verified the molecules' stability and binding to the targeted protein. Collectively these data build the foundation of support demonstrating that D. microcarpum root bark extract could be considered as a promising medicinal drug and concluded its suitable used for pharmacological purposes.
Patrice Bonny, Owade Ombaka Joshua, Kizito Nishimwe, Tlaleo Azael Marole, Rose Omari, Jean Justin Essia Ngang
Elsevier eBooks
Renaud Blanchard Okamba Elouti, Tchikoua Roger, Nardis Nkoudou Ze, Jean Justin Essia Ngang
International Food Research Journal
Cheese is obtained by the coagulation of milk, followed by maturation under the action of microorganisms which are responsible for the development of physicochemical and organoleptic characteristics of cheese. Among various microorganisms, lactic acid bacteria (LAB) play an essential role in establishing sensory characteristics of the cheese. In Cameroon, the effect of isolated LAB on the sensory characteristics of cheese produced from local cow milk has not yet been investigated. Therefore, the present work aimed to isolate LAB and evaluate their influence on the physicochemical and sensory characteristics of locally produced soft cheeses. Four strains of LAB were isolated and identified as Enterococcus sp.1, Enterococcus sp.2, Pediococcus sp., and Leuconostoc sp. These isolates were combined in batches for production of cheeses, including Frm 741 (Enterococcus sp.1 and Enterococcus sp.2), Frm 891 (Enterococcus sp.2 and Leuconostoc sp.), Frm 683 (Pediococcus sp. and Enterococcus sp.1), Frm 425 (Pediococcus sp. and Leuconostoc sp.), Frm 503 (Pediococcus sp. and Enterococcus sp.2), Frm 439 (Leuconostoc sp. and Enterococcus sp.1), and Frm 625 (Enterococcus sp.1, Enterococcus sp.2, Leuconostoc sp., and Pediococcus sp.). Cheese produced from the combination of Enterococcus sp.1 and Enterococcus sp.2 (Frm 741), unlike the others, did not drain properly throughout the production process. However, all products showed excellent microbiological quality in relation to biological contaminants, such as Salmonella, staphylococci, and coliforms. Moreover, cheese Frm 425 was most appreciated by consumers for its sweet taste, yellow colour, pleasant smell, and low acidity (51.7°D). On the other hand, cheese Frm 439 was least appreciated by consumers owing to its bad odour, bitter taste, and high acidity (144.9°D). Taken together, the present work demonstrated that the isolated LAB could be used to produce soft cheese with a natural rind and unique sensory characteristics that are appreciated by Cameroonian consumers.
R. Tchikoua, R. A. Nago Djoufack, Renaud Blanchard Okamba Elouti, Jean Justin Essia Ngang
Biotechnology Journal International
The changing of the diversity of lactic acid bacteria (LAB) from one locality and another is one of the main reasons of the organoleptic and physicochemical differences encountered in the same class of cheese. The objective of this work was to evaluate the influence of LAB isolated from cow's milk produced locally in Cameroon on the organoleptic and physicochemical quality of soft cheese with bloomy rind. To this effect, 05 LAB (IS1, IS2, IS3, IS4 and IS5) were isolated to fresh milk and selected after macroscopic, microscopic and biochemical characterizations. After tests of acidification, fermentation type, compatibility between LAB and LAB concentration on milk coagulation, the combined IS1-IS4-IS5 and IS2-IS3-IS5 were retained to produce 02 soft cheeses with bloomy rind namely respectively FROCAM 145 and FROCAM 235. When used at concentrations of 3×107 CFU/mL, these combined LAB coagulate fresh renneted milk after 3 hours at 26°C. During the production of FROCAM 145, the combined IS1-IS4-IS5 resulted in a firm, moist curd and a pH reduction of 14 and 15% respectively after the milk maturation and ripening of FROCAM 145. This cheese recorded 100% mould recovery, with protein, lipid and calcium content of 6.7, 62.2 and 0.1% respectively. On the other hand, during the production of FROCAM 235, the combined IS2-IS3-IS5 resulted in a dry and crumbly curd. The pH recorded with this combined LAB after maturation of the milk and ripening of FROCAM 235 is 12 and 17% respectively. The FROCAM 235 recorded a low mould recovery estimated at 20% and a protein, lipid and calcium content of 7.8, 65.1 and 0.3% respectively. From a microbiological point of view, FROCAM 145 and FROCAM 235 did not record any contamination by Listeria monocytogenes, Salmonella and Staphylococci. The sensory analysis shows that FROCAM 145 was more appreciated than FROCAM 235 with scores of 0.74 and 0.24 respectively. In view of these results, the IS1-IS4-IS5 combinations isolated from Cameroonian milks present a certain technological interest in the transformation of milk into cheese.
