G. O. Adegoke

Storage of maize and cowpea and inhibition of microbial agents of biodeterioration using the powder and essential oil of lemon grass (Cymbopogon citratus)

Within a storage period of 10 days, samples of maize and cowpea treated with lemon grass powder and essential oil showed no physical deterioration. Off-colour, off-odour and mouldiness however characterized untreated control samples of maize and cowpea. The essential oil of lemon grass also inhibited the growths of moulds like Aspergillus flavus, A. fumigatus, Microphomina phaseoli and Penicillium chrysogenum and bacteria such as Escherichia coli, Pseudomonas aeruginosa, Ps. fluorescens, Bacillus subtilis and Staphylococcus aureus. Phytochemical components like alkaloids, tannins and cardiac glycosides found in the powder are believed to be associated with the preservative and antimicrobial effects of lemon grass.

Inhibition of food spoilage yeasts and aflatoxigenic moulds by monoterpenes of the spice Aframomum danielli

Essential oil monoterpenes (α-terpinene, (+)-limonene, α-pinene, 1,8-cineole) of the spice Aframomum danielli were tested for in vitro antifungal activities against some food spoilage yeasts (Torulopsis candida, Candida tropicalis, Kluveromyces thermotolerans, K. fragilis, Hansenula anomala and Pichia pastoris) and mycotoxigenic moulds (Aspergillus flavus, A. parasiticus). With α-terpinene, the mean minimum inhibitory concentrations (MICs) for T. candida, K. fragilis, K. thermotolerans and C. tropicalis were found to be 4.9, 39, 78 and 156 μg/ml, respectively. With (+)-limonene, the mean MICs for T. candida, K. fragilis, K. thermotolerans and C. tropicalis were 39, 312, 39 and 312 μg/ml, respectively. The minimal fungal concentrations (MFCs) of the monoterpenes varied from 39 to 1250 μg/ml for the food spoilage yeasts examined. Within 60 min, α-terpinene (312 μg/ml) reduced the population of C. tropicalis and H. anomala from 105 to 13 cells/ml. The MIC of (+)-limonene for A. parasiticus was 78 μg/ml. As revealed by NMR, both α-terpinene and (+)-limonene caused membrane injury of C. tropicalis cells. Copyright

Influence of sundrying on the chemical composition, aflatoxin content and fungal counts of two pepper varieties —Capsicum annum andCapsicum frutescens

Samples of sundried, matured red pepper,Capsicum annum with a moisture content (MC) of 12.7–26.8 percent had on dry weight basis, vitamin C, 5.0–6.4 mg/100 g; crude protein, 0.8–1.2 percent; total soluble solids, 3.3–4.1 percent, and fungal counts of log 4.4–4.5/g. Ordinary matured redC. annum had MC, 75.7–78.2 percent vitamin C, 36.1–38.5 mg/100 g; crude protein, 2.4–2.8 percent; total soluble solids, 9.3–9.9 percent and fungal count of log 3.32–3.39/g. Sundried matured redC. frutescens had corresponding values of 9.4–18.7 percent; 5.8–6.3 mg/100 g; 0.8–1.1 percent; 0.9–2.6 percent and log 3.2–3.4/g. No aflatoxins were detected in sundried, matured redC. frutescens, but aflatoxin B1 values obtained fromC. annum varied from non-detectable to 2.2 µg/kg. Dominant fungi isolated fromC. annum andC. frutescens wereRhizopus oryzaze,Aspergillus niger,A. flavus,Geotrichum candidum andSaccharomyces spp.

Nutritional profile and antimicrobial spectrum of the spiceAframomum danielli K. Schum

The spice,Aframomum danielli, on a wet weight basis with a moisture content of 10.5%, protein content of 8.2% (dry matter basis) and caloric value of 469.7 kcal/100 g, contains in varying amounts, minerals like calcium, magnesium, sodium, manganese, phosphorus, zinc and copper. Amino acids found in varying concentrations inA. danielli include L-Threonine, L-Serine, L-Valine, L-Proline, L-Glutamic acid, glycine, L-Leucine and L-Lysine. Using minimum inhibition zone of 20–22 mm in diameter,A. danielli inhibited the growth ofSalmonella enteriditis, Psudomonas fragi, Pseudomonas fluorescens, Proteus vulgaris, Streptococcus pyogenes, Staphylococcus aureus, Aspergillus flavus, A. parasiticus, A. ochraceus andA. niger. The minimum concentration (MIC) determined forKlebsiella pneumoniae andPseudomonas aeruginosa was 1 in 320 whilst the MIC forS. aureus was 1 in 8,000.

Influence of grain quality, heat, and processing time on the reduction of aflatoxin B1 levels in ‘tuwo’ and ‘ogi’: Two cereal-based products

During the production of ‘tuwo’ from laboratory-contaminated corn (AFB1:150 mcg/kg) and sorghum (AFB1:87.5 mcg/kg) grains, reductions in the aflatoxin-B1 levels of pastes boiled for 30 min and 60 min were found to be 68.0% and 80.8%, respectively. In the preparation of ‘ogi’ from contaminated corn and sorghum grains, reductions of about 72.5% and 71.4%, respectively, were obtained after fermentation at ambient conditions. Reconstitution of ‘ogi’ paste into a porridge (akamu) considerably reduced the AFB level.

