Sylvain Leroy Sado Kamdem

Assessment of the Antimicrobial Properties of Ultraviolet Radiation Application and Different Types of Packaging during the Storage of Cocoa Beans

Marc Vincent Maheneck, Abraham Nkoue Tong, Jean Justin Essia-Ngang, Sylvain Leroy Sado Kamdem

Microbiology Research Journal International

Aim: To assess ultraviolet radiation microbial deactivation and impact of different types of packaging during the storage of dried cocoa beans. Study Design: Quasi experimental design. Place and Duration of Study: Department of Microbiology, Faculty of Science, University of Yaoundé 1, between January 2023 and May 2024. Methodology: Dried cocoa beans were used for ultraviolet radiation of 743.6 µW/cm² during 0 to 50 minutes. The total bacteria count, Enterobacteriaceae, Escherichia coli, yeasts, and moulds were enumerated, and the detection of Salmonella was performed. On the other hand, dried cocoa beans were introduced on 5 different packaging, and stored across two seasons, for 180 days and their microbial content and humidity assessed. Results: The study observed that ultraviolet radiation type C with an intensity of 743.6 µW/cm² for 50 minutes reduces total bacteria count (TBC) by 1.62 log CFU/g (98%) and fungal flora by 2.03 log CFU/g (99%). Time of exposure was a significant factor affecting the ultraviolet antimicrobial efficacy. Based on Weibull model adaptation to experimental data, moulds were more sensitive to these radiation (b=0.09) than total bacteria count (b=0.0012). Hermetic bags show the ability to reduce microbial proliferation during the rainy and dry seasons compared to microaerophilic bags and Jute bags. The Hermetic bags also show an ability to resist humidification compared to microaerophilic bags packaging. Conclusion: Ultraviolet radiation for 50 minutes and storage in hermetic packages of cocoa beans can be proposed as alternatives to the only jute bag storage commonly used today in the cocoa sector.

• #food chemistry and fat analysis
• #food composition and properties
• #seed and plant biochemistry
• #antimicrobial

Microbial Quality During Cocoa Mass Production and Effect of Its Storage Conditions on the Survival of Klebsiella oxytoca , Escherichia coli , Saccharomyces cerevisiae and Aspergillus brasiliensis

Marc Vincent Maheneck, Raissa Jespère Nzouengo Tchounda, Jean Justin Essia-Ngang, Sylvain Leroy Sado Kamdem

Journal of Food Quality

Cocoa beans are often obtained from exposed fermentation and hence may carry many microbial hazards in the production of cocoa‐derived products. The aim of this work was to assess the microbial quality along the production chain of cocoa mass and the effect of mild heat (ambient temperature, 50°C, 55°C, 60°C and 65°C) and cold storage (refrigeration and freezing) of the latter on deliberately inoculated Klebsiella oxytoca , Escherichia coli , Saccharomyces cerevisiae and Aspergillus brasiliensis survival. It was observed that steam pasteurisation and cocoa roasting can reduce the level of cocoa bean mould from 4.82 Log CFU/g to nondetected levels and total bacteria counts from 6.63 Log CFU/g to 1.94 Log CFU/g in cocoa nibs. The refining process was a critical contamination stage as it contributed to increased microbial contamination. Regarding the challenge testing with the four strains, the deactivation potential of the different cocoa mass treatments was directly proportional to the increase in temperature. In general, the order of sensitivity to cocoa mass treatments was Klebsiella oxytoca , Saccharomyces cerevisiae , Escherichia coli and Aspergillus brasiliensis. The results obtained in this work will contribute in providing new approaches to food safety assurance in the cocoa industry, in particular during the production of cocoa mass.