Gislaine Aurelie Kemegne, Aurore Vanessa Nana Ngahmi, Abraham Nkoue Tong, Sylvain Leroy Sado Kamdem, Jean Justin Essia Ngang
Microbiology Research Journal International
Aims: The aim of this study was to assess the in vitro antibacterial activity of selected antibiotics and essential oils alone or in combination, on selected presumptive probiotic lactic acid bacteria.
 Study Design: Experimental studies.
 Place and Duration of Study: Department of Microbiology of the University of Yaounde I between August 2017 and December 2017 (5 months).
 Methodology: The chemical composition of five essential oils was determined by gas chromatography coupled with Solid-phase micro extraction. Then the sensitivity of four lactic acid bacteria to the essential oils and four antibiotics was assessed by the well diffusion and macrodilution method. Subsequently, two essential oils active on these bacteria and broad spectrum antibiotics were combined according to the central composite design plan.
 Results: In general, the chemical composition of essential oils is very diverse, with the example of carvacrol found only in Origanum compactum at 53.24% and thymol in Thymus vulgaris at 56.19% and in Origanum compactum at 15.28%. The antibacterial activity shows that the majority of antibiotics used are active on the bacteria in the study compared to the essential oils where two were active (Origanum compactum and Cymbopogon winterianus). The evaluation of the combinations of essential oils and antibiotics in terms of kinetics has given us three cases: the first case is the one with no acidity or no growth at all; the second is the one where growth is normal; the third where growth is delayed with a more pronounced latency phase.
 Conclusion: This study suggest that the effect of essential oils and medicinal plant used alone or in combination to antibiotics on the gut microbiota have to be evaluated for validation as well as their toxicity activities before using them for human therapy.
Nardis Nkoudou Ze, Marie-Joseph MEDZEME ENGAMA, Jean Justin Essia Ngang
Emirates Journal of Food and Agriculture
Aim: the aim of this study was to determine sensory profile, through the use of just-about-right (JAR) scales and penalty analysis, of Bobolo and Chikwangue from the cassava roots fermented with previously cassava-fermented chips powder (PCFCP). Furthermore, retting time, cyanide content and pasting properties of retted roots were evaluated. Methods: for that, two samples of Bobolo and Chikwangue obtained from two cassava retting methods were studied: a control made from the retting without PCFCP and a product made from retting with PCFCP. Results: retting time was carried out in 48 hours less with PCFCP and 60% of cyanide reduction more than control. No major modifications occurs in pasting properties of paste fermented with PCFCP. The sensory analysis indicated high levels of acceptability for products made from retting with PCFCP. The penalty analysis showed that attributes “too sour” and “too much fermented odor” affected the acceptability of the Bobolo from retting without PCFCP significantly. Conclusion: fermentation of cassava through the use of PCFCP is suitable to improvement of sensory characteristics of fermented cassava by-products.
Patrice Bonny, Marion Desdouits, Julien Schaeffer, Pascal Garry, Jean Justin Essia Ngang, Françoise S. Le Guyader
Food and Environmental Virology
Shellfish constitute an important protein source but may be contaminated by viruses from various origins. A study performed on clams collected in Cameroon showed a high prevalence of norovirus and hepatitis A virus. After sequencing, the hepatitis A virus showed similarities with the genotype V simian strains.
Nardis Nkoudou Ze, Robert Ndjouenkeu, Jean Justin Essia Ngang
Asian Food Science Journal
Aims: To compare the physicochemical (water, total titratable acid, amylose and amylopectin contents), functional (swelling and solubility powers) and pasting characteristics of cassava flour retted in two different ways.
 Study Design: Flours were produced from two cassava cultivars subjected to natural and accelerated fermentations using a multi-strain mixed starter.
 Place and Duration of Study: Department of Microbiology of the University of Yaounde 1 and Department of Food Science and Nutrition at the University of Ngaoundere, both in Cameroon, between November 2019 and February 2020.
 Methodology: The cassava roots of each cultivars were divided into two groups and fermented by submerging peeled roots in tap water. One group of each cassava cultivar was inoculated with 1% (w/w) of the starter, while the other was subjected to a spontaneous fermentation. Retting stopped after the softening of the roots; that is after twenty-six hours for the inoculated groups, and after seventy-two hour for the control groups. The fermented roots were then squeezed, dried and grounded in a blender. Flours obtained were subjected to physicochemical, functional and pasting analysis.
 Results: Flours produced in accelerated fermentation (AF) were characterized by their low amylopectin contents (46.59% and 43.57%), swelling power (6.71% and 7.56%), solubility (6.03% and 7.96%), and peak viscosity (6182 cP and 5676 cP) for Six-mois and Mintol-meko flours respectively. Whereas setback viscosity (1032 cP and 1068 cP), stability (0.27 and 0.24) and final viscosity (3565 cP and 3566 cP) of flours from natural fermentation (NF) were lower than those from AF.
