From fish to fillet, from portion to end product

by Thomas Jensen

Most fish processing machines are only suited to processing one single species or similar species that have a comparable body and bone structure and are approximately the same size.

The share of processed fish products on the market is growing constantly. Jobs that used to be carried out by hand are today performed more and more often by machines. In the meantime there are not only machines for the more basic work such as removing scales and slime but also for highly sensitive processes like filleting, fillet trimming or exact portioning. These systems are particularly worthwhile if they can be combined to form complete processing lines.

One of the highlights and visitor magnets at this year’s Bremen fish fair in February was a walk-in production line which showed the complete production process of a smokehouse from incoming raw materials to final product control. The process was presented several times a day so that visitors could see what work is necessary before a smoked salmon fillet can be put into the display counter at the retailer’s. What was unusual about this demonstration was that all the process steps were carried out by machines. The idea of exhibiting processing technology in action, so that visitors could experience it live proved a real success. It attracted numerous people who stopped in their tracks to admire the processing machines’ performance. The purpose of this special demonstration in Bremen was essentially to highlight the potential of modern processing lines, because a lot of the tasks that are necessary in the fish industry and which used to be carried out by hand can today be performed by machines.

The classic ones are the primary processing lines that transform round fish into boneless fillets. What might sound easy often involves several work stages in practice since a cod, for example, has first to be gutted and headed before it can pass through a filleting machine. And even then, the fillets are not quite ready because they still have to be skinned and freed of any remains of the fin bases, bones or impurities. The fact that even these complicated jobs can today be performed by machines shows how efficient processing machines in the fish segment have in the meantime become. They are not only used for gutting, heading, removing scales and slime, filleting or skinning the fish, but can also take the pin bones out of the fillets, trim fillets, sort them according to colour and size and cut them into equal portions. Some machines are even in a position to sort the fish by sex or to separate the more valuable organs such as the liver and roe from the other parts during gutting.

Processing lines enable consistent product quality

The demands made on fish processing machines are high and often very specific. This can already be seen in the fact that most of them are only suited to processing one single species or similar species that have a comparable body and bone structure and are approximately the same size. It is not possible to process demersal fishes on a processing line for pelagic fishes, and vice versa. Every individual process stage in the chain has to be finely tuned to the particular fish species in order to achieve a perfect result and maximum yield. Even heading a fish, which at a fleeting glance may not seem to be a particularly complicated task, demands considerable know-how if unnecessary losses are to be avoided. Depending on the species, between 10 and 25% of raw fish weight is lost through the heading process. The highest yields are usually achieved when the cut follows the rear edge of the gill flap exactly. This material-saving cut demands relatively high technical skills, however, which makes the heading machine accordingly expensive. Its use is thus particularly worthwhile for more high-value fish species such as salmon or cod. In the case of less expensive mass species, such as a lot of pelagic species, it is not so much a clean cut along an exact contour that is important but rather the speed at which the fishes are headed. When processing these fish species, the cut is thus often made at a right angle to the backbone or diagonally downwards whereby the pectoral and sometimes even the ventral fins are removed at the same time. A straight cut is technically less demanding but often leads to the loss of part of the fillet.

Questions of this nature have to be posed for every machine in which a processor considers investment. Speed and precision are not mutually exclusive but there are often priorities which have to be set. Processors who can rely on large quantities of fish of the same species and size are right to consider purchasing a complete processing line. Such lines free company employees of monotonous work leaving more time for other jobs, increase the overall speed of the production process, ensure consistent product quality, and improve hygiene standards: the more often a fish is touched by a human hand, the greater is the risk that pathogens will be passed on which will ultimately endanger the product’s marketability.
Apart from these benefits, machine processing offers great savings potential because it reduces individual errors and material losses that are almost inevitable during hand work.

The fact that a processing line will supply high-quality products is today no longer sufficient – it also has to meet all the regulations that are applicable to food companies, it has to fulfil legal hygiene, sanitary and environmental standards, its operation has to be as economical as possible (e.g. as regards water, energy consumption) and it has to be easy to clean and disinfect.

