| dc.description.abstract | The microbiological and chemical aspects of the traditional manufacturing process of
Muratina (a traditional Kenyan wine) were investigated. The objective was to elucidate the
scientific basis of the process. Various aspects of the process were investigated III
traditional breweries and in experiments. The wine was obtained by fermentation of
sweetened sugarcane juice in the presence of Muratina sponges. These sponges were the
fibrous tissues of Murat ina [Fruit ofthe sausage fruit tree (Kigelia afi-icanus)].
It was revealed that colonisation of sponges with yeasts that occurred in naturally
fermenting cane juice formed the basis of Muratina manufacture. Sponges were colonized
by yeasts in concentrations of 105-106 CFU per gram of their dry matter. This was achieved
when sponges were incubated in the juice to condition them to the brewing process. Yeasts
were then concentrated to a biomass with a concentration of 109_1011 Colony Forming Units
per gram of sponge dry matter, during fermentation. Therefore, sponges were used as
inoculants in Muratina fermentation. In raw brews they achieved inoculation in the range of
105
- 108 CFU /ml. This ensured that yeasts dominated the processes from the beginning.
Alcoholic fermentation was therefore predetermined. Processes were hence successful
irrespective of contamination that came with fresh brews.
Fermentation processes required between 1 and 7 days to complete. The matured product
contained 2 - 8 %(vol) ethanol, and 0.5 - 1.4 % lactic acid, while its pH lay between 2.7 and
3.2. The use of acidic ingredients and production of acids during fermentation ensured that
fermentation processes progressed in acidic environments in between pH 3.0 and 4.0. This
limited participants in the fermentation to yeasts and lactic acid bacteria. Due to evolution of
ethanol, acids and accompanying changes in pH, bacteria were eliminated so that yeasts
dominated the process almost as pure cultures.
The maintenance of great yeast numbers in brewing units ensured process successfulness.
The capacity of sponges to immobilize the yeasts facilitated this. Recycling sponges
between processes ensured adequate inoculation was achieved in every process. On average
this was done in twenty-seven brewing cycles before they caused flavour defects in the end
product. Consequently, the old culture required disposal by washing sponges in water and
then sun drying them. This prepared sponges for re-colonisation in future brewing
processes. These aspects formed the basis of Muratina manufacture. | en |
