Boerewors is a popular dish in South Africa, and it is classified as a ground meat product.
It is a fresh sausage product and the quality of the sausage is affected by the growth of
microorganisms and oxidation spoilage. Boerewors is currently preserved with 450 mg/kg
sulphur dioxide (SO2). The SO2 has antimicrobial, antioxidant and sensory properties in the
boerewors but SO2 may also have negative effects on consumer health. Natural preservatives
have become important in the food industry because consumers are moving away from
consuming chemically preserved food. Rosemary extract is a natural preservative that has been
shown to have antimicrobial and antioxidant properties. Another natural preservative that has
been studied is chitosan which is a deacetylated form of chitin derived from the shell of crabs
and shrimps and the cell wall of fungi and also has been shown to have antimicrobial and
antioxidant properties.
One of the aims of the study was to evaluate the microbiological quality of boerewors
produced in different regions of Bloemfontein and comparing the quality of boerewors from
small butcheries with supermarkets. The boerewors of 50% of the butcheries in Bloemfontein
were subjected to microbial evaluation by using aerobic plate counts (APC), psychrotolerant
plate counts (PPC), Enterobacteriaceae counts, coliform counts, yeasts and moulds counts and
determination of the presence of Staphylococcus aureus and Escherichia coli. No Staph. aureus
was found in any of the boerewors samples. The results of this study demonstrated that the
microbial quality of boerewors sold in the different regions of Bloemfontein retail outlets did not
differ significantly between the regions. The incidence of E. coli in the central region may
indicate that the socio-economic status has an effect on the quality, though the socio-economic
status was not investigated in this study. The significantly high coliform counts in boerewors
purchased from the butcher shops indicate that poor hygienic conditions exist in butcher shops compared to the supermarkets. That may be related to staff being trained in hygienic practices in
the corporate supermarket environment, while no training or very little training takes place in
butcher shops.
The second aim was to determine the effectiveness of rosemary extract, chitosan and
fungi) and sulphur dioxide (SO2) as a conventional preservative, applied individually and in
combination with each other, on improving the quality of boerewors. Eight boerewors treatments
were formulated as follows: control (Con), 450 mg/kg SO2 (S), 260 mg/kg rosemary extract
(Ros), 10 g/kg chitosan (Chi), 260 mg/kg rosemary extract + 100 mg/kg SO2 (Ros+S), 10 g/kg
chitosan +100 mg/kg SO2 (Chi+S), 260 mg/kg rosemary extract + 10 g/kg chitosan (Ros+Chi)
and 260 mg/kg Rosemary extract + 10 g/kg Chitosan + 100 mg/kg SO2 (Ros+Chi+S). Water
activity (aw), microbial properties, colour stability, lipid stability and sensory analysis were
conducted on the different sausage treatments. There were no significant differences between the
aw of the different treatments. Chitosan and chitosan in combination with other preservative
types had a significant effect (p<0.001) on reducing the total bacterial counts, coliforms and
Enterobacteriaceae counts which were comparable to the results of the SO2 treatment. Chitosan,
however, had a better effect on decreasing yeasts and moulds counts than SO2. Chitosan also
showed good colour properties which were comparable to that of the 450 mg/kg SO2 preserved
sausage. Rosemary extract showed a comparable lipid stability to those of the S treatment and it
showed significantly (p<0.001) lower TBARS values when compared to the Chi treatment. The
Ros treatment had a positive effect on the sensory taste of the sausages when compared to the
Chi treatment, but the S treatment was still preferred by the sensory panel. The reduced level of
100 mg/kg SO2 showed good synergistic effects in combination with chitosan as antimicrobial,
colour stabilizer and in combination with rosemary as antioxidant and improving the sensory
score of the sausages.
Keywords: boerewors, natural preservatives, ro
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-10172011-124425 |
| Date | 17 October 2011 |
| Creators | Mathenjwa, Simphiwe Amanda |
| Contributors | Prof A Hugo, Prof CJ Hugo |
| 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-10172011-124425/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. |
Page generated in 0.0113 seconds