Practical Guide to Improved Fish Smoking in West Africa
FAO: Rome, Italy
Prepared in conjunctions with a UNICEF FISH SMOKING EXTENSION PROJECT of the national COUNCIL ON WOMEN AND DEVELOPMENT assisted by the FOOD RESEARCH INSTITUTE
Carried out in coastal Ghana (Greater Accra, Ada and Keta) from June 1983 through January 1984
Based on improved fish smoking technology developed by FAO, the Food Research Institute and the Women of Chorkor, Ghana in 1969-71, and now widely utilized in the area.
FAP Library Fiche AN: 245749
Introducing the Chorkor Smoker
WHY DO PEOPLE SMOKE FISH?
- Preservation – To prolong its shelf life
- Taste - To enhance its flavour and increase its utilization in soups and sauces
- Income – To reduce waste at times of bumper catches and to store for the lean season
- Better Nutrition – To increase protein availability to all people throughout the year
- Improved marketing – To make it easier to pack, transport and market fish
OUT-OF-DATE SMOKING OVENS
1. TRADITONAL CYLINDRICAL MUD OVEN WITH THATCHED COVER
- wears out after 1 or 2 seasons
- time-consuming and smoky to operate
- very uneven smoking and limited capacity
2. CYLINDRICAL OVEN MADE BY JOINING TWO OPENED STEEL DRUMS AND CUTTING STOKE HOLE AT BASE
(Note supporting rods sticking out of midriff)
- same limitations as above
- drums, rods, and cement base are costly
3. TRAYLESS RECTANGULAR OVENS
- The supporting sticks often burn
- The sticks bruise, bend and cover the fish
- The wire nets are difficult to handle, and fish fall off them
- Most of the smoke & heat escape unused
DISADVANTAGES OF SOME IMPROVED OVENS
1. IVORY COAST KILN
This is the most acceptable of modern ovens because it combines efficiency and simplicity. However it deviates considerably from the traditional designs, and the materials are expensive.
2. VARIOUS TYPES OF METAL OVENS
These are far too expensive and difficult to maintain because they are made of metal. They have been tried without success in numerous projects and in many differing situations in Africa.
3. STEEL DRUM SMOKERS
Cumbersome to operate, very limited capacity, and relatively expensive due to current scarcity of drums.
WHY USE THE CHORKOR SMOKER
- It has proven to be readily acceptable by women who practice traditional fish smoking methods…the trays are the only new element—to separate the fish and to form a chimney to effectively utilize the heat and smoke (the wire nets are even used extensively now in the traditional cylindrical ovens).
- Low construction cost.
- Long-life(up to 15 years for a cement block and mortar oven, 8 years for a cement-faced mud oven, and 4 years if bare earth and well-covered when it rains).
- Large capacity(up to 18 kg of fish per tray; as many as 15 trays per oven).
- High quality and uniformity of product due to greater retention of heat and circulation of smoke (and reduced smoking time).
- Easy to operate (no smoke in eyes, trays quickly changed, fireboxes very accessible).
- Low consumption of firewood (very little waste of heat and smoke).
- Much less time and effort required for operation.
1. GENERAL DESIGN
The ovens are rectangular, about twice as long as wide, with two stoke holes in front. Preferably there is a foundation sunk in the ground and a dividing wall in the middle, both being recent improvements on earlier models.
