Food and Nutrition Sciences, 2013, 4, 1201-1208
Published Online December 2013 (http://www.scirp.org/journal/fns)
http://dx.doi.org/10.4236/fns.2013.412154
Open Access FNS
Microbial Load (Bacteria, Coliform and Mould
Count/Flora) of Some Common Hot Smoked Freshwater
Fish Species Using Different Packaging Materials
Olusegun Ayodele Oyelese, Jacob Oyeleye Oyedokun
Department of Aquaculture and Fisheries Management, Faculty of Agriculture and Forestry, University of Ibadan, Ibadan, Nigeria.
Email: segunoyelese@yahoo.co.uk
Received July 13th, 2013; revised August 13th, 2013; accepted August 20th, 2013
Copyright © 2013 Olusegun Ayodele Oyelese, Jacob Oyeleye Oyedokun. This is an open access article distributed under the Crea-
tive Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited. In accordance of the Creative Commons Attribution License all Copyrights © 2013 are reserved for
SCIRP and the owner of the intellectual property Olusegun Ayodele Oyelese, Jacob Oyeleye Oyedokun. All Copyright © 2013 are
guarded by law and by SCIRP as a guardian.
ABSTRACT
Three different packaging materials of (37 cm × 25 cm) size (Sealed Transparent Polythene Bag (STPB) Sealed Paper
Bag (SPB) (Brown envelope), Open Mouth Polythene Bag (OMPB) (Black incolour)) were used for Oreochromis-
niloticus (O), Clariasgariepinus (C) and Mormyrusrume (M). Twenty fish samples per species (averaging 250 gm) were
hot smoked dried whole for 36 hours at an average temperature of 100˚C. Packaged hot at the rate of 6 fishes per pack-
age for each species (three packs for each packaging treatment i.e. 18 pieces were packed while the remaining 2 pieces
were used for initial bacteria load and microbial load). Microbial load (Total Viable Count (TVC), Total Coliform Count
(TCC) and Total Fungi Count (TFC)) for the fresh fish was initial hot smoked and finally at the end of 12 weeks was
monitored. The TVC (bacterial load) of O. niloticus dropped from (10.6 - 8.4) × 104 (fresh state-hot smoked) and M.
rume (9.8 - 7.0) × 104, while C. gariepinus slightly in creased from (12.4 - 12.6 ) × 104. After hot smoking, highest TVC
of 8.6 × 104 (OMPBC), 8.3 × 104 (SPBC) and 8.2 × 104 (STPBC) was recorded in C. gariepinus among the 9 packag-
ing at 12 weeks. However highest tendency for heavy TVC is in all OMPB with highest bacteria load in the OMPBC
(8.6 × 104), 7.6 × 104 (OMPBO) and 6.6 × 104 (OMPBM). After 12 weeks highest ranged TFC of (0.6 - 0.7) × 10 4 was
recorded in M. rume as against 0.2 × 104 recorded in the initial smoked for all. TCC was high est in C. gariepinus (4.0 -
4.3) × 104. Packaging did not limit the existence of micro-organisms. Six bacteria species (Micrococcus (acidiophilus,
luteus), Bacillus (subtilis, cereus, aureus), Staphylococcus aureus, Streptococcus lactis, Proteus (vulgaricus, morganii),
Pseudomonas aureginosa) and three fungi species (Aspergillus (niger, tamari), Rhizopusnigricans, fusariumoxysporum)
were repr esen ted in all th e pack ag es. On the av er age f ive bacteria and two fungi species were represented, excepting for
OMPBM and OMPBO with six bacteria species.
Keywords: Bacteria; Coliform; Mould Count/Flora; Freshwater Fish Species; Packaging Material
1. Introduction
Bacteria are unicellular microscopic organisms which
occur almost everywhere in nature. Up to 1500 species of
bacteria have been isolated since bacteria are living
things; they acquire a source of food, moisture and suit-
able temperature to grow, when thes e condition s are ade-
quate. Bacteria cause spoilage of improperly dried fish
by multiplying inside the fish flesh thereby causing pu-
trefaction. Once bacteria spoilage sets in there it is hard
to remedy. The result of bacteria attack is off odour and
flavor and when pathogenic bacteria are involved, it
could result in illness to consumer [1].
