This article provides an overview of cleaning in the fish industry, including the necessity of cleaning, types of cleaning materials and equipment, detergents, sterilisers, and guidance on selecting and using cleaning agents. It emphasises the importance of cleaning in the fish industry. It highlights the availability of a wide range of cleaning agents tailored for specific tasks. We also briefly discuss the use of mechanical cleaning equipment to enhance the speed and efficiency of cleaning tasks.
What Is Cleaning?
Cleaning involves removing dirt from surfaces. Thorough cleaning ideally eliminates both dirt and bacteria, but this can be challenging. Cleaning differs from sterilising in that a clean surface may still have bacteria, while sterilisation makes bacteria harmless and can slow their regrowth. It is typical to first clean a dirty surface and then sterilise it to remove any remaining bacteria.
Why Is Cleaning Important?
Prevention of Food Poisoning
The bacteria that cause food poisoning in fish can be transferred from humans during processing or may be present on the fish when caught. Most food-poisoning bacteria do not grow in fish below 10°C, and even fewer grow below 4°C. This means the risk of microbial food poisoning is relatively low when fish are kept chilled. However, food-poisoning bacteria can survive at these chill temperatures, and food processed under unhygienic conditions can carry these bacteria, even when refrigerated. The risk of contamination increases when higher temperatures are used during processing, for example, in the production of cooked or partially cooked products such as fish fingers and fish cakes. Bacteria can quickly multiply in warm products and in dirt on equipment, so it’s essential to thoroughly clean equipment and premises to prevent contamination.
Reduction of Spoilage
Unfrozen protein-based foods deteriorate due to bacterial action. Fresh food that touches dirty surfaces gets contaminated quickly, leading to spoilage. This occurs at various stages of the fish industry, from the trawler fish room to the processing factory and the retail shop. “Stinker fish” are produced when fish contact dirty surfaces, allowing certain bacteria to thrive. Spoilage bacteria can grow at 0°C and lower. Thus, maintaining low bacterial counts is vital to reduce spoilage and preserve product quality.
Following HACCP Principles in Fisheries Cleaning
The fish industry has to follow very strict cleaning and disinfection guidelines according to HACCP standards to produce safe and hygienic food products such as fish, lobster, and crabs. Cleaning is essential for removing contaminants, such as residues and microorganisms, using safe agents that won’t harm human health or the equipment surfaces. Establishing a detailed cleaning schedule is also important to ensure that work areas and equipment are regularly maintained. After cleaning, disinfection is necessary to eliminate microorganisms without affecting the quality of the food products. However, the effectiveness of disinfection can be affected by proteins, soap residues, and cold temperatures. To address these issues, alternating between acidic and alkaline cleaners and adjusting disinfectant concentrations can help maintain consumer safety and contribute to the economic success of fishing companies.
Difference Between Detergents and Sterilisers
What Types of Cleaning Agents Are Available?
Cleaning agents come in various forms, including liquids, powders, and jellies, designed to facilitate cleaning. The most important types for the fish industry are detergents and sterilisers, with some utility for jellies and abrasive powders.
Detergents
Detergents are important in the fish industry and are typically mixed with water before use. They can be categorised based on the type of solution they form: acidic, neutral, or alkaline.
Acid Detergents
These are usually based on phosphoric or sulfuric acid and are particularly effective in removing salts precipitated from water in hard water areas and cleaning aluminium surfaces by removing white scales.
Neutral Detergents
These are similar to household detergents and are suitable for light-duty cleaning. Their good wetting ability makes them ideal for dispersing grease and oil.
Alkaline Detergents
These range from mildly alkaline solutions to strongly alkaline ones composed almost entirely of caustic soda, which require careful handling.
Sterilisers
Sterilisers are used to kill bacteria and come in several types:
Chlorine-Based Sterilisers
Chlorine is the most common and cost-effective sterilising agent in powder, tablet, or liquid forms. It is highly effective but loses potency quickly as chlorine evaporates.
Quaternary Ammonium Compounds (QUATS)
These are more expensive but offer residual action, remaining effective on surfaces for a day or more. They are stable, odourless, noncorrosive, and nonirritant.
Hydrogen Peroxide
Although more expensive than chlorine, hydrogen peroxide is odour-free and breaks into oxygen and water, leaving no residue. It is used in the food industry to sterilise packages and machinery.
Phenol-Based Sterilisers
These have strong odours and can taint foodstuffs, so you should use them cautiously.
