IQF stands for Individual Quick Freezing, also known as individual quick freezing technology. An IQF system passes product through a forced-convection stream of cold air at -35°C to -43°C (-31°F to -45°F), bringing the core temperature of the product below -18°C (-0.4°F) in the shortest possible time.
Unlike batch freezing in air blast freezers or freezing tunnels, IQF treats each unit of product independently on a continuous belt, so the pieces never stick together. The result is smaller ice crystals forming inside the product's cells, less damage to cell structure, and product that retains its moisture, colour and tissue structure almost intact after thawing.
This article covers What is IQF?in full: the technical definition, the operating principle, the system's components, the three common types of IQF freezer and the criteria for choosing the right one for each scale of production. Tan Long has more than 20 years in industrial refrigeration and has been manufacturing IQF belts in Vietnam since 2011.
What is IQF in the food industry?
What is IQF? is an important question for any business looking for food preservation to a high standard. IQF (Individual Quick Freezing) is a method of quick-freezing individual pieces, where every unit of product is frozen independently and never touches another unit during the process. Unlike traditional freezing methods, this system runs continuously rather than in batches, which optimises throughput for
The key difference that What is IQF? The key lies in the speed of ice crystal formation. When the temperature drops extremely rapidly (usually from a few minutes to a few tens of minutes depending on the product), the water in the food cells freezes into ultra-small, evenly dispersed crystals. Conversely, slow freezing will create large crystals that break down cell membranes, causing the food to lose water and change its structure upon thawing. Therefore, installing an IQF conveyor belt becomes a crucial factor in preserving the nutritional value and freshness of the finished product.
In the seafood and food processing industry in Vietnam, understanding What is IQF? helps businesses meet export standards, since international markets consistently favour product frozen to IQF standard for its consistent quality after thawing.
How an IQF system works
Understanding What is IQF? helps a business picture the optimal preservation process. An IQF system works on the principle of forced convection: high-speed fans drive cold air through the evaporator, producing an air stream at minus 35 to minus 43 degrees Celsius blown directly and continuously over the surface of the product moving along the belt. This drives the cold into the core of the product extremely quickly.
Commonly used refrigerants are NH3 (ammonia) or R22/R404A (Freon). In large-scale seafood processing plants in Vietnam, NH3 is preferred due to its higher cooling efficiency and lower long-term operating costs. The refrigerant supply system uses a forced-circulation pump, ensuring even distribution of refrigerant throughout the evaporator coil.
The conveyor belt moves at an adjustable speed depending on the product type. Reference Freezing Retention Time for each product group is shown in the table below. The conveyor belt speed determines the contact time with the cold air stream, and engineers adjust this parameter based on the actual measured core temperature of the output product.
Alongside the main freezing belt there is the refreezing conveyor, which handles the product after glazing. Defrost water condenser periodically with water, then blown dry with compressed air before the next shift starts.
The components of an IQF freezing system in detail
To understand how efficiently What is IQF?performs, we need to look at the system's components in detail. A standard IQF line normally comprises five essential parts, working together to bring the core temperature of the product to minus 18 degrees Celsius to international export standard.
- Insulated enclosure: This encloses the whole freezing area and is built from insulated panels — two skins of 304 stainless steel over a polyurethane (PU) core 150 to 200 mm thick at a density of 40 kg/m³. This solid structure prevents heat loss entirely, holds the chamber temperature steady and minimises the electricity drawn by the compressors.
- Product belt: Made from high-grade 304 stainless steel, with either a fine mesh or a flat surface depending on the characteristics of the food. The 304 stainless gives good heat transfer and withstands frequent high-pressure cleaning in a food environment. The speed of the IQF conveyor is adjusted freely by inverter, allowing throughput to change without stopping the machine.
- Evaporator: Usually made from stainless steel tube with aluminium fins, arranged in two parallel rows along the belt. This layout optimises the heat exchange area and keeps the cold air stream distributed evenly across the whole product surface — a key reason for the advantages of What is IQF?.
- Central PLC controller: Acts as the "brain", monitoring and coordinating every operating parameter: chamber temperature, belt speed, defrost cycle and compressor status. The system PLC and SCADA control stores the data history, supporting traceability and precise quality control of the finished product.
- Sensors and safety systems: Comprising temperature and pressure instruments and emergency switches. When a reading exceeds the set threshold, the system shuts down automatically and raises an alarm.
Beyond those five main parts, the system also integrates important ancillary equipment: the high-pressure receiver, the low-pressure receiver, the oil separator, the liquid pumps and the defrost system. refrigeration system engineering solutions delivered comprehensively in Vietnam.
