A literature review on the role and presence of microorganisms in cheese was
reviewed. The biochemical pathways involved in the cheese manufacture from the
milk to the resultant cheese curd at the end of manufacturing were also reviewed. The
activity of microorganisms used in cheese manufacture and microorganisms isolated
from cheeses were also discussed and their role in the cheese curd formation.
Yeasts, one of the microorganisms isolated from cheeses, were reviewed in detail.
The use of yeasts as adjunct starter cultures in matured Cheddar cheese was
investigated. The yeast cultures (Yarrowia lipolytica, Debaryomyces hansenii,
Torulaspora delbrueckii and Dekkera bruxellensis) were inoculated in milk for the
manufacture of matured Cheddar cheese as adjunct starter cultures. The yeast
cultures supported the role of the starter culture (LAB) รข lactose fermentation, and
assimilated the organic acids present and inhibited spoilage microorganisms. The
growth of the yeast and LAB was mutualistic in all the cheeses and no defects were
detected in the cheeses as observed by the favourable sensory scores for the yeast
inoculated cheeses.
Co-inoculation of yeasts in the making of matured Cheddar cheese resulted in
enhanced survival of the yeasts and the LAB population in the cheeses. The yeasts
exhibited increased growth, without suppressing the viability and activity of LAB.
Organic acids which are associated with aroma and flavour compound production
were increased in the cheeses. The cheese inoculated with Dekkera bruxellensis +
Yarrowia lipolytica had superior Cheddar cheese scores which were greater than 5 as
well as the cheese single inoculated with Dekkera bruxellensis. The pH
measurements of the cheeses indicated the deacidification abilities of the yeasts and
the spoilage inhibiting acidity in the cheeses. Free amino acid accumulation in
cheeses was also investigated. It was observed that the yeast inoculated cheeses
had greater free amino acid accumulation compared to the control cheese. The
dominant amino acids were Leu and GABA amino acids in all the cheese samples and
low concentrations were observed for the other amino acids.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-11112011-110048 |
| Date | 11 November 2011 |
| Creators | Mehlomakulu, Ngwekazi Nwabisa |
| Contributors | 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-11112011-110048/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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