Experimental polysaccharide chars and their 'fingerprints' in charred archaeological food residues

As a model for polysaccharide char formation in archaeological food residues, bulk samples of microcrystalline cellulose were charred under anoxic conditions at atmospheric pressure and at temperatures ranging from 190 to 310°C. The resulting chars were characterised by pyrolysis—mass spectrometry (Py—MS) and Curie-point pyrolysis—gas chromatography-mass spectrometry (Cu-Py—GC/MS). Although very few polysaccharide moieties were preserved in the experimental chars after heating above 270°C, a characteristic distribution of pyrolysis products representing the condensed char is shown. A selected charred archaeological food residue was analysed using the same analytical techniques. In this way, polysaccharide input can be detected in archaeological residues after approximately 1800 years of burial.