Abstract:
Dagaa (Rastrineobola argentea) is one of the most important fish foods for the lowincome
households
in
the
Nyanza
Province,
Kenya.
However,
the
off-flavour
and
offodour
that
results
from
the
traditional
sun-drying
process
of
sun-dried
dagaa
is
a
major
disincentive
to
the use
of
the
fish
for
human
consumption,
hence
leading
to
utilization
in
animal
feed.
Chemical
analyses
for
pH,
Thiobarbituric
reactive
substances
(TBARS),
Total
volatile
bases-nitrogen
(TVBN)
and
aerobic
bacterial
counts
were
carried
out
on
dagaa
sampled
from
various
process
steps
within
the
open
field
sun-drying
and
market
conditions.
Dagaa
was
also
oven-dried
at
30
C and
50
o
o
C, 40
o
C after washing with selected solutions namely salted (3% sodium chloride),
chlorinated solutions (100ppm) and potable tap water (control). Results indicated that
TBARS values increased significantly (p<0.05) from 1.39 mgMA/kg in fresh fish to
10.55 mgMA/kg in the market samples. The TVBN values increased significantly
(p<0.05) from 9.42 mgMA/kg in fresh fish to 29.51 mg/ 100g in the market samples.
The pH values declined significantly (p<0.05) from pH 6.72 in the fresh fish to pH
5.88 in the market samples .Lipid oxidation (TBARS) was significantly (p<0.05)
higher in dagaa subjected to salted-wash treatments when compared to the chlorinated
and control-wash treatments. The rate of lipid oxidation was significantly (p<0.05)
higher at elevated temperatures of 50
C conditions. The
TVBN levels observed in the salted and chlorinated-wash treatments showed
significantly (p<0.05) lower TVBN values when compared with the control-wash
treatments. However, the values of TVBN obtained at 30
o
o
C relative to 30
o
C and 40
C were significantly
(p<0.05) higher when compared with the 40
o
C drying temperature
conditions. The salted-wash treatments resulted in lower pH values relative to the
chlorinated and control-wash treatments on drying at 30
o
o
C and 50
C. In this study, the
most appropriate treatment that showed the least TVBN and moderate TBARS values
was drying the dagaa at 50
o
o
C and 40
C after washing with chlorinated solution.
o
