|Small-Scale Processing of Fish (ILO - WEP, 1982, 140 p.)|
|CHAPTER II. SALTING - DRYING - FERMENTING|
|I. FISH PREPARATION|
It is important that fish for salting and drying be prepared in a way which allows rapid salt penetration and water removal. Very small fish, such as anchovies, sardines and other species less than 10 cm long, are sometimes cured without any preparatory cutting, with only the guts removed whenever necessary. Fish longer than 15 cm are split open so that the surface area is increased and the flesh thickness is reduced. With fish more than about 25 cm long, additional cuts (scores) should be made in the flesh.
Fish must always be prepared in a manner acceptable to the buyer and consumer. For example, some consumers prefer that the head be cut off, while others prefer that it is left on. In some fisheries, the front two-thirds of the backbone of big fish is taken out once the fish have been split open. Removal of the bone increases the surface available for salt penetration and water removal. Another example refers to fish scales: some consumers prefer scaled fish while others prefer fish with their scales on. It is, however, preferable to scale fish for easy salt penetration and drying.
Fish should never be prepared on the ground as it will pick up dirt even if it were prepared on a board or mat. A table or bench at comfortable working height should be used. The table may be made of wood, metal or concrete. A good design of such a table is shown in Figure II.1 & plate II.2. The surface of the table should be smooth so that it is easily cleaned. Drainage should also be provided to allow scrubbing of the surface with a brush. Whatever the material used for the surface of the table, it is preferable to use a separate wooden cutting board in order to avoid damaging a wooden surface or blunting knives on a metal or concrete one.
Knives are the most important tools for fish preparation. A selection of these is shown in Plate II.1. Short knives should be used for small fish, long flexible knives for filleting and stout knives for splitting big fish. Knives must be kept sharp. Blunt knives tear the fish and slow down the work. If a grind-stone is available, it should be used to shape or profile the cutting edge and to remove nicks. An oilstone or water lubricated stone may then be used to sharpen the cutting edge. A steel should be used to remove burrs on the edge. Proper grindstones are expensive and steels are not easily obtained in some countries. In any case, a fish curer should always have a good sharpening stone available.
It is usual to split lean fish from the belly side, a method known as cod splitting, although all large round-bodied fish can be processed in a similar way.
Plate II.1. Cutting knives and sharpening tools
1. Oilstone (in protective box)
3. Or skinning
5. Block fillet knife
6. Kippering (herring splitting) knife
7. Gutting knife
8. Cod splitting knife
9. Large broad-
10. bladed knives
Plate II.2. Protective clothing and filleting table
Figure II.1. Fish filleting table
This method can only be practised if the fish has been gutted before splitting. In some fisheries, however, splitting from the back is the usual practice. This latter method of splitting is known as mackerel splitting. Whatever the method, all cuts should be made with a clean sweep of the knife as ragged cuts spoil the appearance of the fish and salt penetration and drying are likely to be uneven. Cod-style splitting of a large fish is illustrated in the sequence of Plates II.3 to II.10.
To gut the fish, prior to splitting, a single cut should be made from the vent to the throat. The guts should be pulled out in one piece and cropped into a barrel or other suitable container.
After splitting and if the flesh is thicker than about 2 cm, scoring cuts should be made along the length of the fish at intervals of 2-4 cm depending on the flesh thickness. These scores should not be so deep as to cut through the skin.
All black membranes should be removed from the inside of the fish. It is important that no pieces of gut remain. The fish should then be carefully washed.
Back or mackerel splitting is commonly used with smaller and fatty fish. The head is invariably left on. The method is illustrated in Plates II.11 to II.15 in the case of herring. After splitting, the guts, gills and hearts should be removed and, using a small brush, the dark coloured blood next to the backbone cleaned out. The fish should then be washed thoroughly.