Saithe of good quality makes very good eating, especially as the main ingredient of many fish products where the basic requirement is the flesh of any white fish. Saithe could, and should, be used much more widely than it is; what can the fish industry do to make it more acceptable?
This note suggests ways of improving the handling of saithe, both at sea and during processing and distribution on shore, as a first step towards improving its appearance, increasing its acceptability and raising its market value. The importance of bleeding soon after capture is emphasized.
The saithe or coalfish is plentiful and is caught and landed in large quantities by British fishing vessels, but is not highly prized as a food fish in the UK. The flesh is darker and less attractive in appearance than that of related species like the cod, but when cooked it is considered by many to be superior in flavour. Because the saithe has traditionally been regarded as an inferior fish, its price at the ports has remained low and, consequently, there has been little incentive to handle this species with the same care that is accorded to more valuable ones; for this reason quality is often poorer than it need be, and the market for saithe remains depressed. Better quality and more imaginative use could make saithe a more important food fish.
The present scientific name for saithe is Pollachius virens, but was formerly Gadus virens.
There are on record more than 140 names which have been used in the UK for this species, more than for any other British commercial fish, but most of these are local names and need not be listed here. The officially recommended names for retail sale are saithe, coalfish or coley.
Finnish: seiti; kuijan
French: lieu noir; colin noir
German: Seelachs; Köhler
Italian: merluzzo nero
Portuguese: escamudo; paloca
Russian: sajga; galija
Spanish: palero; bacalao perro
Swedish: sej; grasej; grasik
The colour of the saithe ranges from greenish brown to almost black along the back and sides, fading to dull silvery grey under the head and along the belly. The fins are dark, except for the pelvics, which are reddish-white. The lower jaw of the adult fish protrudes very slightly beyond the upper, and carries a minute barbel. The light-coloured lateral line is not arched above the pectoral fin, but runs straight from head to tail. There are three dorsal and two anal soft-rayed fins.
The saithe occasionally reaches a length of 120 cm, but the majority of the adult fish caught are from 60 to 90 cm long. Fish weighing up to 7 kg are quite common and occasionally fish weighing 10 kg or more are taken.
The saithe spawns offshore in 100-200 m of water to the north-west of Britain, in the northern North Sea, off Norway, Faroes and south Iceland. It spawns from January to April, and the eggs, which are about 1 mm in diameter, float in the upper 30 m of the open sea for 6-9 days before hatching. The young fish moves close inshore by midsummer, and may spend from 1-2 years in shallow water there, feeding on animal plankton and the eggs and fry of other fish species. The immature fish then moves offshore, but continues to live near the surface for a further 1-2 years, feeding on small crustaceans, sand eels, herring and other small fish.
The saithe grows about 15 cm a year for the first three years, and about 10 cm a year for the next three; it reaches a length of 100 cm when it is 10-11 years old.
The mature fish is demersal and is found from Norway and Iceland in the north to Biscay in the south; it forms small shoals, and is caught in quantity in northern waters during its migration to the spawning areas.
Saithe is not greatly prized as a food fish on the British market, in spite of the fact that it can be good eating. The very dark grey-black colour of the skin is not very attractive; the flesh, even when the fish has been handled very carefully, is not as white as that of cod and has a slightly greyish appearance. When the skin is removed from a fillet, a wide band of brownish-red flesh is exposed, giving that side of the fillet a discoloured and sometimes bloody appearance. The appearance of the flesh is often further marred by bloodstains and bruises, the result of careless handling, particularly on board the fishing vessel.
Saithe should be treated with as much care as more highly-prized species, from the time they are released from the codend until they are landed at the market.
Saithe in particular should never be thrown about the deck, but should be moved carefully to reduce bruising.
It is essential that saithe be bled as soon as possible after capture, preferably within 30 minutes of coming on board, in order to reduce discoloration of the flesh.
Bleeding is very important. The fish can be bled either by gutting them or as a separate operation. Whenever saithe are likely to lie any length of time before gutting, they should be bled first, either by cutting the throat or by cutting the main blood vessel in the tail. Once the saithe have been cut, either by gutting or as a separate step, they should be held in ice-cold water for at least 30 minutes to clear as much blood as possible from the system. Ungutted fish should then be gutted and washed, and the catch stowed in ice in the fishroom, or frozen on board.
Saithe should be stowed carefully in ice in the same manner as for other species, either in bulk in shallow layers, or in boxes, with plenty of ice. All too often saithe are put away with an inadequate amount of ice on them, or stowed in deep shelves or underfoots, where they become badly squashed and spoil more rapidly.
Saithe should not be mixed with other species, because the dark slime of saithe may discolour them. Advisory Notes 4 and 15 give more detailed advice on the principles of handling and stowing white fish, advice which is as applicable to saithe as it is to cod and haddock.
The shelf life of saithe in ice is much the same as for cod; saithe keeps in first-class condition for 5-6 days, develops some off flavours after 9 days, and becomes inedible after 15 days in ice. There is a noticeable improvement in the colour of fillets taken from saithe that have been bled immediately after capture and then held in ice before filleting.
