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Research Publications (Applied Sciences)

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    Inactivation of Listeria monocytogenes ATCC7 644 Biofilms using Sodium Dodecyl Sulphate, Levulinic Acid and Sodium Hypochlorite solution
    (MN Khan, 2014-06) Singh, Suren; Mnyandu, Elizabeth; Oluwatosin Ademola Ijabadeniyi
    A study was done to assess the effectiveness of 200 ppm sodium hypochlorite (chlorine), 1% sodium dodecyl sulphate (SDS) and 0.5% levulinic acid in reducing L. monocytogenes ATCC7644 biofilms. 0.05% SDS and 0.5% levulinic acid were also used combined (mixture). After treatment with sanitizers, the biofilms were stored at 4°C for up to 72 hours and samples were tested at 0, 24, 48 and 72 hours. The contact times were varied to 1, 3, 5 minutes. Results revealed that biofilms were still viable after treatment with these sanitizers. There was no significance difference between storage times. Varying contact times from 1 to 3 minutes did not show a significance difference however there was a significance difference when the contact time was increased to 5 minutes. Non-adapted biofilms had highest log reductions compared to chlorine adapted and heat adapted biofilms. Treatment with chlorine was least effective in reducing viability of biofilms, followed by levulinic acid then a mixture of levulinic acid and SDS. SDS used alone had highest log reductions. Application of sanitizers at different contact times combined or individually may be successful in reducing biofilms in food manufacturing units. A careful selection of sanitizer for each specific pathogen may be required if sanitizers are to work effectively against biofilms.
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    Irrigation water and microbiological safety of fresh produce : South Africa as a case study : a review
    (Academic Journals, 2012-09-11) Ijabadeniyi, Oluwatosin Ademola; Buys, E. M.
    Irrigation water is perhaps the leading pre-harvest source of contamination of fresh produce in the world. In this review, the impact of contaminated surface irrigation water on bacterial contamination of fresh produce was examined. Some practical solutions to prevent or reduce this challenge were also considered. In South Africa, fruit and vegetables are produced on a large scale by commercial farmers who depend on surface water for their cultivation. However, the surface water, that is, rivers- has been reported to be heavily contaminated with Escherichia coli and feacal coliforms. There is a concern that contaminated surface water used for irrigation may contaminate fresh vegetables which may also have a negative effect on the export of vegetables to the EU and USA. Consumption of vegetables contaminated with foodborne pathogens presents a public health risk especially in countries like South Africa that has more than 5 million people with immune-system compromised diseases such as HIV and tuberculosis. Other groups of people that may be negatively affected because of the contaminated surface water are those who are directly and indirectly associated with the production of fresh vegetables such as pickers, handlers, packers and farmers that participate in the production of vegetables during pre-harvest and post-harvest. Prevention of contamination of fresh produce from both pre-harvest and post-harvest sources especially irrigation water still remains the only effective way to protect the public. However, for this to occur, every stakeholder in the production industry must have a culture of food safety.