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Artifacts from archaeological sites in Alaska and Canada were selected at the National Museum of Natural History and residues were analyzed to determine their lipid and protein composition. Residues were found in cooking vessels, either absorbed in the clay matrix of ceramics or trapped as a charred layer of residues adhering on the surface of pots. Seals, whales and walrus were the principal source of food, as well as oil for the lamps. In the arctic treeless regions, blubber-burning lamps were an essential household utensil in the daily life: they were used for heating, lighting, drying and cooking. By analyzing cooking residues in the arctic archaeological context, we can characterize, identify and understand the degradation of organic compounds resulting from the processing of foodstuffs and correlate this information with the anthropological context.
Organic residues were analyzed together with modern reference samples of whales and seals. The fresh specimens were also thermally degraded to simulate cooking and aging. Extraction of the lipids was followed by derivatization and analysis by gas chromatography and mass spectrometry. Methods to analyze proteins on archaeological artifacts have in the past given few reliable results, especially because proteins are denatured and modified when they are processed. An original methodology developed in this study and derived from new developments in proteomics offers promising perspectives to identify species-specific proteins. Proteins are extracted, denatured and digested by an enzyme, and their peptide fingerprint and sequencing are characterized by techniques of mass spectrometry (MALDI-TOF and Electrospray-MS).