Essential Machinery for Fish Mince Production

Fish mince is the foundation of dozens of popular seafood products – from fish balls and fish cakes to surimi-based crab sticks. But turning a whole fish into a smooth, bone-free mince is not a simple task. It requires a carefully sequenced set of specialized machines, each performing a distinct role. Understanding these machines – what they do, how they work, and why they matter – is essential for anyone involved in fish processing at any scale.

Why machinery matters in fish mince production
Pre-processing machines: preparing fish before deboning
Headers and gutters
Scaling machines
Filleting machines
The core machine: the fish deboner (meat-bone separator)
How the belt-and-drum deboner works
Drum hole size and its effect on mince quality
Belt-type vs. drum-type deboners
Washing and dewatering equipment
Auxiliary and downstream equipment
Choosing the right machinery: key considerations

Why machinery matters in fish mince production

Unlike filleting, where the goal is to preserve large, intact pieces of flesh, fish mince production focuses on extracting the maximum amount of usable meat from bones, skin, and other unwanted parts. According to the FAO’s guidelines on preliminary fish processing, a filleting operation that also produces mince from waste material results in practically no unused raw material – making mechanization central to both quality and economic profitability. The machines involved must handle differences in fish size, species, bone structure, and flesh texture. They work in sequence: each step prepares the fish for the next, and a weakness at any stage reduces the yield and quality of the final product.

Pre-processing machines: preparing fish before deboning

Before a fish ever reaches the deboning machine, it goes through a series of preparation steps. These are not optional – they directly affect the microbial safety, yield, and texture of the final mince.

Headers and gutters

Heading and gutting machines are among the first pieces of equipment in any mince production line. A heading machine uses sharp blades – in linear, V-shaped, or arc-cutting configurations – to remove the head cleanly, with the cutting method influencing how much meat is recovered in subsequent steps. Gutting machines then remove the viscera, either by cutting open the belly cavity or, in some designs, by suction through the mouth – a method that avoids opening the belly but requires careful inspection to confirm complete organ removal, as noted in peer-reviewed research on primary fish processing.

The importance of gutting goes beyond just physical preparation. Provincial fish processing guidelines from British Columbia’s Centre for Disease Control outline four key reasons why gutting is essential: it removes spoilage bacteria and digestive enzymes from the gut; allows blood to drain, preventing tissue discoloration; eliminates the highly perishable liver; and prevents later contamination from residual gut contents. When fish haven’t been rapidly chilled post-harvest, the digestive enzymes in ungutted fish accelerate autolysis – breaking down flesh from the inside and producing off-flavors, a particularly serious problem in mince intended for surimi or value-added products.

Modern combination heading-and-gutting machines, such as those designed by Pisces Fish Machinery, merge both operations into a single unit. These machines open the belly, remove the viscera, and clean the bloodline using a system of wheels and brushes – producing a head-off, belly-open fish ready for the next processing stage in one pass.

Scaling machines

Scaling is a necessary step for many species, particularly freshwater fish like carp, perch, and bream. The FAO notes that manual scaling of larger fish can account for nearly 50% of the total time required to produce headed and gutted fish – making mechanical scalers essential for high-volume operations. Automated scaling machines use rotating drums or brushes to strip scales under running water. Importantly, scales harbor bacterial pathogens; their removal slows spoilage during refrigeration or freezing. That said, fish destined for filleting and subsequent mincing in a separator may not require scaling, since the deboning process separates skin and scales from the flesh mechanically.

Filleting machines

Filleting machines produce flat, boneless pieces of fish flesh from headed and gutted fish. During this step, water nozzles clean the fish and remove residual visceral tissue, while mechanical guides ensure consistent cut angles. A significant amount of usable meat – typically 30-50% – remains along the ribs and backbone after filleting. These carcasses, or “frames,” are a primary raw material for mince production. Research published on ScienceDirect highlights that new equipment has been developed specifically to recover flesh from frames and collar cuts, maximizing yield from each fish processed.

The core machine: the fish deboner (meat-bone separator)

The deboning machine – also called a fish meat separator or fish mince machine – is the centerpiece of the entire production line. Its function is to mechanically separate soft flesh from hard structures like bones, skin, scales, and cartilage using compression force.

How the belt-and-drum deboner works

The most widely used design is the belt-and-drum type. Fish portions or frames are fed into the machine and pressed between a rubber conveyor belt and a rotating perforated drum. The compression forces the soft flesh through the small holes in the drum while bones, skin, and other hard materials remain on the outside and are carried away by a scraper. The flesh collects inside the drum and exits through a dedicated outlet as raw mince.

A peer-reviewed study published in the Journal of Food Science and Technology on a small-scale belt-and-drum fish meat-bone separator confirmed that this compression-based design achieves meat separation efficiency of up to 75% on a dressed-fish-weight basis, with bone content in the resulting mince as low as 0.1-0.2% on the first pass. Critically, the study also found no significant change in the proximate composition (protein, fat, moisture, ash) of the mince compared to unprocessed fish meat – confirming that mechanical deboning does not materially compromise nutritional quality.