Detergent-Sterilisers
These products combine cleaning and sterilising in one operation. They are often based on quaternary ammonium or chlorine compounds and are suitable for light cleaning duties.
Abrasive Cleaners
These consist of powders with varying degrees of hardness and particle sizes, useful in manual cleaning tasks for removing stubborn dirt.
Jellies
Jellies, often based on caustic soda, are designed for cleaning vertical surfaces as they can adhere long enough for the active ingredients to work on the dirt.
Foam Cleaners
Foam cleaners, used in conjunction with foam cleaning machines, are also available for specific cleaning tasks.
How Do Detergents Work
Wetting the Soiled Surface
The initial step involves wetting the dirty surface. When grease or oil is present, a detergent with good wetting properties facilitates this process by reducing the surface tension of water, allowing it to spread and penetrate the grime more effectively.
Softening and Removing Dirt
The next step is to soften dirt and remove it from the surface. This is achieved through mechanical action (such as scrubbing) and the use of a hot detergent solution, which helps to break down and dissolve or disperse the dirt.
Suspension of Dirt Particles
Finally, the dirt particles are suspended in the solution, preventing them from re-depositing on the surface. This suspension allows for the removal of by rinsing with clean water.
Choosing and Using Detergents and Sterilisers
Purchase from Reputable Manufacturers
Ensure you buy detergents and sterilisers from reliable manufacturers. Inform them of the specific cleaning tasks and application methods. For example, low-foaming detergents are suitable for mechanical washing equipment, and water-softening agents can be added for use in hard water areas.
Quality Over Cost
Avoid cheaper alternatives that may contain less active ingredients or inferior materials. Although they seem cost-effective initially, they could result in a false economy due to their lower effectiveness and potential additional costs in the long run.
Proper Usage
Follow Manufacturer's Instructions
Adhere strictly to the manufacturer’s guidelines. Using twice the recommended concentration will not double the effectiveness and could lead to less satisfactory results. Typically, solution strengths of 1-2% are sufficient. Overly strong solutions can damage surfaces and pose safety risks to the operator.
Use Hot Solutions
Whenever possible, use hot detergent solutions. A solution at 55-60°C is approximately twice as effective as at 5°C.
Soaking Equipment
Soak dirty equipment in a tank of detergent solution. Prolonged soaking in the right solution can soften even the hardest dirt, making it easier to remove.
Precautions Necessary When Cleaning
Awareness of Hazards
Following the ‘Health and Safety at Work Act’, both manufacturers and users need to be aware of the potential hazards associated with chemical cleaning agents. Many companies now provide safety instructions with their products, detailing any risks, handling procedures, and first aid measures in case of accidents.
Avoid Mixing Cleaning Agents
Do not mix detergents with other detergents or with sterilisers. This can neutralise their effects or even produce dangerous fumes. For example, mixing a product containing hypochlorite with an acid can release harmful gases.
Protective Gear
When using strong acids or alkaline cleaning agents, operators should wear suitable protective clothing made of rubber or plastic to prevent skin contact and potential injuries.
Rinsing
Most detergents and sterilisers should not come into contact with food. After cleaning, thoroughly rinse all surfaces with clean water to remove any traces of these chemicals.
Compatibility with Surfaces
Ensure the cleaning agent is safe for the surface being cleaned. Seek advice from the manufacturer of the cleaning agent. For instance:
- Acid cleaners can corrode galvanised surfaces.
- Strong alkalis can damage aluminium.
Precautions for Specific Materials
Surface Material | Precautions to be Taken |
Aluminium | Susceptible to attack by some alkalis and acids. Use low alkalinity alkalis with silicates. |
Aluminium Bronze | Safe with alkalis; avoid acids. |
Brick, Concrete | Smooth, impervious finish recommended for cleanability. Avoid strong acids. |
Bronze, Gunmetal | Some alkalis may attack these metals. Use non-caustic detergents based on silicates, phosphates, and carbonates. |
Galvanized Metal | Acids and some alkalis attack zinc. Long-term brine contact can cause reactions, especially where the coating is damaged. |
Glass | Any detergent may be used. |
Mild Steel | Any alkali may be used. For hard water scale removal with acid solutions, ensure they are corrosion-inhibited. |
Nickel Alloys | Any alkali may be used. |
Plastics | Clean below the material’s softening point. Discard cracked or heavily scratched containers. Avoid abrasive cleaners and solvents like carbon tetrachloride or white spirit. Consult the manufacturer if unsure. |
Rubber | Strong alkalis can be used, especially to remove harmful fats and oils. Avoid solvents like carbon tetrachloride or white spirit. |
Stainless Steel | Any alkali may be used. Use acids with caution and avoid abrasive cleaners to prevent scratching. |
Tinned Steel, Tinned Copper | Some alkalis corrode the coatings. Use low-alkali detergents with silicates, phosphates, carbonates, and 2-5 g/litre of anhydrous sodium sulphite to reduce corrosion. |
Vitreous Enamel | Attacked by caustic alkalis and many acids. Use low alkalinity detergents with high silicate content. |
Wicker Baskets | Very difficult to clean; not recommended for use. Avoid strong acids and alkalis. |
Wood | Highly porous and difficult to clean; not recommended for use. Avoid strong acids and alkalis. |
Precautions Necessary When Cleaning
The primary goal of mechanical cleaning equipment is to simplify the cleaning process. However, no single machine can handle all cleaning tasks; operations such as vacuum cleaning, scrubbing, and pressure washing require specialised equipment.
