Seafood Processing Planning
Seafood processing plant planning presents challenges unique to the industry including waste management, temperature control, water quality and packaging. In this article we discuss how these challenges should be addressed in best practice plant design, along with specific concerns facing the seafood industry in 2022 and beyond.
Introduction to Seafood Processing
The seafood processing industry covers the processing of any aquatic organism harvested for commercial purposes, including all edible finfish, molluscs, and crustaceans. The definition of processing covers the procedures implemented between the time the fish is caught/harvested before being delivered to the end customer that ensure the final product is fit for human consumption. The main activities involved in fish processing include handling, filleting, chilling, freezing, cooking/heating, canning, preservation processes, packaging, and delivery. In the UK, fish will be prepared for final distribution to retail outlets and restaurants or via intermediary wholesalers.
Fish processors can be segregated into primary and secondary processors. Primary processors will typically prepare the fish into fresh fillets or steaks and/or remove any other edible meat from the fish or will focus on cooking/shucking raw shellfish. Secondary processors may heat and/or prepare ready-to-eat seafood items such as sushi, frozen items, breaded items, packaged meals and canned or smoked products.
The UK seafood industry employs almost 15,000 people and is worth over £3bn per annum and is expected to increase at an average of 0.1% over the next 5 years. The Covid-19 pandemic did impact the industry but pivots to supply different markets such as supermarket trade have helped sustain trading. Brexit has brought its own specific challenges, but the industry is responding with appropriate variations to processes and equipment within its operations.
Characteristics of Seafood Processing
Contamination & Perishability
Due to the aquatic environment and soft tissues of seafood there is an elevated risk of microbial contamination, of which a high load is already present on their skin, in their digestive system and in their gills, even at the time of harvest or farming. This risk is increased during the processing procedure and common spoilage and pathogenic microorganisms include Listeria, Acinetobacter, Moraxella, Salmonella and E-Coli.
The nutritional properties and quality of seafood also depend on correct processing and handling following harvesting as the produce is highly perishable. A key challenge during fish processing is therefore the prevention of deterioration and contamination.
Chilling, water control activity, drying, salting, vacuum packing, smoking, freeze-drying, high pressure, and irradiation are also be used as preservation methods, as well as the ultimate measure of keeping the fish alive until ready for cooking or eating. Heat processes and pasteurisation can be used to remove the microorganisms and canned products can be sterilised, removing the need for chilling. Typically, more than one of these techniques is used throughout the storage, preparation, packaging, and transportation processes during seafood processing plant planning.
The Value-Added Process & Incorporation of By Products
Value addition is a growing focus in all areas of the food processing industry, including the fish and seafood sector. Seafood is a high value product, and the raw material cost of fish is typically much higher than with other produce, so any wastage cost is relative. Successful production must therefore include maximisation of yield and minimisation of waste at its core.
The butchering of fish can leave around 50% of the edible flesh still attached to the skeleton frame and the many ways of using this discarded waste have been explored within the industry, resulting in wide range of profitable convenience products to bring additional revenue and activity into the seafood value chain.
Surimi and surimi-based products are an example of this, where products such as crab sticks can be made from mechanically recovered fish flesh. Animal feed, fishmeal and fish oil are other such value-added by products.
Recovered, minced fish flesh is also used in a vast range of products such as nuggets, fish cakes and chowders and is processed similarly to surimi but must undergo the addition of cryoprotectants prior to freezing due to the presence of residual oils and sarcoplasmic enzymes that may oxidise and degrade.
Even packaging, often of a higher quality for fish than other food products, should be looked at as an opportunity to reduce waste and increase profitability.
Labelling & Packaging
Labelling and packaging must conform to legal regulations for seafood, including fair trade marking where required. There are wide varieties of packaging options depending on the product type and end audience. Typically, packaging is higher cost in the fish industry and so careful consideration must be given to whether any final solution meets needs best.
