Lipid determination in fish meal: An investigation of three standard methods applied to stabilised and non‐stabilised anchovy meals at increasing stages of maturity

An investigation into the relative merits of three standard laboratory procedures for lipid determination in fish meal is described. It was found that the amount of lipid extracted by these methods from both stabilised and non‐stabilised anchovy meals decreased on storage of the meals. The decrease in lipid yield as a function of the storage time may be approximated by straight lines, which reveal clear distinctions between the three methods as well as the two types of meal. The cold Bligh and Dyer method gave consistently higher lipid yields than either the hot hexane or a modified EEC method, and the decrease in the Bligh and Dyer lipid content with storage was less than that found in the hot hexane or the EEC lipid content. This difference was more pronounced in the non‐stabilised than in the stabilised meals. No fundamental difference between the hot hexane and the modified EEC lipid extraction method could be established since the hydrolysis step in the EEC procedure does not de polymerise the lipid portion which is unextractable by hot hexane. The effectiveness of the antioxidant ethoxyquin in protecting polyunsaturated fatty acids in anchovy meal from oxidation is demonstrated.