3.4. Microbiological analysis
The total count of bacteria and yeast were increased rapidly
until 9 days of fermentation and thereafter continued
to decrease (Fig. 2). The decreased number of bacteria
and yeast after 9 days of fermentation was likely caused
by acid shock (low pH), which influenced the multiplication
of bacteria and yeast. Chen and Liu (2000) reported
that anaerobic and starved environment created could also
be the reason for the decrease in microbial content during
the fermentation period. Carbon dioxide generated as a
result of alcohol fermentation by yeasts accumulated in
the interface between the pellicle and broth. This separates
the pellicle from the broth and creates an anaerobic and
starved environment due to block of transfer of nutrients
from broth to pellicle and transfer of oxygen from the surface
of the pellicle to broth