Seasonal variation of fatty acid profiles from textiles associated with decomposing pig remains in a temperate Australian environment

Abstract

A methodology to examine the human post-mortem decomposition process has been developed through the monitoring of chemical changes to decomposition fluids absorbed by clothing. Model surface burials using clothed pigs were established during summer and winter seasons in a temperate region of Australia. Three clothing materials were investigated: cotton, polyester and cotton-polyester. Lipid decomposition products were extracted from the textiles and the fatty acid composition measured as a function of burial time using gas chromatography – mass spectrometry (GC-MS). Two derivatisation methods for the fatty acids were compared to establish the most effective approach and it was established that a trimethylsilylation derivatisation method is the optimal preparation technique. The summer trials revealed two rates of transformation of fatty acids from unsaturated to saturated forms, with a faster rate of change occurring earlier in the trials. A different pattern of behaviour was observed for the fatty acids detected during the winter trial, with a decrease in saturated fatty acids initially observed, followed by the conversion of unsaturated to saturated fatty acids until the end of trial. The initial change observed during the winter trial was attributed to a dehydrogenation process caused by microbiological enyzymatic activity. The study has demonstrated the feasibility of examining lipid decomposition products collected in clothing from burials to provide insight into the conditions and length of burial.