Advantages of middle wall:
- It gives added strength to the oven
- Protects the median cross piece of the bottom tray from burning
- Gives greater support to the loaded trays
- Allows for smoking of small quantity of fish over just one chamber, using less wood
There are four appropriate approaches for construction of smoking ovens:
- Clay mud, packed and shaped by hand (85-95 “headloads” or basins for one oven)
- Packed clay mud faced with cement (1/2 bag)
- Clay mud blocks (sun-dried or baked) and mortar
- Cement blocks with mortar (requires 3 to 4 bags of cement and sand that is well-washed)
- the ground is cleared and leveled; the outline of the oven walls is drawn; a trench 6-8" deep is dug for the foundation
- preparation of materials (delivery of clay soil or blocks); if loose clay, it is mixed with water and pounded until it becomes malleable and sticky
- construction of walls in layers (if clay mud, it is done in 3 stages—first the lower half is packed and allowed to dry, then about 40% more, and finally the upper surface is packed and squared) … three days for packed clay ovens, two days for block construction
- for the clay oven, the stoke holes are cut in the front wall once it is dry (with any sharpened strip of iron); the area to be cut must first be wetted
- for the cemet oven, an arch is made with a piece of scrap plywood, and packed with cement well-bonded to the blocks surrounding it
- the last step is plastering (with clay or cement) after the oven and stoke holes have dried
4. KEY POINTS OF DESIGN
- the top of the oven must be square, level, and flat, so that the wooden-framed trays can rest flush upon the walls
- the stoke holes should be arches for greater structural strength, and large enough for stoking and removing wood (but not so large as to permit heat and smoke to escape)
- the oven should be low (for ease of stacking up to 15 trays) but the fire should always be at least 20 inches from the lowest tray, so a 4-8 inch fire pit should be dug for each stoke hole
1. GENERAL DESIGN
The Chorkor Smoker is designed so that the wooden frames of the trays will rest along the midlines of the oven walls (thus, they are firmly supported, and will not catch fire). For each oven there should be 12-15 smoking trays, plus several deeper storage trays.
Ideally, hardwood planks (such as odum) should be used for tray frame construction (greater strength; resistance to heat, moisture, insects). In practice, however, softwoods (primarily wawa) are used almost exclusively because they are 2-4 times less expensive.
Wire nets of ½” to 1” mesh and 18 to 20 gauge are required (though often bigger meshes and finer gauges are accepted, if nothing else is available). These normally come in rolls of 1 x 50 (yards or metres), enough for 22-25 trays.
About 50 nails are required to frame a tray and batten down the wire net.
The 3 cross-pieces are butted inside the 2 long members (which normally terminate in handles). By nailing these together, the basic frame is made.
TOP VIEW OF SMOKING TRAY
Two 70 cm (2-1/2 - 3") nails are used at each of the six joints of the smoking trays (width of boards: 5.5 cm, or 2.2"). Three or four nails are used for the wider (15cm, or 6") storage tray boards at each joint.
4. KEY POINTS OF DESIGN
- the trays must be square and fit flush together in order to form a proper “chimney”
- the nets much be stretched in both directions across the bottoms of the frames in order to support 15 or more kg. of fish per tray
- the frames can last as long as 3 years and the nets for two if the trays are properly constructed and maintained:
- Avoid burning and scorching
- Apply vegetable oil regularly to nets
- Avoid reckless handling and bumping
- Cover to protect from sun and rain
C. SPECIFICATIONS (IN INCHES AND CENTIMETERS)
||FOR TRAYS OF 1 YARD
||FOR TRAYS OF 1 METER
| || Total Length || Inside Length || Useable Length || Including Handles || Oven Total || Oven Inside || Cross Members || Oven Total || Oven Inside || Cross Members |
| Acceptable Range (cm.) || 210-240 || 180-210 || 195-225 || 215-245 || 103-109 || 75-81 || - || 111-118 || 84-90 || - |
| Acceptable Range (in.) || 83-95 || 71-83 || 77-89 || 85-96 || 41-43 || 29½-32 || - || 44-47 || 33-35½ || - |
| Best (cm.) || 230 || 200 || 215 || 235 || 106 || 78 || 86 || 114 || 87 || 95 |
| Best (in.) || 90 || 79 || 85 || 93 || 42 || 31 || 33½ || 45 || 34 || 37 |
OVEN WALL THICKNESS: 13-15 cm (5-6")
THICKNESS OF FRAMING BOARDS: 2.2-3.0 cm (0.8-1.3")
DEPTH (SIDE) OF SMOKING TRAY: 5-6 cm (2.0-2.4")
DEPTH (SIDE) OF STORAGE TRAY: 14-16 cm (6")
DEPTH (THICKNESS) OF UNDER BATTENS: 1-2 cm (0.4-0.8")
MESH SIZE (WIRE NETS): 1.2 cm (0.5"), 2 cm (0.75"), 2.5 cm (1")
GAUGE OF WIRE (WIRE NETS): 18 or 20 (22 is too weak) (0.9 mm)
WIDTH OF ROLL OF WIRE NET: 1 metre or 1 yard
LENGTHS OF CUT PANELS OF WIRE NET: 195-225 cm (77-89")
A. TYPES OF FISH
A great variety of marine and freshwater fishes are smoked in West Africa (see Appendix III).
