faculty of Science
School of Molecular and Cell Biology
9605145v
vhaakuria@yahoo.co.uk / Cassava is a food crop planted in many countries in Africa. Its tubers are a major
source of food and are processed to produce a variety of food products, one of which
is the fermented product called gari. This research report aimed to evaluate the
performance of three lactic acid bacteria for several properties with regard to the
fermentation of cassava to produce gari. Three organisms were used for the
evaluation, namely Lactobacillus plantarum, Lactobacillus fermentum and
Leuconostoc mesenteroides. The organisms were evaluated for viability, biomass
formation and glucose utilisation in static flasks, biomass formation and glucose
utilisation in 2 L fermenters, cell viability after dehydration processes and pH and
cyanide reduction in cassava substrate. In static flasks, the organisms were found to
retain above 80% cell viability after cryopreservation. Maximum biomass of 108
cells/ml was formed within the first 12 hours by all the organisms. While L.
fermentum, depleted glucose within 24 hours, L. plantarum formed the highest
biomass of 4 x 108 cells/ml. In 2 L Braunstat B fermenters, a cell count of 109 cells/ml
was obtained by L. fermentum and Leuconostoc mesenteroides within 12-15 hours.
Biomass formation for L. plantarum during the same period was 1010 cells/ml.
Glucose was depleted within 12 - 15 hours. The viability of cells between the
dehydration processes of centrifugation, glycerol and maltodextrin addition and
lyophilisation, was above 80% for all the organisms. However, this high cell viability
was influenced by concentration of cells during the centrifugation step. In cassava
substrate, L. fermentum, though heterofermentative, was found to be particularly acid
tolerant and reduced pH to 3.98. All the organisms were able to retain good viability
after lyophilisation. However, the results of cyanide reduction were inconclusive.
These results show that while cultures show promise for pilot scale studies of starter
culture development, further cyanide experiments need to be conducted, and synergy
between the organisms investigated.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/1782 |
| Date | 16 November 2006 |
| Creators | Haakuria, Vetjaera Mekupi |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 717681 bytes, application/pdf, application/pdf |
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