The bacteria that most often involved in the spoilage
of fish are part of the natural flora of the external slime of
fishes and their intestinal content [2]. They lamented that
the predominant kinds of bacteria causing spoilage vary
with the temperatures at which the fish are held as follows:
Chilling temperature
Species of pseudomonas
Achromebacter and
Flavobacterium
Higher temperature
Genera micrococcus and
Microbial Load (Bacteria, Coliform and Mould Count/Flora) of Some Common Hot Smoked
Freshwater Fish Species Using Different Packaging Materials
1202
Bacillus
Atmospheric temperature
Escherichia
Proteus
Serratia
Sarcina and
Clostridium
Bacteria are unicellular microscopic organisms which
occur almost everywhere in nature [1]. Up to 1500 spe-
cies of bacteria have been isolated since bacteria are liv-
ing things. They acquire a source of food, moisture and
suitable temperature to grow [3], when these conditions
are adequate. Bacteria will grow by a process known as
Binary Fission in which the cell divides into two new
cells. Some bacteria causing fish spoilage might have a
generation time of 20 minutes at 30˚C [1]. In such a case,
a single bacterium may give billions in 10 hours [4].
Whilst increase in the population of micro-organisms
by geometric progression is theoretically possible, its
practical application is limited by environment factors
prevailing. These factors are:
1) Temperature
Table 1 below shows the ranges of temperature for the
growth of micro-organism.
2) Water Content
Table 2 shows the minimum water activity for the
growth of micro-organism.
3) Acidity or Alkalinity (pH)
Bacteria grow well over a wide range of hydrogen ion
concentration pH ranging from 4.0 - 9.0. The optimum
pH growth for most bacteria lies between pH 6.5 and 7.5
although some bacteria are capable of growing at the
Table 1. Temperature ranges for growth of micro-organ-
ism.
Types of micro-organism Minimum
(˚C) Optimum
(˚C) Maximum
(˚C)
Psychrophiles 0 15 - 25 30
Mesophiles 10 37 43
Thermopliles 25 50 - 65.5 85
Table 2. Minimum water activity for growth of micro-or-
ganism [5].
Micro-organism Minimum water activity
Normal bacteria 0.90
Normal yeast 0.88
Normal moulds 0.80
Halophilic bacteria 0.75
Dryness resistant moulds 0.05
Osmotic pressure resistant yeast 0.61
extremes of the pH ranges. Bacteria growth and toxin
production are inhibited if the conditions are more lethal
to micro-organisms than alkaline [6].
4) Nutrient Composition
Bacteria are living organisms and like other living
things such as plants and animals, they require a source
of energy to survive. Such energy can be obtained from
sunlight or by breakdown of nutrients which are mainly
carbohydrates, proteins, fats and oil, vitamins and other
growth factors. The breakdown of each of these nutrients
requires the possession of the appropriate enzymes by
bacteria [1,6].
1.1. Bacterial in Smoked Fish
Smoked fish and shellfish products can be a source of
microbial hazards including listeria monocytogenes, Sal-
monella species and Clostridium botulinium, L. mnono-
cytogens has been identified in several food borne out-
breaks, in which pasteurized milk, coleslaw and soft
cheese were implicated [7]. These organisms have also
been isolated from a variety of fish and shellfish products
[8].
1.2. Fungal Attacks in Smoked Fish
Insufficient dried fish (still containing approximately
40% moisture) especially at the processing location are
prone to fungal infection, principally from the non-spe-
cific Penicillium spp., Aspergillus spp. Substantial quali-
ties of fish are usually discarded during drying due to
fungal growth. Fungal spp. also associated with smoked
fish include: Aspergillus fumigates, Absidia spp., Rhizo-
pus spp., Mucor spp., Cladosporium spp. [9-12]. It was
observed that though smoking fish provides longer shelf
life than other preservative methods, smoking will be
effective if properly done (especially to reduce packag-
ing).
Adebayo-Tayo et al. [9] identified 12 different fungi
and aflatoxin B1 and G1 in three main markets in Nigeria
on smoked dried fish with moisture content ranging from
22.7% - 27.6%. He said the level of infestation might be
due to high percentage of moisture content of the smoked
fish.
