Three extraction methods for determination of lipids in fish meal: Evaluation of a hexane/isopropanol method as an alternative to chloroform‐based methods

Abstract

AbstractThree different extraction methods were compared for the determination of lipids in both oxidised and antioxidant‐stabilised brown fish meal. The three methods under investigation were those of Smith‐Ambrose‐Knobl using chloroform/methanol/water, Bligh and Dyer also using chloroform/methanol/water but monophasic, and Hara and Radin using hexane/isopropanol. The fat content, determined gravimetrically, was significantly lower (P < 0.05) when hexane/isopropanol was used for lipid extraction from both oxidised and antioxidant‐stabilised fish meal, than when either of the chloroform systems was used. Determination of lipid classes in the lipid extracts using silica gel thin‐layer chromatography on Chromarods‐SIII, with flame ionisation detection by latroscan, suggested that the lower lipid recovery by the hexane/isopropanol method may be due to a less effective extraction of the more polar lipid classes. including oxidation products, present in brown fish meal.