Before alluding to recent processes for preserving fish in a fresh state, some space may be devoted to the ordinary methods of curing fish.
The fish are spread on a floor, and sprinkled with salt; when sufficiently salted, they are thrown into large vats, and washed. Each fish is then threaded through the gills, on long thin spits holding 25 each. These are hung upon trestles in the smoking-room, where fires of oak-boughs are kept smouldering. For "bloaters," to be consumed in England, the smoking lasts about 24 hours; "red-herrings "for export are salted more, and are smoked for 3 or 4 to 40 days, usually about 14 days. "Kippers" arc taken while fresh, and split up. They are then washed, and thrown into vats with plenty of salt for a few minutes; finally they are spread out on tenter-hooks, on racks, and hung up for 8 hours' smoking.
A method of preserving oysters is adopted by the Chinese. The fish are taken from the shells, plunged into boiling water for an instant, and then exposed to the sun till all the moisture is removed. They remain fresh for a long time, and retain their full flavour. Only the fattest can be so treated. Oysters are also largely "canned," much in the same way as salmon.
The fish are beheaded and cleaned, and cut by a series of knives into the right lengths to fill 1-lb. cans. When these have been filled to within 1/4 in. of the top, the covers are put on and soldered. In an air-tight condition, the full cans are passed to the boilers, vats measuring 5 ft. X 4 ft. X 4 ft., where they are steamed for 1 hour. They are then taken out and cooled. A small hole in the centre of each lid, hitherto remaining soldered up, is opened by applying a hot iron, and the air and cooking-gases are allowed to escape. The cans are then instantaneously made air-tight again, and are boiled for two hours in a bath of salted water, the salt being added to raise the boiling-point. They are then left to stand till quite cool.
The beheaded and cleaned fish are spread upon sieves, and plunged for 1 or 2 minutes beneath the surface of boiling oil in coppers. After draining a little, the fish are packed closely in tin boxes, which are filled up with pure cold oil, and soldered. The quality deteriorates with every immersion, owing to the matters disengaged by the boiling oil, and the coppers need frequent replenishing with oil.
To preserve shrimps in a dried state, they are boiled for 1/2 hour with frequent sprinkling of salt; then spread out on hard dry ground, with frequent turning, to dry and bleach for 3 or 4 days. They are then trampled to remove the shells, and are winnowed and bagged.
This consists in the application of an antiseptic under great pressure. The antiseptic solution is made by adding 33 lb. salt and 1/4 lb. saltpetre to 100 lb. water; and 1/2 lb. salicylic acid to 100 lb. of water. A mixture is then made of 75 parts of the salt solution and 25 of the salicylic acid solution. This is applied under a pressure of at least 12 atmos. The goods are then packed in barrels or cases, and surrounded with gelatine, to exclude the air and prevent desiccation. The fish keep good and retain their flavour for 10 or 14 days. The same process is applicable to meat, game, etc.
This process, described further on under Meat, is equally applicable to all kinds of fish.