Identification of Cooked Bone Using TEM Imaging of Bone Collagen
Mild heating (≤100° C, 1 h)—typical of cooking—does not lead to detectable changes in any biochemical parameter yet measured; consequently bones that have been cooked, but which have not reached a temperature that will induce charring go undetected. We have used a microscopy based approach to investigate changes in the organization of the bone protein, collagen, as it is heated, using bone from heating experiments, short term burials, and archaeological sites. The work has revealed that the presence of a mineral matrix stabilizes the collagen enabling the damage to accumulate, but preventing it from causing immediate gelatinization. Once the mineral is removed, the damage can be observed using appropriate visualization methods. This chapter describes the transmission electron microscopy (TEM) technique that has been used to detect cooked bone by visualizing minor heat-induced damage at the level of the collagen fibril.
Key words:Transmission electron microscopy Bone collagen Collagen fibrils Cooked bone Heated bone Gelatinisation Positive staining
This method has been refined over a number of years and with the help and advice from TEM technicians at Newcastle, Bradford, and York Universities. Particular thanks must go to J. Fearnley and M. Stark. The majority of the method development was supported by a NERC CASE studentship (NER/S/A/2002/12028) with the BLC Leather Technology Centre.
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