Imitation crab as they do it.

What is the imitation crab made of? Have you ever wondered?

It has many, many ingredients, it is made by mixing processed fish, known as surimi, with various texturizing, flavoring and coloring ingredients.

Raw materials

Various ingredients are mixed to make a product that has the color, flavor and texture of crab meat.

The surimi used is mainly processed from Alaska pollock, walleye pollock, New Zealand pollock. These fish are useful because they are abundant, have little taste and are inexpensive. Other fish that have been used include blue hake, croaker, lizardfish.

During surimi manufacture, cryoprotective materials such as sugar and sorbitol are added prior to freezing to prevent degradation of the gel-forming properties of surimi. These ingredients also have an impact on the flavor of the final product and help extend its shelf life.

While surimi gels provide structure, other ingredients are needed to help stabilize and modify their texture. An important ingredient is starch. Improves texture and stabilizes the gel matrix. This is particularly important for product stability when frozen. The amount of starch is generally 6% of the recipe. Egg white is also added to the surimi to improve the gel structure. Vegetable oil is also used to improve the appearance and modify its texture.

Flavors are added which may be natural or artificial, but typically a mixture of both is used. Natural flavor compounds include amino acids, proteins and organic acids, that are obtained through the aqueous extraction of edible crabs. Artificial flavoring compounds can be made to closely match the flavor of crab meat and are generally superior to naturally derived flavorings. Artificial flavoring compounds include esters, ketones, amino acids and other organic compounds. In addition, seasonings and secondary flavorings are added to meat to improve the overall flavor. Common ingredients include nucleotides, monosodium glutamate, vegetable proteins and mirin.

Water-insoluble compounds such as carmine, caramel, paprika and annatto extract are often used for coloring. By combining these and other ingredients, various shades of red, orange and pink can be obtained.

Preparation of surimi

Prepared fish fillets can be mechanically minced or deboned and made into surimi. This is done using a mechanical deboner, which removes the skin, scales, fins and bones.

Formation of the crab imitation

Frozen surimi is converted into imitation crab through several steps.

It is cut, a process known as crushing, and mixed in a stone mill with other ingredients of the crab recipe. These ingredients include starch, salt, natural crab meat, egg white and flavors. This mixture results in a thick surimi paste, which is then transferred to a storage tank.
The slurry is pumped from the storage tank to the sheet forming equipment. Here, continuous sheets of surimi, approximately 25 cm wide and 1.2 mm thick, are produced. Due to the chemical nature of surimi protein, these sheets are very smooth.

After the sheets are formed, they are sent to machines for initial baking. This cooking helps to fix the slices and prepares them for the cutting operation, which gives the product the appearance and texture of crab meat.
The cutting is done with a machine that consists of two steel rollers that cut the surimi sheet into thin strands of 1.5 mm wide. These fine strands are bundled and coiled into a rope. This rope is dyed in the appropriate color, wrapped and cut to the desired size.
It is then steamed, forming a product that looks and tastes much like the crab meat it is intended to imitate.

References

Lanier, Tyre, and Chong Lee, eds. Surimi Technology. Marcel Dekker, 1993.
Sikorski, Zdzislaw. Seafood Proteins. Chapman and Hall, 1994.
Okada, Minoru. “A fish story. What is the ‘plastic food’ really made of?” Chemtech, October 1991, pp. 588-591.