It is not possible to reduce the intensity of colour of saithe fillets by dipping the fillets in chemical solutions; proper bleeding at sea is therefore essential to minimize discoloration. Removal of the unattractive dark skin results in a weight loss of about 10 per cent. In addition it is possible to remove the dark brown band from skinned fillets if this is found to be objectionable, but this entails a further loss in weight. One way of doing this is to put the skinless fillets through a skinning machine of the type that cuts a thin slice, thus removing most of the brown flesh, which amounts to an additional 10-15 per cent loss of the original weight of the fillet. The brown flesh can be used for other products such as fish cakes, where colour is less important.
Saithe that have been properly bled immediately after capture retain a better appearance after freezing and cold storage than unbled ones; thus once again the importance of prompt and thorough bleeding is emphasized.
Gutted and bled whole saithe can be frozen satisfactorily in 10-cm blocks in a vertical plate freezer. The frozen blocks should be dipped in, or sprayed with, cold water before being put into cold store; additional protection against dehydration can be given by storing the glazed blocks in heavy-duty polyethylene bags. The storage life of frozen whole saithe kept at the recommended temperature of - 30°C is 6 months in good condition. After 6 months they tend to lose their characteristic flavour, and some discoloration of the flesh begins to develop.
Whole saithe can also be frozen singly in an air blast freezer; single fish take up more space in cold storage and, as a greater surface area of fish is exposed to dehydration, glazing and protective wrapping are even more important.
Fillets taken from properly bled whole saithe must be frozen without delay, and kept chilled while awaiting freezing. When left exposed in air at room temperature they darken quickly and become much greyer in appearance. Fillets can be frozen in a horizontal plate freezer or an air blast freezer. Fillets are particularly susceptible to drying out in cold store; the frozen blocks must be well glazed and wrapped in either waxed paper or polyethylene film before putting them in cartons to prevent rapid dehydration. Fillets will keep in good condition in cold store at - 30°C for 6 months. For general advice on freezing and cold storage, see Advisory Notes 27 and 28.
Saithe fillets, because of their greyish colour, are at present used mostly in products where the appearance can be masked or disguised, for example in fish cakes, or are sold coated in batter or breadcrumbs. Saithe can also be used in a number of fish products where the basic requirement is the flesh of any white fish species, for example in fish sausages, fish pies, and fish chips. In some products like savoury fish fingers the darker colour of saithe can be masked by tomato sauce or some other coloured ingredient. Recipes for many of these products are given in Advisory Note 43.
A considerable quantity of saithe is now marketed as cold smoked fillets, both in the UK and abroad. The product is made in much the same way as for smoked cod fillets. The saithe fillets are brined in an 80° brine for 4-10 minutes depending on size, with an amber dye added to the bath. The brined fillets are hung over banjoes, left to drip for 2 hours, and then smoked at 27ºC for 3-5 hours in a mechanical kiln.
This delicacy was developed in Germany during the First World War when salmon was unobtainable. Although it does not compare with good quality smoked salmon either in texture or flavour, it is nevertheless a pleasant delicatessen product which has sufficient merit to be worthy of greater attention that it receives in Britain. It is very popular on the Continent, especially in Germany.
Saithe are usually at their best in the early part of the year, and in Germany many firms salt the sides or fillets at this time and use them throughout the rest of the year. The first step is to fillet the fish, leaving on the lug bone and skin. For immediate use, the fillets are buried in vacuum salt for about 24 hours, or less if the sides are small, in the same way as for salmon. The liquor that is produced is allowed to drain away. When the sides are to be kept for use at a later date, they are packed in vacuum salt in a vat, in which the liquor is allowed to collect. The pickled sides, when weighted to keep them below the surface, will keep for many months in a cool room.
After a long period in brine pickle, the sides must be desalted in water or weak brine before use. Sides salted overnight can be used at once after a preliminary wash to remove adhering salt. At this stage the sides should be firm and springy, and it should be possible to cut them into thin slices. The salt content of the flesh should not be below 9 per cent; this is important for subsequent keeping quality.
The sides are first cut into portions suitable for slicing, and then cut into slices 2-3 mm thick, either by hand or, preferably, by machine. The slices are immersed for a few minutes in a dye bath containing 5 per cent saturated brine, 0-2 per cent acetic acid and a suitable dye mixture. The dyed slices are laid on plastic coated mesh trays and smoked at 30°C for about 30 minutes in dense smoke in a mechanical kiln, with just enough smoke passing up the chimney to keep the fires burning.
The smoked slices, which should contain not more than 60 per cent water, are left to dry at room temperature for 2-4 hours before packing in cans or in glass in pure vegetable oil; olive oil makes a very good but expensive product; good quality peanut oil makes a perfectly acceptable product.
The shelf life of the packed product is at least 4 weeks at 0°C; at higher temperatures it is rather less.
The raw flesh of saithe is composed of 79-81 per cent water,
16-20 per cent protein, and less than 1 per cent fat.