World Health Organization estimates of the global and regional disease burden of four foodborne chemical toxins, 2010 : a data synthesis

Background Chemical exposures have been associated with a variety of health effects; however, little is known about the global disease burden from foodborne chemicals. Food can be a major pathway for the general population’s exposure to chemicals, and for some chemicals, it accounts for almost 100% of exposure. Methods and Findings Groups of foodborne chemicals, both natural and anthropogenic, were evaluated for their ability to contribute to the burden of disease. The results of the analyses on four chemicals are presented here - cyanide in cassava, peanut allergen, aflatoxin, and dioxin. Systematic reviews of the literature were conducted to develop age- and sex-specific disease incidence and mortality estimates due to these chemicals. From these estimates, the numbers of cases, deaths and disability adjusted life years (DALYs) were calculated. For these four chemicals combined, the total number of illnesses, deaths, and DALYs in 2010 is estimated to be 339,000 (95% uncertainty interval [UI]: 186,000-1,239,000); 20,000 (95% UI: 8,000-52,000); and 1,012,000 (95% UI: 562,000-2,822,000), respectively. Both cyanide in cassava and aflatoxin are associated with diseases with high case-fatality ratios. Virtually all human exposure to these four chemicals is through the food supply. Conclusion Chemicals in the food supply, as evidenced by the results for only four chemicals, can have a significant impact on the global burden of disease. The case-fatality rates for these four chemicals range from low (e.g., peanut allergen) to extremely high (aflatoxin and liver cancer). The effects associated with these four chemicals are neurologic (cyanide in cassava), cancer (aflatoxin), allergic response (peanut allergen), endocrine (dioxin), and reproductive (dioxin).

A comparison of the essential oils of Aframomum daniellii (Hook. f.) K. Schum. and Amomum subulatum Roxb

Volatile oil from Nigerian cardamom (Aframomum daniellii (Hook. f.) K. Schum.) was analysed by GC and GC MS and its physicochemical and sensory properties were compared to those of large cardamom (Amomum subulatum) from India. 41 constituents were identified in A. daniellii essential oil; 1,8-cineole was the predominant constituent (59.8%), followed by beta-pinene, alpha-terpineol, alpha-pinene and alpha-terpinyl acetate (13.2, 9.3, 4.3 and 3.2%, respectively). Oil composition was similar to that of large cardamom, particularly with respect to the presence of monoterpenes and their oxygenated derivatives. However, only Nigerian cardamom oil contained alpha-terpinyl acetate, which is believed to improve the flavour quality of cardamom oils.

Bacteriocin and cellulose production by lactic acid bacteria isolated from West African soft cheese

Sixteen colonies of lactic acid bacteria (LAB) were selected and screened for their ability to produce bacteriocin by agar well diffusion method using the supernatant of centrifuged test cultures. Four isolates inhibited the growth of Listeria monocytogenes and Escherichia coli. Lactobacillus plantarum (6) and Lactobacillus brevis (5) were the most dominant species. The remaining were Lactobacillus lactis (2), Streptococcus lactis (2) and Lactobacillus fermentum (1). Lactobacillus spp. accounted for 87.5% of all isolates. LAB4 (Lactobacillus plantarum) showed some levels of antimicrobial activity after 15, 20 and 25 min heat treatments at 100oC against Listeria monocytogenes . While antimicrobial activity of LAB70 (Lactobacillus lactis) was against both Listeria monocytogenes (after 20 and 25 min) and E. coli 0157:H7 (after 15, 20 and 25 min) heat treatment at 100oC. All the lactic acid bacteria used in this study produced cellulose. The correlation between cellulose production (an adhesion factor) and bacteria growth was highly significant after 72 h of incubation having a R2 = 0.800. This study offers useful information on growth and cellulose production as factors affecting the efficacy of bacteriocin produced by these strains which could be good for biopreservation.

Strategies for the Prevention and Reduction of Mycotoxins in Developing Countries

According to the Fod and Agricultural Organization (FAO) of the United Nations, up to 25% of the world’s food crops have been estimated to be significantly contaminated with mycotoxins (WHO, 1999). Significant losses due to mycotoxins and their impact on human and animal health have been linked with national economic implications and all these factors have combined to make mycotoxins important worldwide (Bhat and Vashanti (1999). According to Plancinta et al. (1999), surveillance studies showed that world-wide contamination of cereal grains and other feeds with Fusarium mycotoxins is a global problem. Thus, in recognition of the global public health importance of food borne diseases and in order to promote economic growth and development, the World Health Organization (WHO) commissioned the Foodborne Disease Burden Epidemiology Reference Group (FERG) to undertake the systematic reviews of some chemicals and toxins like cyanide in cassava, aflatoxin, dioxins and peanut allergens (Hird et al. 2009).

Bacteriological study of West African clam (Egeria radiata Lamarch) and their overlying waters

Bacteriological examination of the natural waters in which clams ( Egeria radiata ) grow in the Cross River in Akwa Ibom State, Nigeria, showed that the waters were generally of an unacceptable quality for growing market shellfish. Egeria radiata samples collected from the waters were also found to be highly contaminated by bacteria. Mean log total aerobic bacterial count, total coliform and faecal coliform most probably numbering densities as high as 6·64, 2·18 and 1·40 per 100 ml water, respectively, were found at the most contaminated growing area. A mean total aerobic bacteria of 8·1×10 7 per 100 g meat was found on clams from this area which also showed a bacterial concentration factor as high as 1:26. The bacterial counts between the three locations studied were, however, not statistically significant ( P >0·05) with respect to any of the tests conducted. Depuration was very effective in eliminating bacteria from the clams, with a 97% reduction observed within the first 24 h of depuration.