What is blast freezing?

Blast freezing is an industrial freezing method where cold air is moved at high velocity across food products to freeze them as quickly and uniformly as possible.

The goal is to remove heat from the product efficiently. Faster freezing supports production capacity, energy efficiency and product quality. Blast freezing is widely used for seafood, meat, poultry, bakery products, ready meals and other food products where quality, texture and shelf life matter.

Problem: Slow or uneven freezing increases process time.
Solution: Improve cold-air contact with the product.
Effect: Faster freezing, better product quality and more efficient freezer operation.

Why is freezing speed important for food quality?

Freezing speed affects ice crystal formation inside the product. Slow freezing gives water molecules more time to form larger ice crystals, which can damage cell structure. Faster freezing creates smaller ice crystals and helps preserve texture, firmness and overall product quality.

For food producers, this matters because product quality has a direct commercial impact. Better quality can support stronger market positioning, while poor freezing performance can reduce product value.

Key point: Faster and more uniform freezing helps protect texture, appearance and product integrity.

Why is airflow important in blast freezing?

Airflow is critical because cold air must reach the product surface to remove heat. If air only moves around the outside of a pallet stack, the outer layers freeze first while the centre layers freeze much more slowly.

Air always follows the path of least resistance. Without airflow channels between product layers, cold air may bypass the product instead of moving through the stack.

FreezeTeq highlights this same principle: the solution is to create maximum space with minimal blocking between stacked layers, allowing air to move more efficiently through the pallet.

Problem: Air bypasses the product.
Solution: Use freezer spacers to create airflow channels.
Effect: More uniform freezing and shorter freezing time.

Can a cold storage room be used as a blast freezer?

A cold storage room is usually not designed to work as a blast freezer. Cold storage rooms are generally built to keep already frozen products at a stable temperature, while blast freezers are is designed to remove large amounts of heat from warm products quickly.

A cold store may lack:

• Enough refrigeration capacity
• Sufficient air velocity
• Correct air distribution
• Low enough operating temperatures for effective blast freezing

Adding fans alone will not turn a standard cold room into an efficient blast freezer. The full system must be designed for freezing duty.

However, it should be mentioned that applications have been designed for installation in coldstores, which “suck” the room’s cold air through pallets that are to be frozen.

Key point: Efficient blast-freezers are specially designed to guide maximum air-flow trough all pallet stacks, ensuring fast and uniform freezing

What is more important in blast freezing: low temperature or high airflow?

Both temperature and airflow matter. Low temperature creates the potential for fast freezing, but airflow determines whether that cold air actually reaches the product.

A very cold room with poor airflow can still freeze slowly. If warm air remains close to the product surface, the product does not experience the full cooling effect of the freezer air.

The best result comes from the combination of:

• Correct freezer temperature
• Strong but controlled airflow
• Low air resistance
• Uniform air distribution through the product stack

Freezer spacers support this by helping cold air move between layers rather than only around the outside of the pallet.

Problem: Slow,  uneven freezing of the batch load in blast freezer
Solution: Use pallet placements and spacers to create conditions for the cold air to reach all pallets and box surfaces
Effect: Faster and more uniform freezing in Industrial blast freezers

Can higher fan power always reduce freezing time?

No. Increasing fan power has limits. Larger fans can improve airflow, but fan motors also add heat to the freezer. At some point, more fan power may increase energy consumption without delivering a proportional improvement in freezing time.

The goal is not simply more airflow. The goal is better airflow through the product.

That is why airflow design and pallet spacing are important. A well-designed spacer can help use available airflow more effectively by reducing blocked areas and improving air access to the centre of the stack.

By using efficient spacers, fan power can actually be significantly reduced, resulting in niticeable energy savings, without compromising freezing time.

Problem: Increased fan power in blast freezers led to exponential increase of energy-consumption
Solution: Using spacers with low air-resistance
Effect: Lowering fan power in industrial blast freezers results in noticebale energy savings

What are freezer spacers?