B. ACQUISITION OF FISH
The fish used for smoking is purchased either directly from the landing centre (usually a beach) or from cold stores (frozen or packed in ice).
The final product is of greatest quality and has the longest shelf life when the fish is smoked fresh. Frozen fish can also be smoked immediately after thawing, however great care must be taken in selection. Often fish is frozen only after sitting in the sun for several hours, or it may have been thawed and refrozen a few times, resulting in a very low-quality raw material which is not acceptable for smoking. In some countries, fish hawkers will smoke whatever fish is left over after a day’s selling. The resulting smoked fish is of poor quality.
C. PREPARATION OF FISH FOR SMOKING
Except for larger fishes such a grouper, tuna, snapper, etc., the gills, guts and scales are normally not removed.
The larger the fishes are normally cut into steaks or fillets, but fish of small and medium size are smoked whole. The fish are washed in clean water (fresh or salt) and carefully arranged on the trays. Sometimes they are left for about an hour to dry in the sun before smoking.
The trays filled with fish are stacked on top of each other upon the ovens, resulting in a smoking chamber/chimney. Up to 15 trays may be used on one oven, though most commonly the women use 10-12 trays for one smoking cycle (with a total of 100-160kg. of wet fish).
Hardwood is used for the fire (particularly for the cooking phase), producing temperatures in the vicinity of 80ºC. (see Appendix IV for a list of some common woods used for smoking).
D. THE SMOKING
Depending on the type of fish to smoke (species, thickness, way of cutting it), what it will be used for, and the length of time it may have to be stored, the smoking process can take anywhere from one hour to two days. For Sardinella, Ethmalosa and similar small-to-medium oily fishes, the “hot smoking” process takes 2-5 hours, and yields a moist, versatile product, but of limited keeping quality (1-2 weeks). To “smoke-dry” the same fish, it will take 10-18 hours of smoking, mainly at lower temperatures (and it may take as much as three days if smoked very slowly). The latter method is by far the most common since the distribution process may take quite a long time, and the consumer will then often want to store it for several months.
The fish are turned and the orientations of the trays are changed 2-4 times during the smoking cycle. The upper trays are placed closer to the fire, while the lower ones are moved higher. Sometimes the trays are turned 180º on the oven. Smaller fish are turned over by placing an empty tray on top of one filled with smoked fish, flipping them over together, and beating the bottom (now top) so that the fish fall in order onto the new tray. Larger fishes (cut in chunks) are turned individually by hand on each tray.
After two to five hours of hot smoking , the contents of 2 or 3 trays of partly smoked fish can be combined in one tray. Then it can be smoked over a moderate fire (below 60°C.) to continue the drying process. This second stage is the most important from a preservation standpoint, and may last as long as 2 days, yielding a very dry (10-15% moisture) product with a potential shelf life of 6-9 months.