2. Materials and Methods
2.1. Collection of Samples\Packaging
Twenty pieces (sample) of each fish species of average
weight 250 grams were collected for Oreochromisniloti-
cus (O), Clariasgariepinus (C) and Mormyrusrume (M).
Also fresh samples were collected for the initial proxi-
mate analysis while the remaining fresh fishes were
transported to the processing unit for smoking. After
Open Access FNS
Microbial Load (Bacteria, Coliform and Mould Count/Flora) of Some Common Hot Smoked
Freshwater Fish Species Using Different Packaging Materials 1203
which the initial proximate analysis of the hot smoked
fish was also taken before packaging in the 37 cm × 25
cm packaging materials for each of the smoked fish spe-
cies (using each of the three different packaging material
for each fish species) at the rate of six (6) fish species per
package and labeled e.g. for Oreochromis (STPBO—
Sealed Transparent Polythene Bag Oreochromis, SPBO—
Sealed paper Bag Oreochromis, OMPBO—Open Month
Polythe ne Bag Oreochromis.
2.2. Hot Smoking of the Fish Species
The smoking kiln was locally improvised. Three broken
blocks each of 0.3 m height was used to raise the wire
gauze (on which the fish were laid) to avoid direct con-
tact with fire. Big wire gauze of mesh size 2 cm was set
on the fire when the fire was fully lit. The three species
of the fish to be smoked were placed on the gauze. Big
aluminum basin with a opening at the centre was used to
cover the fish species in order to conserve the fire. It was
through the opening that the temperature of the smoking
kiln (chimney) was taken daily, until the three fish spe-
cies were hot smoked dried. Hot smoking was done for
36 hours (this was achieved in three days at an average of
12 hours smoking per day) at an average temperature of
100˚C.
Hot smoking was done with an exotic hard wood
(Eucalyptus species), collected from the Forestry De-
partment of the University of Ib adan. Turning of the fish
species were done at the same time to maintain uniform
drying\smoking at an interval of one hour (1.5 hr) thirty
minutes for 3 days.
2.3. Packaging and Shelfing
After three days of intensive smoking, each species of
the three freshwater fish species were packaged under
three different packaging materials (Sealed Transparent
Polythene Bag (STPB), Sealed Paper Bag (SPB) (Brown
envelope), Open Mouth Polythene Bag (OMPB) (Black
in colour)) under room ambient temperature range of
25˚C - 32˚C for 12 weeks. Mould growth: insect infesta-
tion was checked daily during this period for each of the
fish species.
The three different materials used were:
A. Sealed Transparent Polythene Bag (STPB)
1. Tilapia (Oreochromisniloticus) (STPBO)
2. Clariasgariepinus (STPBC)
3. Mormyrusrume (STPBM)
B. Sealed Paper Bag (SPB)
1. Tilapia (Oreochromisniloticus) (SPBO)
2. Clariasgariepinus (STBC)
3. Mormyrusrume (STBM)
C. Open Mouth Polythene Bag (OMPB)
1. Tilapia (Oreochromisniloticus) (OMPBO)
2. Clariasgariepinus (OMPBC)
3. Mormyrusrume (OMPBM)
The fishes were packaged hot in the packaging bags
and stored in the laborator y for 12 weeks.
2.4. Preparation of Media
All analytical procedures in this study are according to
the A.O.A.C [13].
2.4.1. Nutrie nt Agar
Twenty eight (28) grams of powdered commercially
prepared of nutrient agar was weighed on Analytical
metller balance into a clean dry 1 litre conical flask and
1000 ml of distilled water placed inside a water bath set
about 90˚C, allow the agar to dissolve. Distribute them
into MacCantney bottles and placed them inside auto-
clave and set the autoclave at 121˚C for 15 mins.
2.4.2. Macconkey Agar (Mcca)
Fifty five (55) grams of macConkey Agar was weighted
into a 1 litre capacity of conical flask and brings to boil
to dissolve the agar. Distribute them into Mac Cartney
bottles and autoclave as for Nutrient Agar.
