Brine freezing of fish

Brine freezing was valued in the first half of this century as an inexpensive way of quick freezing. It is widely used since it allows relatively fast freezing.

In freezing with brine, the fish is frozen by contact with a refrigerated liquid suitable for contact with the fish. Various types of brine are used but those with sodium chloride are most important and most economical for fish.

The freezing temperatures are then limited to -18 °C (NACl) to around – 25 °C due to their eutectic points, and the fish is frozen by spray freezing or by immersion in the brine.

In tuna fisheries, such brine has been used for quick freezing of fish on board directly in the wells.

Spray brine has been used in smaller vessels on order to decreases the weight of brine on board. A small tank of brine can be kept as a reservoir for the spray, thus eliminating the full flooded holds.

Freezing by sprinkling is used for freezing herring and mackerel in Scandinavia particularly Norway. The boxes of fish are placed in stacks.

On top there is a box with a perforated base in order to distribute the brine evenly. The brine passes from one box to other and down into a tank where it again passes over cooling coil and is then pumped up and sprinkled over the boxes of fish until the fish is frozen (1-2 hours).

Using modern blast freezers operating at temperatures as low as -50 to -60 C, the fish may be frozen less than 24 hr.

Brine freezing, once popular in the tuna fishing industry, is begin replaced by air-blast freezers for preservation of the catch.
Brine freezing of fish 

Canning of fish

Canning is a method of storing food in airtight containers in a way that destroys potentially harmful microorganisms such as bacteria.

Most canned fish products are composed of ingredients that result in finished product with pH above 4.6 and water activity greater than 0.85.

These characteristics result in canned fish products being considered ‘low-acid canned food’. Canned fish have a shelf life of one year while frozen, oily fish should be used within two months.

Processing of Fish Canning 

Canned fish is conventionally covered with a liquid such as brine, vegetables oil tomato sauce or other sauces.

The canning process depends on the size of the fish. Small fish species such as sardines and pilchards are generally canned whole, with only the heads and tails removed. These whole-fish products are cooked in the can after it has been filled with brine or oil.

Canned fish is that it’s already cooked and ready for many easy dishes such as fish cakes, quiche, loaf, salads, sandwiches and appetizers.
Canning of fish