Joseph Allotey

Occurrence of aflatoxins, fumonisin B1, and zearalenone in foods and feeds in Botswana.

Sorghum and maize form the main dietary staple foods in Botswana. Other products such as peanuts, peanut butter, phane (an edible larval stage of an emperor moth Imbrasia belina Westwood), and pulses (cowpeas and beans) are also widely used as food and for the manufacture of feeds. These important food and feed commodities were analyzed for the presence of aflatoxins, fumonisin B1, and zearalenone. Aflatoxins were detected in 40% of the samples analyzed. The concentration of total aflatoxins ranged from 0.1 to 64 microg/kg. The mean concentration ranged from 0.3 microg/kg in sorghum to 23 microg/kg in peanut butter. Peanut butter samples were the most contaminated (71%). No aflatoxins were detected in maize. Fumonisin B1 was detected in 36% of the samples. Maize samples were the most contaminated (85% of the samples) with the concentration ranging from 20 to 1,270 microg/kg. No fumonisin B1 was detected in peanuts, phane, and beans. Zearalenone was only found in 2.6% of the samples analyzed at 40 microg/kg. Aflatoxins were the most common toxins detected in foods and feeds in Botswana. However, fumonisin B1 was more prevalent in maize than aflatoxins or zearalenone.

Quality deterioration of phane, the edible caterpillar of an emperor moth Imbrasia belina.

Abstract The cause for the deterioration of quality in phane, the edible larva of the emperor moth, Imbrasia belina (Westwood) was investigated. Samples were subjected to bacteriological and mycological analyses. In addition insect pests which affect storage life of the product were also assessed. 70% of the bacterial isolates associated with phane were proteolytic and 75% were either chitinolytic, lipolytic or both. Most isolates were sporeformers. But, other Gram-positive and negative isolates were also present in significant numbers. The most frequent fungal isolates were species of Aspergillus, Penicillium, Fusarium, Cladosporium and phycomycetes. Some of the fungal isolates are known to be mycotoxin producers. The insect which were associated with phane were Dermestes maculatus, Sitophilus zeamais, Corcyra cephalonica, Tribolium confusum, Tribolium casteneum, Oryzaephilus surinamensis, Bracon hebetor, Anisopteromalus cavandrae, and Stathmopoda species. Mites were also found infesting stored phane. The postharvest deterioration of phane appeared to be a concerted effort by the bacteria, moulds and insects.

A mycological investigation of phane, an edible caterpillar of an emperor moth, Imbrasia belina.

Phane worm (an edible larval stage of the emperor moth Imbrasia belina Westwood) is an important food source, and its harvesting is an economic activity in rural Botswana. When the larva is feeding on leaves and later during processing, phane gets contaminated with fungi from the leaves and soil. We examined 73 jars, each containing approximately 608 g (+/-0.25 g) of processed phane stored under laboratory conditions (temperature range 20 to 24 degrees C and 50 to 80% relative humidity) and combined intestinal contents of five phane squeezed into each of 74 Duran bottles for fungi. Ninety seven percent of 74 samples of intestinal contents and 57.5% of 73 laboratory-stored phane were positive for either molds and/or yeasts. Yeast population in intestinal contents ranged from 2 x 10(1) CFU/g to 5 x 10(3) CFU/g, whereas molds ranged from 1 x 10(1) CFU/g to 2 x 10(2) CFU/g. Laboratory-stored phane had a mold population of 1 x 10(2) CFU/g to 6 x 10(5) CFU/g. Species of Chaetomium 13.8%, Aspergillus 12.4%, Fusarium 5.5%, and Mucor racemosus 4.1% were the most prevalent in intestinal contents of phane, whereas Aspergillus 42.1%, Penicillium 33.9%, and Mucorales 5.7% were predominant in laboratory-stored phane. The important mycotoxigenic fungi A. flavus, A. parasiticus, A. ochraceus, P. aurantiogriseum, P. citrinum, and P. verrucosum were isolated mainly from the laboratory-stored phane. The genera isolated from both intestinal phane contents and laboratory-stored phane were Alternaria, Aspergillus, Chaetomium, Drechslera, Fusarium, Mucor, Phoma, and Penicillium, suggesting recontamination of phane during drying and storage.