Pouches are cost-effective, keep products fresh and are convenient for transportation and storage. Canning is a tried and tested method for storing and preserving processed fish, with non-discolouring fish such as sardines, salmon and tuna commonly used. IQF (Individually Quick Frozen) processing is frequently used for frozen sea products and fish steaks/fillets whereas vacuum packaging provides excellent preservation characteristics and can also enhance the visual appeal of a product. Multi-layer films have excellent sealing properties for freshness and have the benefit of showing the product well.
The seafood sector has experienced major disruption because of Brexit, with new trading requirements and logistical challenges causing delays and interruption to supply and manufacturing. Live bi-valve mollusc producers have seen the greatest challenge, with those in class B and C waters now unable to sell into EU markets.
A key disruptor is simply the additional documentation and time that has been added to the export process. For live fish exporters this has impacted ability to control quality of produce on arrival. For example, the effectiveness of low-temperature freshwater to invoke clean states of fish and crustaceans on arrival is now inconsistent, as the additional time to transport may mean the produce does not survive the journey.
Many UK live fish exporters are now turning to domestic markets instead, including langoustine and spider crab producers, who have targeted supermarkets and hospitality operators.
Much as with other produce in the food industry, pressure for increased productivity and reduced costs is driving the agenda for automation and Industry 4.0 within the seafood processing plant sector. Equipment such as automatic skinning machines, filleting machines and electronic scales are now commonplace. Despite this, many freshwater fish are still manually processed by hand with knives, especially in smaller plants, though sometimes automation is the only option due to the manual labour involved in dealing with larger fish.
Processes typically analysed for automation opportunities include:
Packaging – one of the most communal areas for automation. Sophisticated packaging machines offer excellent payback due to the consistency, quality, and speed they bring to the process.
Sorting and grading – sorting is often still a manual process, but the automation of fish grading can give excellent efficiencies and cost-effectiveness when sufficient volumes are being processed.
De-heading and fin removal – these are usually automated processes using cutters or blades as the human effort is intense. This stage of automation can also incorporate other tasks within the process such as gutting and removal of entrails.
Scaling – scaling is a hard manual process, involving scraping or brushing. Electric scrapers are one way of semi-automating this process.
Slicing – typically a band saw or slicing machine is used for this process, with large fish requiring mechanical slicing simply due to the effort required.
Filleting – a filleting machine incorporating conveyor and rotating disc knife can significantly quicken the process at this stage.
De-boning – this is the removal of small pin bones typically found in larger fish such as salmon and cod can be automated but often requires manual intervention to both visually check and physically removal of any fugitive bones. The use of X-ray scanning technology has improved the detection rate significantly.processing
Considerations for Seafood Processing Plant Planning
Contamination & Perishability
Quality Control & Hygiene
Regardless of production processes involved within the plant – which could include heating, cooking, chilling, freezing, irradiation, canning or preservation procedures – it is imperative to work to an appropriate quality control and hygiene programme to remove the risks for both consumer and handler. Nasties such as salmonella and listeria are accepted as widespread within the environment, and it is about management of their presence rather than removal.
Spoilage and deterioration during seafood processing presents not only a risk to health but also to the ability of the business to sell its products and make a profit. Quality control of temperature, moisture, oxygen, and microbial growth are all imperative to factory success.
Quality control and data points will depend on the specific processing taking place, which should be mapped out on a flow chart from raw material to final product to develop a HACCP (Hazard Analysis and Critical Control Point) plan of the process which will identify the key points that must be met to ensure a consistent and safe product.
Machinery design, and build standards such for food machinery is BS EN 1672-2:2005 Food processing machinery along with good maintenance and cleanliness should be implemented as per the quality control programme and audited regularly for adherence to standards on types of cleaner and procedures, as well as frequent measurements of microorganisms and bacteria.
Segregation and separation of processes and differing states of produce throughout the process is key to effective hygiene and reduction of contamination. Production lines and plans should be organised to separate conflicting processes, such as early-in-the-day processing of clean products and late-in-the-day processing of less clean products.
Wet environments such as those found in fish processing factories present ideal conditions for listeria, which is a naturally occurring bug with seafood and can be found all around in these environments. Use of hygienic wall, floor and drain materials is essential, as is the separation of all contact surfaces to avoid spread.
