Safety assessment of some traditionally fermented foods produced in Nigeria and South Africa

D.Tech. (Food Technology)Abstract: Traditional fermented foods from cereals and leguminous oil seeds contribute significantly to the energy and protein requirements of many households across Africa. Their production in many sub-Saharan African countries is still a household art and is influenced by chanced inoculants, which in some cases, compromise their quality and safety. Different locations within South-west Nigeria and Gauteng Province of South Africa were sampled between February 2015 and July 2016 to establish the quality and safety of traditionally fermented products (ogi, ogi baba, ugba, iru, ogiri, mahewu and umqombothi). During this period, a descriptive cross-sectional study was carried out within the sampling regions amongst 86 fermented food sellers using open and close-ended questionnaires to establish their perceived attitudes, practices, and knowledge of fungal colonization, being an antecedent to mycotoxin contamination. Ninety-eight percent of the respondents could not link fungi colonization to mycotoxin contamination and associated health risks while majority (61%) of the respondents only had primary education. Furthermore, 11% of the respondents had no formal education and their educational levels slightly correlated (r = 0.308, p < 0.01) with the level of awareness. The chemical properties of the fermented foods as well as their microbiological quality were investigated including the occurrence of bacteria, mycotoxigenic fungi, endotoxins and mycotoxins. The pH, total titratable acidity and moisture content of the samples ranged from 3.62 - 8.07, 0.12 - 1.20% lactic acid and 27.5 - 94.7%, respectively, and umqombothi samples had the highest water activity (mean: 0.91) and moisture content (mean: 94.7%). The mean total aerobic plate counts of the samples were between 5.50 x 105 and 6.59 x 1010 CFU/g, 450 bacteria isolates were identified amongst which 42% (190) were Gram-negative. Sphingomonas paucimobilis, the most frequently occurring bacterium was detected in 24% of the samples, while the model organism for endotoxin production Escherichia coli, was isolated from 9% of the samples. The presence of endotoxins in the samples was assayed by the Limulus Amebocyte Lysate (LAL) method and the lowest endotoxin contamination level occurred in ogi from Nigeria (42.90 EU/g) while the highest was from iru from Nigeria (5.49 x 104 EU/g). Cronobacter sakazakii and Acinetobacter haemolyticus species were only isolated from ugba and umqombothi samples. Gram-positive bacteria were isolated less frequently and included: Paenibacillus polymyxa, Bacillus oleronius, Enterococcus durans and Enterococcus..