Flash freezing fish helps preserve the fish’s look and feel, without the use of preservatives. It also helps protect against freezer burn.
Commercial fishermen often use this technique right on the ship before they even get back to shore.
While they use ultra-low temperatures and industrial freezers, you can easily learn how to flash freeze fish at home.
It’s important to understand that flash freezing is ideal for freshly caught fish, not days-old or previously frozen fish from the supermarket.
Before you freeze the fish, it needs to be washed, gutted, and dressed. Larger fish should be cut into steaks or filets.
Next, you need to consider the type of fish, whether it’s considered a “fat fish” or a “lean fish.”
Fat fish are the oily varieties such as tuna, salmon, trout, and mackerel. Lean fish include grouper, snapper, flounder, cod, and most freshwater fish.
To preserve quality, fish should be pretreated by dipping for 20 seconds in a prepared solution, depending on the type.
(You can skip this step is you choose the lemon-gelatin preparation described in the next section.)
- Lean Fish should be dipped in a salt brine solution of 1/4 cup salt to 1 quart water. This increases firmness and reduces loss when thawing.
- Fat Fish should be dipped in an ascorbic acid solution of 2 tablespoons crystalline ascorbic acid to 1 quart of water. This prevents the fats from going rancid and preserves the flavor
Adding a glaze layer helps protect the fish, and you can choose an ice glaze or a lemon-gelatin glaze. (Some people advocate for freezing fish in a block of ice, but this results in a lower-quality product.
If you choose this method, simply place the fish in a shallow dish, fill with water, and freeze until solid. Then follow the packaging instructions at the end of this section.)
- Ice Glaze: Place unwrapped fish in the freezer. Once it’s frozen, dip in near-freezing ice water and return to the freezer for a few minutes. Once the glaze is hardened, repeat the dip-and-freeze glazing cycle until you’ve formed a solid layer of ice.
- Lemon Gelatin Glaze: Combine 1/4 cup lemon juice and 1 3/4 cup water. Dissolve 1 package of unflavored gelatin in 1/2 cup of the mixture. Bring the remaining lemon-water to a boil, add the gelatin mix, and cool to room temperature. Dip the fish in the cooled mixture and drain.
Once you have completed the glaze process of your choice, wrap the prepared fish in freezer paper or place in freezer bags, label, and freeze.
The storage conditions are also important, preferably a stable sub-zero temperature rather than a self-defrosting freezer.