Freezing is one of the oldest and most common techniques of preserving food, which maintains the taste, texture and nutritional value of products more efficiently than any other technique.

The frozen food industry is mainly based on science and technology, therefore appropriate equipment suitable for continuous processing of the products is highly valued. Development in freezing technology is mostly represented by improvements in mechanical handling and process control, with the purpose of increasing the freezing rate and reducing costs. The freezing process mostly depends on thermodynamic and kinetic factors. When the first ice crystal appears and the liquid temperature is in equilibrium with the solid, it means the product has reached the freezing point. However, the process of freezing a product is much more complex. The freezing time is a crucial factor in the process and is defined as the time necessary to lower the temperature of the product, starting with its initial temperature until a certain temperature is reached at its thermal core. The freezing time highly influences the quality of the product.

There are two essentially different freezing techniques available: Cold Store freezing and IQF freezing, which provide distinctive results.

From a practical point of view, Cold Store freezing is used for large volumes of big products, like a whole chicken, packed meat and other protected products and IQF freezing is used for small products, like berries, fruit cubes, vegetables, shrimps, mussels, cheese, and pasta. Technically, Cold Store freezing involves placing the product on trays inside a cold storage and waiting until the product is totally frozen. This process takes a long time and it ends when the core of the product is completely frozen. On the other hand, the IQF freezing technology requires placing the product inside a freezer that uses thermodynamics by permanently moving the product. During the process of IQF freezing, the product is placed on a fluidized bed that transports and moves it, while fans provide an efficient air flow. With the help of IQF freezing, the product is frozen faster to the core. The main difference between Cold Store freezing and IQF freezing is the freezing time needed. In the case of Cold Store freezing, the increased quantity of water creates larger ice crystals and this process requires a long time. Big ice crystals affect the membrane and the delicate structure of the product. In comparison to that, the IQF freezing technology benefits of a quick freezing time, while the growth of ice crystals is limited. This is the reason why during the IQF freezing process the membrane and structure of the product are not damaged. Besides the limited freezing time, the IQF freezing technique has the advantage of preserving the taste, texture and nutritional value of the food. In comparison, while frozen in cold storage, products suffer a substantial drip loss and their texture is altered. When these products are defrosted, they may present a soaking texture, along with a loss of nutrients.

Other important differences between Cold Storage and IQF freezing are provided by the color of the product, its shape and damage of the surface. Products frozen at a slow rate normally look more colorful than IQF products. But after defrost, the natural look is often lost and the color turns gray.

The IQF quality freezing technology distinguishes itself by the rather pale and white colored IQF product, which has a natural look when defrosted. In addition, the IQF freezing technique provides a considerable better separation of the product. Some products can be more difficult to separate if frozen in a Cold Store, and as a result, the additional lumps and blocks cause yield losses. IQF freezing has the advantage of a fluidized bed which maintains the natural shape of the IQF product. Usually, no deformation of the product occurs when it’s individually quick-frozen, not to mention that with modern efficient IQF freezing even the surface damages are avoided.

Cold Store freezing normally requires considerable manpower resources to handle the boxes or the trays. If the product is frozen partly in blocks, mechanical separation is necessary, resulting in a damaged appearance and the creation of fines on the product. Cleaning, handling and repairing the trays is time and manpower consuming.

While an IQF freezing line only requires supervision and very little intervention, in the case of cold store freezing this is usually done by the packing crew. With the efficient IQF freezing technology, it is even possible to add surface water to the product before freezing. This procedure is also called glazing, and it creates a thin transparent film to protect the product during storing, while it prevents dehydration, and therefore, increases profits.

Food safety represents one of the most important factors of IQF freezing. A modern in-line process combined with an IQF freezer can benefit of no contact between the product and the workers. While in the case of Cold Store freezing, due to large-scale manual handling and exposure, there is a major risk for contamination.

Moving from Cold Store to IQF freezing looks like an obvious and substantial solution for the future, especially since consumers prefer the advantages of IQF products.

In addition, IQF freezing can manage the transporting, storing and handling of small, cut, sliced or diced products compared to big, packed products in cold stores. This will further determine the shift from the old methods such as cold store freezing to the cutting-edge solutions like IQF freezing.