• #food chemistry and fat analysis
• #cocoa and sweet potato agronomy
• #african botany and ecology studies
• #cocoa bean

Serological and molecular analysis of henipavirus infections in synanthropic fruit bat and rodent populations in the Centre and North regions of Cameroon (2018–2020)

Cyrille Mbanwi Mbu’u, Pierre Gontao, Abel Wade, Maren Penning, Balal Sadeghi, Aristid Ekollo Mbange and 6 more

BMC Veterinary Research

BACKGROUND: Bats and rodents have been identified as reservoirs for several highly pathogenic and zoonotic viruses including henipaviruses, a genus within the Paramyxoviridae family. A number of studies have revealed the circulation of henipaviruses at the wildlife-human-livestock interface in Cameroon. In this study, we describe the molecular analysis as well as the development and evaluation of a Bead-based Multiplex Binding Assay (BMBA) using an in-house Indirect Enzyme Linked Immunosorbent Assay (ELISA) to confirm the detection of henipavirus infection in wildlife species. RESULTS: A total of 600 fruit bats and 600 rodents were sampled between March 2018 and June 2020. Samples were analyzed using a semi-nested RT-PCR assay followed by sequencing of the PCR fragments. Transudates (754) were screened for the presence of henipavirus-specific antibodies in a BMBA and confirmed by ELISA using Hendra virus (HeV), Nipah virus (NiV) and Ghana virus (GhV) glycoproteins expressed in Leishmania tarentolae, and commercially available HeV G and NiV G glycoproteins. Henipavirus-specific antibodies were detected in 19/531 (3.6%) bat transudates screened by BMBA and confirmed by ELISA. Seroprevalence rates in the Centre and North Regions were 12/291 (4.1%) and 7/240 (2.9%) respectively. All rodents and shrews were serologically negative. Henipavirus RNA sequences were not detected in any of the samples screened in this work. CONCLUSION: This study provides further data supporting the circulation of Henipaviruses in fruit bats (Eidolon helvum) which are roosting and reproducing in proximity to human and livestock populations in the Centre and North Regions of Cameroon. This also establishes the first detection of Henipavirus specific antibodies in Eidolon helvum populations in the North Region of Cameroon.

• #virology and viral diseases
• #mosquito-borne diseases and control
• #herpesvirus infections and treatments
• #hendra virus

Fresh Vegetables and Irrigation Water Microbial Quality in One Village and Two Periurban Farms in the Centre Region of Cameroon

MINKA Joseph Dalambert, FOGANG FOKO Desoeuvres, Mobou Estelle Yolande, Sylvain Leroy Sado Kamdem

International Journal of Current Microbiology and Applied Sciences

The present study investigated the seasonal variation of microbial quality of irrigation water and vegetables produced at Nkolondom, Ebogo1 and Meyo farms in the Centre region of Cameroon. The physicochemical analysis of irrigation water was also studied. A total of 81 fresh horticultural products were harvested in the three farms and 27 water samples collected. For microbial quality, total aerobic mesophilic bacteria, total coliforms, E.coli and Vibrio spp were researched. Parameters such as pH, temperature, electrical conductivity, turbidity and total dissolved solids were measured at the water sampling sites. Data collected were analyzed using Statgraphics version 7.1 software. Results showed that total aerobic mesophilic bacteria had the highest count (9.78 log cfu/g) followed by total coliforms (7.5 log cfu/g), while faecal coliforms and Vibrio were the least represented. The maximal number of aerobic mesophilic bacteria was counted in parsley during the dry season (9.78 log cfu/g). The microbiological quality of irrigation water and vegetables was unacceptable, exceeding the standards accepted by WHO and International Commission on Microbiology Standards for Foods limits for safe consumption. These results indicate that the microbial hazard of these vegetables is alarmingly high and that consumers should be aware to take correct actions while consuming them.

• #agriculture and rural development research
• #irrigation
• #geography
• #water resource management

Involvement of Certain Genes in the Mechanism of Acquisition of Antibiotic Resistance in <i>Salmonella</i> Typhi After Exposure to Medicinal Plant Extracts

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.