2.4.3. Potato Dextrose Aga r (PDA)
Thirty nine (39) grams of PDA was weighted into a 1
litre capacity of conical flask bring to boil an d distributed
them into Mac Cartney bottles and placed them inside an
autoclave as for Nutrient Agar.
2.5. Pouring of Plates
After autoclaving the media were placed inside a water
bath set at 45˚C to maintain the media in a molten state.
1 g each of the sample was weighed into a test-tube
containing 9 ml of sterile distilled water and serially di-
lute them until you reach your dilution factor (10-5) and
plate out 1 ml of the last dilution factor into a sterile
plates (sterilized by placing them in an over set at 160˚C
for an hour). Pour the media individually i.e. Nutrient
Agar, Mac Conkey Agar and Potato Dextrose Agar into a
separate plate i.e. each sample will have 3 plates and they
were duplicated.
After solidifying the plates were incubated in an incu-
bator set at 370˚C for Nutrient Agar and Mac Conkey
Agar while the potato Dextrose Agar was incubated at
280˚C - 30˚C. All the plates were incubated invertedly.
2.6. Microbial Count
The plate was counted at 48 hours for Nutrient Agar and
Mac Conkey Agar while it was read for potato Detrose
Agar t 72 hours.
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Microbial Load (Bacteria, Coliform and Mould Count/Flora) of Some Common Hot Smoked
Freshwater Fish Species Using Different Packaging Materials
Open Access FNS
1204
2.7. Lactic Acid Bacterial Count est TCC of 0.8 × 104, was recorded for O. niloticus, fol-
lowed by C. gariepinus (0.4 × 104) and lastly M. rume
with TCC of 0.3 × 104.
Fifty five (55) grams of Man De Rogsa and shape me-
dium (MRS) was weighed as for the above nutrient agar
preparation procedures. Table 4 and Figure 1 show that the TVC of O. niloti-
cus dropped from 10.6 × 104 (in the fresh state) to 8.4 ×
104 in the initial hot smoked and M. rume dropped from
9.8 × 104 (fresh state) to 7.0 × 104 after hot smoking,
while the TVC of C. gariepinus slightly increased from
12.4 × 104 in the fresh state to 12.6 × 104 after hot smok-
ing. While TFC increased from zero to 0.2 × 104 for the
three fish species; highest TCC of 9.8 × 104 was recorded
in C. gariepinus, followed by 4.2 × 104 in O. niloticus
and lastly 3.0 × 104 in M. rume.
2.8. Statistical Analysis
Analysis of Variance (ANOVA) in completely random-
ized design was performed on the data obtained using
SPSS (2006). Significant means were compared at 5%
probability level using Duncan’s New Multiple Range
Test (DMRT) as provided in the same SPSS (2006).
Table 5 shows that the least bacteria load (TVC) was
recorded in the SPBM and STPBM, both recording TVC
6.4 × 104 in each case. Generally highest TVC of 8.6 ×
104 (OMPBC), 8.3 × 104 (SPBC) and 8.2 × 104 (STPBC)
were recorded in all C. gariepinus among the nine pack-
ages at the end of 12 weeks storage/packaging. Next is O.
niloticus packaging 7.6 × 104 (OMPBO), 7.4 × 104
(STPBO) and 7.2 × 10 4 (SPBO) and lastly M. rume 6.6 ×
3. Result
As shown in Table 3 the microbial load varied signifi-
cantly (P < 0.05) among the three species. In the fresh
fish the highest TVC of 12.4 × 104 was recorded in C.
gariepinus, this is followed by O. niloticus with 10.6 ×
104 and lastly M. rume 9.8 × 104. However while TFC
was zero in the fresh fish for the three fish species, high-
Table 3. Microbial load of fresh fish samples.
Fish species Total Viable Count (TVC) Total Coliform Count (TCC) Total Fungi Count (TFC)
C. gariepinus 12.4 × 104 0.4 × 104 NIL
O. niloticus 10.6 × 104 0.8 × 104 NIL
M. rume 9.8 × 104 0.3 × 104 NIL
Table 4. Microbial load of initial hot smoked fish.