 Conclusion: The accelerated fermentation reduces the tendency of paste to downgrade, that is responsible for staling in baked products and could therefore produce flours that are less fluid.
Michel Arnaud Mbock, William Feudjou Fouatio, Raceline Gounoue Kamkumo, Patrick Valère Tsouh Fokou, Florence Tsofack Ngueguim, Paul‐Keilah Lunga et 7 autre(s)
Journal of Ethnopharmacology
Caroline I. Sibomana, Sylvain Leroy Sado Kamdem, Gustave Mushagalusa Nachigera, Jean Justin Essia Ngang
Journal of Advances in Microbiology
Aims: This experiment was done to investigate the effect of adding Rosmarinus officinalis essential oil (REO) in tomato juice and paste during processing in condition of reduced thermal treatment on nutritional qualities and evaluate their postharvest shelf life under Bacillus cereus spore contamination.
 Place and Duration of Study: Laboratory of Microbiology, University of Yaoundé I, Cameroon, from January 2017 to June 2018.
 Methodology: Total polyphenol content was determined using the Folin Ciocalteu coloric method; the Titatrable acidity and vitamin C content were determined by titration with indicator method. The effect of level of Bacillus cereus contamination, time of thermal treatment and concentration of REO was assessed using a experimental CCD plan. The shelf life was estimated using the storage efficacy of the product on a period of time, and calculated based on the percentage of spoiled products. Data were analysed using XLSLTAT and STATISTICA packages for non-linear regression analyses.
 Results: Only 10 min pasteurization at 95°C in the presence of 100ppm of ROE was necessary to totally deactivate 104 Bacillus cereus spores/g in tomato juice while for tomato paste the same concentration of ROE needed 20 min pasteurization at 95°C to totally deactivate up to 108 Bacillus cereus spores/g. Total polyphenols, Titratable acidity and Vitamin C content were affected under this combined processing technique. The storage efficacy of tomato products and hence the extended shelf life was as a result of combined effects between cooking time and microbial load percent reduction that depended on the spore load concentration.
 Conclusion: Using Rosmarinus officinalis essential oil can help reduce the thermal impact during tomato juice and paste processing even in condition of high contamination of spores of Bacillus cereus. Moreover in this processing condition, nutritional compounds are not significantly impacted.
François‐Xavier Etoa, Abraham Nkoue Tong, Jean Justin Essia Ngang, Sylvain Leroy Sado Kamdem
Microbiology Research Journal International
International audience
Raoul Bakari Afnabi, R. P. Nameni, S. S. Kamdem, Jean Justin Essia Ngang, Rianatou Bada Alambédji
Alex Tchuenchieu, Carmen Rodica Pop, Sylvain Sado Kamdem, Elena Mudura, Jean Justin Essia Ngang, Ancuţa M. Rotar et 1 autre(s)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Food Science and Technology
The growth response of Zygosaccharomyces bailii acid adapted cells was assessed in acidified media. Yeast cells were first pre-cultured in nutrient broth adjusted with hydrochloric, citric and malic acid to pH 4; 4.5; 5; 5.5; 6 and 6.5. Moreover, they were also grown in two controls consisting of nutrient broth and nutrient broth supplemented with 1% of glucose both adjusted at pH 7. The variation of pH before and after the growth along with yeast concentration was measured. The cells pre-cultured in controls conditions and in the three conditions at pH 5 were then each inoculated in six BHI medium consisting of BHI adjusted with hydrochloric, citric and malic acid at pH 5.5 and 3.5. The growth was monitored by spectrophotometry and the yeast concentration after incubation was obtained by microscopy using a Thoma cell chamber. DMFit 2.1 was used to plot the growth curves and to estimate the growth parameters. All the pre-cultures and cultures were made at 37C during 24 hours. During the pre-cultures, an important decrease of pH was noted in nutrient broth supplemented with glucose, moving from 7 to 3.81. In all the other pre-cultures, just a little variation was observed ranging from -0.57 to 0.50. Growth was observed in all the conditions, except at pH4. By growing the cells coming from the selected pre-cultures conditions in the different acidic BHI media, it appears that acid adaptation enhance the growth at pH 5.5 no matter the acid contains in the medium and the acid to which the cells were adapted. However, this acid adaptation was not sufficient to initiate growth at pH 3.5 after 24 hours of incubation at 37C. Growth rate was significantly affected by the pH of the pre-culture medium and the acid present in the culture medium. Pre-culture with glucose supplementation was the only parameter studied affecting the latency.
James Ronald Bayoï, Djoulde Darman Roger, Justine Maïworé, Daoudou Bakary, Josiane Soppe Essome, Barak Noura et 4 autre(s)
International journal of innovation and applied studies
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