If the general meaning of the term “fluidization” refers to a process similar to liquefaction in which a solid material transforms into a fluid, fluidization in IQF freezing means the ability of a product to act as a liquid, at the influence of airstreams, and have a constant moving and advancing inside the freezer at the feeding rate.c
Why is fluidization important for the IQF freezing process?
Fluidization is responsible with maintaing the separation between different units of product in order to be individually frozen. By having a deeper understanding of the fluidization process, frozen food processors can use the most suitable type of fluidization for each type of product, in order to obtain the best result as possible. For example, heavier products such as mango or broccoli need a different type of fluidization than lighter products like chopped basilica for instance. In order to obtain the best-looking product with perfect separation, processors need to adjust the fluidization depending on the characteristics of the product such as water content, weight, shape, brix level or fragility.
There are 3 major types of fluidization related to IQF technology:
– circulating fluidization
– bubbling fluidization
– fixed bed fluidization
Circulating fluidization is used to completely lift the product from the bed using cold airstreams and its usually used in the first part of the IQF freezer for crust-freezing the products that are still warm and wet.
Bubbling fluidization (or semi-fluidization) is a gentler type of fluidization than the previous one and it only partially lifts the product. It is usually used on the second bed where the crust-frozen product acts like a boiling liquid (hence the name of bubbling fluidization).
Fixed bed fluidization is used at the final stage of the IQF freezing process, in the last section of the IQF tunnel freezer, where the product is mostly resting on the bed.
How to achieve the right fluidization
There are three elements that play an important role in achieving the optimal fluidization: the type of fans, the design of the bedplate and the overall design of the IQF freezer.
The type of fans is a crucial aspect to be taken into consideration. Not all type of fans can contribute to the creation of the optimal fluidization. For example, the OctoFrost™ IQF tunnel freezer uses vane axial fans, custom designed to integrate and efficiently use frequency converters. This means that the airflow can be increased or decreased depending on the fluidization type the processor is aiming to obtain. IQF freezers which do not have this option must bypass or hinder the unnecessary, extra air current. This means that part of electricity consumed by the tunnel and the refrigeration plant is a waste and this many times affects the profitability of the business.
The design of the bedplate is a major influence on the pressure drop achieved, especially the size and distribution of the holes through the bedplates. The OctoFrost IQF tunnel freezer was designed with thicker bedplates in order to allow bigger holes that allow a higher pressure-drop, which is an important factor in achieving the optimal fluidization.
Last, but not least, the overall design of the IQF freezer body is a direct influence on the aerodynamics and the degree of control over the fluidization. This is the reason why the OctoFrost IQF tunnel freezer was designed as a compact freezer with minimum details which could obstruct the airflow. Therefore, the fluidization process is easier to control and be customized for each type of product.
Yet again, we learn that IQF technology is a fine art, based on pure science, and OctoFrost is committed to master it. For more visit www.octofrost.com
