About 70% of the total fish is processed before sealing them, and example of fish processing is stunning, grading, removing the head, gutting, washing, cutting, removing of the bones. So, depending on the type of process, 20% to 80% of waste will be produced. And the type of waste will be, head, tails, skin, gut and frames. These by-product can be used to make other product such as, fish silage, fish sauce, and fish amino acid; but, the most fish by- products produced are fish meal and fish oil.
25% of the fish meal is produce from fish by-product. And, 63% of the fish meal is consumed by aquaculture industry, 25% by pigs, 8% by poultry and the remaining consumed by other.
Fish oil contain a high amounts of omega-3 PUFA, therefore, has become a valuable product not only as raw material for omega-3 concentrates production but also as a valuable ingredient itself in omega-3 enriched food products.
The composition of fish waste is different depending on the type of fish. Mackerel had the highest amount of fat content which about 11.7%. And, salmon had the highest amount of protein content which about 23.5%.
The processing for the production fish meal consist of heating, pressing, separation, evaporation, drying and grinding.
1. First the fish waste will be heated in order for the present protein to coagulate and rupture of the fat deposits. So, this will cause liberation of oil and water.
2. Then the fish waste will be pressed to remove the liquid,
3. The liquid will be collected to separate oil from water (After the fish oil extraction processes, the refining processes are presented then the omega-3 concentration from fish oil.).
4. The water (stick water) will be evaporated to thick syrup containing 30% to 40% of solid.
5. The rest of the material will be dried using press cake method in order to get a stable meal.
6. The meal will grinded to specific particle size