What Is Ice Glazing on Frozen Fish?

The biggest enemy of frozen fish is water slowly evaporating from its surface; this loss leaves the flesh dry and dull, with whitened edges. Ice glazing is applied specifically to slow this process: after the product is frozen, it is dipped in cold water and removed, forming a thin ice shell on the surface. This shell limits contact with air and protects quality. A thin glaze benefits the product; the problem starts only when the layer becomes thick.

When the glaze is thick, part of the product is effectively sold as water. That is why the package may show two different weights: gross weight includes the glaze, while net or drained weight is what remains after the glaze melts. Compare products by net weight. If the label shows only one weight and the product visibly has a thick layer of ice, its price per kilogram is misleading and cannot be compared with another product.

There are a few things you can check by looking at the package. The glaze should be thin enough that it does not hide the product’s shape, and the outline of the fillet should be visible. If the package also contains loose ice crystals or a pool of frozen water, the product may have thawed and been refrozen once, which is not a good sign. Frost inside the package or the product stuck to one corner raises the same concern. Whitened, dried-out areas at the edges indicate freezer burn.

The glaze also makes a difference in the kitchen. This water is released during thawing and runs into the container; do not leave the fish sitting in it. Drain the fish and pat it dry with paper towels. Fish that has not been dried will not sear in the pan; it will steam in its own liquid. A heavily glazed product can also throw off the amount in a recipe, because a 1 kg package contains less actual fish. That is why portion calculations should be based on net weight, not the large number printed on the package. Do not thaw glazed fish under running water; warm water starts to cook the outside and softens the texture.

Keep glazed fish frozen until it gets home; do not refreeze a package that has partially thawed. Arrange the product in the freezer so it will not be crushed and damage the glaze, and wrap it in a second layer if the package is punctured. The glaze gradually thins; its protection decreases over the months, so use packages in order by their dates. Thaw fish in the refrigerator, in a covered container on the bottom shelf; do not thaw it at room temperature. Frequently opening the freezer door also thins the glaze, because each temperature fluctuation removes some ice from the surface.