E. THE FIRE
The fires are set in the fire pit of each chamber of the oven. Thus, the base of the fire is about 6 inches below ground level and the flame is 15-20" below the first layer of fish. The fire is started with a small amount of hardwood. Normally, the fish is dried briefly this way (low temperature) before stoking up the fire with more hardwood for the hot smoking. Hardwoods burn slowly, producing plenty of heat and a minimum of soot, and they impart a sweet taste to the fish.
The fire is closely watched, and as soon as it becomes too intense, some sticks of wood are removed. Near the end of the smoking process, some sugar cane is added to the fire to give the fish a yellowish-brown colour.
For the final stage (drying) and also for re-smoking the fish after several weeks of storage, only a small amount of wood is used. In this case the fuel may be straw, sawdust, coconut husks, palm fronds, etc. that have been moistened to produce plenty of smoke.
Due to the “chimney” formed by the stacking of the trays on the oven (and covered at the top), the heat and smoke constantly circulate inside. Thus, a high-quality, evenly smoked product is achieved with a minimum of fuel.
Fish that is properly smoke-dried and not salted can be kept for up to nine months in the tropics if the following simple rules are observed:
- Use storage containers that can be adequately sealed against the introduction of moist air and insects (preferably Chorkor-type storage trays or baskets)
- Tightly cover the containers (outside for stacks of trays, inside for baskets) with plastic sheets, brown paper or banana leaves (in order of preference)
- Handle the fish as little as possible
- As soon as the smoked fish cools, pack it away carefully
- Re-smoke it periodically (about every 2 months on the average for fish kept in a humid climate, but securely covered) to drive out moulds, fungi, bacteriae and insect larvae that will eventually work their way inside.
The Chorkor system is simply a stack of 5-10 storage trays (often piled on top of an old oven), well-enshrouded in flexible, resistant sheeting materials, usually with a sheet of plywood above and below it, and well battened-down.
Traditional storage in cylindrical ovens with thatched roofs is similar in principle, but the fish is not sufficiently enclosed, so it has to be re-smoked over a low fire quite frequently.
PACKING FOR MARKET
Smoked fish is packed tightly in baskets, then covered with sheets of paper or plastic which are firmly sewn to the rim of the basket. If the baskets are small (40x50 cm), they are often sewn together, rim to rim. Sometimes, grain sacs or wooden boxes are used to transport the smoked fish over short distances.
Since the women prefer to sell the smoked fish in large quantities, and when the price is high, they will store as much as possible (for several weeks to several months). Then they will hire a truck individually or collectively to transport it to whatever market will bring the best price. Alternatively, they will sell to itinerant wholesalers (also women, in most cases) who come with their own trucks. For smaller quantities, they will either prepare a headload of smoked fish and walk to market, or carry a few baskets or bundles of it by public transport to nearby markets. At the market, they will either wholesale or retail it themselves, or they will work through a wholesaling agent.
More than half of the fish produced at the coast is transported to distant markets in the interior of the country, or to neighboring countries, where smoked fish is in greater demand (often the only source of protein that can be purchased with limited family budgets).
The handling of the fish during smoking, packing and transporting is very important. If the fish is bent, broken, burned, or missing the head, its market value will be much lower.
Most of the women do not keep any written records, so they do not know how much money they have spent to produce x number of baskets of smoked fish, nor how many hours of labour are involved. During the peak season, there is very little demand for smoked fish near the production centres, so the price is only slightly higher than that of fresh fish (even though the smoked fish is more than twice as concentrated). During the lean season (particularly far up-country) the price for smoked fish may be more than five times the value of the fresh fish at the time of purchase.
In Chorkor, very few smoking concerns fail, while most are actually expanding. The women know how much they can pay for fresh fish, firewood, baskets, new trays and ovens, while still making a reasonable profit on their receipts at the end of a given period. It is clear that nearly all of the Chorkor women make enough profit to improve the living standard of their families, but it is still impossible to calculate specific margins of profit.
