Abstract:
Utilization of cassava, which contributes 22% of the gross agricultural product in
Ghana, is limited by its high perishability, low protein content and toxicity due to the
presence of the cyanogenic glucoside, linamarin and lotaustralin. Akyeke, a fermented
and granulated, steamed-cooked cassava meal consumed extensively along the
southwestern parts of Ghana is one of several products prepared from cassava in order
to reduce postharvest loss of the crop. Fermenting grated cassava for 5-7 days with an
inoculum, water is added several times to remove some amount of starch and colour
from the fermented cassava mash, dewatered, sifted and sun dried before steaming.
During fermentation, a breakdown of the texture of cassava dough occurs to give a
smooth and non-rubbery texture.
The microflora of Akyeke inoculum and the inoculated fermenting cassava dough
were examined to determine microbial and biochemical changes associated with
fermentation of cassava into Akyeke as well as detoxification of the product during
fermentation.
The microflora in Akyeke inoculum and during fermentation were dominated by
Bacillus spp., lactic acid bacteria and yeasts.The Bacillus species identified were
Bacillus subtilis, Bacillus licheniformis, Bacillus cereus, Bacillus pumilus and
Corynebacterium. sp. Isolated lactic acid bacteria were Lactobacillusplantarium,
Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus salivarius and
Leuconostoc mesenteroides at levels of 109 to 1010 in both laboratory and field samples.
Yeasts species Candida tropicalis, Candida krusei, Zygosaccharomyces
florentinus and Geotrichum candidum.
Bacillus sutilis, Candida tropicalis and Zygosaccharomyces florentinus were found to
be responsible for the disintegrated cassava tissues when plated directly on sterile
cassava slices
Titratable acidity expressed as lactic acid increased from 0.38%-0. 32% to
1.67%-l. 11 % after fermentation for field and laboratory samples respectively. pH
dropped from 5.15 to 3.21 after fermentation. The large number of lactic acid
bacteria, low pH and high acidity confirms the fermentation of cassava in the
production of Akyeke to be lactic acid fermentation.
There was substantial reduction of total cyanide from 69.3 and 110.3 mg/kg to 1.4 and
2.8 mg/kg for field and laboratory' samples respectively.
