HOW TO MINIMIZE DEHYDRATION INSIDE THE IQF FREEZER

In the open air, the moisture just escapes, but in a closed IQF freezer, the air will start to create snow and ice, when the air is saturated with moisture. This is called precipitation. The effect of dehydration in the IQF freezer is the shrinkage and damage to the products' surface and an actual weight loss of the product, that turns out as snow.

As the air gets colder, it will also get dryer, and hence there will be more dehydration of the products inside the IQF freezer since there is a correlation between temperature and dew point. IQF will allow for a lower dehydration since more sublimation happens before the surface of the product is crust frozen.

A smaller product, with more surface compared to weight and volume, will naturally dehydrate more than a larger product. Moreover, water or juice on the product surface has a higher tendency to evaporate. A product with more moisture content will dehydrate more than a dry product.

Basically, dehydration inside an IQF freezer is limited if precipitation or snow formation can be avoided. The key is keeping the air saturated, so it can't take up moisture from the products. Even if the air is saturated, the dehydration needs to be avoided by any means. A low infeed temperature and an efficient crust freezing are other good methods of avoiding dehydration inside the IQF freezer. The challenge is optimizing the settings of airflow and speed, as too much airflow might remove moisture, and too low will slow down the freezing time.

Having an airflow with optimal aerodynamics reduces turbulence and lowers the precipitation inside the IQF freezer, as is the case with the OctoFrost IQF tunnel freezer. Air should be kept moving because, as soon as it stops, the air will start to precipitate and create snow.

Freezer burns will decrease the quality and value of the product. If the products are washed before being placed inside the IQF freezer, they will be protected, but the loss in weight is still applicable. Traditional IQF tunnel freezers have a 1.5 - 2% dehydration which can be measured as snow formation, but, in optimal conditions, it can be reduced to 0.3 - 0.5%. In a spiral freezer, the dehydration can be up to 4% of product loss in weight. Sometimes, this can be seen on products as ice crystals, which gives a less favorable appearance.

A cold storage freezer will not handle a washed product, so the comparison can't be made directly. A cold storage freezer and a spiral freezer are both so slow that ice crystals will be large, and the cell structure will be damaged. In these cases, the drip loss after a defrosted product is of even more importance to quality.

The snow formation during dehydration requires the same amount of energy as it takes to freeze a product, therefore the final product will suffer a loss. For example, with a yearly production value of 1.000.000 EUR, there is a saving of 10.000 EUR per year, if dehydration is reduced by 1%. In conclusion, there are many factors in the food production process that influence the dehydration level of the products. By understanding those factors, IQF processors can reduce dehydration and the output of products can be increased without spending any money on manpower, power consumption, or raw material.