An Optimized Approach for Protein Residue Extraction and Identification from Ceramics After Cooking

Abstract

Extraction of protein residues from archaeological matrices, such as pottery clay, lithics, and grinding stones, has proven to be methodologically challenging. Protein residue analysis is fraught with technical challenges in analytical chemistry. In cooking pottery, protein residues are thought to bind to clay surfaces in vessel walls through a variety of primarily non-covalent interactions. Removal of protein residues requires the disruption of these interactions, and a diverse set of tools has been proposed and applied. Here, we test extraction procedures through varying combinations of physical parameters and solvents to derive an optimal approach yielding efficiencies of recovery from experimental pottery above 60%. The utility of our extraction approach was further validated through liquid chromatography–mass spectrometry analysis of experimental residues. We have identified several hurdles to developing a successful study of protein residues from pottery, each of which is surmountable with additional method development in the realm of archaeological chemistry.