Values are drying up

The Fish Site
by The Fish Site
7 May 2007, at 1:00am

NORWAY - Stockfish that dries too much means at least 25 million NOK in lost revenues for the stockfish industry. According to Fiskeriforskning's studies, the fish should be kept in cold storage after it is brought in.

Stockfish can become too dry. In a traditional stockfish warehouse, it is not possible to control temperature and humidity and thus one cannot stop the drying process at the ideal stage.

Stockfish is stored for several months before it is sold. Cold storage will mean a lot for the economy in the companies.

"Proper afterdrying of the stockfish means a lot for the economy. Even though costs are involved with investments in and operation of cold storage facilities, such a solution will pay for itself for the producers", says Scientist Even Tidemann, who has carried out the studies.

Temperature and humidity

Both temperature and humidity are very important for the weight development of the stockfish. For example, the fish will have 5 % higher water content when it is stored at 3 degrees instead of 20 degrees, with humidity of 80 %.

"At today's stockfish prices, 5 % higher water content will correspond to stockfish for at least 25 million NOK for the producers in Lofoten."

Cold storage allows control

When the stockfish is brought in, it will be driest furthest out towards the skin and moistest furthest in.

In cold storage, the humidity and temperature can be controlled such that the water content in the fish is evened out, but without losing water from the fish. Fish that has dried out too much will absorb moisture such that the water content increases.

For the producers, cold storage can give a more predictable quality of the stockfish. Here, a consumer selects stockfish in an Italian supermarket.

The tests show that the fish should be stored between 80 and 100 days in cold storage in order to get the best result.

"In cold storage, the differences in water content amongst the fish are smaller. This also gives an advantage in that the producers are able to offer a uniform and predictable quality", says Tidemann.

Should be handled as a refrigerated product

Another advantage of cold storage is that one can avoid fungi.

When stored at 20 degrees Celsius, there was considerable fungal growth, even with low water content in the fish. At 3 degrees, there was no fungal growth, even in fish with high water content.

"Eventually, one should consider handling stockfish as a refrigerated product from the time it is taken down from the drying rack until it is delivered to the buyers in Italy", says Even Tidemann.

The project is carried out on assignment for the Stockfish Forum in the Norwegian Seafood Federation and is financed by the Fishery and Aquaculture Industry Research Fund.