Bacterial contamination determination and performance of a solar heater in the pasteurisation of cow milk in Western province, Zambia.

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Chibwe, Mary
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The University of Zambia.
Although milk contains many nutrients necessary for growth, raw milk may harbor numerous pathogens. The milk pathogens may be shed in harvested milk from an infected animal and may transmit zoonotic diseases. Consumption of raw milk is common in developing countries. However, milk needs to be pasteurised to render it safe for human consumption. In resource poor communities milk pasteurization is hindered due to lack of access to electricity and heat energy forcing people to consume raw milk. In this study, the presence of pathogens in raw milk was investigated and the identified pathogens were subjected to solar heating in order to determine the possible u province was collected. The collected milk was subjected to bacterial contamination determination and identification of selected bacterial species. Escherichia coli, Staphylococcus aureus and Bacillus species were identified as the major contaminants. Milk contaminated with these pathogens was subjected to heating using conventional methods and solar heating in the months of April, May, June and July 2017. Furthermore, other organisms that included Salmonella and Methicillin resistant Staphylococcus aureus were also subjected to solar heating. Further, 63 farmers who supplied milk to the milk collection centres in the study area were interviewed in order to capture bio-data, milk handling and consumption practices. The results indicated that solar heating is not effective in the cooler months of the year. It was also observed that sterilized milk allows rapid bacteria proliferation when contaminated compared to raw milk suggesting the presence of intrinsic antimicrobial factors in unsterilized milk. Pasteurization using electricity is expensive for rural communities and solar energy is a cheaper source of energy which can be used to inactivate pathogens in the months with no cloudy cover. This study also demonstrated that consumption of raw milk is a common traditional practice in western province where knowledge and application of good hygiene practice during milk collection, storage and transportation is inadequate. There is need to discourage consumption of raw milk and promote boiling of milk using affordable and environmentally friendly methods. More milk collection centres need be established and the traditional farmers should be trained in milk handling.
Thesis of Masters of Science in Public Health and Zoonoses.