• #heavy metals in plants
• #agriculture and biological studies
• #salmonella typhi
• #salmonella

Effect of Food Matrix, Cooking and Preservation Modalities on the Outgrowth of Bacillus cereus Spores in Some Starchy Foods

A. Nkoue Tong, M. R. Djoumene Kenne, R. Tchikoua, Sylvain Leroy Sado Kamdem, François‐Xavier Etoa

Journal of Advances in Microbiology

Aim: Starchy products are very important in the fight against food insecurity in developing countries, where they are widely consumed. This study is aimed to assess the impact of cooking and storage methods on the spoilage of some cooked starchy products by spore-forming bacteria
 Place and Duration: Department of Microbiology of the University of Yaoundé I betweenJune 2020 and September 2022
 Methodology: In order to better understand the alteration of these foods by spore-forming bacteria, a survey was carried out among some households and restaurant owners in the city of Yaoundé to determine the cooking and preservation methods for cassava, maize and rice couscous. Then, cooking parameters and conservation modalities from the survey were simulated in the laboratory in order to assess the deactivation kinetics of Bacillus cereus.
 Results: It emerged from this experiment that cooking time varies according to the foodstuffs, the most important being maize. The packaging is mainly done in non-food plastic bags, and the thermos is used more often than the fridge and the pot. Cassava flour was more contaminated in aerobic spore (1.105 spores/g) than maize and rice (5.103 and 9.103 spores/g) after cooking of different starchy food enriched with Bacillus cereus spores, their inactivation was more important in rice followed by cassava and maize couscous as indicated by the Weibull scaleparameters which were respectively 1.1; 0.52 and 0.08. It was also noted that increase in cooking time also reduced the time for spores to initiate outgrowth and this time was affected by the type of flour. These two parameters also affected the time of spore outgrowth to 5logufc/g.
 Conclusion: Storage in the fridge is still the best way to store food, but the thermos flask is more often used. The use of electric thermostats set at temperatures around 60°C would increase the optimal shelf life and significantly reduce the risk of spoilage and foodborne illness.

• #food safety and hygiene
• #cassava research and cyanide
• #food security and health in diverse populations
• #spore

Effect of Sporulation Medium Content in Carbohydrates, Lipids, and Proteins on Outgrowth of Bacillus spp Spores Activated with Heat and Ethanol Solution

Abraham Nkoue Tong, Sylvain Leroy Sado Kamdem, H. Djeudjeu Ngougue, F. X. Etoa

Journal of Advances in Microbiology

Aims: evaluate the effect of the nutrient content of the medium on the sporulation percentage and the efficiency of ethanolic activation on the outgrowth of Bacillus spp.
 Place and Duration: Department of Microbiology of the University of Yaoundé I between june 2020 and September 2021.
 Methodology: In order to contribute to the understanding of the effect of the environment of spore origin on the ability to sporulate and outgrow in foods, spores of Bacillus cereus and Bacillus subtilis were produced in different media differenciated by the carbohydrates, lipids and proteins composition. Mathematical models predicting sporulation rates and germination yields of heat- and ethanol-activated spores were evaluated as a function of the factors selected. The reliability of these models was assessed by comparing the predicted values with those obtained in real food.
 Results: It was found that spores originating from high carbohydrates and proteins media had high sporulating and germination rates. It was found that the origin of the spores, mainly the carbohydrate and protein content, resulted in high sporulation rates and that spores from nutrient-rich media germinated faster than those from nutrient-poor media. Germination efficiency varied from strain to strain depending on the method of activation and the composition of the medium in which the spores were produced. The mathematical models obtained were validated in food matrices with correlation of predicted and observed values higher than 0.85.
 Conclusion: The ethanolic activation of spore varies depending on the strain and the nutrient content especially the fat content in sporulating medium. The proteins and carbohydrates have significant content for thermal activation.

• #bacillus and francisella bacterial research
• #probiotics and fermented foods
• #microbial inactivation methods
• #spore

Comparing checkerboard, isobologram and CCD methods for drug combination: A case study of ciprofloxacin and plant extracts on Escherichia coli and Shigella

Gislaine Aurelie Kemegne, Sylvain Leroy Sado Kamdem, Maximilienne Ascension Nyegue, Chantal Menut, François‐Xavier Etoa

Journal of Medicinal Plants Research

To investigate the interactive antimicrobial activity of conventional antibiotics, namely ciprofloxacin and Mangifera indica bark ethanol extract, Psidium guajava leaves essential oil against two Gram-negative bacteria using checkerboard, isobologram, and central composite design (CCD) methods. The checkerboard method was used for the determination of the fractional inhibitory concentration index (FICI) value needed for the interpretation of the interaction. The isobologram was constructed and the geometrical disposition of the combinations used to define the type of interaction. The CCD experimental plan was used to obtain the bactericidal probability. In general the results indicated that the methods do have few similarities in their output for the same combination. According to the results, the isobologram method can be considered as more adapted and can be confirmed using the CCD method for antimicrobials combination because of the flexibility in the testing ratio of antimicrobials to be used. This study brings into light the fact that isobologram and CCD methods should be compared when studying drug interaction. Key words: Antibiotics, central composite design, checkerboard, isobologram, plant extracts, Escherichia coli, Shigella species.

