Surimi & imitation crab

Production process of surimi

Main ingredient

The main ingredient for imitation crab is fish. Often several species of fish are used like Arctic cod, walleye and the New Zealand hoki. These species are used because there are many of them and because they have relatively little flavor. Therefore, the flavor can be influenced a lot with for example flavoring agents and aromas.

Sorting, cleaning and again sorting

The fish is sorted to specie. By sorting them to specie the machinery can be adjusted more specifically which makes the process more precise. Afterwards the fish is cleaned with cold water. The larger unwanted parts are removed. Afterwards the fish is sorted to size. This aids the cutting process so that as few fish as possible is lost.

Filleting

The fishes are filleted, a process in which head, tail, fins, bones and scales are removed. Filleting can happen completely automatically. First the head and the tail are cut off. This is not difficult to accomplish because the fish was sorted to size.

Cleaning

Afterwards the fish is cleansed with cold and clean water. In this phase, the small and unwanted parts of the fish are removed. In this way scales that stick to the meat are removed, but also fat and inorganic salt are removed. Part of the proteins get lost. To accomplish this, the fish is put into water to soak. Later, the dirty water is sieved from the fish.

The above mentioned phases can happen on the fishing boat as well as in the factory.

Refining

The refining of fish means that the fish is put in a drum. Here the fish is subdivided in soft and white parts of the fish in the front of the drum and the harder and darker fish at the back of the drum. Useless fish is removed at the back of the drum.

Pressing

After the fish is refined it still contains a lot of water. Superfluous water is removed by pressing. The fish is pressed with such pressure so that the structure of the fish is not damaged.

Additives

Sugar and sorbitol are added to the fish. These additives make sure that the proteins of the fish itself are not damaged due to freezing. Besides that, it also gives a good flavor to the end product and a longer storage life.

Packing and freezing

After mixing the fish, which at this moment is already called surimi, it is packed in big polythene bags. These are filled with 10 kg of surimi.
The bags of fish frozen fast to a temperature of 20°C below zero. In freezing the fish fast many and small ice crystals are formed. This damages the fish less than when it is frozen slowly, in which the ice crystals receive much time to grow and to become large. The fish is kept at this temperature until it can be further processed. This can take a few days but also several weeks. The time of storing the fish depends on the supply and demand of imitation crab.

Production process of imitation crab

Heating up

The final imitation crab is produced from surimi. The surimi is heated to a temperature of 4°C below zero. This temperature is high enough to obtain good cutting surfaces, but it is low enough to avoid the growth of microorganisms.

Cutting

The surimi, which is still in big pieces, is cut into coarse flakes. These are small pieces of fish of only several millimeters.

Mixing and storing

The pieces of surimi are mixed with several ingredients. Starch, protein (plasma), vegetable oil, salt, real crab and aromas are added. The starch that is added will in the end be 6% of the total weight. Therefore it is very important for the structure. It forms and stabilizes the structure and it adds extra freezing stability. The plasma increases the strength of the jellyness and gives the product a more smooth and white appearance. Vegetable oil is added for the appearance and the structure. The aromas and the real crab lend the imitation crab its real flavor of crab.
The mixture can be stored in a tank for a few days if it is stored with a temperature around zero.

Forming, boiling and cooling

Afterwards the mixture is molded into bars of 25 cm long with a diameter of 1.2 mm. Because of the natural fish proteins the bars have a smooth appearance. The shape of these bars is fixed by boiling them for a few minutes. Now, the structure of the mixture is formed. The bars are again rapidly cooled down to a temperature of 3°C below zero to avoid micro-biological growth.

Splitting or cutting

The bars are cut into small parts with a length of 1.5 mm. Due to their smallness they split. This results in very small pieces of imitation crab that has the appropriate structure.

Shaping

These small pieces are given shape by clustering and rolling them. In this way, the complete structure of the crab is very well pursued. The most frequent occurring shape of imitation crab is a roll of 7 cm long with a diameter of 1.5 cm.

Coloring

The rolls are colored by spreading their outside with a mixture of surimi and coloring agents. By using a mixture with coloring agents it is easier to apply it which gives a better result. Besides that, several mixtures with different colors can be applied.

Packing and pasteurizing

The bars are vacuum-packed in bags of polythene, nylon or polyester. The bags with bars are pasteurized by means of steam to kill vegetative microorganisms which increases the storage life.

Stocking

The place of stocking of the imitation crab needs to be cooled. With a temperature of 3°C at most the bars have a storage life of one to two weeks.