Safety of Street-Vended Soy Wara in Nigeria

Soy wara is a common ready-to-eat food whose production and sale are currently unregulated. Microbiological sampling indicated that 21% of the samples had standard plate counts exceeding 100,000 CFU/g, and 14% had Staphylococcus aureus counts higher than 100,000 CFU/g. The occurrence of S. aureus at these levels can result in food poisoning. Listeria monocytogenes was isolated in 14.4% of the samples, although the counts were generally low, typically <1,000 CFU/g. Although counts of L. monocyto genes were low, immunocompromised individuals and children may particularly be at risk of listeriosis. All samples showed low counts of Bacillus cereus (<10,000 CFU/g). Escherichia coli and Salmonella enterica were detected in 5.6 and 2.2% of all samples, respectively, indicating fecal contamination and possible links to gastroenteritis and enteric fever. Fungal counts were variable, ranging from 6.0 x 10(3) to 2.0 X 10(4) CFU/g, with Alternaria spp., Fusarium spp., and Rhizopus spp. being the predominant species. Aluminum content was as high as 0.776 mg of Al per g in soy wara processed with alum. Significantly higher aluminum contents were observed in alum-processed soy wara compared with those processed with lime or ogi (an acid-fermented gruel of either maize [Zea mays], sorghum [Sorghum bicolor], or millet [Pennisetum glaucum]) (P < 0.05). These results indicate the need to improve personal hygiene and environmental sanitation in the production and preparation of soy wara, and further studies are warranted for the implication of the accumulation of aluminum.