• #mangiferin and mango extracts
• #essential oils and antimicrobial activity
• #computational drug discovery methods
• #checkerboard

Influence of Some Antibiotics and Essential Oils Used Alone or in Combination on the Vitality of Presumptive Probiotic Lactic acid Bacteria

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.

• #essential oils and antimicrobial activity
• #antibiotics
• #thymol
• #carvacrol

Antifungal properties of lactic acid bacteria isolated from cocoa beans fermentation in the centre region of Cameroon

SANDRINE AIMÉE YOUTE FANCHE, ANTOINE LAURENT WOUAPI TCHOKONTHE, Camelia Diguță, Sylvain Leroy Sado Kamdem, Florentina Israel-Roming, Florentina Matei and 1 more

ROMANIAN BIOTECHNOLOGICAL LETTERS

The objective of this study was to identify lactic acid bacteria (LAB) with antifungal activity usable in the fermentation of cocoa beans to limit the moulds growth and to characterize their inhibitory mechanism. A total of 28 LAB strains were isolated from fermented cocoa beans and tested for their antifungal activity against 10 moulds of the genus Aspergillus and Penicillium. An initial selection was made using the transversal method and the inhibition percentage was determined. The most active isolates were subjected to biochemical and molecular analysis; their cell free supernatant was analysed by HPLC and submitted to various treatments (acid neutralization, heat and enzymes). The best lactic acid selection has been subjected to molecular identification and were identified by molecular tools and belong to the species Lactobacillus farciminis, Lactobacillus brevis, Pediococcus pentosaceus, Weissella cibaria and Enterococcus faecium.

• #food chemistry and fat analysis
• #cocoa and sweet potato agronomy
• #proteins in food systems
• #lactic acid

Henipaviruses at the Interface Between Bats, Livestock and Human Population in Africa

Cyrille Mbanwi Mbu’u, Wilfred Fon Mbacham, Pierre Gontao, Sylvain Leroy Sado Kamdem, Alexandre Michel Njan Nlôga, Martin H. Groschup and 3 more

Vector-Borne and Zoonotic Diseases

Nipah virus (NiV) and Hendra virus (HeV) are closely related members within the genus Henipavirus , family Paramyxoviridae , for which fruit bats serve as the reservoir. The initial emergence of NiV infections in pigs and humans in Malaysia, and HeV infections in horses and humans in Australia, posed severe impacts on human and animal health, and continues threatening lives of humans and livestock within Southeast Asia and Australia. Recently, henipavirus-specific antibodies have also been detected in fruit bats in a number of sub-Saharan African countries and in Brazil, thereby considerably increasing the known geographic distribution of henipaviruses. Africa is progressively being recognized as a new high prevalence zone for henipaviruses, as deduced from serological and molecular evidence of past infections in Madagascar, Ghana, Republic of Congo, Gulf of Guinea, Zambia, Tanzania, Cameroon, and Nigeria lately. Serological data suggest henipavirus spillover from bats to livestock and human populations in Africa without reported clinical disease in any of these species. All virus isolation attempts have been abortive, highlighting the need for further investigations. The genome of the Ghanaian bat henipavirus designated Ghana virus (GhV), which was detected in a pteropid Eidolon helvum bat, is the only African henipavirus that has been completely sequenced limiting our current knowledge on the genetic diversity and pathogenesis of African henipaviruses. In this review, we summarize the available data on the circulation of henipaviruses in Africa, discuss potential sources for virus spillover, and highlight existing research gaps.