The three types of IQF freezer and how to choose
The three types of IQF freezer common on the market today are spiral, straight and high-speed, each optimised for a different product group and scale of production.
The comparison table below brings together the parameters that decide which system is right:
| Criteria | Spiral IQF | Straight IQF | High-speed IQF |
|---|---|---|---|
| Capacity (tonnes/hour) | 0.5 to 3 | 1 to 10 | 0.5 to 5 |
| Operating temperature | -35°C to -40°C | -35°C to -43°C | -35°C to -43°C |
| Installation footprint | Compact, but tall | Needs a long floor area | Medium |
| Suitable product | Cut meat, vegetables, round products | Shrimp, fish fillets, squid | Thin fish fillets, shrimp, potato products |
| Investment costs | Medium | High | High |
| Cleaning and maintenance | Harder | Easiest | Easy |
| Capacity expansion | Limit | Coils can be added | Expandable in modules |
Spiral IQF
Spiral IQF suits small and medium processing facilities where the floor length is limited but the building height is sufficient. The belt spirals upward inside a sealed insulated enclosure, creating a long travel path within a small floor area.
It operates between -35°C and -40°C (-31°F to -40°F). The enclosure uses stainless steel with 150 mm polyurethane insulation at a density of 40 kg/m³. The spiral design reduces the tension on the belt compared with a long flat belt, extending its mechanical life.
Its main drawback is that a spiral belt is harder to clean thoroughly than a straight one, particularly where the coils meet. That calls for a rigorous cleaning procedure.
Straight IQF
Straight IQF freezing belt is the standard choice for large-scale seafood and food processing plants in Vietnam, handling 1 to 10 tonnes per hour.
Product enters one end and leaves the other along a straight line, which fits a continuous production line inside a plant. The clearance between the product and the enclosure walls is kept to a minimum to reduce heat loss. A flat belt is easy to clean with high-pressure water after each shift.
A plant can expand capacity by adding air cooler and belt modules as production grows, without replacing the whole system. However, the straight design requires a substantial run of floor space, typically 6 to 20 metres depending on capacity.
High-Speed IQF
High-speed IQF is built like the straight type but upgraded with one or two stacked belt layers, each with independently adjustable speed. The air coolers sit in two rows either side of the belt, combined with air deflectors that concentrate the cold air stream directly and evenly onto the product.
The freezing speed of high-speed IQF matches a liquid nitrogen (cryogenic freezing) system, but at a considerably lower operating cost because no liquid nitrogen is consumed. The products it suits best are thin fillets (under 20 mm), whiteleg shrimp, black tiger shrimp, squid tubes, potato products, baked goods and egg-based products.
Tan Long has been manufacturing high-speed IQF freezing belts successfully since 2011 and supplying them across Vietnam.
Choose the IQF type according to the product: flat, mesh, fluidized bed, spiral
IQF (Individual Quick Freezing) is a rapid freezing method where products continuously pass through the freezing chamber, exchanging heat with a high-speed stream of cold air. This results in each piece freezing quickly and minimizing clumping. The conveyor belt supporting the product and the airflow over the product determine the appropriate IQF type.
| IQF type | Characteristic | Suited to |
|---|---|---|
| IQF flat conveyor (Solid Belt) | The bandage surface is tight or nearly tight, without mesh lines, and easy to clean. | Shrimp and seafood with wet surfaces, fish fillets, squid, meat, marinated goods, and products that easily stick to surfaces. |
| IQF mesh conveyor belt (Mesh Belt) | Stainless steel mesh ice allows cold air to pass through. | Vegetables, sliced fruits, potatoes, relatively dry seafood, and products in pellet form. |
| IQF fluidized bed (Fluidized Bed) | The air was strong enough to penetrate the product layers, causing the products to move and separate. | Small, loose, and uniform products: peas, corn kernels, diced carrots, diced mango, small shrimp. |
| Spiral IQF (Spiral) | The conveyor belt runs in multiple spiral layers, with a long residence time over a small floor area. | Goods requiring long freezing times, tray-packed/packaged goods, meat, poultry, baked goods. |
The actual efficiency depends not only on the type of conveyor belt but also on the air distribution, product density on the belt, product layer thickness, and conveyor speed. See also: Spiral or straight IQF: which to choose.
What is the IQF capacity?
For typical food processing lines, the reference yield range is approximately... 300–3,000 kg/hour; The benchmarks of 500, 750, 1,000, 1,200, and 1,500 kg/hour are commonly used as design benchmarks. Actual capacity must be determined based on product type, size, inlet temperature, outlet core temperature, loading density, and required freezing time.
Tan Long manufactures IQF mesh and IQF flat conveyor belts at capacities of 500, 750, and 1,000 kg/h per unit; factories requiring higher productivity may combine multiple units, for example. Kyokuyo Vina Foods Using 8 high-speed IQF conveyor belts, with a total capacity of 4,300 kg/h.
