Basic HTML Version
International Journal of Aquaculture, 2014, Vol.4, No.21 123
-
130
http://ija.biopublisher.ca
126
decrease in crude protein of preserved
Oreochromis
niloticus.
The fat content of smoked
C. gariepinus
increased
significantly at 18 weeks compared to the values
obtained after 24 hours after smoking, this might be
due to loss of moisture and an increase in the dry
matter content per unit of weight following sample
dehydration. The values of crude fibre showed a
decrease in all treatments at the end of the experiment.
There was a general increase in ash content of the
smoked
C. gariepinus
at 18 weeks and this may be
attributed to the salt uptake during smoking as
reported by FAO (1992). Also, this finding is similar
to the work of Oetterer et al., (2003).
Measurement of peroxides value is used to estimate
the degree of rancidity and the result of the peroxide
value revealed that the values increased as the storage
period increased and the treated groups recorded
lower values of peroxides value compared to the
control and there were significant differences (p<0.05)
among the treatments. Also, results obtained from the
study showed that the values decreased as the
concentration of salt and pepper spice mixture
increased. A similar result was observed by Antonia da
Silva et al, (2008). The results of Thiobarbituric acid
revealed that the values increased as the weeks of
storage increased and the treated groups recorded
lower values of Thiobarbituric acid compared to the
control and there were significant differences (p<0.05)
among the treatments. This might be as a result of
anti-oxidant properties present in pepper and
antimicrobial properties present in salt (Ravishankar
and Juneja, 2000).
The result of free fatty acid in this present study
revealed that the values were higher at 24 hours after
smoking and the values decreased as the weeks of
storage increased. Although the study showed lower
values at 6 weeks and increase in values at 12 and 18
weeks, the values recorded in the treated groups were
better than the control. There were significant
differences (p <0.05) among the treatments. The
values of free fatty acid recorded in all the treatments
decreased as the concentration of salt and pepper spice
mixture increased. This might be as a result of the
mechanism of action of pepper and salt spice mixture.
The result of total volatile base revealed that the
values increased as the weeks of storage increased and
the treated groups recorded lower values of total
volatile base compared to the control and there were
significant differences (p<0.05) among the treatments.
Also, the values decreased as the concentration of salt
and pepper spice mixture increased. The results of
total volatile base shows that the values obtained were
still within the limit of acceptability of fish which is
30-mg N per 100g (Eyo, 2001).
The aim of bacteriological test is to determine
qualitatively and quantitatively the microbial flora that
is harboured by the skin, gut, gills and tissue of fish.
The results of the study revealed lower microbial
loads at 24 hours after smoking with highest value
(2.91 log
10
cfu/g) of total viable count recorded in
control and the least in 20% salt and pepper spice
mixture (2.26 log
10
cfu/g). At 18 weeks, significant
increase in values of total viable count were recorded
with highest value in control (53.31 log
10
cfu/g) and
least (8.13 log
10
cfu/g) in 20% salt and pepper spice
mixture. The reason for this might be as a result of
increase in moisture content of all the treatments at 18
weeks, high pH and temperature that might tend to
encourage the growth of microorganisms. These
values decreased as the concentration of salt and
pepper inclusion increased. There were significant
differences (p<0.05) among the treatments, the treated
groups recorded decrease in microbial loads compared
to the control which could be attributed to the
antimicrobial properties present in salt (Ravishankar
and Juneja, 2000) and anti oxidant properties in
pepper (Deni, 1996). Antimicrobial action suppresses
growth for extended periods of time, assuring a longer
shelf life and increased product safety
Also, isolation, identification and characterization of
microorganisms were done at the end of the
experiment to ascertain the presence of food borne
pathogens present in the fish, the results revealed the
presence of
Staphylococcus aureus, Clostridium
welchii, Proteus morganii, E. coli
and
Bacillus subtilis
from smoked
C. gariepinus
at 18 weeks and the
effects on the fish which can create serious public
health hazards (ICMSF, 1986)
Organoleptic assessment is very important in quality
assessment and the quality of the smoked fish (both
treated and untreated) was evaluated immediately after