PIECES OF TIMBER REQUIRED FOR ELEVEN SMOKING TRAYS, TWO STORAGE TRAYS AND PLYWOOD COVER FOR ONE CHORKOR SMOKER
Note: 2 half-length battens (39”) to a side
TOTAL COST OF ONE CHORKOR SMOKER
A LIST OF THE WEST AFRICAN FISHES MOST OFTEN SMOKED
POISSONS OUEST-AFRICAINS LE PLUS SOUVENT UTILISES POUR LE FUMAGE
|LATIN||ENGLISH||FRANÇAIS||Some Local Names (Country)|
Quelques Noms Locaux (Pays)
| Arius spp. || Sea catfish || Machoiron || Konko (Guinée), Gangangri (C.I.), Kokoté (Togo) |
| Caranx spp. || Jack mackerel || Caranque || Kawra (Guinée), Kpankpan (Bénin) |
| Trachinotus spp. || Pampano || Trachynote || Naniaranzoba (C.I.), Adjagboé (Bénin) |
| Trachurus spp. || Horse Mackerel || Chinchard || Kpanla (Ghana), Silivi (Bénin) |
| Chloroscombrus || Bumper || Caranque médaille || Zozorobi (Togo), Tantemile (Ghana) |
| Decapterus spp. || Scad Mackerel || Faux Maquereau || Chiyl (Bénin), Emule (Ghana) |
| Squalomorphii || Sharks || Requins || Tsaflobi (Ghana), Séréki (Guinée), Anamu (Togo) |
| Batoidea || Skates & Rays || Raies, Anges, Aigles de Mer || Ajibete, avako, Tantra (Ghana), Adadu (Togo), Ozouin, Zouin-gangan (Bénin) |
| Anchoa guineensis || Anchovy || Anchois || Abobi (Ghana), Bobi (Bénin), Langamina (S.L.) |
| Ilisha africana || Long-fin herring || Rasoir || Kanfla (Ghana), Kpankpadé (Bénin) |
| Ethmalosa spp. || Shad || Ethmalose || Bonga (Guinée), Aywo (C.I.), Ehoue-Kpako (Bénin) |
| Sardinella spp. || Sardines || Sardinelle || Bonga séry (Guinée), Kankaman (C.I.), Maoun (Bénin) |
| Parakuhlia || Burro || Crocro gros-yeux || Takpetakpe (Ghana), Kokouimoun-Kounon (Bénin) |
| Brachydeuterus || Burrito || Pelon || Boro firé (Guinée), Agbonzo (C.I.), Efinvi (Togo), Boiboi (Ghana) |
| Elops senegalensis || Ten-pounder || Guinée du Sénégal || Gbanvi (Togo), Téni (Guinée), Diglikari (C.I.) |
| Albula vulpes || Ladyfish || Banane de Mer || Tenny (S.L.), Finouin (Bénin) |
| Drepane africana || Spadefish || || Ghagbadza (Togo), Gbagha (Bénin) |
| Istiophorus || Sailfish || Voilier || Onyake (Ghana), Adjete, Abadanon (Bénin) |
| Lutjanus spp. || Snappers || Lutjans || Kessan, Aidjoin (C.I.), Ta (Ghana), Agnato (Bénin) |
| Galeoides decadactylus || Thread fish || Faux capitaine || Sukwe (Ghana), Tikué (Bénin), Sénu (Guinée) |
| Pseudotolithus spp. || Cassava fish || Otolithe || Whiting (S.L.), Nkan (Ghana, Bénin), Konkuyé (Guinée) |
| Auxis spp. || Frigate mackerel || Melva || Guégou (Bénin), Opoku (Ghana) |
| Scomber japonicus || Spanish mackerel || Maquereau espagnol || Saman (Ghana), Ouo (Sénégal), Mankere (Nigeria) |
| Cybium tritor || Kingfish || Maquereau bonite || Dzadu (Togo), Saflo (Ghana), Makré, Bariaké (Guinée) |
| Sarda sarda || Bonito || Bonite à dos rayé || Guégou (Togo), Kirikiri (Sénégal) |
