Air Blasting Method

Cold air is fed into the freezer to lower the temperature inside to freeze products. This is the most familiar freezing technology since it is also used in the freezer of refrigerators.

Slow freezing is one of the methods to freeze foods which takes a long period. The slow freezing air blasting method, however, has drawbacks such as loss of flavor and nutrition.

After food is frozen, the water that makes up 70% to 80% of the food becomes ice crystals. The longer you freeze, the longer it will take to pass through the range of -1℃ to -5℃ where ice crystals are formed. This temperature range is called the zone of maximum ice crystal formation temperature, and ice crystals become larger. Since these crystals are hard, they can damage the cell membranes in the food. As a result, the taste of umami and nutrients went out from the cells through the wound. When the food is thawed, these ingredients will flow out with the water. In addition, the texture of the food will also deteriorate.

But that’s not it. When frozen foods are stored for a while, the water evaporates from the surface, causing the food to dry, a phenomenon called “freezer burn.” In addition, the oxygen in the air oxidizes the lipids in the food, resulting in “oil burn.”

Thus, slow freezing deteriorates the quality of food.