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International Journal of Aquaculture, 2014, Vol.4, No.21 123
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130
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smoking (24 hours), 6, 12 and 18 weeks of storage.
The assessment was based on taste, flavour, texture,
appearance and odour (overall acceptability). The fish
flesh overall score was given to both control and
treated groups (5 – 20% salt and pepper spice mixture)
using a hedonic scale of 1-7, fish scoring less than 2
being regarded as unacceptable. The overall
acceptability of the smoked
C. gariepinus
were higher
after 24 hours smoking than value on 6, 12 and 18
weeks, the acceptability decrease as weeks of storage
increased and increased as the concentration of salt
and pepper spice mixture increased, they were
significantly different (p <0.05) among the treatments
and this results show that 20% salt and pepper spice
mixture were more acceptable (4.15) compared to the
control (3.03) at 18 weeks. The result of organoleptic
assessment shows that salt and pepper spice mixture
retards the activities of bacteria, enzymes and
chemicals in fish. This is due to the movement of
water out of bacteria cell that is more than into the cell
and this result is in agreement with the report of
Omojowo
et al.
(2010).
3 Conclusion
This study demonstrated the effect of smoking, salt
and pepper spicing on proximate composition,
biochemical parameters, microbial loads and
organoleptic assessment of smoked
C. gariepinus
during 18 weeks ambient storage. Using pepper and
salt spice mixture may be useful in improving the
shelf life and consumer acceptability of smoked
C.
gariepinus
and it was concluded that 20% spice
mixture would positively influence shelf life, reduce
and prevent pathogens in smoked
C. gariepinus
.
4 Materials and Methods
4.1 Sample collection and treatment
Ninety (90)
C. gariepinus
(1000-1250g) was
purchased from the Research and Teaching Farm of
the Department of Aquaculture and Fisheries
Management, University of Ibadan, Nigeria. The fish
were acclimatized for two weeks before the
commencement of the experiment. The fish were
killed by severing the spinal cord with a sterile knife
and aseptically eviscerated, washed and rinsed in
distilled water and placed on a white tray. The
prepared weight to weight spice mixture of pepper
50% and salt 50% was neatly rubbed on the
C.
gariepinus
with different concentrations after degutting:
E
1
= 0%, E
2
= 5%, E
3
=10%, E
4
= 15%, E
5
= 20%. The
C.
gariepinus
were bent, hooked together with
palm-tree material and were cold smoked in an oven
between 40
℃
to 65
℃
for 6 hours and hot smoked
between 120-150
℃
for 18 hours for proper drying.
The
C.
gariepinus
were removed after 18 hours,
allowed to cool and placed in perforated plastic
containers. Each treatment was separately placed in a
plastic container in the office for further assessment.
4.2 Isolation of microorganism/counts
Five grammes (5g) representative sample was
obtained aseptically from the loin muscle of the
smoked catfish,
Clarias gariepinus
and were
separately macerated and put into sterile capped test
tube containing sterilized peptone water and
homogenized (Shalaby
et al.,
2006). Serial dilution
was carried out and 1ml each from 10
-1
to 10
-6
dilution
factors were dispensed into Petri dishes that were
appropriately labelled and molten sterile medium
(MacConky agar for total viable count) was poured
aseptically into each Petri dish. The plates were
swirled gently for even distribution of inocula and
allowed to set /gel and then incubated at 37
℃
for
24-48 hours. The organisms grew into visible different
colonies after 24 hours. Visible colonies were counted
and recorded as Total viable count, the result were
expressed in cfu/g.
4.3 Biochemical assessment
Total Volatile Base (TVB), Free fatty acid (FFA),
peroxide value (PV) and Thiobarbituric acid level
(TBA) were determined.
4.4 Free fatty acid determination (FFA)
10g of the sample (melted fat) was mixed with neutral
solvent and titrated with aqueous 0.1M Sodium
hydroxide and shaken constantly until a pink colour
which persisted for 15 seconds was obtained. The
values were calculated as;
FFA = Titration value (mL) ×weight of Oleic acid /
Weight of the sample used (Pearson, 1968).
4.5 Total volatile base value (TVB)
The total volatile base values were determined using
Conway micro-diffusion method (Conway, 1968). The
values were calculated as;
TVB = (ml of HCl)/(ml of NaOH) = (mlA- mlB ×f ×
96 ×14 ×100)/(2 ×25 ×100).