What is Surimi? An Overview of Its Definition and Preparation

If you’ve ever eaten a California roll and wondered what that white, slightly chewy filling actually is – that’s surimi. It’s also the ingredient behind crab sticks, fish sausages, and those beautifully shaped fish cakes you find in Japanese cuisine. Surimi is far more than just ground fish. It’s a precisely engineered food intermediate with a centuries-old Japanese origin and a processing method that sets it apart from any ordinary minced fish product.

What is surimi? 🔗

Surimi is a wet concentrate of myofibrillar proteins derived from fish muscle – produced by mechanically deboning fish meat, mincing it, washing it repeatedly with water, dewatering it, and then stabilising it with cryoprotectants before freezing. The word comes from Japanese, literally meaning “ground meat.” In practice, though, surimi is not simply ground fish – it is a functionally refined protein ingredient with unique gel-forming ability, water-binding properties, and a long frozen shelf life.

Good quality surimi is odourless and has a creamy white appearance. Its excellent gelling properties allow it to be formed into a wide range of shapes and textures, which is why it serves as the foundation for so many processed seafood products worldwide.

Surimi vs. regular minced fish: what’s the difference? 🔗

This is the most important distinction to understand. When fish is simply minced, it retains blood, fat, pigments, enzymes, and water-soluble proteins – all of which accelerate spoilage, cause off-flavours, and degrade texture during frozen storage. Surimi processing technology involves washing the minced fish specifically to purify and concentrate the muscle proteins, stripping away these unwanted components.

What remains after washing is a clean, white, nearly odourless protein mass dominated by myofibrillar proteins – primarily myosin and actin. These are the proteins responsible for surimi’s high gel strength, excellent binding capacity, and minimal flavour profile – functional properties that plain minced fish simply does not possess. This washing step is what makes surimi stable enough for long-term frozen storage and versatile enough to form the base of a wide range of end products.

A brief history of surimi 🔗

The earliest recorded surimi production in Japan dates back to 1115, when it was first used to make kamaboko. For centuries, surimi products were sold and consumed fresh, because freezing caused the fish proteins to denature, ruining the gel-forming ability that gives these products their characteristic texture.

The breakthrough came in the post-World War II period, when researchers at the Hokkaido Fisheries Research Station began investigating how to preserve surplus pollock meat. A team led by K. Nishiya discovered that adding salt during processing prevented the spongy texture that resulted after freezing, and they also began using salted surimi in fish sausages. Then, in 1969, Nishitani Yōsuke found that sucrose and other carbohydrates like sorbitol acted as cryoprotectants – stabilising the fish protein without denaturing it the way salt does. This discovery transformed surimi from a fresh, locally consumed product into a globally traded frozen ingredient.

Raw materials: which fish are used? 🔗

Pacific pollock is currently the predominant resource for commercial surimi production, prized for its white flesh, mild flavour, low fat content, and high protein biomass. However, a wide range of species are used globally. In India, species such as pink perch, threadfin bream, croaker, big-eye snapper, ribbonfish, and leather jacket are commonly used.

The choice of fish matters significantly. White muscle fish – those with low fat content and pale flesh – are preferred for their clean colour and superior gel-forming proteins. Dark muscle fish such as mackerel and sardines contain higher haem pigment and lipid content, which negatively affect both the colour and flavour of the final surimi. Active swimmers with more dark muscle are less desirable for surimi production than sluggish, white-fleshed species. That said, research into processing dark muscle species for surimi is ongoing, given that they make up 40-50% of the global fish catch.

The surimi preparation process 🔗

Surimi production follows a defined sequence of steps, each critical to the quality of the final product.

Heading, gutting, and mincing 🔗

Fresh fish is first headed, gutted, washed, and mechanically deboned. The flesh is then passed through a mechanical mincer to produce a uniform fish mince – called otoshimi in Japanese. The quality of this raw mince, including fish freshness and species, directly determines the quality of the final surimi.

Washing and refining 🔗

The minced fish undergoes multiple cycles of washing with cold water – typically three to four rounds – to remove water-soluble proteins, blood, pigments, fat, and odour-bearing compounds. The water-to-mince ratio during batch processing typically varies from 5:1 to 10:1, and the number of washing cycles depends on fish species, freshness, and desired surimi quality. After each wash, the mince is strained or passed through a rotary screen to remove wash water along with dissolved impurities. The result is a concentrated mass of myofibrillar protein with significantly improved gel-forming ability.

Dewatering 🔗

After washing, the mince still contains excess water and must be dewatered – typically by screw pressing or decanter centrifugation – to bring the moisture content down to the standard level of approximately 78%. The decanter-based system, developed in the mid-1990s, improved fish meat recovery during washing and eliminated the need for a second washing stage in some operations.

Mixing with cryoprotectants 🔗

This is a defining step that separates frozen surimi from plain washed mince. After dewatering, the mince is blended with cryoprotectants – additives that prevent protein denaturation during frozen storage. The most commonly used cryoprotectant blend is a mixture of sucrose and sorbitol in a 1:1 ratio, typically at a combined concentration of 8%, along with sodium tripolyphosphate (STPP) at around 0.25-0.3%.

