From the extensive literature review given in Chapter 1, it is evident that milk is
an important part of the diet and can also serve as a good medium for growth of
microorganisms. These microorganisms can be either pathogenic or being
undesired causing spoilage. The pathogenicity and incidence of undesired
microorganisms were reviewed and as a result one of the aims of this study was
to assess the hygienic quality of milk sold in and around Bloemfontein. The
results obtained during this study proved interesting as it showed an alarming
high percentage of these milk samples were of a poor microbial quality as they
did not confirm to the National Legislation regarding milk sold to consumers.
The importance of yeasts in the dairy industry has been highlighted on a number
of occasions by various authors. Despite indications of yeasts associated with
dairy products, especially in yoghurts and cheeses, and milk being the raw
material of these products, surprisingly few studies have been conducted on the
specific occurrence of yeasts in either raw or pasteurized milk. The results
obtained showed an ability of these yeasts to survive and proliferate in both raw
and pasteurized milk. However, the number of yeast cells was low and
insignificant to cause major problems. A wide diversity, including 14 different
species was isolated and characterized. The alarming effect remains that
predominant species like Candida albicans was found, a severe human
pathogen.
Due to concerns that some potentially dangerous and high numbers of undesired
microorganisms may derive from the dairy farm, the ability to efficiently control
these populations at the farm level seemed desirable. Consequently, the effect of
ultraviolet irradiation on the microbial loads and chemical composition of raw milk
was investigated. The results showed a 90% reduction on the microbial populations, except yeast
numbers showing more resistance being reduced by 73%. Chemical analysis
compared from results performed before and after UV radiation showed no
significant alterations in the milk composition. Based on the results obtained, it
was suggested that the usage of UV radiation on the milk resulted in an
enhanced shelf-life and better microbial quality.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-06282007-123824 |
| Date | 28 June 2007 |
| Creators | Cawe, Nangamso Buntukazi |
| Contributors | Dr A Hatting, Prof BC Viljoen |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-06282007-123824/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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