Burnt to a crisp: disentangling the taxonomic composition of foodcrusts via palaeoproteomics

The main application of palaeoproteomics is taxonomic identification. The most
commonly analysed sample types in palaeoproteomics are osseous materials. A shared
characteristic of osseous objects is that they each derive from a single species, allowing
researchers to focus on the peptides with the highest taxonomic resolution. However, other
material types, such as charred organic residues (foodcrusts), are gaining attention in
particular due to their potential to study past diets. The analysis of foodcrusts has its own
advantages and disadvantages. On the one hand foodcrusts provide direct evidence of
cooking, facilitating the investigation of culinary behaviour rather than just diet. On the other
hand, apart from severe heating, which damages and modifies the remaining proteins, it is
not clear what is required for the formation of foodcrusts. Additionally, no a priori
assumptions can be made regarding the contents of a foodcrust, of which the taxonomic
diversity can easily stretch over several taxonomic kingdoms.
This thesis aims to contribute to the analysis of foodcrusts with several
methodological experiments and test what information foodcrusts can provide by applying it
to an archaeological case study. First of all, to highlight the taxonomic resolution of
palaeoproteomics in a controlled setting, we apply several proteomic workflows to a bone
tool from a Dutch Bronze Age site. Secondly, to investigate the formation of foodcrusts and
the degree to which the recovered proteins represent the cooked contents, a set of
foodcrusts with known composition was generated and analysed. Another experiment
consisted of a blind test of identifying the resources cooked in experimental foodcrusts,
highlighting both the over- and underrepresented taxa in proteomic analysis. Finally,
foodcrusts from the Mesolitic-Neolithic site Syltholm II (MLF00906-I/II) were analysed with
palaeoproteomics, lipid analysis, and SEM to highlight the different resources identified by
each of these methods.