Epsilon Archive for Student Projects

Abstract

The aim of this study is to investigate the lipid content and lipid composition of fatty acids in Atlantic salmon (Salmo salar), pink salmon (Oncorhynchus gorbuscha) and striped catfish (Pangasius hypophthalmus), obtained at the local retailers in Uppsala, Sweden. Then explore the cause of the differences in the fatty acids between the three fish species. In addition, the present data will be compared to the data available at National Food Ad-ministration in Sweden (SLV) and National Institute of Nutrition and Seafood Research in Norway (NIFES).
Fish is a main food that provides n-3 long chain polyunsaturated fatty acids (LCPUFA), and is to many people known to be a healthy choice as food. It is particularly the n-3 LCPUFAs that have been shown to have positive effects on for example cardiovascular disease and cancer. Docosahexaenoic (DHA) and eicosapentaenoic (EPA) are n-3 LCPUFAs, present in fish and fish oils. The demand for fish raw material as fish feed is rising around the world, and this depends on a steady increase of aquaculture production. A change from using fish raw material to use more ingredients based on vegetables have been investigated. There is a consequence of this change from fish raw material to plant based material on human health, where the degree of long chain n-3 fatty acids have been lowered in the fish and the beneficial health effects of fish on humans is therefore decreas-ing. In vegetable oils there is a high concentration of n-6 and n-9 fatty acids that is mostly linoleic acid and oleic acid respectively. In vegetable oils there are also low or moderate levels of n-3 fatty acids (excluding linseed oil) of mostly α-linolenic acid. Although vege-table oils do not have the long chain highly unsaturated fatty acids (LCHUFA), EPA and DHA.
In this study seven different samples were taken from Atlantic salmon, pink salmon and striped catfish. The samples all have different origin and label, and all the samples were from a farmed fish fillet except one wild fish. The samples tested in this study were all homogenized and the fat of the samples was extracted. Fatty acid composition was ana-lyzed by a gas chromatograph (GC).
The fat content in the four farmed Atlantic salmon samples was: 7.0, 7.6, 9.4 and 7.4 % respectively. The fat content in the wild pink salmon was: 3.0 %. The fat content in the two farmed striped catfish samples was 0.3 and 0.5 %. The proportion of fatty acids was all measured in % of total fatty acids. The percentage of EPA (20:5 n-3) and DHA (22:6 n-3) was higher in the farmed Atlantic salmon and wild pink salmon, compared to the farmed striped catfish, as expected. Linoleic acid (18:2 n-6) was significantly higher in the farmed striped catfish, and lower in both the farmed Atlantic salmon and wild pink salmon. α-linolenic acid (18:3 n-3) was present at a smaller percentage in the farmed striped catfish than in both the farmed Atlantic salmon and wild pink salmon. The n3/n6 ratio was signifi-cantly higher in the wild pink salmon, than in both the farmed Atlantic salmon and farmed striped catfish.