Fish species Total Viable Count (TVC) Total Coliform Count (TCC) Total Fungi Count (TFC)
C. gariepinus 12.6 × 104 9.8 × 104 0.2 × 104
O. niloticus 8.4 × 104 4.2 × 104 0.2 × 104
M. rume 7.0 × 104 3.0 × 104 0.2 × 104
Table 5. Final microbial load at the end of twelve weeks storage/packaging of the three hot smoked freshwater fish species.
Fish species Total Viable Count (TVC) Total Coliform Count (TCC) Total Fungi Count (TFC)
SPBC 8.3 × 104 4.0 × 104 0.6 × 104
OMPBC 8.6 × 104 4.3 × 104 0.6 × 104
STPBC 8.2 × 104 4.2 × 104 0.5 × 104
SPBO 7.2 × 104 3.8 × 104 0.4 × 104
OMPBO 7.6 × 104 3.4 × 104 0.3 × 104
STPBO 7.4 × 104 3.3 × 104 0.5 × 104
SPBM 6.4 × 104 3.2 × 104 0.6 × 104
OMPBM 6.6 × 104 3.1 × 104 0.7 × 104
STPBM 6.4 × 104 3.2 × 104 0.7 × 104
Microbial Load (Bacteria, Coliform and Mould Count/Flora) of Some Common Hot Smoked
Freshwater Fish Species Using Different Packaging Materials 1205
104 (OMPBO), 6.4 × 104 (SPBM) and 6.4 × 104 (STPBM)
respectively. However all the OMPB packages (Open
Mouth Polythene Bag)—OMPBC (8.6 × 104), OMPBO
(7.6 × 104) and OMPBM (6.6 × 104) had the highest bac-
teria load in each of the 3 fish species. However the high-
est ranged fungi (TFC) of 0.6 × 104 - 0.7 × 104 was re-
corded in M. rume. This is followed by C. gariepinus
with 0.5 × 104 - 0.6 × 104 while least TFC range of 0.3 ×
104 - 0.5 × 104 was recorded in O. niloticus. TCC was
highest in C. gariepinus ranging from 4.0 × 104 - 4.3 ×
104 followed by O. niloticus (3.3 × 104 - 3.8 × 104) and
lastly M. rume (3.1 × 104 - 3.2 × 104) respectively.
Generally M. rume was the best packaged in terms of
bacteria load (TVC) with the least range of (6.4×104 -
6.6×104) followed by O. niloticus (7.2×104 -7.6×104) and
lastly C. gariepinus (8.2×104 - 8.6×104) which is the
poorest in terms of bacteria loads. There were significant
(P < 0.05) differences between and within the TVC (i.e
bacteria load), TCC and TFC for the three species in this
study.
0
2
4
6
8
10
12
14
TOTALVIABLECOUNT(TVC)
C.gariepinus
O.niloticus
M.rume
Figure 1. Total Viable Count (TVC) (Bacteria load) for the
three fish species for the fresh fish, initial hot smoked and
inal/smoked packaged at the end of 12 weeks. f
Table 6 shows that 6 bacteria species were identi-
fied in the fresh O. niloticus, while 5 species each were
identified for C. gariepinus and M. rume in their fresh
state. Also Micrococcus acidiophilus and Proteus vulga-
ricus were identified in the three fresh fish species under
study, while Streptococcus lactis and Staphylococcus au-
reus were absent in C. gariepinus. However Serra-
ticmacescenes was only present in the fresh C. garie-
pinus.
Table 7 shows that only C. gariepinus had only one
fungi species (Rhizopusnigrica) represented in the ini-
tially hot smoked three (3) fish species. While 6 bacteria
species were each represented in C. gariepinus and M.
rume; O. niloticus had 5 bacteria species; also only
Staphylococcus aureus was present throughout in the 3
initially hot smoked fish species.
Table 8 shows th at only the OMPB for M. rume had 6
bacteria species and 2 fungi species, while the remaining
8 packages had 5 bacteria species and 2 fungi species.
The prominent fungi species represented all the 9 pack-
ages are Aspergillu ssp (niger, tamari), Rhizopusni-
gricans (in SPBO, OMPBO, OMPBC, SPBM AND
STPBM), WHILE Fusari umoxysporum is only repre-
sented in STPBO.
