Most of the fish marketed throughout Nigeria are in either smoked or dried form. The technological requirement for other forms of preservation like chilling and freezing cannot be afforded by the small scale fisher folk. Considerable quantities of fish processed for distant consumer markets are lost at handling, processing, storage and marketing stages. Significant losses occur through infestation by mites, insects, fungal infestation and fragmentation during transportation. This paper attempts to describe the effect of these losses on fish quality and suggests methods of protecting fish from agents of deterioratio

Eyo, A.A.

English

Aquatic Commons

T I EFFECT OF TRADITIONAL I A, ILThÍGPROCESSING
AND STO GE METHODS ON TI I QUALITY OF DRIED
FISH IN S L-SCALE FISHE S IN NIGERIA
A.A. EY0
National Institute for Freshwater Fisheries Research (NIFFR)
P.M.B. 6006, New Bussa, Nigeria
INTRODUCTION
Fish is becoming increasingly important in the diet
of the Nigerian as the cost of beef increases daily.
Fish constitutes 40% of animal protein intake in
Nigeria at present (Olatunde 1989). Most of the
fish marketed throughout Nigeria are derived from
remote inland waters at different points along the
Niger-Benue rivers, the Kainji Lake and the Lake
Chad (Osuji 1975; Uboma et al. (1981). Most of
this fish are caught, processed and marketed by
fisherfolk who employ the old aaditional methods
of smoking and or sun drying as the major
processing technique before the fish are marketed.
This paper examines the major processing
techniques as practiced in Nigeria with their
attendant problems and suggests ways of improving
the technology of fish preservation to enhance fish
quality.
t ISH PRESERVATION
The major fish preservationnaethods are sundrying,
salting and smoking (Eyo 1992). The traditional
techniques adopted in fish processing in the Lake
Chad and Kainji districts have been fully described
by Osuji (1975) and Eyo (1977, 1983). These
techniques as practiced at present pose a lot of
problems to the quality of the final product and
sometimes even encourage early infestation by
agents of deterioration such as fungi, beetles and
fly pests.
ABSTRACT:
Most of the fish marketed throughout Nigeria are in either smoked or dried form. The technological requirement for other forms of
preservation like chilling and freezing cannot be afforded by the small scale fisherfolk. Considerable quantities of fish processed for distant
consumer markets are lost at handling, processing, storage and marketing stages. Significant losses occur through infestation by mites,
insects, fungal infection and fragmentation during transportation. This paper attempts to describe the effect of these losses on fish quality
and suggests methods of protecting fish from agents of deterioration.
50
Because of the high demand for smoked dried fish
which is highly relished in Nigerian traditional
diets, smoking is mostly inadequate. Mildy smoked
fish have been found to contain as much as 35% or
more moistuxe content in Shagunu (Osuji 1975)
and Asa dam area (Eyo & Awoyerni 1990).
Resmoking is hardly done and these improperly
dried fish are packed in cartons by fish mongers
to markets in Lagos, Onitsha and other urban areas.
This improper smoking and drying leads to
considerable losses to fishmongers. 'There are few
reliable estimates available but it is believed that
30-50% of fish processed at Lake Chad is lost by
the time the fish arrive at Maiduguri for onward
transportation to consumer markets in the Southern
States (Proctor 1977). A survey conducted in Ilorin
fish market in Kwara State reveals that losses
incurred on processed fish arriving from Shagunu,
Patagi and even Maiduguri range from 15-20% due
to improper smoking at source. There is fungi
infestation and fragmentation due to improper
packaging (Eyo and Awoyemi 1990). Fragmented
fish encourages the rapid development of beetle
pests, particularly Dermestes maculatus (Degeer)
and could endanger whole fish staying too long in
storage. The quality of fish produced in the
processing methods highlighted above are generally
low and losses could be serious when transported
over long distances. The main sources of these
losses are discussed briefly.
FUNGAL LOSSES.
Fish that are insufficiently dried having moisture
content of 40% or more are prone to attack by
Rhizoctonia spp., Penicillin spp and Aspergillus
spp. In a survey of Ilorin fish Markets an.d Faku
(Kainji Lake district) samples of dried fish brought
into the laboratory started going moldy about the
third day of storage (Eyo and Awoyemi 1990).
This is evidently as a result of improper smoking
at the processing stage. It is pertinent to mention
b.ere that to check these type of infestation redrying
or resmoking before sale is often necessary. By this
the cost of production increases tremendously to
the fish monger and often time these costs are
passed to the consumers. Data on the actual losses
of dried fish due to fungi infestation are rare in.