Freezer- or ventilation spacers are specially designed devices, usually the same size as EUR pallets (120x80cm) or industrial pallets (120x100cm), manufactured from wood, cardboard, steel and plastic.
The spacers are placed between the layers of stacked boxes or crates to enable ventilation between such. Learn more about FreezeTeq’s spacers

Key point: Ventilation spacers are used to facilitate ventilation between stacked layers

How do freezer spacers improve blast freezing?

The ventilation spacers are placed between the layers of boxes, crates or cartons to create open channels for air during blast freezing. This helps the cold air to be in contact with more surfaces of the product and as such to extract heat from the centre of pallet stacks while improving airflow in the freezing chamber. 

This ensures a faster and more uniform freezing or thawing process resulting in faster freezing, significan energy savings and enhanced product quality.

Freezer spacers can help with:

• Faster heat removal
• More uniform freezing
• Reduced freezing time
• Lower energy consumption
• Reduced CO₂ emissions
• Better use of existing freezer capacity
• Improved product quality through more consistent freezing
• Less risk of box collapse and better stability of the pallet stacks

Key point: Spacers facilitate  improved air-circulation in the freezeing chamber and allows the cold air to better reach also boxsurfaces in the middle of the pallet stacks.

How do freezer spacers affect freezing time?

The freezing time of a batch is defined by when the slowest freezing pallet or box has reached it’s target temperature.

Long freezing cycles waste energy, reduce throughput and occupy freezer capacity for longer than necessary. By improving airflow through the pallet stack, spacers can support shorter and more efficient freezing processes.

Consequently the aim is to ensure that there are no boxes or pallet stacks that freeze significantly slower than the others in the freezing batch.

Without spacers, the middle layers of a pallet may be cooled indirectly and much more slowly.

When air more unhindered can move through the pallet stacks, heat can be removed from more sides of the product.

Using spacers between the box layers not only allows the cold air flow to reach the interior of the pallet stacks. Spacers also facilitate airflow throughout the enitre freezing chamber, so that the cold air also effectively reaches the pallet stacks at the far end of the chamber.

In combination this improves freezing uniformity and can reduce the total time required to reach the target core temperature of the entire pallet batch.

Problem: The centre of the pallet freezes slowly.
Solution: Create airflow channels with spacers.
Effect: Faster, more uniform freezing.

How do freezer spacers reduce energy consumption?

The basic concept of all spacers is to facilitate airflow between the stacked box layers. Thereby all spacers, to a greater or lesser extent, reduce freezing time and as such the energy consumption related to the time of the freezing cycle. 

However, much larger energy savings can be achieved, if the the fan speed can be reduced – of course without affecting freezing time.

This, because the fans not only requirey energy, but also generate heat. The higher the speed, the more energy required and heat created.
Heat which again needs to be cooled which in total results in an exponential increase in energy consumption.

Learn more about freezing strategies here

With their 50mm high, open profiles, FreezeTeq spacers are specially designed not only to facilitate airflow through its cavities, but also to provide minimal air resistance. In practice this means that less air pressure is needed to circulate sufficient cold air in freezing chamber.

Less airpressure means lower fan speed required which is where the biggest energy savings can be foun.

Learn more about fan speed, spacer differences and test results from the Danish Technological Institute.

Problem: High energy consumption and long freezing cycles in industrial blast freezers
Solution: Using airflow spacers to facilitate better airflow in the freezer and cold air to access more box-surfaces.
Effect: Reduced energy consumption and shorter freezing cycles.

How do freezer spacers improve product quality?

From a quality perspective, ideally the shortest possible freezing time is desired. This is because slow or uneven freezing cycles involves the risk of ice crystal build-up’s in the products – Ice crystalines which can influence the product’s texture, and ability to hold juice. Ultimately this can result in unwanted change in product appearance and deterioration of product quality.

Also when it comes to thawing, the aim is an even, controlled thawing of the entire batch. This because if parts of the batch are thawed before others, such risk to lose juice and thus become dry. On top of this, comes of course the problem of bacterial growth in the earliest thawed parts if these are outside preservation temperatur ranges for too long. 

As spacers are designed to facilitate both shorter and more even freezing and thawing cycles, these consquenly contribute to improving product quality.

For food producers, this means better quality control, more consistent customer deliveries and ultimately better prices.

