Lipidreste

Lipidreste, or lipid residues, refer to remnants of lipids that survive after partial degradation in biological or environmental samples. Lipids are a broad class of hydrophobic biomolecules that include fatty acids, triglycerides, phospholipids, sterols, and waxes. Because many lipids are relatively resistant to hydrolysis and oxidation, traces can persist for extended periods under favorable conditions.

Lipid residues occur in diverse contexts: in archaeological pottery to infer ancient diets and trade, in soils and sediments as biomarkers of past vegetation and animal input, in forensic science as clues from clothing, tools, or crime-scene materials, and in food science and industry as indicators of processing, adulteration, or contamination. Their composition can reflect source organisms and environmental conditions at the time of deposition.

Analytical methods for lipid residues typically begin with solvent extraction using methods such as Folch or Bligh and Dyer. The extracts are often converted to fatty acid methyl esters for gas chromatography (GC) analysis or analyzed directly by GC–MS or LC–MS. Stable isotope analysis and the identification of specific lipid biomarkers (for example, long-chain n-alkanes, sterols, or certain wax esters) help distinguish plant versus animal sources and processing state.

Challenges include diagenesis, contamination, and low concentrations. Preservation is favored by anoxic, dry, or cold conditions and by mineral matrices that protect lipids. Proper blanks, controls, and replication are essential for reliable interpretation.

See also: Lipidomics, biomarker, archaeochemistry.