literature. However personal observations at the
major fi.shing villages and markets in the Kainji
Lake basin revealed that substantial quantities of
fish are usually infested by fungal growth. This
infestation requires additional drying before sales
thus increasing cost to the fish processor.
HANDLING LOSSES
Most of the fish caught in Nigerian waters are
either caught with nets, hooks, or traps. Fish being
removed from capture materials are sometimes
roughly handled and most of the time dropped in
the open at the canoe bottoms under tlae usually
prevailing higb. temperatures. Rapid deterioration
particularly through bacterial decomposition under
the warm conditions that prevail set on. Fish that
suffers bacterial putrefaction whether they are later
smoked or sundried are generally unsuitable for
long distant transportation from processing site to
market because of rapid deterioration in storage.
Such bacterial infested fish are usually rejected by
consumers due to their soft texture which are easily
identified. This constitutes an additional loss to the
fish processor. Another source of loss of quality
that can be attributed to careless handling of fresh
fish being prepared for processing is unsanitary
way of g,utting fresh fish and throwing of wastes
all around the processing sites. These activities
have been identified to have contributed to the
rapid infestation of fish by blow flies particularly
Gluysomya spp. and the common housefly, Musca
domestica at Faku (Kainji Lake), Odore (Asa dam,
Ilorin) and Shagunu (Kainji Lake) fishing villages
51
processing sites (Eyo and Awoyemi 1990). These
blowflies oviposit on fish being prepared for
smoking and inadequate smoking does not lcill the
eggs. The ravaging effect of the emerging larvae
on partly dried fish reduces the quality of the
finished product and die income accruing co the
fish monger.
PACKAGING AND STORAGE
Fish being prepared for market are packed in card-
board boxes or baskets. Cardboard boxes are the
most commonly used for fish being prepared for
transportation to Southern markets particularly
from Shagunu, Yauri, Faku (Kaiuji Lake areas) and
at Baga market - a major fishing market on Lake
Chad (Proctor 1976). In a survey of Asa Dam area
(Eyo and Awoyemi, 1990), it was revealed that
these packages often lead to fragmentation of fish
during the long transportation from these sources to
Icli-Ape fish market in ¡brin for example. For
every 25kg pack of fish about 1.5 kg is lost to
fragmentation through rough handling during
transportation. Fragmentation does not only lead to
quantitative loss of the smaller fragments and down
grading of this fraction for use as animal feed but
there is a loss of value due to quality reduction
since a higher price is often obtained for intact
pieces of fish. Fragmentation often also encourages
pest damage (FAO 1981) as fragmented particles
are favoured for rapid breeding of insects and
mites.
Unclean an ill prepared storage houses do cause
reduction in the quality of dried fish being
prepared for market. Most of the fish stores around
Lakes Kainji and Chad are mudwalled. Packaged
fish are left directly on the floor of the inud
houses. Temperature changes between the fish
directly resting on the bare floor and those in the
upper units of cardboards, jutes or packet packages
have been observed to vary by as much as 15vC by
Osuji (1974). This temperature variations encourage
infestation by beetle pests and could lead to serious
damage to fish quality in storage. Fish at the
bottom of packages left directly on the floor
sometimes get humid. High humidity not only
encourages rapid multiplication of insects but the
growth of molds and of vaiious fungal organisms
too that make the fish unsightly for marketing.
INSECT AND MITE INFESTATION
Insects and mites are often fotmd infesting cured
fish during and after processing especially in the
tropics and subtropics where higher temperatures
and humidity arc prevalent all the year round.
Quantitative losses due to feeding damage by insect
and mite pests on cured fish have been reported to
be up to 30% due to fly damage during processing
and up to 50% due to beetle damage during
processing for several months (Haines & Reos
1989). Some examples of world wide losses of
dried fish due to insect infestation are given by
Pouher et al. (1965). James (1977) estimated
weight losses of dried fish due to Dermestes spp.
(Coleoptera) infestation at about 50%. Rollings and
Haward (1963) estimated such losses at Lake Chad
at 50%. while the FAO (1988) estimated dried fish
weight losses due to Dermestes spp. damage in a 6
- month storage period at 26 - 34%. The hurry to
get improperly dried fish to market increases the
susceptibility of processed fish to blowfly
infestation and also beetle infestation in storage.
The indiscriminate method of mixing wet fish with
properly dried ones particularly as observed among
fish mongers at Faku and Shagunu markets
encourages cross infestation of fish being packaged
