Measuring Total Lipid Content in Rat Carcasses:  A Comparison of Commonly Employed Extraction Methods

Abstract

Intermethod differences between four common procedures for measuring carcass lipid content, lipid composition, and lipid energy value were determined: chloroform−methanol extraction, saponification plus hexane extraction, dichloromethane−methanol extraction (Soxhlet) and hexane extraction (Goldfisch). Samples were either freeze-dried or air-dried prior to Soxhlet or Goldfisch extraction. Carcass lipid content ranged from 7.8 (chloroform−methanol) to 8.8 (saponification) g/100 g carcass: the lowest and highest values were significantly different from each other but not from other procedures. The energy value of the extracted lipid ranged from 8804 (dichloromethane−methanol) to 9176 (saponification) kcal/g. Lipid class compositional analysis and fatty acid profile analysis showed significant differences between all methods showing that these are best determined after extraction with chloroform−methanol. The results also illustrated that small discrepancies may exist between methods for measuring total carcasses lipid content and carcass lipid energy but showed that no single, best method exists for measuring these parameters. Keywords: Lipid extraction; methods; rat carcass

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