The microbiology of phane, an edible caterpillar of the emperor moth, Imbrasia belina

The larvae of Imbrasia belina (Westwood) are cooked and sun dried to make a product known as phane, which is consumed as a delicacy. A study was conducted to determine the sanitary quality of phane and the kinds of microorganisms associated with it. It also looked into the potential for the existence of health risk associated with its consumption. Laboratory- and field-processed phane and that from open markets were subjected to microbiological analyses. The total microbial population for the larvae was in the range of 3 × 105 to 2 × 107 CFU/g. Species belonging to seven genera of bacteria and five genera of fungi were isolated from the larvae. About 50% of the identified bacteria were gram-positive, yet their combined population was much lower than that of the gram-negative bacteria. Cooking (89 to 93°C) under both sets of conditions (laboratory and field) reduced the microbial population to less than 9 × 103 CFU/g. The survivors were mostly sporeformers. Laboratory-processed phane was contaminated during drying, but none of the isolates were coliforms and the population increment was marginal. Field-processed phane, on the other hand, had a population of 4 × 104 to 1 ×108 CFU/g after 24 h of drying. The high moisture content of phane (55%) and a high degree of contamination from the soil and air appeared to have contributed to the increased population. Aspergilli including A. flavus and phycomycetes were frequently isolated from the samples. Coliforms were present in 30% and 50% of the phane processed in the field and in market phane, respectively. Escherichia coli and Klebsiella pneumoniae were found in 33% and 21%, respectively, of samples acquired from the market. The presence of K. pneumoniae . E. coli , a toxin-producing sporeformer ( Bacillus cereus ), and mycotoxin-producing fungi ( A. flavus , Penicillium sp., and Fusarium sp.) all point to the possible existence of health risks associated with its consumption.

Carriage of micro-organisms by domestic cockroaches and implications on food safety

Domestic cockroaches Blattella germanica were trapped from various homes in Gaborone, Botswana using ‘Dyroach’ traps. Isolations of bacteria, yeasts and moulds were done on external body parts and on the faecal pellets using various selective media. Body parts of cockroaches were also fixed with OsO4 vapour for 24 h, sputter coated with gold under special conditions and examined in a Phillips (1) XL30 ESEM in low vacuum mode. Awide spectrum of bacteria including common food spoilage and pathogenic organisms, such as Bacillus spp., Staphylococcus spp., Escherichia coli, Pseudomonas spp., Enterobacter spp., Klebsiella spp., Erwinia spp. Salmonella sp., Shigella sp. and Serratia spp. were isolated. Yeasts commonly associated with food spoilage, such as Pichia sp., Candida sp. and Torulopsis spp. were found on many cockroaches. In addition, various groups of moulds, some associated with food spoilage and others known to produce mycotoxins, such as Aspergillus flavus, Aspergillus fumigatus and Aspergillus parasiticus were isolated. Antimicrobial sensitivities of bacterial isolates revealed resistance patterns to various agents. Since cockroaches are prevalent in homes, particularly in food preparation areas and since their body parts and faecal pellets have been found in food storage areas, concern about their impact on food quality and safety is raised and possible control measures including education of communities on proper sanitation are suggested.RésuméDes blattes domestiques Blattella germanica ont été piégées dans plusieurs maisons à Gaborone, au Botswana à l’aide de pièges ‘Dyroach’. On a réalisé des isolements de bactéries, de levures et de moisissures à partir de plusieurs morceaux d’exuvie et des fèces en utilisant différents milieux de culture sélectifs. Des morceaux d’exuvie ont également été fixés avec des vapeurs d’OsO4 pendant 24 h, recouverts d’une couche d’or et examinés en microscopie électronique à balayage sous vide à l’aide d’un microscope Phillips (1) XL30 ESEM. On a réussi à isoler un vaste spectre de bactéries comprenant des organismes pathogènes et présents dans les déchets de nourriture tels que Bacillus spp., Staphylococcus spp., Escherichia coli, Pseudomonas spp., Enterobacter spp., Klebsiella spp., Erwinia spp., Salmonella sp., Shigella sp. et Serratia spp. Des levures fréquemment associées aux déchets de nourriture, telles que Pichia sp., Candida sp. et Torulopsis spp. ont été trouvées sur plusieurs blattes. De plus, plusieurs groupes de moisissures, certains associés aux déchets de nourriture, d’autres connus pour produire des mycotoxines tels qu’Aspergillus flavus, Aspergillus fumigatus et Aspergillus parasiticus ont été isolés. Des tests de sensibilité aux antibiotiques appliqués à plusieurs isolats bactériens ont permis la mise en évidence de forme de résistance à différents antibiotiques. Dans la mesure où les blattes sont très communes dans les habitations, en particulier sur les lieux de préparation des aliments et où leurs exuvies et leurs fèces ont été trouvés dans les lieux de stockage de la nourriture, on a pumontrer l’importance de leur impact sur la qualité et l’innocuité de la nourriture, imaginer des mesures de prévention et suggérer l’éducation des communautés sur des mesures sanitaires adaptées.