Each additive plays a specific role:

• Sucrose prevents the denaturation of actomyosin proteins during freezing by interacting with and protecting protein molecules. It also increases the surface tension of water, enhancing the amount of bound water in the surimi.
• Sorbitol (a sugar alcohol) acts as a humectant and cryoprotectant, improving water-holding capacity and contributing to protein stability.
• Sodium tripolyphosphate (STPP) increases moisture retention, slightly raises pH, and improves gel strength and cohesiveness. Polyphosphate added at 0.3% is considered optimal for both gel strength and flavour.

These antifreezing agents collectively reduce viscosity, improve moisture retention, and enhance protein stability during long-term frozen storage – enabling surimi to be stored frozen for up to a year without significant loss of functional properties.

Block freezing and frozen storage 🔗

The cryoprotectant-blended surimi is packed into polythene-lined blocks – typically 10 kg – shaped and packed by automated machinery. The blocks are blast frozen at −35°C and then transferred to cold storage maintained below −18°C. Under these conditions, with proper cryoprotection, surimi can be stored frozen for up to one year while retaining the gel-forming properties needed for downstream product manufacturing.

Surimi-based products: what is surimi used for? 🔗

Frozen surimi is not a finished food product – it is an industrial intermediate, a building block for a wide range of processed seafood. Surimi can be further used to obtain restructured fabricated foods or analogues of costlier products, such as lobster, scallop, and crab imitations, as well as kamaboko, after undergoing appropriate texturising, colouring, and flavouring processes.

Kamaboko 🔗

Kamaboko is a type of cured surimi – a processed seafood product made by forming pureed deboned white fish with additives and flavorings into distinctive loaves, which are then steamed until fully cooked and firm. It is one of Japan’s oldest and most commercially important seafood products, with production dating back to 1115. Kamaboko showcases surimi’s gel-forming ability: when surimi is mixed with salt and heat-set at controlled temperatures, the myosin proteins form a three-dimensional protein network, creating the firm, elastic, bouncy texture kamaboko is known for. Depending on region, cooking method, and shape, kamaboko products are known by different names – chikuwa (grilled on a bamboo stick), satsuma-age (deep-fried), and hanpen (boiled).

Fish sausages 🔗

Fish sausages are a major category of surimi-based products, particularly popular across Asia. In Japan, fish sausages and other extruded fish products are commonly sold as cured surimi. Surimi provides the binding protein matrix that gives fish sausages their structural integrity and texture, while seasonings, starch, and other proteins are added to achieve the desired flavour and consistency.

Crab analogues (imitation crab meat) 🔗

Perhaps the most internationally recognised surimi product is kanikama – imitation crab meat, known in the West as crab sticks or seafood sticks. Kanikama is made by adding crab extract, salt, starch, and egg white to fish surimi, then steaming and pasteurising the shaped product. Imitation crab products were first developed in Japan between 1973 and 1975, and they opened the door to global surimi consumption. The product uses surimi’s natural white colour as a base, to which orange-red colouring is applied on the surface to replicate the appearance of real crab meat – at a fraction of the cost. Beyond crab, the same principle is applied to make scallop analogues, shrimp analogues, and lobster-style products.

Global significance of surimi 🔗

Two to three million tons of fish annually – roughly 2-3% of the world’s total fisheries supply – are used for the production of surimi and surimi-based products. In China alone, total production of surimi-based products in 2022 exceeded 1.35 million tons. The United States, Japan, and Thailand are among the major producers, with countries like Vietnam, Chile, France, and Malaysia emerging as important players. Surimi has also become a practical tool for utilising low-value or underutilised fish species, adding economic value at the processing level while reducing waste.

From a nutritional standpoint, fish surimi contains approximately 76% water, 15% protein, 6.85% carbohydrate, and 0.9% fat – making it a lean, high-protein ingredient well-suited to processed food applications.

What do you think? Given that surimi production requires significant quantities of water for washing and generates considerable wastewater, how should the industry balance processing efficiency with environmental sustainability? And as global fish stocks face increasing pressure, which underutilised fish species in your region might have the potential to become viable surimi raw materials?

References

1. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/surimi
2. https://en.wikipedia.org/wiki/Surimi
3. https://courseware.cutm.ac.in/wp-content/uploads/2020/05/S-14-Fish-surimi-1.pdf
4. https://link.springer.com/chapter/10.1007/978-1-4615-2181-5_15
5. https://www.alfalaval.us/industries/food-dairy-and-beverage/food-processing/protein-processing/fish-processing/surimi-processing/
6. https://egyankosh.ac.in/bitstream/123456789/9838/1/Unit-4.pdf
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC4008746/
8. https://scialert.net/fulltext/?doi=ajft.2011.19.30
9. https://www.tandfonline.com/doi/full/10.1080/87559129.2020.1768403
10. https://www.slideshare.net/slideshow/preparation-of-surimi-and-minced-based-fishery-products/238294854
11. https://en.wikipedia.org/wiki/Kamaboko
12. https://www.slideshare.net/rnsImran/surimi-and-surimi-based-products
13. https://www.foodinjapan.org/japan/kanikama/