for distant consumer markets. Consequently
products are usually moved into storage with a
high level of infestation. The prevailing warmth in
the storage environment encourages rapid
development of the eggs to larvae which are the
most destructive stages on stored dried fish. Within
few weeks, most of the infested fish could be
reduced to frass and bones. The contaminations of
felx surviving whole fish by live or dead pests or
their cast skins and excreta, also causes a change in
visual quality and this may reduce the value of the
fish.
Lardoglyphid mites occur on dried fish at various
stages in storage and marketing especially during
cool wet season, insect and mite pests often
transmit mold spores. The additional heat and
moisture produced by heavy infestations can create
conditions suitable for fungal growth on fish that
have previously been dried but indiscriminately
packaged with infested ones. The principal effect
of all these activities is the imparting of an
unsavoury odour to the commodities and reduction
in their aesthetic appeal to consumers.
52
ECOLOGICAL FA.CTORS IN RELATION
TO LOSS REDUCTION
The present methods of fish handling, processing
and marketing need considerable modification to
make fishing a profitable business for fish mongers
and to ensure a high panty product for the
consumers. Better handling of fish at capture will
minimise injury and reduce b acterial decomp o sition
of fish to the barest minimum. Time reduction of
time between capture and processing will also
reduce infestation of fish by blowflies. In particular
smoking and or salt-drying are still the major
methods of preserving fish for die market in
Nigeria. It is going to remain so for some time to
come as the teclmology of freezing and chilling is
still too expensive for most fishermen to adopt.
Effort should be made to improve on the pre-
treatment of fish before smoking and drying to
ensure a high quality preservation of dried fish
both at storage and marketing stages.
CONCLUSION AND RECOMMENDATIONS
Use of Fly-Screens.
Initial infestation of fish is often due to invasion by
flying adults of insects which lay their eggs on
partially or fully dried fish. Fly-screens around and
over drying racks may reduce beetle and 'fly
infestation pressure during processing. Time
techniques of preventing fish from beetlepests will
control mite infestation since beetles usually can-y
mites to the fish.
P revention of Fragmentation
Fragmentation of the fish flesh should be avoided
though careful handling as it increases the surface
area of the flesh and consequently encourage heavy
mite infestation.
(Hi) Prevention of Infestation.
The use of clean. good-quality sacks lined with
polythene or thick brown paper to slow down rates
of immigration of Dermestesspp. and prevent cross
infestation in storage is suggested. Infestation may
also be initiated by crawling larvae and adults
present in fish residues available in dirty stores or
by adillts emerging from pupation chambers in
wooden structures. The riSk of such infestation can
be reduced by improved hygiene and by treatment
of such wooden structures with recommended
insecticide.
Common Preventive Measures
Salting, use of polythene bags for storage and use
of oils and neem tree extracts (Bossia senegalensis)
are some of the non-physical measures comployed
in protecting fish against agents of deterioration in
storage (Walker 1988, Osuji 1975; Amos 1968).
Use of Insecticides
Insecticides are also being tried in protecting fish
against insect pest attack. Most of the work has
centered on the use of pyrethrine, which are
normally synergised to some extent with piperony
butoxicle . Other insecticides commonly tried are
pirimiphosmethyl (Actellic) and tetrachlorvinphos
(Blatchford, 1962; Taylor and Proctor 1979; FAO
and Taylor 1982). There is still very little
information available on the efficacy of the use of
chemicals as fish protectants against insect pest
infestation because of the long standing reluctance
of fisheries technologists to use insecticides and the
general lack of attention paid to fisheries post-
harvest sector. Around Lake Chad, it is reported to
be a common practice for fishermen to sprinkle
fish with Gammalin HCH (lindane) and household
aerosols containing lindane (Taylor 1981). Neither
of these insecticides is suitable for use in treating
consumable food items because of their long
persistence and high mammalian toxicity. (Walker,
1988).
The points highlighted above if properly harnessed
would guarantee the production of good quality
dried fish for the market
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The effect of traditional handling, processing and storage methods on the quality of dried fish in small scale fisheries in Nigeria

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The effect of traditional handling, processing and storage methods on the quality of dried fish in small scale fisheries in Nigeria

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