• #virology and viral diseases
• #viral infections and vectors
• #vector-borne animal diseases
• #livestock

Antimicrobial Potential of Carvacrol and Its Effect at Sub-lethal Concentration during Low Thermal Pasteurization of Fruit Juices

Alex Tchuenchieu, Jean‐Justin Essia Ngang, Carmen Rodica Pop, Sylvain Leroy Sado Kamdem, Ancuţa M. Rotar, François-Xavier Etoa and 1 more

Journal of Advances in Microbiology

International audience

• #microbial inactivation methods
• #listeria monocytogenes in food safety
• #pasteurization
• #carvacrol

Effect of Substrates on Nutritional Composition and Functional Properties of Pleurotus Ostreatus

E G Mbassi Josiane, Y Mobou Estelle, Atul Francis, Sylvain Leroy Sado Kamdem

Current Research in Agricultural Sciences

Pleurotus species, commonly known as oyster mushrooms, are edible fungi cultivated worldwide. Pleurotus genus is one of most extensively studied white-rot fungi due to its exceptional ligninolytic properties. These mushrooms have the ability to colonize and degrade a wide variety of lingo-cellulosic wastes with relatively short cycle. The objective of this study was to review published research works on the effect of substrates on nutritional composition and functional property of Pleurotus ostreatus. A literature search was done on the internet and university libraries in this area. It was found that different substrates used in cultivating mushrooms do have effect on the functional, organoleptic and nutritional properties of mushrooms. This review presents a practical checklist of effect of substrates on quality of Pleurotus ostreatus that may help different users.

• #fungal biology and applications
• #phytochemistry and bioactivity studies
• #phytochemicals and antioxidant activities
• #pleurotus ostreatus

Antimicrobial structure activity relationship of five anthraquinones of emodine type isolated from Vismia laurentii

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.

• #phytochemistry and biological activity of medicinal plants
• #morinda citrifolia extract uses
• #natural compound pharmacology studies
• #antimicrobial

Effect of Acid Adaptation of Listeria monocytogenes on Its Mild Thermal Inactivation in a Simulated Fruit Juice Supplemented with Carvacrol

Alex Tchuenchieu, Jean‐Justin Essia Ngang, Martial Juengue, Sylvain Leroy Sado Kamdem, François-Xavier Etoa

British Microbiology Research Journal

International audience

• #listeria monocytogenes in food safety
• #essential oils and antimicrobial activity
• #edible oils quality and analysis
• #carvacrol

Assessment of Cassava (Manihot esculenta Crantz) Fermentation and Detoxification Using Previously Cassava-fermented Chips

Nardis Nkoudou Ze, Sylvain Leroy Sado Kamdem, Hélène Agnia, Fabrice Mengo, Jean Justin Essia Ngang

British Journal of Applied Science & Technology

International audience

• #cassava research and cyanide
• #date palm research studies
• #manihot esculenta
• #fermentation

Effect of Processing Parameters on the Stability of Nonpasteurized Mango Slice Preserves

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.

• #postharvest quality and shelf life management
• #essential oils and antimicrobial activity
• #nanocomposite films for food packaging
• #shelf life

Antifungal properties of selected lactic acid bacteria and application in the biological control of ochratoxin A producing fungi during cocoa fermentation

Jean‐Justin Essia Ngang, Germaine Yadang, Sylvain Leroy Sado Kamdem, Christiant Kouebou, SANDRINE AIMÉE YOUTE FANCHE, Danielle L. Tsochi Kougan and 2 more

Biocontrol Science and Technology

Thirteen Lactic acid bacteria strains isolated from fermenting cocoa and seven reference strains were used in order to assess their antifungal properties towards three ochratoxin A (OTA) producing fungi (Aspergillus carbonarius, Aspergillus niger and Aspergillus ochraceus). Furthermore, two of the isolates strains (A19 and A21) identified as belonging to the genus of Pediococcus as well as Lactobacillus plantarum B4496, Lactobacillus brevis 207 and Lactobacillus sanfranciscensis BB12 showed interesting in vitro broad antifungal activities towards the three ochratoxin-producing fungi with inhibition percentages ranging from 15% to 66.7%. Treatment of cell-free supernatant at 100°C affected antifungal activity suggesting that the main compounds responsible for this activity were of proteic nature, and hence could be bacteriocins. Application of isolate A19 in cocoa fermentation as starter inhibited the growth of each of the OTA-producing species. At the end of fermentation in boxes inoculated with A19, A. niger was not detectable while A. carbonarius concentration was found to be 2 Log CFU/g of wet beans. The assessment of the ochratoxin produced during fermentation of cocoa inoculated with A. carbonarius indicated that the use of isolate A19 as starter could reduce their level of growth so as to have only a toxin production of 0.0012 ± 0.0005 μg/kg after 40 days of storage, while this was 2.45 ± 0.35 μg/kg of fermented and dried cocoa beans in the absence of A19. This work is a contribution for the application of biological control of OTA-producing fungi during cocoa production.