Vacuum Cleaners
Scrubbers and Polishers
These machines are primarily intended for floor use, as they rely on the machine’s weight to keep rotating brushes in contact with the surface being cleaned. They are particularly effective for scrubbing large floor areas, but the best results are achieved on smooth, level floors. Floors cluttered with machinery and equipment are less suitable for mechanical cleaning than large, open floor spaces.
Steam Cleaners
Steam cleaners are highly effective for heavy-duty cleaning. Some models have built-in steam generators, while others need an external steam source. These machines can be hazardous if operated by untrained personnel.
High-Pressure Cold Water Cleaners
These machines enhance the pressure of cold water from the mains using a pump, delivering water at pressures ranging from 1000 to 5000 kN/m², typically as a fine jet through a lance head, at flow rates starting from about 8 litres per minute. They are ideal for cleaning fish processing machinery, as the high-pressure jet can reach areas that are normally difficult to clean by hand. Additionally, they use less water than traditional hoses, offering significant water savings.
Box Washing Machines
Box washing machines are efficient and labour-saving for cleaning large numbers of similar containers. These machines typically follow a sequence of rinsing and washing using suitable detergents. At least one step in the process involves hot water. These machines are particularly effective for cleaning market containers in a box pool or large processing factories.
Foam Cleaning Machines
Foam cleaning machines deliver detergent as a foam, extending the contact time between the detergent and dirt. This method is effective on horizontal, vertical, or inverted surfaces. It makes it easy to see where the foam has been applied. It is also suitable for cleaning machine parts that are hard to reach by hand. Various detergents with foaming agents are available, and this technique is increasingly popular in the industry.
Safety Considerations
When using water or steam cleaners, ensure all electrical equipment is fully enclosed and waterproof.
Additional Advantages of Cleaning
In the food industry, maintaining clean equipment and facilities is crucial for minimising bacterial contamination. This leads to safer, higher-quality products with longer shelf lives, especially for perishable commodities like fish. However, thorough cleaning also has several other significant advantages.
Enhanced Sales Appeal
A clean and well-maintained factory can significantly boost the sales appeal of its products. Consumers are more likely to trust and purchase products from a facility that demonstrates good housekeeping practices. A pristine factory setting conveys a commitment to quality and safety, which can lead to increased sales and better business outcomes.
Improved Staff Morale
Clean working conditions contribute to higher staff morale. Employees are more likely to feel content and take pride in their work environment when it is clean and well-maintained. When management prioritises cleanliness, it encourages staff to follow suit, fostering a culture of care and attention to detail.
Modern Standards in the Fish Industry
Historically, the fish industry has tolerated a certain level of dirt and discomfort in the processing environment. However, there is no longer any justification for such conditions. Today’s fish processing facilities should be clean and wholesome, reflecting their status as part of the food industry. Adhering to high cleanliness standards ensures a healthier workplace and higher-quality products.
Future Improvements in Fisheries Cleaning
The key objective for the future should be the better design of factories and processing machinery. Many new factories are now built with modern features such as tiled walls, smooth floors, and enhanced staff hygiene facilities, all of which make cleaning easier. However, much of the equipment and machinery still poses cleaning challenges.
Improved Equipment and Materials
The transition from wooden boxes to plastic and aluminium is already underway, with wooden fish rooms at sea gradually being replaced. Even traditional wooden filleting blocks are sometimes being substituted with synthetic, easily cleaned materials. Nonetheless, the pace of change can be slow.
