Freezing and thawing of food stuff is often an important as well ass a critical process in the value chain of food processing companies. Especially freezing is often a major cost driver but both processes highly influence the product quality of the frozen or thawed product.

Even though the food industry generally is highly effective, the processes of freezing and thawing often gets low attention. Often we meet situations or questions from end users which indicate a lack of focus to this important process.

Meat, Ice-crystalines and freezing-time

Meat contains up till 75% water which in the process of freezing is converted into ice-crystalline. The longer the freezing process takes the larger are the ice crystals formed. As large ice-crystals tend to ”merge” this can disrupt the structure of the meat-cells. Amongst others this impairs the meats ability to hold or ”bind” water Fluctuating temperatures during the freezing process can also lead to the merger of ice-crystal. A fast and effective controlled freezing therefore not only influences the energy consumption in the freezing-process but also the defrosting process and the ”drip-loss” related hereto.

Blast- / shock-freezing

One of the dominating freezing techniques within industrial food processing is still blast- or shock-freezing.  Here the products are placed in a blast freezing chamber where a number of fans and cooling devices expose the products to airflow with temperatures down to -40º. A technique which first was developed by the American inventor Clarence Birdseye in the early twenties.

Factors influencing freezing time

The time to freeze a product to the desired temperature is influenced by a number of factors; Such as the products density, start temperature, packaging, air-temperature, air–speed, design of the freezing chamber including efficient design and usage of the created air-flow.
(Typical Blast-Freezer set-up’s)
As such airflow is the obvious parameter to adjust in order to increase the efficiency in existing freezing facilities.

Open profile freezer spacers™

As airflow will always chose the path with least resistance the cooled air must be ”forced” not only in-between the stacked layers of products but also in-between the pallets. Hence the location of the pallets in the blast freezing chamber and the use of open-profile freezer spacers™ in-between the stacked box-layers is of utmost importance for the total freezing efficiency. The use of open profile freezer Spacers™ allow a high airflow is therefore one of the most profitable investments you can do in order to reduce energy costs, increase efficiency and improve product quality. Freezer spacers are offered in a variety of designs and materials. The more open profiled a spacer is the more airflow is allowed through the spacer and as such the shorter the freezing time. In short a reduced freezing time leads to;
  • Reduced use of energy and as such cost savings
  • Faster flow and as such better utilization of existing freezing facilities
  • Increased product quality including reduced drip-losses.
During the years we have had several clients claiming that the investment in highly effective freezer spacers had reached break even within months.

Uniform and fast thawing is equally important

The tendency that ice-crystals merge to larger units is also seen during defrosting as various temperature fields arise when foodstuff thaws from the outside in. Consequently it is also here a big advantage if the defrosting can be as uniform and fast as possible, (not exceeding normal cold-storage-temperatures) Using freezer spacers to create an improved airflow in-between the thawing products therefor highly influences the product quality and drip-loss.