The prominent bacteria species represented in all the 9
packages are Micrococcus sp (acidiophilus and luteus),
Bacillus sp (aureus, cereus andluteus ). Staphylococcus
aureus is present in 8 packages with the exception of
OMPBO, Streptococcus lactis is also present in 8 pack-
ages excepting SPBO. Proteus sp (vulgaricus and mor-
gani) were presented in 7 packages, excepting OMPBC
and STPBM. Lastly, Pseudomonas aureginosa is present
in only 3 packages (SPBO, OMPBO and OMPBC).
Since micro-organisms are ubiquitous the type of pack
aging (as shown in the study) will not limit their exis-
tence.
Tables 6. Bacteria species identified from the fresh three fish species.
Fish species Micro organism
C. gariepinus Micrococcus acidiophilus, Bacillus cereus, Serraticmacescenes, Bacillus subtilis, Proteus vulgaricus (5 b a c t e ri a specie s )
O. niloticus Pseudomonas auregionosa, Streptococcus lactis, Micrococcus acidiophilus, Micrococcus luteus,
Staphylococcus aureus, Proteusvulgaricus (6 bacteria species)
M. rume Staphylococcus aureus, Bacillus subtilis, Micrococcus acidiophilus, Proteusvulgaricus, Streptococcus lactis (5 bacteria species)
Table 7. Bacteria and fungi species identified from the initial hotsmoked three fish species.
Fish species Micro organism
C. gariepinus Micrococcus luteus, Bacillus cereus, Staphylococcus aureus, Streptococcus lactis, Pseudomonas aureginosa,
Proteus vulgaricus, 6 bacteria species + 1 fungi (Rhizopusnigrica)
O. niloticus Streptococcus lactis, Micrococcus acidiophilus, Staphylococcus aureus, Bacillus subtilis, Micrococcus acidiophilus,
Bacillus macerans. 5 bacteria species + Nil (0) fungi species
M. rume Staphylococcus aureus, Bacillus subtilis, Micrococcus acidiophilus, Micrococcus luteus, Proteus morganii,
Pseudomonas aureginosa (6 bacteria species + Nil (0) fungi species)
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Microbial Load (Bacteria, Coliform and Mould Count/Flora) of Some Common Hot Smoked
Freshwater Fish Species Using Different Packaging Materials
1206
Table 8. Bacteria and fungi species identified from the smoked three fish species at 12 weeks of storage/packaging.
Packaging Micro-organism (bacteria and fungi species)
SPBC Bacillus cereus, Streptococcus lactis, Staphylococcus aureus, Proteus vulgaricus, Micrococcus acidiophilus, 5 bacteria + 2 fungi
species Aspergillustamari, Aspergillusniger
OMPBC Staphylococcus aureus, Bacillus ce reus, Micrococcus luteus, Pseudomonas aureginosa, Streptococcus lactis, 5 bacteria + 2 fungi
species Rhizopusnigricans, Aspergillusniger
STPBC Staphylococcus aureus, Bacillus cereus, Micrococcus acidiophilus, Proteus vulgaricus, Streptococcus lactis, 5 bacteria + 2 fungi
species Aspergillustamari, Aspergillusniger
SPBO Micrococcus luteus, Bacillus subtilis, Staphylococcus aureus, Proteus vulgaricus, Pseudomonas aureginosa, 5 bacteria + 2 fungi
species Rhizopusnigricans, Aspergillusniger
OMPBO Streptococcus lactis, Micrococcus acidiophilus, Bacillus cereus, Streptococcus lactis, Proteus vulgaricus, Pseudomonas
aureginosa, 6 bacteria + 2 fungi species Rhizopusnigricans, Aspergillusniger
STPBO Micrococcus acidiophilus, Streptococcus lactis, Proteus vulgaricus, Bacillus cereus, Staphylococcus aureus, 5 bacteria + 2 fungi
species Aspergillusniger, Fusariumoxysporum
SPBM Staphylococcus aureus, Micrococcus luteus, Bacillus macerans, Streptococcus lactis, Proteusmorganii, 5 bacteria + 2 fungi
species Rhizopusnigricans, Aspergillustamari
OMPBM Staphylococcus aureus, Bacillus cereus, Proteus vulgaricus, Bacillus subtilis, Streptococcus lactis, Micrococcus acidiophilus, 6
bacteria + 2 fungi species Aspergillustamari, Fusariumoxysporum
STPBM Micrococcus acidiophilus, Micrococcus leteus, Streptococcus lactis, Staphylococcus aureus, Bacillus subtilis, 5 bacteria + 2 fungi
species Rhizopusnigricans, Aspergillusniger
4. Discussion
The highest bacteria load (TVC) of 12.4 × 104 was re-
corded in the fresh C. gariepinus followed by 10.6 × 104
in O. niloticus and lastly 9.8 × 104 in the fresh M. rume.
