several methods for freezing fish

Lemon-gelatine method

1.Mix 1¾ cups of water with ¼ cup of fresh lemon juice.
2.Separate the liquid into quantities of ½ a cup and 1½ cups.
3.Dissolve and mix one packet of plain gelatine into the ½ cup mixture of water and lemon juice.
4.Heat the larger quantity of liquid in a saucepan until it is boiling.
5.Stir in the gelatine mixture.
6.Allow to cool to room temperature.
7.Dip the prepared fish into the cool liquid and then drain.
8.Wrap the fish in airtight packaging, squeezing out excess air. Seal and label.
9.Freeze immediately.

If not using the above method to freeze the fish, you will need to treat the fish beforehand if using any of the following methods in order to achieve a high quality frozen fish. The way in which you treat the fish depends on the type of fish. Fish can either be labelled as "lean" fish or "fat" fish due to the amount of fat that they contain. Lean fish contain less than 4% fat and include cod, sea bass, haddock, snapper, hake, grouper, plaice, John Dory, whiting, sole, sea bream and most types of freshwater fish. Fat fish contain over 4% fat. Although these types of fish contain more fat, studies have actually proven that eating fatty fish is more beneficial for one's health than eating lean fish. Fatty fish increase the levels of omega-3 fatty acids, which are good for the heart and help protect against heart and cardiovascular diseases. Examples of "fat" fish include salmon, tuna, halibut, monkfish, mackerel, red mullet, herring, trout, eel and sardines.

Lean fish treatment
Lean fish should be dipped in a brine solution before freezing. Prepare the brine solution by mixing together ¼ cup of salt with 2 pints of water. Dip the fish in the solution for about ½ a minute and then drain. This will give the fish a firmer texture and prevent moisture loss on freezing.

Fat fish treatment
Fat fish on the other hand should be dipped for the same amount of time in a solution of ascorbic acid. This can be prepared by mixing 2 tbsp of ascorbic acid with 2 pints of cold water. This preparation is done in order to slow down deterioration due to rancidity, which would occur quicker in fatty fish due to the higher amount of fat contained in the flesh. After treating the fish with one of the above preparations, you can continue to freeze the fish by one of the following methods.

Ice block
1.Place the fish in a shallow pan, container or dish.
2.Place into the freezer and leave overnight.
3.The following day, remove the solid frozen block from the container and wrap in moisture-vapour proof packaging. Label and return to the freezer.

Freezing times for fish
For the best quality fish, freeze lean fish for up to 6 months and fatty fish for between 2 - 3 months.

Defrosting frozen fish
Never defrost fish at room temperature. It can either be thawed in the refrigerator or under very cold running water. Defrost fish overnight in the refrigerator and ideally it should be covered with a plastic bag or placed in a bowl, so that water does not drip onto other products inside the fridge. If defrosting fish under a cold running tap, this could take up to an hour depending on the size of the fish. Never use hot water to defrost the fish as this could cause the fish to become contaminated with bacteria. If using this method, try to cook the fish as soon as it defrosts.