That a processing line will supply high-quality products is today no longer sufficient – it also has to meet all the regulations that are applicable to food companies including legal hygiene, sanitary and environmental standards.

Complete solutions from one supplier

In order to make it easier for prospective customers to choose one of the numerous complex system solutions a lot of machine and plant manufacturers offer complete processing lines as turnkey solutions. This has both advantages and disadvantages for the customer. The benefit is clear in that every supplier knows the performance of his machines best and also how they fit together best so that bottlenecks and material hold-ups can be avoided during production. Where complete solutions are concerned this should ensure that all processes work together smoothly. On top of this, in the event of technical problems there is only one contact which makes service easier. On the other hand, being dependent on just one supplier can bring with it certain risks because not all plant producers are equally competent for all machines. Any supplier who offers an efficient system for a particular work stage does not have to be so well-informed where other work processes are concerned, particularly since a lot of processing lines are IT-driven today, have their own system-specific intelligence, so to speak. Automatic image recognition technology, three-dimensional scanners and computer controls are in the meantime an absolute must in a lot of prod
uction processes.

Because it is hardly possible for a single supplier to meet all these requirements alone there has been an increasing trend in recent years for companies to act together on the market. They do everything they can to bundle their competences, from equal co-operation to the takeover of other companies whose profile complements or extends their own perfomance spectrum.

Marel, an acknowledged developer and manufacturer of intelligent processing machines already joined forces years ago with Carnitech, Pols, CP Food Machinery and Geba to form ‘Partners in Processing’. Since then, Stork and Townsend have also joined the group. With offices in more than 30 countries, 3,500 employees and a worldwide sales network the ‘partners’ have become a global player whose machines and plants are to be found in over 60 countries. The plants and machinery for seafood processing that marked the early years of Marel’s company history and with which the Icelandic company grew, today account for only part of total sales: In the meantime, the Group does not only produce its machines, software and processing lines for fish but also for meat and poultry. In the fish segment the range includes superchilled lines and complete systems for salmon processing, sorting, weighing and batching plants, freezer plants and lines for low-pressure forming.


The Danish company Scanvaegt, which entered a strategic partnership with the Icelandic company Skaginn in May 2006, joined the Group some months later and today operates as a subsidiary of Marel. Scanvaegt is mainly specialised in large-scale industrial solutions for processing white fish and pelagic species. One of the highlights in the Scanvaegt range is super fast portion cutters with laser scanners which in just fractions of a second can optimize the cutting angle for every fillet. In order to enable full use of the machine’s performance capacity of up to 1,500 cuts per minute there is an automatic vacuum infeed system for the processing line. This system is in a position to isolate products such as fillets or portions reliably and very fast and feed them into the processing line.

Robust machines with intelligent computer controls

The traditional company Baader has for decades been producing processing machines for various work processes from gutting and heading, filleting and trimming to processing lines for pelagic species, demersal species and salmonids. A salmon processing line is a good example to portray here. First the salmon is gutted using a Baader 142 Princess Cut machine. Afterwards the heading machine Baader 434 removes the head with a cut along exact contours to guarantee maximum yield. Filleting is done on the Baader 200 and subsequently the fillet sides are passed on to the Baader 988 which analyses the size and colour of the fillet automatically and trims it for maximum yield. The final control is carried out by the Baader 560. Then the Baader 1900 sorts the fillets according to size. The Line Monitoring Control System (LMC System) visualizes product flow within the line, makes processes and product batches transparent and thereby enables company employees to make fine adjustments to maximize the line’s performance. Operator intervention is largely limited to the passing on of intermediate products to the next machine and certain control tasks.