Basic good practice for seafood factory planning includes:
- Effective drainage for high volume wet processing environment
- Segregating raw materials and finished produce
- Separating pre-cleaning and post-cleaning processes
- Positioning drainage away from clean/finished product areas
- Separation of wet and dry areas
- Ease of access to all equipment and surfaces for cleaning and maintenance
- Smooth, washable surfaces, protected from corrosion
- Hygienic building materials or coatings
- Building materials that are non-porous and stand up to wet conditions and chemicals/acids
Regardless of product type and processes there will be an element of controlling temperature within seafood factory environments. An all-round low temperature (typically 8 degrees Celsius or less) will inhibit/prevent the growth of microorganisms and bacteria, but worker comfort must be considered in these circumstances.
Likewise, elevated temperature processes such as cooking and frying will ensure effective kill rates of bugs on the produce but must be balanced with their impact on the product, for example protein cook-out with delicate fish such as salmon or cod. Smoking and lower temperatures can be used but these methods require more rigorous monitoring and testing for micro biological activity.
A good turnover of fresh filtered air must be ensured with any ventilation design, so that bacteria-laden air can be removed more readily. It is however important that the flow of air does not push bugs from one area to another – it is not simply a case of pushing air around the factory but, again, segregating flows wherever possible. Ventilation should be easy to clean, insect-proof, corrosion-proofed and free from dusty areas.
High quality water standards prevent contamination and ensure proper moisture levels for fish processing. In addition to this, the seafood processing plant design needs to consider whether the product will lend itself well to more organic or more chemical treatments during processing. During the fish cleaning process, additives, and chemicals such as acetic acid and chlorine dioxide may be added to water to provide additional sterilising and cleaning properties. This has the benefit of breaking down mucous and pathogenic/spoilage microorganisms more quickly and effectively but is frowned upon by the FSA and does not portray the same ethical stance as the use solely of potable water. Potable water use means more regular, disruptive cleaning, testing, and sampling regimes, which adds to cost and lends more readily to artisan, higher end-cost products that promote sustainability.
Preservation of the products, including management of the seafood cold chain, is paramount to ensure end products remain fit for human consumption. Duration of transportation, correct conditions of storage, temperature controls and suitable loading methods must all be considered within the process flows, along with the methods of verifying and recording these conditions have been met.
Fish processing waste can be either solid or liquid and include bones, heads, skin, and viscera. With the elevated levels of waste typically found in fish processing, combined with the prohibitive cost of raw materials, it is key that effective ways to resell or reuse by products and waste are incorporated into the core factory processes.
Solid waste can go on to be processed into fish meal rather than being incinerated. Depending on the fish, skins and heads can be used in animal feeds, deep-fried for snacks, and used as stock. Flesh recovery machines can also be included in the process to allow edible fish to be made into alternative products such as fish paté.
Even packaging can be repurposed and used as an additional revenue stream. For example, polystyrene packaging that cannot be easily recycled can be de-densified and compacted to sell on to plastics processors, rather than incur costly disposal charges.
Fish waste must also be managed correctly in line with any consent to discharge. Liquid waste includes brine, blood water and cleaning/washing discharges and is subject to the same regulation and environmental-friendly obligations as other wastewater, with particular focus on monitoring COD/BOD, oil, nitrogenic and phosphorous levels to decide final waste management treatment before discharge.
Waste treatment methods include those that are primary such as sedimentation, filtration, screening, and floatation. These methods focus on the removal of suspended solids including fats and oils. Secondary methods typically either metabolise the pollutants through biological, chemical, or even organic treatments such as reed beds. Hydrolysis, bioremediation, and anaerobic digestion are all common methods within the fish processing industry.
Our Seafood Expert
Martin has over 18 years’ experience working primarily in fish processing for major UK producers. His involvement included salmon, cod, seabass, and trout processing. Martin has managed and engineered large-scale seafood factory planning and design projects, including factory layout and process development.
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