Fermented fish and processed fish have been considered a widespread industry since a very long time. The drying of different varieties of fishes is one of the world’s oldest known preservation method, and dried fish has a storage life of several years. Ancient methods of preserving fish included drying, salting, pickling and smoking. All of these techniques are still used today but the more modern techniques of freezing and canning have taken on a large importance.
The whole process of drying the fish or any kind processing done to the fishes is nothing but putting enzymatic or microbiological activity either in the presence or absence of salt. The larger fish processing companies have their own fishing fleets and independent fisheries. The products of the industry are usually sold wholesale to grocery chains or to intermediaries.
Dry Fish or dried fish is described as any fishes which had developed a strong odour within hours of capture and salted for about four days and then dried. It is highly salted and semi-dried fishery products with an obnoxious odour and a cheesy but rich fishy flavour widely liked as a sea food item worldwide. The fish most commonly dried and salted are cod, herring, mackerel, and haddock. Smoking preserves fish by drying, by deposition of creosote ingredients, and, when the fish are near the source of heat, by heat penetration. Herring and haddock (finnan haddie) are commonly smoked. Kippers are split herring, and bloaters are whole herring, salted and smoked.
Sardines, pilchards and anchovies are small fish of the herring family, often salted and smoked and then preserved in oil. Fish are dried under controlled conditions of temperature, humidity, and air velocity. Since the dried product is relatively unappetizing and re-hydrating slow, other preservation methods are common. All these render a preservative characteristic to the fishes and when packed properly they can be stored for ages. Cod is the fish most commonly used for for processing and can be preserved by salting, drying, or both. Salted and dried cod is usually called salt cod, and fish which is dried without the addition of salt is called stockfish. Salt cod is produced in Canada, Iceland, and Norway.
In the ancient times, dry and preserved fish were important as an export item to the economies of British North America (especially the fishing ports of Newfoundland, New England, Nova Scotia). Preserved cod was the favourite staple food of Iceland for centuries. The drying of food is the world’s oldest known preservation method, and dried fish has a storage life of several years. The method is cheap, the work can be done by the fisherman or his family, and the resulting product is easily transported to market.
Dry fish has extreme popularity and is widely consumed in Catholic Mediterrenean countries, notably Portugal, Spain, and Italy. It remains part of the national cuisines of the Caribbean, having arrived there with the so-called Triangular Trade — manufactured goods from Europe, slaves from West Africa, sugar from the Caribbean plantations. It still forms part of nationally significant dishes in all three regions.
Processing of fish involves primarily the application of preservation techniques in order to retain quality and increase shelf life. It may also mean adding value to produce a wide variety of products. A number of methods are used to preserve fish. There are various techniques based on temperature control, using ice, refrigeration or freezing; others on the control of water activity that includes drying, salting, smoking and freeze-drying.
Techniques may rely on the physical control of microbial fish loads, such as through microwave heating or ionizing irradiation, or on chemical control of microbial activity and loads by adding acids. Techniques are also used that are based on oxydo-reduction, such as vacuum packaging. Most often a combination of different techniques is used to preserve fish. The common techniques are:
• Eviscerating • Skinning
• Blanching • Filleting
The fish is prepared immediately after capture. After gutting the fish, it is either dried whole, or split along the spine leaving the tail connected. The fish is hung on the flakes from February to May (ideal time; I.e. summer). The fish flakes are subjected to vacuum packaging or by controlling or modifying the atmosphere around the fish. After three months of hanging on the flakes, the fish is then matured for another two to three months indoors in a dry and airy environment. During the drying, about 80% of the water in the fish disappears.
A temperature just above zero degrees celsius, with little rain, is ideal. Too much frost spoils the fish, as ice destroys the fibers in the fish. Earlier some ancient techniques of fish processing were used like fermentation with salting and drying, fermentation and drying without salting, fermentation with salting but without drying. Drying fish on the ground is a source of contamination with sand and micro-organisms. It also renders the fish prone to attack by pets and other domestic animals such as goats, sheep, pigs and rodents.
The dried fish retains all the nutrients from the fresh fish, only concentrated; it is therefore rich in proteins, vitamins, iron, and calcium.
USE OF MODERN TECHNOLOGY
Earlier primitive and manual drying methods were used in the drying process but with the advent of modern methods, fishermen have started using solar drier for drying the fishes. Different types of driers like solar tent drier, solar cabinet drier, solar dome drier and solar drier with a separate collecting and drying chamber are being used. These driers are efficient in achieving higher drying temperatures and reduced humidity. They also increase drying rates, producing lower moisture content in the final product and highly improved quality.
It is possible to attain temperatures as high as 45°C inside solar driers and it has been suggested that this relatively high temperature offers some protection against attack by blowflies, beetles and other vermin. Additionally, solar driers also offer some protection against adverse weather conditions, especially in wet seasons.
DRY FISH USAGES
The by-products formulated during the drying process include fish oil, which when taken, can help regulate cholesterol in the body. There is a wide variety of delicious dishes that can be prepared from dry fish. Fish meal is a commercial product made from both whole fish and the bones and offal from processed fish. It is a brown powder or cake obtained by pressing the whole fish or fish trimmings to remove the fish oil. Fish emulsion is a special kind of coat that is produced as a by-product is a fertilizer emulsion that is produced from the fluid remains of fish processed for fish oil and fish meal industrially. The emulsion is anti corrosive and has wide industrial usages as paints and coating.
PACKAGING AND STORAGE
Packaging of processed fish is important as it facilitates handling during storage and distribution within the marketing chain. A little carelessness can cause damage and wastage. Generally old jute bags and poly sacks are used for packaging the fishes. Sometimes straw mats and ropes are used to wrap and tie fermented dried tilapia. Most of these packaging materials are reused a number of times before they are discarded. It was observed that packaging materials such as baskets, ropes and mats have a life-span of 612 months. The oil cans, jute bags and polysacks can last for two to three years.