However, initial hot smoked reduced th e bacteria load of
O. niloticus to 8.4 × 104 and M. rume to 7.0 × 104 while
the initial hot smoked C. gariepinus TVC of 12.6 × 104
was not affected by hot-smoking since a slight increase
of 0.2 × 104 was recorded after hot smoking.
Packaging had a significant (P < 0.05) effect at 12
weeks storage/packaging of smoked fish for C. garie-
pinus which reduced from 12.6 × 104 TVC to OMPBC
(8.6 × 104)—SPBC (8.3 × 104)—STPBC (8.2 × 104) and
M. rume with TVC reducing from 7.0 × 104 (in the initial
hot smoked fish) to 6.6 × 104 (OMPBM)—6.4 × 104
(SPBM)—6.4 × 104 (STPBM). However all the OMPB
packages (Open Mouth Polythene Bag)—OMPBC (8.6 ×
104), OMPBO (7.6 × 104) and OMPBM (6.6 × 104) had
the highest bacteria load in each of the 3 fish species.
This is also revealed in Figure 1.
Total Coliform Count (TCC) generally increased from
the fresh fish sample 0.4 × 104 to 9.8 × 104 (C. garie-
pinus) 0.8 × 104 to 4.2 × 104 (O. niloticu s) and 0.3 × 104
to 3.0 × 104 in the initial smoked (M. rume). Total Coli-
form Count (TCC) dropped significantly (P < 0.05) from
9.8 × 104 in the initial hot smoked C. gariepinus to a
range of 4.0 × 104 - 4.3 × 104 in all the 3 C. gariepinus
packaging, while TCC virtually remained the same for
the M. rume packaging and dropped from 4.2 × 104 to a
range of 3.3 × 104 - 3.8 × 104 for O. niloticus at the end
of 12 weeks. This is shown in Figure 2.
No Fungi count was recorded in the fresh fish sample
0
2
4
6
8
10
12
TOTALCOLI FO R MCO UNT(TCC)
C.gariepinus
O.niloticus
M.rume
Figure 2. Total Coliform Count (TCC) for the three fish
species for the fresh fish, initial hot smoked and final/
smoked packaged at the end of 12 weeks.
for the 3 fish species. However a value of 0.2 × 104 fungi
count was recorded for the 3 fish species after initial hot
smoking. This value increased; highest for M. rume (0.6
× 104 to 0.7 × 104) next is 0.4 × 104 to 0.6 × 104 in C.
gariepinus and lastly 0.3 × 104 - 0.5 × 10 4 in O. nilo ticus.
Since micro-organisms are ubiquitous the type of pack-
aging (as shown in this study and Figure 3) will not limit
their existence.
The bacterial load (TVC) count for all the three spe-
cies of fish in the nine packages used for this study are
below the maximum bacteria count of 5 × 105 cfu for
good fish product according to the International Com-
mission on Microbiology Safety for Food [14].
For C. gariepinus significant (P < 0.05) decreases
were observed in the TCC 9.8×104 in the initial smoked
fish which reduced to a range of 3.1 × 104 - 3.2 × 104 at
the end of 12 weeks. This was in conformity with Wil-
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Microbial Load (Bacteria, Coliform and Mould Count/Flora) of Some Common Hot Smoked
Freshwater Fish Species Using Different Packaging Materials 1207
0
0.2
0.4
0.6
0.8
FreshFish
Initial
SPB
OMPB
STPB
TOTALFUNGICOUNT (T FC)
C.gariepinus
O.niloticus
M.rume
Figure 3. Total Fungi Count (TFC) for the three fish species
for the fresh fish, initial hot smoked and final/smoked
packaged at the end of 12 weeks.
liam, C.F and Dennis, C.W [15] who reported that the
faecal coliforms count of fresh C. gariepinus fillets were
similarly low after 8 days of cold storage.