Freezing Retention Time (IQF) for each product type
The table below is a preliminary reference range., Not a guarantee parameter for all production lines.
| Product | Reference time |
|---|---|
| Shrimp | 3–8 minutes |
| Fish fillet | 8–15 minutes |
| Squid | 5–12 minutes |
| Sliced mango | 8–15 minutes |
| Vegetable | 5–12 minutes |
| Potatoes and similar products | 5–10 minutes |
| Meat, processed foods | 10–25 minutes |
When selecting IQF, the freezing time must be determined by thermal testing or calculation based on thickness, weight of each piece, water content, product inlet temperature, and required core temperature.
Optimal evaporating temperature of IQF
There is no single optimal evaporation temperature. In many industrial rapid freezing applications, the evaporation temperature is typically selected within the range of... approximately -40°C to -45°C, Then, optimize based on the product, refrigerant, cooling system design, and freezing time.
Lowering the evaporation temperature too much can shorten the freezing time but reduces the COP and increases compressor power. The design objective is... Achieve the required core temperature with the highest possible evaporation temperature. while maintaining productivity and quality.
How much electricity does IQF consume?
First, we need to standardize the measurement scope. If we only consider the freezer's fan and drive system, the figure will be much lower than if we include the compressor, refrigerant pump, fan, conveyor belt, and auxiliary components.
With a well-designed and operating industrial mechanical IQF system, the initial reference range is approximately 0.20–0.40 kWh/kg of product. Under adverse conditions or when the energy consumption range is wider, it may be around 0.40–0.60 kWh/kg or higher. A fixed figure should not be used as a guarantee for all products.
The indicators to monitor are: SEC (Specific Energy Consumption) = total electricity consumption (kWh) / weight of frozen products (kg). To compare two systems, the same product conditions and the same range of electrical equipment must be used.
Do IQF foods require automatic defrosting?
Moisture from the product and invading air causes frost to form on the evaporator coils, increasing airflow resistance, reducing heat exchange, and decreasing efficiency. For long continuous runs, automatic defrosting or alternating evaporator/evaporator operation is a worthwhile solution; the method can be water, hot gas, or other depending on the refrigeration system and cleaning requirements. Automatic defrosting is not mandatory for all IQF (Individual Quick Freezing) systems — it depends on the continuous run time, product moisture content, and evaporator configuration.
How to clean an IQF conveyor belt.
Conveyor belts come into direct contact with food, so they must be cleaned according to the factory's SSOP and manufacturer's instructions: remove leftover product → pre-rinse → use appropriate detergent → clean top, bottom, and contact surfaces → rinse thoroughly → disinfect as required → inspect before production.
Pay attention to the belt edges, underside, support bars, rollers, guide wheels, and hard-to-reach areas. Automatic belt washing systems or CIP systems reduce cleaning time, but the design must ensure good drainage and prevent residue buildup.
IQF device lifespan
With its stainless steel construction, properly designed refrigeration and drive systems, and good operation and maintenance, the main equipment is capable of serving about 15–20 years or longer (For reference only, not a guarantee). Conveyor belts, bearings, seals, sprockets, motors, gearboxes, and sensors have shorter inspection or replacement cycles.
IQF applications across food processing sectors
Understanding What is IQF? helps businesses recognise how important this technology is in raising the commercial value of their product. Today, IQF solutions serve three strategic sectors:
- Fisheries industry: This is the strongest area of application, where What is IQF? has become a mandatory technical standard for products such as whiteleg shrimp, black tiger shrimp, pangasius fillets, squid rings and octopus. Under the demanding requirements of export markets,.
- Fruit and vegetable processing: IQF technology helps preserve the cellular structure of beans, corn, bell peppers, broccoli, and diced potatoes much better than traditional blast freezing methods.
- Meat and convenience food processing: IQF is widely used for chicken fillets, sausages, fried spring rolls and ready-to-eat prepared foods. This segment is growing rapidly. refrigeration system equipment working together keeps product quality consistent as it reaches the market.
With experience across many real projects for major partners such as Lotte Foods, CP Group and SG Food, Tan Long is confident in providing optimal IQF solutions — helping businesses not only understand What is IQF? but operate them as efficiently and economically as possible.
Operating and maintaining an IQF system
To get the most out of the technology once you understand What is IQF?, following the operating and scheduled maintenance procedures is critical to equipment life. An IQF system only runs reliably and economically when technicians carry out the correct steps before, during and after every production shift.
