Nutritional quality of red shrimp, Aristeus antennatus (Risso), pink shrimp, Parapenaeus longirostris (Lucas), and Norway lobster, Nephrops norvegicus (Linnaeus)

The proximate composition, amino acid and fatty acid profiles, lipid classes and cholesterol and glycogen contents were determined in the edible part of red shrimp, Aristeus antennatus (Risso), pink shrimp, Parapenaeus longirostris (Lucas), and Norway lobster, Nephrops norvegicus (Linnaeus), in two distinct periods of the year. The proximate composition did not vary significantly between species or between periods of sampling. Significant differences in glycogen content were obtained between winter and summer; the lowest values were attained in winter (1.2, 1.1 and 1.0% wet weight for red shrimp, pink shrimp and Norway lobster respectively). With the exception of Norway lobster, an opposite trend was obtained for cholesterol content, ie lower values in summer (60.8 and 57.8 mg per 100 g wet weight for red shrimp and pink shrimp respectively). The major essential amino acids (EAA) were arginine, lysine and leucine and the limiting amino acid was methionine in all three crustacean species. The most important non-essential amino acids (NEAA) were glutamic acid, aspartic acid, proline and glycine. In respect to lipid classes, phospholipids and free cholesterol predominated. The major fatty acids were 16:0, 18:1n-9, 20:5n-3 and 22:6n-3. The polyunsaturated fraction was dominant (42.1-48.4%), followed by the monounsaturated (26.3-34.6%) and saturated (22.9-27.4%) fatty acids. In conclusion, the nutritional quality of these shellfish species is similar, they are valuable protein and lipid sources for the human diet and are adequate elements of the traditional Portuguese diet.