Water is the principle component (up to 80%) of the edible portions of seafood.
Among fish researchers there is no such accepted norm. Moisture content may be reported on a dry basis, a wet basis, a salt-free basis and often the basis is not specified.
However, mostly moisture content is expressed in a wet-weight basis – i.e., is the mass of water in a unit mass of the fish. Moisture contents range from 64.3 to 82.8 percent, with the exception of caviar; this range is very similar to that of mammalian species.
The moisture content of fish is usually determined by oven drying at 100 to 102° C for 16 to 18 hours; the loss of mass in that time being equated to the mass of water in the original sample.
The Karl Fisher method is probably suitable for material in which only a small percentage of moisture is present. But the method is hardly followed for fish and allied materials.
The method of storage as well as further processing, such as freezing determines the final moisture content of the fish flesh.
Considerable moisture, as well as soluble nutrients, may be lost in thaw drip. Water retention is highest in fresh fish. Finfish moisture contents generally show an inverse relationship to the lipid content.
Depth and latitude of fish catch also influence the moisture content of fish. Fish from deep water and from northern latitudes have higher moisture and lower fat content.
Raw shellfish moisture contents fall in the same range as finfish, but average is slightly higher, 80.1%.
About one fourth of the moisture can be lost during cooking, which results in concentration of other components.
Moisture content in fish