Drum hole size and its effect on mince quality

The diameter of the holes in the perforated drum is a key process variable. According to FAO processing guidelines, drum openings are typically 3-7 mm in diameter, with 4-5 mm being standard for freshwater fish. Smaller holes produce finer mince with a stronger grinding action – ideal for surimi and fish balls – while larger holes produce coarser output more suited to patties or pet food. For at-sea surimi processing, industry practice favors 3-4 mm orifices for optimum quality and yield; shore-side plants may use 5 mm drums. Drums with openings greater than 5 mm generate larger particles but can make contaminant removal more difficult in downstream processing.

The pressure between the belt and the drum is adjustable and must be calibrated according to fish species, size, and bone hardness. Too much pressure damages the protein structure of the flesh; too little reduces yield. The cylinder in a standard separator also rotates slightly faster than the conveyor belt, creating a shearing action that enhances meat extraction.

Belt-type vs. drum-type deboners

While the belt-and-drum configuration dominates commercial fish mince production, processors sometimes distinguish between belt-type and drum-type variants based on the orientation and design of the separation surface. Belt-type deboners feature a continuous belt system that carries fish portions against a perforated drum or plate; the belt wraps around roughly 25% of the cylinder’s perimeter, as described in FAO technical documentation. In drum-type designs, the drum itself is the primary structural element around which the belt operates under tension. In practice, both rely on the same core principle – compression force against a perforated surface – and the terms are often used interchangeably in commercial settings.

Washing and dewatering equipment

Once mince exits the deboner, it contains water-soluble components including blood, fat, pigments, and sarcoplasmic proteins. For products like surimi, these must be removed through repeated washing cycles. Industrial surimi processing lines wash the mince multiple times to remove blood, small bones, and impurities before moving it to a decanter. The Alfa Laval surimi processing system notes that replacing traditional screw presses with decanter centrifuges in the dewatering stage results in significantly higher meat recovery, requires fewer washing steps, and supports CIP (clean-in-place) sanitation – improving both yield and hygiene. The moisture content of the mince must typically be reduced to 80-84% before blending with cryoprotectants and freezing.

Auxiliary and downstream equipment

A complete fish mince production line includes several supporting machines that maintain quality between the key processing steps.

Refining machines – placed after washing – use fine screens (typically 0.5-1.5 mm) to remove any remaining fragments of skin, connective tissue, or bone that passed through the deboner drum. Screen size and rotation speed determine how clean the final mince is and how much product is recovered in the process. Chilling and freezing systems – plate chillers, blast freezers, or refrigerated conveyors – are critical at multiple points in the line. Deboning generates frictional heat that can denature fish proteins if not managed; many modern deboners include integrated cooling. Freshly produced mince must also be rapidly chilled immediately after separation to preserve gel-forming proteins and limit microbial growth. Finally, metal detection systems are standard in food-grade processing lines, placed near the end of the line to catch any metal fragments before packaging – a food safety requirement in commercial operations globally.

Choosing the right machinery: key considerations

Equipment selection for a fish mince facility depends on several factors that affect both performance and long-term costs. Species and bone structure significantly influence deboner performance: flat fish like flounder require different handling than round fish like pollock or mackerel, and fatty species such as sardine and mackerel need adjusted drum sizes and additional washing steps to manage lipid content and prevent rancidity. Throughput capacity must be matched across the line – a deboner rated at 500 kg/h paired with a gutting machine rated at 200 kg/h will create a bottleneck. Commercial deboners range from 180 kg/h for small-scale operations to over 6,000 kg/h for industrial plants, as noted by equipment manufacturers. All contact surfaces must be constructed from food-grade stainless steel (typically SS304) and designed for easy disassembly and cleaning, since fish processing involves aggressive cleaning chemicals and constant water exposure.

What do you think? As fish mince production becomes increasingly mechanized and automated, do you think small-scale processors in developing regions can realistically access and maintain this equipment – and what role should technology transfer play in making that possible? Also, given that gutting and heading significantly reduce microbial load and improve mince quality, how should processors prioritize these pre-processing steps when working with fish that has already been stored for several hours post-harvest?

References

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Table of Contents

Why machinery matters in fish mince production 🔗

Pre-processing machines: preparing fish before deboning 🔗

Headers and gutters 🔗

Scaling machines 🔗

Filleting machines 🔗

The core machine: the fish deboner (meat-bone separator) 🔗

How the belt-and-drum deboner works 🔗

Drum hole size and its effect on mince quality 🔗

Belt-type vs. drum-type deboners 🔗

Washing and dewatering equipment 🔗

Auxiliary and downstream equipment 🔗

Choosing the right machinery: key considerations 🔗