• #food chemistry and fat analysis
• #cocoa and sweet potato agronomy
• #biochemical and biochemical processes
• #lactobacillus plantarum

High pressure homogenization vs heat treatment: Safety and functional properties of liquid whole egg

Francesca Patrignani, Lucia Vannini, Sylvain Leroy Sado Kamdem, Isabel Hernando, R. Marco-Molés, Maria Elisabetta Guerzoni and 1 more

Food Microbiology

• #microbial inactivation methods
• #listeria monocytogenes in food safety
• #meat and animal product quality
• #homogenization (climate)

Modellazione delle cinetiche di inattivazione cellulare

Fausto Gardini, Sylvain Leroy Sado Kamdem

Food

• #microbial inactivation methods
• #listeria monocytogenes in food safety
• #meat and animal product quality
• #humanities

Potentialities of High‐Pressure Homogenization to Inactivate Zygosaccharomyces bailii in Fruit Juices

Francesca Patrignani, Lucia Vannini, Sylvain Leroy Sado Kamdem, Rosalba Lanciotti, Maria Elisabetta Guerzoni

Journal of Food Science

UNLABELLED: This experimental work was aimed to evaluate the effects of repeated high-pressure homogenization (HPH) treatments at 100 MPa on the inactivation and regrowth of Zygosaccharomyces bailii inoculated in apricot and carrot juices. Thus, the spoilage yeast was inoculated in both the juices at level of about 5 log CFU/g and the 2 systems were treated with a lab-scale Panda homogenizer for 8 passes at 100 MPa. Microbiological and chemico-physical analyses were performed immediately after the treatment and during the juice storage at room temperature. Microbial data highlighted that yeast inactivation increased with the number of passes applied. Eight passes at 100 MPa allowed yeast inactivation higher than 2.5 log CFU/mL regardless of the juice considered. On the contrary, the juice type affected the yeast fate (growth or death) over the storage at 25 degrees C. In fact, Z. bailii was able to attain the spoilage threshold (6 log CFU/mL) in apricot juice, although with growth kinetics dependent of the survivor levels after HPH treatment. In carrot juice this microorganism was unable to recover over the storage in the most severely treated samples. The HPH treatment had a significant effect on apricot juice pH and viscosity, while no significant effect was observed in carrot juice. The viscosity measurements showed that the application of one pass at 100 MPa resulted in the triplication of apricot viscosity index. No further significant viscosity increase (P > 0.05) was observed increasing the number of passes at 100 MPa. PRACTICAL APPLICATION: The results obtained in the present study and the proposed technology could be exploited by the industries of the beverage sector to increase the shelf life of these kinds of products. Moreover, from a technological point of view, the increase of viscosity, following the high-pressure homogenization treatment, represents a tool to expand the product gamma without the use of gelling additives or thermal treatments, which are detrimental for the sensorial and nutritional properties of this kind of products.

• #microbial inactivation methods
• #food drying and modeling
• #listeria monocytogenes in food safety
• #food science

Composition of four essential oils obtained from plants from Cameroon, and their bactericidal and bacteriostatic activity against Listeria monocytogenes, Salmonella enteritidis and Staphylococcus aureus

Fausto Gardini, Nicoletta Belletti, Maurice Ndagijimana, Maria Elisabetta Guerzoni, François Tchoumbougnang, P. H. Amvam Zollo and 3 more