Slicer manufacturer Salmco who recently celebrated their silver jubilee supplies not only their tried and tested slicers but also made-to-measure processing lines for numerous work processes and fish species. Over the course of the years Salmco has diligently developed and diversified its slicers further. Single and multi-lane cold and fresh slicers, also called soft slicers, cover all cutting needs. They enable cutting angles of between 0 and 90° and so can produce technically demanding vertical and horizontal cuts. These slicers have proved their worth for salmon and 35 other fish species in practical work environments. In cases where a complete processing line is required, Salmco co-operates with other manufacturers to fulfil customized applications.

The product range of the Danish machine manufacturer Kaj Olesen includes pinbone and dark meat removers, filet turners, trim lines and packing tables, tail cutters, and slicers for processing frozen fillets. These machines which cover a large number of tasks that are necessary during fish processing can easily be combined to form processing lines. In Olesen’s trim line into which the well-known pinbone remover is integrated the fillets are captured by photo cells after the pinbones have been removed and then passed to manual workplaces as required. This enables the avoidance of material hold-ups and ensures smooth-running work processes without interruptions.

Where shrimp processing machines are concerned, Laitram – which placed the first automatic shrimp peeling machine onto the market in 1949 – is a leading supplier. In addition to peeling, cooking, cooling and sorting machines the American company’s product portfolio also comprises complete processing lines for cold and warm water shrimps. At its simplest, a line can consist of the supply tank for shrimps and the peeler. For some years now Laitram has been producing new peelers that are said to achieve high yields amounting to only 1-2% less than the results of hand peeling. In contrast to hand peeling there is practically no risk of contamination of the shrimps during machine peeling. Depending on customer requirements, the processing lines can include systems for deveining and sorting the shrimps, too. Of particular advantage for the customers is the company’s after-sales service. In the context of special industry leasing agreements Laitram employees visit plant operators regularly to carry out preventive maintenance checks and to refit the machines with new additional systems.

In order to make it easier for prospective customers to choose one of the numerous complex system solutions a lot of machine and plant manufacturers offer complete processing lines as turnkey solutions

Despite technology, people are essential

Processing lines do not only exist for primary processing of raw fish but also for the production of convenience products (secondary processing) such as chilled fresh products, frozen products or canned products. Such solutions are rarely available “off the peg” but are sooner individually tailored to the requirements and wishes of the customers. Suppliers of these kinds of system solutions thus require a tremendous amount of know-how in this field plus far-reaching experience.

Stork Food Systems, which together with Townsend has belonged to the Marel Group since 2008, is one such company. The company’s strengths were originally to be found in poultry, meat, potato and vegetable processing, but today Stork also develops machines and systems for fish processing. Their range includes complete solutions for numerous tasks within the production process: preparation, forming, coating, thermal treatment, cooking and freezing, plus in-company transport. Some systems, like the low-pressure forming machine RevoFormer are even equally suited to both meat and fish. This processing machine forms products of exact and consistent shape and weight whereby the typical structure of the products is maintained. Subsequent processing stages such as flouring, wet coating and cooking or packaging of th
e fresh products can be carried out directly afterwards, for example using the RotoCrumb. This machine is for adding a variety of crumbs, coatings or marinades to the products.

One of the leading suppliers of complete technical solutions for secondary processing of fish, seafood and other products is Convenience Food Systems (CFS) to which more than 40 different firms with special competence in the areas technology, distribution and service belong. CFS extensive product list ranges from individual machines and accessories, through special developments, to complete production lines, particularly for ready meals, case ready and individual meal components. Together with their customers, CFS develops new food and packaging products that are exactly tailored to their special needs and are economical, i.e. profitable. The products and services mainly concentrate on the processing and packaging of fish and seafood, meat and poultry products, cheese products, pasta and vegetable meals plus special solutions for technical packaging.

Despite these numerous technical solutions, however, it is still impossible to do without people during fish processing. The human eye recognizes more reliably than some computerised image recognition systems the optical inadequacies of a fillet; and the complexity of a hand’s motion as it moves the knife for a particular cut can only be imitated at great technical cost.


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