Chemical composition

The chemical composition of the edible part of seafood varies greatly from one species to another and even among individuals of the same species changes due to the degree of sexual maturity, age, sex, environment, year's season and food availability are observed. Moreover, for a single individual, there are differences not only between the frontal and back sides but also between the dorsal and ventral areas.

Water (50 to 85 %), proteins (12 to 24 %) and lipids (0.1 to 22.0 %) are the main constituints, making up about 98.0 % of the edible fraction's total (Table I). The remaining 2.0 % correspond to minor components, among which minerals (0.8 to 2.0 %), carbohydrates (0.1 to 3.0 %) and vitamins. For the bivalve molluscs, protein content vary typically between 9 and 13 %. Moreover, in most fish species, glycogen content varies between 0.1 and 0.3 %, however in bivalves it may reach about 4.5 %.

 
 
 
 

Table I. Proximate chemical composition of various seafood species (per 100 g of edible part).

 
 

Species

Water (%)

Protein (%)

Lipids (%)

Minerals (%)

Tuna (Thunnus thynnus)

69,7

24,8

3,5

1,7

Horse mackerel (Trachurus trachurus)

77,5

21,8

2,5

1,4

Hake (Merluccius merluccius)

81,7

18,0

1,3

1,3

Sardine (Sardina pilchardus)

77,2

20,8

10,9

1,5

Clam (Ruditapes decussatus)

81,1

11,7

0,9

1,0

Cuttlefish (Sepia officinalis)

78,6

18,9

0,4

1,4

Squid (Loligo vulgaris)

81,4

15,8

0,9

1,3

Octopus (Octopus vulgaris)

83,1

15,6

1,2

0,9

Norway lobster (Nephrops norvegicus )

76,1

20,9

0,5

2,4
 
 
 
 

If you want to know more, see:

FAO, 1995. Quality and quality changes in fresh fish. FAO Fisheries Tech. Pap. Nº 348. 195p.

Ferreira, F.G.; Graça, M.S., 1985. Tabela da composição dos alimentos portugueses . Instituto Nacional de Saúde Dr. Ricardo Jorge. 2ª edição. 182p.

Murray, J.; Burt, J. R., 2001. The composition of fish. Ministry of Technology, Torry Research Station, Torry Advisory Note, Nº 38. (FAO in partnership with Support unit for International Fisheries and Aquatic Research, SIFAR, 2001)

Sikorski, Z.E.; Kolakowska, A.; Pan, B.S., 1990. The nutritive composition on the major groups of marine food organisms. Seafood: Resources, nutritional composition and preservation. CRC Press Inc. Florida, pp 29-54.