African Journal of Microbiology Research

The composition of four essential oils (EOs) extracted by hydrodistillation from plants of common use in Cameroon (Curcuma longa, Xylopia aethiopica, Zanthoxylum leprieurii L., Zanthoxylum xanthoxyloides) was assessed by gas chromatography-mass. Their bactericidal and bacteriostatic activity was tested in vitro against three food borne pathogenic bacteria: Listeria monocytogenes,Salmonella enteritidis and Staphylococcus aureus. The bacteriostatic activities of this EOs on food borne bacteria were assessed in vitro through optical density measurements. The minimal bactericidal concentrations (MBC) were determined in broth combined with a spot plating method. Z. xanthoxyloides and Z. leprieuriishowed a similar composition, with a prevalence of oxygenated monoterpenes (about 58%). The EO of Z. xanthoxyloides was the most effective against the microorganisms tested. Its higher concentration of geraniol could be linked to this higher activity. In almost all cases, the MBC was higher than the maximum concentration tested (3000 ppm). Notwithstanding their low bactericidal effect, the EOs studied showed interesting inhibiting activities against the tested food borne pathogens. S. enteritidis was the most resistant to the bacteriostatic effect of the four EOs. The knowledge of the antimicrobial potential of local plant EOs used in developing countries could help in their choice and their use to improve food safety and shelf-life.   Key words: Essential oils, composition analysis, antimicrobial activity, pathogens.

• #essential oils and antimicrobial activity
• #insect pest control strategies
• #ethnobotanical and medicinal plants studies
• #listeria monocytogenes

Effects of acidic stress on flavour compounds (isovaleric acid) production and gene epression in Lactobacillus sanfranciscensis

Diana Isabella Serrazanetti, Sylvain Leroy Sado Kamdem, Maurice Ndagijimana, Andrea Gianotti, Matthias A. Ehrmann, Rudi F. Vogel and 2 more

Archivio istituzionale della ricerca (Alma Mater Studiorum Università di Bologna)

In lactobacilli stress conditions can elicit overproduction of specific compounds or a metabolic shift, which may result in flavour improvement or off-flavour generation depending on the type of food. In particular in food-systems the organoleptic perception of isovaleric acid (IVA) depends on its concentration and interactions with other metabolites. IVA is a key intermediate in the branched-chain-fatty-acids biosynthesis and its role as signalling molecule in bacteria has been proven. 
\nThe mechanism for IVA production/overproduction by Lactobacillus sanfranciscensis under acid stress conditions was investigated upon exposure to pH3.6 in the presence of maltose or fructose and precursors of IVA. The metabolites released were analysed by GC-MS/SPME and HPLC. For the gene-expression analyses RT- PCR was used.
\nThe results obtained demonstrated that the availability of the precursors is not limiting for IVA overproduction. IVA accumulation (>100 folds than the control) was associated with acid stress. In the samples at pH3.6 the concentration of IVA was particularly elevated in the presence of fructose. The maximal IVA production was obtained at pH3.6 with fructose combined with citrate, or leucine, or a-ketoglutarate. The gene-expression analyses were calculated for gluAT, bcAT, idh, which are involved in the IVA pathway, in respect to the control. The results revealed that, in the presence of maltose, leucine or glutamate, gluAT was overexpressed. Moreover gluAT and idh were overexpressed in the presence of fructose and citrate, or a-ketoglutarate, respectively. 
\nInteresting relationships between flavour compounds from branched-chain-amino-acid and fatty-acids biosynthesis were observed during analysis of the metabolic fate of deuterate-leucine. The control of the metabolic mechanisms and the effects of acid stress on overproduction of flavour compounds represent an important tool to optimise fermented-food production.

• #probiotics and fermented foods
• #microbial metabolic engineering and bioproduction
• #protein hydrolysis and bioactive peptides
• #flavour

A logistic approach to assess the suitability of aroma compounds to improbe stability of soft drinks inoculated with Saccharomyces cerevisiae.