Addressing Specific Challenges
Smoking Kilns
These present significant cleaning challenges. Although mechanical kilns are easier to clean than traditional chimney kilns, they still require frequent and thorough maintenance. A potential solution is to design kilns with removable parts that can be soaked or steam-cleaned.
Filleting, Splitting, and Skinning Machines
Due to their tasks, these machines are inherently complex, making them difficult to clean. However, modern design techniques, combined with improved cleaning facilities, should simplify the cleaning process for future processing lines. When purchasing new equipment, processors should consider ease of cleaning as a crucial factor.
Regulatory and Technological Advancements
Hygiene standards in the fish industry have improved significantly over the past decade. As fish becomes more integrated into the broader food industry, regulations are expected to become stricter, and processors will become more hygiene-conscious. Continuous advancements in cleaning agents and the development of new cleaning techniques will further facilitate the cleaning process.
Additional Advantages of Cleaning
Surface | Soil | Wet Fish Slime, Blood, Gut Contents, Scales, Skin and Oil | Air Dried Fish Residues | Cooked and Hardened Fish Residues | Tars | Starches and Frying Oil | Processing Material, Tomato Puree, and Dyes, etc. | Common Salt | Miscellaneous Soils Such as Marine Mud and Fuel Oil |
Aluminium | Water or acidic. Scrub with neutral or mildly alkaline where necessary | Mildly alkaline or acidic. Strongly alkaline for mechanical cleaning plants | Mildly alkaline or acidic | Caustic alkaline detergents are the only really effective substances for removing tars. Steam lances and strongly alkaline solutions may be used with some success. | Neutral, mildly alkaline or acidic. Strongly alkaline may be necessary for charred residues | Neutral, mildly alkaline or acidic. Strongly alkaline may be necessary for hardened soil | No detergent is particularly effective in the presence of a high concentration of salt. Salt should therefore be washed away before application of detergent. Neutral or mildly alkaline based on polyphosphate are then adequate. | Neutral, mildly alkaline or acidic. In some instances water alone may be adequate | |
Stainless Steel | Water. Scrub with neutral or mildly alkaline where necessary | Mildly alkaline. Strongly alkaline for use in soaking troughs | Mildly alkaline. Strongly alkaline for use in soaking troughs | Neutral or mildly alkaline. Strongly alkaline may be necessary for charred residues | Neutral or mildly alkaline. Strongly alkaline may be necessary for hardened soil | Neutral or mildly alkaline. In some instances water alone may be adequate | |||
Mild Steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | |||
Galvanized Iron | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | |||
Glass | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | |||
Vitreous Enamel | As stainless steel | As above (care with strongly alkaline) | As above (care with strongly alkaline) | As above (care with strongly alkaline) | As above (care with strongly alkaline) | As stainless steel | |||
Plastics | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | |||
Bronze Gun Metal | As stainless steel | As above (strongly alkaline should be based on silicate, phosphate or carbonate) | As above (strongly alkaline should be based on silicate, phosphate or carbonate) | As above (strongly alkaline should be based on silicate, phosphate or carbonate) | As above (strongly alkaline should be based on silicate, phosphate or carbonate) | As stainless steel | |||
Rubber | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | |||
Wood | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | |||
Wicker | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | As stainless steel | |||
Concrete, Brick, etc. | Water or acidic. Scrub with neutral or mildly alkaline where necessary | Acidic, mildly alkaline or strongly alkaline | Acidic, mildly alkaline or strongly alkaline | As stainless steel | As stainless steel | As stainless steel | |||
Tinned Steel and Tinned Copper | Water. Scrub with neutral or mildly alkaline where necessary | Mildly alkaline. Strongly alkaline based on silicate, phosphate or carbonate with sodium sulphite for use in soaking troughs | Mildly alkaline. Strongly alkaline based on silicate, phosphate or carbonate with sodium sulphite for use in soaking troughs | Neutral or mildly alkaline. Strongly alkaline based on carbonate, phosphate or silicate with sodium sulphite may be necessary for charred residues | Neutral or mildly alkaline. Strongly alkaline based on carbonate, phosphate or silicate with sodium sulphite may be necessary for charred residues | As stainless steel |
Conclusion
This article stresses the importance of thorough cleaning in the fish industry to prevent food poisoning and reduce spoilage. It discusses various cleaning agents, equipment, and their applications, emphasising the need to follow HACCP principles and use appropriate detergents and sterilisers to improve cleanliness and efficiency. The industry’s future relies on improved factory designs and advanced cleaning technologies to maintain stringent hygiene standards.
