Evaluation of food grade solvents for lipid extraction and impact of storage temperature on fatty acid composition of edible seaweeds Laminaria digitata (Phaeophyceae) and Palmaria palmata (Rhodophyta)

• Comparison of food grade solvents for lipid extraction from seaweeds.
• Extraction with ethanol achieved high levels of PUFA.
• Evaluation of the effect of storage temperature on fatty acids in P. palmata and L. digitata.
• Levels of TFA and PUFA stable when stored at −20 °C.

This study evaluated the impact of different food- and non-food grade extraction solvents on yield and fatty acid composition of the lipid extracts of two seaweed species (Palmaria palmata and Laminaria digitata). The application of chloroform/methanol and three different food grade solvents (ethanol, hexane, ethanol/hexane) revealed significant differences in both, extraction yield and fatty acid composition. The extraction efficiency, in terms of yields of total fatty acids (TFA), was in the order: chloroform/methanol > ethanol > hexane > ethanol/hexane for both species. Highest levels of polyunsaturated fatty acids (PUFA) were achieved by the extraction with ethanol. Additionally the effect of storage temperature on the stability of PUFA in ground and freeze-dried seaweed biomass was investigated. Seaweed samples were stored for a total duration of 22 months at three different temperatures (−20 °C, 4 °C and 20 °C). Levels of TFA and PUFA were only stable after storage at −20 °C for the two seaweed species.