Problem: Uneven freezing or thawing cycles adversely affect product quality
Solution: Improving air-flow between the product layers with ventilation spacers
Effect: More uniform freezing and thawing of the entire batch/pallet stacks

What is good airflow design in a blast freezer?

Good airflow design ensure that cold air is distributed evenly through all pallet loads and back to the evaporator. As airflow will always choose the way with least resistance, measures must be taken to guide the air-flow to reach all product racks in the freezer

Important airflow design principles include:

• Air should pass through the product stack, not only around it
• The freezer layout should reduce air bypass
• Pallet configuration should match the airflow direction
• Air resistance should be minimized
• Spacers should create open channels between layers

Key Point: Even distributed air-flow is essential to facilitate fast, even and efficient blast freezing

What role does the evaporator play in blast freezing?

The evaporator removes heat from the air and cools it before the air is circulated through the freezer. An effective blast freezer evaporator must have enough refrigeration surface, suitable fin spacing and fans capable of moving air through the product zone.

If the evaporator becomes blocked with frost, airflow drops and freezing performance declines. This can increase freezing time and energy consumption.

For this reason, freezer performance depends on both refrigeration capacity, maintenance and air-flow management.

Key Point: Correctly dimensioned and maintained evaporators are key for a well functioning blast freezer.

Why does frost reduce blast freezer efficiency?

Frost blocks airflow through the evaporator coil. When airflow is restricted, less cold air reaches the product, and the freezing process becomes slower and less efficient.

Frost can be caused by moisture from products, leaking doors, poor enclosure sealing or incomplete defrost cycles.

To maintain efficient blast freezing, operators should monitor:

• Door seals
• Defrost performance
• Drainage and pipe traps
• Evaporator frost build-up
• Airflow before and after the evaporator

Key Point: Frost build-up blocks airflow and thus the efficiency of the blast freezer

Why are door seals important in blast freezing?

Poor door seals allow warm, moist air to enter the blast freezer. This adds heat load and moisture to the system. The moisture can freeze on the evaporator coil, restrict airflow and slow down the freezing process.

Even small air leaks can affect freezer efficiency. Maintaining door seals is one of the simplest ways to support stable freezing performance.

Problem: Warm, moist air enters the freezer.
Solution: Maintain tight door seals and enclosure integrity.
Effect: Less frost, better airflow and more stable freezing performance.

How to know when a freezing cycle is finished?

A freezing cycle should be based not only on time, but on product core temperature and validated process data. The objective is to reach the required product temperature without over-freezing.

Over-freezing wastes energy, reduces capacity and can increase product dehydration.

FreezeTeq recommends wirelesly monitoring product core temperature in different freezer locations to validate the correct pull time. About wireless sensors

A good freezing process should define:

• Target core temperature
• Pull temperature
• Equalization time
• Product type and size
• Pallet configuration
• Freezer loading pattern

Problem: Freezing batches are rarely identical why freezing cycles can vary signifcantly and are defined by the slowest freezing box-load. Rules of thumb can be very unreliable
Solution: Wireless, real time measurements from various boxes can give exact knowledge of each freezing cycle
Effect: Knowledge about and avoiding unnecessarily long freezing cycles = energy savings and better utilization of freezer capacity

Can freezer spacers be used in existing blast freezers?

Yes. Ventilation spacers are typically used to improve airflow in existing setups without major reconstruction. When inserted between product layers they create airflow channels through the pallet stack.

This makes spacers a practical optimization tool for all who want to improve freezing efficiency before investing in major equipment changes.

FreezeTeq positions its spacers as a way to improve the freezing process and lower energy usage and costs.

Key points; Ventilation spacers are an easy and low cost way to optimize thawing and freezing process for the benefit of both quality and economy.

Can spacers be used also during transport?

As freezing is increasingly outsourced to external, specialized cold stores, it often makes sense to apply the spacers at the manufacturing site, so that the pallet stacks do not have to be repacked with spacers in the cold store.

Traditionally spacers have not been suitable during transport. Mainly because the boxes are manufactured of ever thinner cardboard which tend to collapse over the spacers, leading to damaged boxes and unstable pallet stacks.

