The influence of aerosolized microorganisms on the safety and quality of fortified biscuits

Thesis (M. Tech.(Environmental Health)) - Central University of Technology, Free State, 2005

As the concentration of dust has been shown to be proportional to seasonal change in the Free State Province of South Africa, one might expect the prevalence of associated microorganisms to follow the same pattern. The presence of dust is also associated with an aerosolised microbial population that gets blown into almost any unsealed environment including food storage facilities at schools. In addition, facility design and storage practices at these schools are under-developed and could subsequently lead to the contamination of stored food by dust, insects and rainwater. The foods in question include fortified biscuits that are intended for malnourished, and in several cases immunocompromised, children who are susceptible to opportunistic pathogens. Therefore this study aimed to determine the impact of facility design on the level and distribution of viable airborne microorganisms (fungi and bacteria) in the storage rooms and the outdoor environment at both rural (higher dust exposure) and urban schools. Besides the pathogenicity of these organisms, their ability to degrade the sugars (major fortifying agent) in the mentioned biscuits was also established. The results showed the presence of Escherichia coli, which signifies faecal contamination and could be attributed to the lack of toilet facilities in the schools, especially in rural areas. Although Staphylococcus sp. is normally related to poor personal hygiene practices, these organisms were also isolated from the air of the storerooms and school premises. The presence of moulds and airborne microorganisms was attributed to unfavourable environmental conditions as well as crowding in the classrooms. The microbial contamination originally present on the fortified biscuits or originating from the air further caused deterioration in the quality of the food. The fungi present in the air (identified species) cause respiratory problems when inhaled by children as they are opportunistic pathogens. It is further evident that a change of season corresponded to a general change in bioaerosol composition, such as the increased presence of dust during the winter months. It was further concluded that schools situated in different environments (urban/rural) should have storerooms that address the various environmental factors influencing bioaerosols. This would impact not only directly on the health of children in terms of their exposure to possible allergens, but also indirectly through the food that they consume as part of the feeding programme.