Nicoletta Belletti, Rosalba Lanciotti, Sylvain Leroy Sado Kamdem, Francesca Patrignani, Fausto Gardini

Archivio istituzionale della ricerca (Alma Mater Studiorum Università di Bologna)

The combined effects of a mild heat treatment ) and the presence of three aroma compounds [citron essential oil, citral, and (E)-2-hexenal] on the spoilage of noncarbonated beverages inoculated with different amounts of a Saccharomyces cerevisiae strain were evaluated. The results, expressed as growth/no growth, were elaborated using a logistic regression in order to assess the probability of beverage spoilage as a function of thermal treatment length, concentration of flavoring agents, and yeast inoculum. The logit models obtained for the three substances were extremely precise. The thermal treatment alone, even if prolonged for 20 min, was not able to prevent yeast growth. However, the presence of increasing concentrations of aroma compounds improved the stability of the products. The inhibiting effect of the compounds was enhanced by a prolonged thermal treatment. in fact, it influenced the vapor pressure of the molecules, which can easily interact within microbial membranes when they are in gaseous form. (E)-2-Hexenal showed a threshold level, related to initial inoculum and thermal treatment length, over which yeast growth was rapidly inhibited. Concentrations over 100 ppm of citral and thermal treatment longer than 16 min allowed a 90% probability of stability for bottles inoculated with 10(5) CFU/bottle.

• #fermentation and sensory analysis
• #phytochemicals and antioxidant activities
• #sensory analysis and statistical methods
• #saccharomyces cerevisiae

Modelling pathogen thermal inactivation potential of two industrial processes for precooked meat patties: the case of Listeria monocytogenes

Lucia Vannini, Sylvain Leroy Sado Kamdem, Federico Ferioli, María Fiorenza Caboni, Maria Elisabetta Guerzoni

Archivio istituzionale della ricerca (Alma Mater Studiorum Università di Bologna)

Meat patties obtained from chicken fed with animal fat (A) and vegetable fat (V) were deliberately inoculated with Listeria monocytogenes 12 hours before being processed according to innovative (I) and traditional (T) industrial flow charts. Survival data were modelled using the Weibull equation introducing the pasteurisation value concept in place of the Temperature, hence converting a non isothermal process into an isothermal-like one. The model used gave a good fitting of the experimental data and the curvature parameter was <1 in all the cases. Given the same meat origin, T industrial process was more efficient in deactivating L. monocytogenes than the innovative one. In the meat patties obtained from chicken fed with vegetable fat (V), L. monocytogenes was more sensitive to thermal inactivation particularly when the I process was adopted.

• #meat and animal product quality
• #advanced chemical sensor technologies
• #listeria monocytogenes in food safety
• #listeria monocytogenes

Characterization of yeasts associated with Alto Adige speck and identification of biochemical markers for the product authentication

C. Medici, Sylvain Leroy Sado Kamdem, Letizia Di Biase, Lucia Vannini, Diana Isabella Serrazanetti, Maria Elisabetta Guerzoni

Archivio istituzionale della ricerca (Alma Mater Studiorum Università di Bologna)

• #fermentation and sensory analysis
• #food quality and safety studies
• #identification (biology)
• #authentication (law)

Differentiation of fresh seafood products and storage time using an electronic nose: features selection for data analysis

Sylvain Leroy Sado Kamdem, Maurice Ndagijimana, Lucia Vannini, Maria Elisabetta Guerzoni

• #advanced chemical sensor technologies
• #food supply chain traceability
• #meat and animal product quality
• #electronic nose

Importanza dell'aspetto microbiologico nella valutazione della shelf-life residua dei prodotti ittici di nuova generazione

Sylvain Leroy Sado Kamdem, Lucia Vannini, E. Spiller, Maria Elisabetta Guerzoni

• #organic food and agriculture
• #art
• #humanities

Influence of chicken diet and tray disposition of breast packaged in high oxygen modified atmosphere on the dishomogeneity of microbial population, discoloration and oxidation dynamics

Sylvain Leroy Sado Kamdem, Andrea Gianotti, Maria Elisabetta Guerzoni

• #meat and animal product quality
• #tray
• #modified atmosphere
• #atmosphere (unit)

Comparative analysis of the effects of different strategies to reduce the listeria monocytogenes growth extent in italian flash fermented sausages

Sylvain Leroy Sado Kamdem, Francesca Patrignani, Alessandra De Cesare, Fausto Gardini, Maria Elisabetta Guerzoni

• #meat and animal product quality
• #biopolymer synthesis and applications
• #protein hydrolysis and bioactive peptides
• #listeria monocytogenes