- Preparation before operating: The technician needs to check that the chamber temperature has reached the design threshold and confirm the belt speed is configured for the product running that shift. Every food-contact surface must be thoroughly cleaned. The freezing temperature needs setting precisely: whiteleg shrimp typically needs minus 38 degrees Celsius, while thick fish fillets require minus 40 to minus 43 degrees Celsius.
- Control during the shift: This is the most important stage for proving the throughput of What is IQF?. The technician needs to check the core temperature of the outgoing product with a probe thermometer every 15 minutes. If the core temperature is above minus 18 degrees Celsius, reduce the belt speed immediately to increase the time the product is exposed to the forced cold air stream..
- Cleaning and maintenance after the shift: Once production finishes, defrost the air coolers with water and blow them completely dry with compressed air. Then clean every 304 stainless surface with a food-grade sanitizer.
Tan Long recommends a full inspection of the mechanical, electrical control and refrigeration systems every 3 months. Scheduled maintenance keeps cold storage running at its best.
With a core team of more than 20 years' experience, we support customers through a professional maintenance and warranty service, responding to requests within 02 hours so that production is never interrupted.
Tan Long – IQF belt manufacturer and installer in Vietnam
Understanding What is IQF? is only the first step; choosing a contractor capable of manufacturing in-house and mastering the technology is what really lets a business optimise its investment. Tan Long is proud to be one of the
Tan Long Refrigeration and Electrical Engineering providing turnkey solutions, from design consultancy through manufacture to complete installation. Our product range covers mesh IQF belts, flat IQF belts, NH3 or freon refrigeration systems, and modern control cabinet PLC and SCADA. With an engineering team of more than 20 years' experience, we make sure every system operates reliably after handover and meets global HACCP standards in full.
What sets Tan Long's service apart is not only answering What is IQF? but the after-sales support. We provide a warranty on the entire IQF freezing system Up to two years from the date of acceptance. Our maintenance team is always available to provide online support or on-site troubleshooting to ensure uninterrupted production for our customers.
Free technical consultation: 0933 357 058 (Mr. Thinh)
For more on the principles behind this technology: IQF freezing engineering.
Frequently asked questions about IQF technology
How does IQF differ from conventional blast freezing?
IQF freezes individual pieces on a continuously moving belt, while blast freezing works in batches inside a static chamber. IQF cools 3 to 5 times faster, forming smaller ice crystals and preserving the product's cell structure far better.
Which products suit an IQF system in Vietnam?
IQF suits shrimp, fish fillets, squid tubes, octopus, frozen vegetables and prepared foods (spring rolls, potato products, sausages). For export whiteleg shrimp and pangasius fillets, IQF is a mandatory standard required by Japanese and EU importers.
What does an IQF system cost to install?
The cost depends on the capacity, the type of freezer (spiral, straight or high-speed), the refrigerant (NH3 or freon) and the level of automation. Contact Tan Long directly on 0933 357 058 for a detailed quotation against your actual requirement.
How much electricity does an IQF system use?
With a well-designed and operated industrial-grade IQF system, the reference energy consumption is approximately 0.20–0.40 kWh/kg of product (equivalent to 200–400 kWh per ton), including compressor, refrigerant pump, fan, conveyor, and auxiliary equipment. The SEC (Security, Consumption, and Energy) ratio should be monitored as follows: Total electricity consumption (kWh) / weight of frozen product (kg), and only compare two systems under the same product conditions and with the same range of electrical equipment.
Frequently asked questions about IQF systems
What is IQF?
IQF (Individual Quick Freezing) is a technology that quick-freezes individual pieces, so they do not stick together after freezing and retain a structure and colour close to the original.
How does IQF differ from block freezing?
Block freezing freezes the whole mass into a single slab, which has to be thawed as one. IQF freezes each piece separately, so the end customer can take exactly the quantity needed — convenient for retail and for further processing.
How many types of IQF freezer are there?
Three common types: spiral IQF, straight IQF and high-speed IQF. Which one to choose depends on the product, the throughput and the available floor area.
Which industries use IQF systems most?
Mainly seafood processing, meat and poultry, fruit and vegetables, and prepared foods — the sectors that need product quality kept at its highest after freezing.
Does Tan Long build IQF systems?
Yes. Tan Long designs and installs IQF freezing systems to the specific throughput and product type of each plant. Get in touch for a survey and a proposal.
Tan Long B2B Technical Consulting
Get your Cold Chain Capacity Calculation & Estimate within 24 Hours
Tan Long's engineering team conducts on-site surveys, calculates cooling load, and advises on equipment configurations to optimize operating electricity costs and meet stringent export standards (HACCP, FDA, GACC China).
✓ 10,000m² factory in Duc Hoa 1
✓ Partners: Bitzer, Mayekawa