Table 3 shows that there was absence of fungi in the
fresh sample of the three fish species, while in Table 4
only one species of fungi (Rhizopusnigrica) was present
in the initially smoked C. gariepinus. At the end of the
12 weeks of storage/packaging three (3) more fungi spe-
cies (Aspergillusniger, Aspergillustamari and Fusaru-
moxysporum) were represented at th e rate of 2 fung i spe-
cies per packaging. That is fungi species were repre-
sented in all the 9 packages. The results obtained were
similar to those observed by Adebayo-Tayo et al. and
Fafioye, O.O et al . [9,16]. During storage of smoked fish
product there was significant (P < 0.05) increase in the
fungi count with length of storage as seen in this study.
This is in line with Oyebamiji, O. F et al. and Wogu,
M.D et al [11,12] who worked on stored smoked fish
products marketed in the open market. The presence of
fungi may be due to the difference in the chemical com-
position of th e fish species and to which different moulds
react differently [16,17].
Only the OMPBM and OMPBO had 6 bacteria species
represented while the remaining 7 packages had 5 bacte-
ria species. The prominent bacteria species represented in
all the nine (9) packages are Micrococcus sp (acidiophi-
lus and luteus), Bacillus sp (aureus, cereus and luteus),
staphylococcus aureus (is present in 8 packages) except
in OMPBO. Streptococcus lactis also in 8 packages ex-
cepting SPBO. Others are Proteus vulgaricus, P. mor-
ganii and Pseudomonas aureginosa.
5. Conclusion
Highest Bacteria Count (TVC) was recorded in C. garie-
pinus packages among the nine packages at the end of 12
weeks. The 3 packaged fishes for C. gariepinus had the
highest bacteria load with OMPBC (Open Mouth Poly-
thene Bag Being the Highest). Highest tendency for
heavy bacteria load (TVC) is in the Open Mouth Poly-
thene Bag which has been confirmed in the OMPB for all
the 3 fish species. Highest ranged Total Fungi Count
(TFC) was recorded in M. rume followed by O. niloticus.
Total Coliform Count (TCC) was highest in C. garie-
pinus followed by O. niloticus. Packaging did not limit
the existence of micro-organisms. There were 5 bacteria
species and 2 fungi species represented in each of the
packages (with the exception of OMPBM and OMPBO
with 6 bacteria species). The prominent fungi species
represented in the 9 packages at the end of 12 weeks are
Aspergillus species (niger and tamari), Rhizopusnigri-
cans and Fusariumoxysporum. Prominent bacteria spe-
cies represented in all 9 packages are Micrococcus spe-
cies (acidiophilus and luteu s), Bacillus species (aureus,
cereus and luteus). Staphylococcus aureus is present in 8
packages (excepting OMPBO) and also Streptococcus
lactis (excepting SPBO). Proteus species (vulgaricus and
morganii) (in 7 packages excepting OMPBC and STPBM)
and lastly Pseudomonas aureginosa are present in only 3
packages (SPBO, OMPBO and OMPBC).
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Abbreviations
TVC: Total Viable Count
TCC: Total Coliform Count
TFC: Total Fungi Count
SPBC: Sealed Paper Bag-Clariasgariepinus
OMPBC: Open Mouth Polythene Bag-Clariasgariepinus
STPBC: Sealed Transparent Polythene Bag-Clariasgari-
epinus
SPBO: Sealed Paper Bag-Tilapia (Oreochromisniloticus)
OMPBO: Open Mouth Polythene Bag-Tilapia (Oreo-
chromisniloticus)
STPBO: Sealed Transparent Polythene Bag-Tilapia (Ore-
ochromisniloticus)
SPBM: Sealed Paper Bag-Mormyrusrume
OMPBM: Open Mouth Polythene Bag-Mormyrusrume
STPBM: Sealed Transparent Polythene Bag-Mormyrus-
rume