There are several types of fish meals made from a wide range of fish varieties. Fish meal is a type of commercial fish product that is obtained from the flesh and bones of fishes and often processed into cake of powder. They are processed by fish trimming or drying after they are cooked, and then grinded into powder. For the kind of fish with a lot of oil, they are pressed or squeezed to remove the oil. Fish meal is high in proteins and rich in other nutrients which can be well stored and utilized as high quality fertilizers or as basic diet for domestic animals. Most types of fish meals are made from wild-caught, which have high percentage of oil and bones, and are not usually ideal to b eaten by humans. This is why these types of fish meals are referred to as industrial. But there are equally other mediums of manufacturing fish meals which are primarily made for human consumption. Though most fishes in the rivers and oceans can be made into different types of fish meals, there are some very few species that may be poisonous when they are used.
Selecting the right kind of fish meal
Different types of fish meals can be produced in different places with each region specializing in one types of fish meal or the other. Sardines, mackerels, and sauries are mainly produced in Japan, sand eel in central and northern Europe, pout in Norway, menhaden in the US, and anchovies in Peru. Mackerel is equally produced in northern Europe.
The processing of fish meals can be through grinding, drying, pressing, or cooking. For the production of one dry ton of fish meal, 5 tons of fishes are needed. The most basic method of processing fish into fish meals is by drying under the sun, which is still practiced in places without processing plants. But the final product is not at par in terms of quality in comparison with production with processing machines.
Most types of fish meals are made through a combination of these processes:
Cooking: The fishes are conveyed using a screw conveyor and packed in a steam cylinder. This stage is very important in the preparation of the different types of fish meals since overcooking makes it very soft for the fish to be pressed while undercooking makes it difficult for the fish to be pressed out properly.
Pressing: In the pressing stage, the water and oil from the fish is successfully removed while the solid (press cake) remains. The oil content in the pressed fish is reduced to 4% while the water is reduced from 75% to 40%. Drying: The drying process should be done properly as under-dried fish meals will be exposed to bacteria and moulds while over-dried contents may reduce the fish meal’s nutritional value. There are two main kinds of dryer used in drying: direct dryer or indirect dryer.
Grinding: This stage is the final phase of the processing which deals with the cracking of particles of bone or lumps in the meal to transform it into powder.