| Epinephelus spp. || Groupers || Merou || Awro (C.I.), Shoi, Klanla (Ghana), Toboko (Bénin) |
| Dentex spp. || Dentex || Denté || Sika-sika (Togo), Tsile, Wiriwiriwa (Ghana) |
| Sparus spp. || Sea Bream || Pagre || Sika-sika (Bénin) |
| Pagellus coupei || Sea Bream || Pageot || Wiriwiriwa (Ghana), Sika-sika (Togo) |
| Lethrinus atl. || Sea Bream || Dorade grise || Ekpimmèkpaviyii (Bénin), Yiyiwa (Ghana) |
| Trichiurus lep. || Ribbon fish || Sabre, Ceinture || Anipa (Togo), Wawagyan (Ghana), Lipa (Bénin) |
| Mugil spp. || Mullet || Mulet || Séki (Guinée), Wétin, Guéssou (Bénin), An Shek (S.L.) |
| Gerres melanopterus || Mojara || Friture argentée || Noutouivi (Bénin), Ngoiossan (C.I.), Buin yékhé (Guinée) |
| Sphyraena spp. || Barracuda || Brochet, sennet || Lizi (Bénin), Kuta (Guinée), Ekoudi (C.I.), Edoe (Ghana) |
| Belonidae || Needlefish || Aiguillettes || Lébé (C.I.), Dayi (Togo) |
| || || || |
|Eau Douce Fresh Water|
| || || || |
| Bagridae || Catfish || || Kosso (Gambia) |
| Lates spp. || African Perch || Capitaine || |
| Tilapia spp. || Tilapia || Tilapia || Epiya (Nigeria), Aboyi, Kobi (Ghana) |
| Hemichromis app. || St. Peter's fish || || Mabli (Ghana), Akpavi (Togo) |
| Clarias spp. || Catfish || || Obokum (Nigeria), Mereke Dene (Ghana) |
TYPES OF WOOD MOST COMMONLY USED FOR FISH SMOKING AND TRAY CONSTRUCTION.
TYPES DE BOIS LES PLUS UTILISÉS POUR LE FUMAGE DE POISSON ET LA CONSTRUCTION DES CLAIES EN AFRIQUE DE L'OUEST.
| ENGLISH || FRANÇAIS || GHANA || GUINÉE |
| B || Combretaceae || Terminalia || Black Bark, Shingle Wood || Framiré || Idigbo, Amire, Dzobedodo || |
| B || Meliaceae || Azadirachta || Margosa || Nim || Abode || |
| B || Lecythiadaceae || Combretodendron || Stink Wood || Essia || Esia Kokobin, Esia, Osa || |
| B || Sterculiaceae || Mesogordonia || Danta || Danta || Odanta || |
| B || Papilionaceae || Baphia || Camwood || || Odwene, Odzori || |
| B || Rhizophoraceae || Rhizophora || Red Mangrove || Paletuvier || Mutuku, Atrati || |
| B || Anacardiaceae || Mangifera || Mango || Mangue || Mango || |
| C || Moraceae || Chlorophora || Iroko || Iroko || Odum, Elui || Semei |
| C || Sterculiaceae || Triplochiton || Wawa || Obeché || Wawa, Pataboa || Samba |
| C || Cesalpinaceae || Afzelia || Afzelia || || Papao || Léngué |
| C || Meliaceae || Khaya || Mahogany || Acajou || || Djala |
B=Bois de Chauffe; Burning (firewood)
C=Construction (claies; trays)
(N.B. Certain other materials, such as sugar cane, coconut husks, wet grass and sawdust are often used at the end of the smoking process to provide plenty of smoke at low heat and to give a desired flavour and colour, as well as to kill undesirable organisms that tend to spoil the fish after a given period of storage)
Bill Brownell and Jocelyne Lopez