| Fish handling, preservation and processing in the tropics: Part 2 no. G145 |
In this session, we will consider the many different products from the fishing industry which do not make up a main livelihood for a processor or processing plant but could be said to be by-products from the main industry. Many of the examples used are from the Japanese fishing industry. Japan is a great fish-eating nation and almost all the products from the fishing industry in Japan are used in one form or another.
Dried shark fins are used in Chinese cookery and produced in considerable quantities in many parts of the world. The main exports are to China, Hong Kong and other Chinese-orientated societies. The process used for shark fins is similar throughout the different countries. The fins, mostly the spinal and caudal, are cut from the animal and any adhering flesh is removed as far as possible. The fins may be dusted with salt in a ratio of approximately 1 part of salt to 10 parts of fish, the cut portions being liberally sprinkled with salt and then set aside for about 24 hours. The fins are then washed in water and either hung up or spread out to dry in the sun for a very long period (up to one month). The moisture content after drying is generally about 7 to 8 per cent. The dried fins are then packed in sacks under pressure so that they are flattened during storage.
Shark fins are prepared not only as plain dried fins but also as dried fin rays. By boiling shark fins to remove the outer skin, naked fin rays can be obtained. Shark fins are removed from the fish bodies and soaked in fresh water to soften for 4 to 5 days. After softening, the fins are heated in water at 90°C for 20--30 minutes so as to swell them and remove the epidermis. Once the epidermis has been removed, the rays can be separated from one another by softening the gelatine between them in hot water. The rays are called shisai in Japan and can be either white or black; the fin rays which have been dried in the sun are called taishi.
Also in Japan the cartilage from rays and sharks is prepared for export to China in the same way as shark fins. The cartilage of the jaw, fin and head is cut into pieces 7 - 9 cm long and soaked in hot water to remove the adhering meat. The prepared cartilage is then boiled in water and dried in the sun. The product should be an amber colour after drying. The product is known as meikotsu in Japan.
The dried fins and cartilage are generally used in Chinese cookery as thickening agents in soups.
In Japan, cod stomachs together with the gills and gullets are salted for preservation and consumption. In many countries, the entrails of fin fish, sea cucumbers and urchins etc. are fermented in much the same way as products from whole fish and fish flesh to make sauces and pastes for condiments. In many parts of the world, fish entrails are included in a process or a preserved product and are consumed with the rest of the fish. In other areas where guts are removed, they may be sold separately at the retail market usually at a very low price; they may even be given away to beggars. In other circumstances, of course, the guts etc. may be converted into fish meal, silage etc. for animal feeding.
In many fish preparation procedures, the fish may be salted in brine or boiled in brine or plain water as part of the procedure. Sometimes this water is used as a food because it contains fishy flavours and some nutrients. Most often it is used as a condiment to other dishes.
In Hong Kong, boiled dried oysters are produced. After boiling and removal of the oysters, the water in which they have been boiled is concentrated to form a brown liquid. Starch is added to this liquid to thicken it and sodium benzoate to preserve it. It is then bottled or canned and used as a condiment.
On the Minicoy Islands of India, a tuna fish paste is prepared from diluted sea water in which tuna fillets have been boiled. After this water has been used up to eight times for tuna boiling the liquid is concentrated to a thick paste.
The petis produced in Indonesia is made from the concentration of water used in boiled fish preparation. Sugar is added to the water after the fish have been boiled in it and the mixture slowly concentrated to a brown viscous fluid. The petis can also be produced from the water used in the production of shrimp products such as matsuurazuke in a similar fashion.
In Vietnam, a shrimp extract is prepared from the heads and shells of dried shrimp. The shrimp waste is boiled in water for several hours, sugar is added and the liquid concentrated to a thick syrup.
In Japan, the soft bone of whale may be sliced and pickled in salt and rice wine lees to produce a product known as matsuurazuke. Also in Japan the eggs of sea cucumber may be salted and dried for consumption as hoski konoka.
There are many other such products throughout the world using bits and pieces which would otherwise go to waste.
Much fish which would otherwise be wasted is not used in fact for human consumption but can be used as pet food. In Japan, the dark meat of tuna, which can constitute up to one sixth of the total from the fish, is canned and used for pet food. In many countries similar sorts of operations are undertaken either with canning the entrails or possibly freezing them into packs for retail sale.
SUBBA RAO, G. N. (1967) Fish processing in the Indo-Pacific area. Food and Agriculture Organization of the United Nations, Rome (FAO) Indo-Pacific Fisheries Council Regional Studies, No. 4.
TANIKAWA, E. (1971) Marine Products in Japan. Tokyo: The Koseisha-Koseikaku Company, 507 pp.