FreezeTeq NFS-III spacers have an unique edge-to-edget support of the box-layers making them suitable for also transport, as they facilitate the integrity of pallet stacks even under rough handling.

Problem: Collapsing boxes and unstable pallet stacks during handling and transport
Solution: Use rigid spacers with full support of the box layers
Effect: Process savings, as the spacers can be applied at the production site, avoiding time consumable repacking before entering the blast freezer

What are the signs of poor airflow in a blast freezer?

Common signs of poor airflow include:

• Long freezing times
• Uneven core temperatures
• Outer layers freezing much faster than centre layers
• High energy use per batch
• Frost build-up on evaporators
• Inconsistent product quality
• Bottlenecks in freezing capacity

If these issues occur, the pallet configuration, air bypass, freezer loading pattern and use of spacers should be reviewed.

When should you consider freezer spacers?

Ventilation spacers should be considered as a possible solution when freezing time, energy use or product uniformity are limiting production efficiency.

Typical situations include:

• Pallet stacks freeze or thaw unevenly
• Centre layers are slow to reach target temperature
• Freezing or thawing cycles are longer than expected
• Energy consumption is high
• Freezer or thawing capacity is a bottleneck
• Product quality varies between pallet layers
• The company wants to optimize without major freezer modification

Are freezer spacers relevant for thawing as well as freezing?

Yes. The same airflow principle during freezing also apply to thawing and tempering proecesses. Air should reach the product evenly to create a controlled and uniform process.

What is the main benefit of using FreezeTeq spacers?

FreezeTeq spacers are engineered with optimal airflow geometry, high durability, and easy handling in mind.
Our design focuses on performance, hygiene, and sustainability, helping our clients to achieve better freezing results with lower operational costs.

The main benefit is improved airflow through stacked food products during blast freezing or thawing. Better airflow can reduce freezing time, lower energy consumption, improve temperature uniformity and support better product quality.

In short: FreezeTeq freezer spacers help cold air reach the product more effectively.

Problem: Airflow is blocked inside pallet stacks.
Solution: Insert open-profile freezer spacers between product layers.
Effect: Faster, more uniform and more energy-efficient blast freezing.

When does it makes sense looking into applying spacers in your freezing process?

You might benefit from spacers if you are:

• Expanding your freezing capacity
• Struggling with uneven or slow freezing
• Dealing with high energy costs
• Concerned about product damage or collapsing pallet stacks

What are the main factors I should consider when choosing a spacer solution?

There can be multible objectives when considering choice of spacers – top decision parameters include:

• Reduction of Freezing time?
• Energy savings?
• Issues with product quality due to uneven freezing?
• Will spacers be applied also during transport – now or in the future?
• Box quality – issues with collapsing boxes?
• Ease of handling and durability?
• Compliance with sustainability goals
• Life time and ROI?

Automated or manual insertion and removal of spacers

FreezeTeq spacers are designed to work seamlessly with both manual and automated handling systems, improving operational efficiency without needing major infrastructure changes.

Clients handling a limited quantity of pallets, most often insert and retrieve the spacers manually.

Semi automation of this process can be acchieved with automated pallet inverters. Learn more about such here

In fully automated processes, psacers are applied and retrieved fully automatically with robots.

Lifetime and ROI

FreezeTeq spacers are made of long-lasting, recyclable HDPE designed for years of repeated use also in the rather extreme conditions within industrial freezing

Obviously ROI is influenced by individual setups, but based on feedback from our clients, ROI of less than 6 month are not unusual.

Getting started with spacers

FreezeTeq offers product samples so you can experience the design and quality of the spacers and not least how these support your cardboard-boxes. However – in order to experience the full effect the spacers must be applied all pallet-stacks in your freezing batch – only in this way you can exploit the full potential of spacers by improving the airflow throughout your freezer compartment.

You are always most welcome to contact us or to complete our short Client Discovery Questionnaire
With years of experience from a wide range of clients around the world, we will do our utmost to asses you current setup, and objectively identify solutions that maximizes your freezing performance.

All of course completely non-binding