Milk-boilers of the Italian Bronze Age: from archaeological hypotheses to analytical evidence

This contribution presents new data and observations on protohistoric ceramic vessels characterized by an internal ledge, interpreted as milk-boilers, and on the multi-perforated lids, possibly intended for collecting boiling milk spills. These two ceramic forms are largely attested during the Bronze Age in central and southern Italy, but they also occur, within more limited chronological phases, in northern Italy, Sardinia, Sicily, and Corsica; in addition, a few artefacts can be dated to the Early Iron Age. Despite their long-standing interpretation as milk-processing vessels based on morphology, no direct chemical evidence has so far been available for Italian milk-boilers, and just two lids have previously been subjected to organic residue analysis. A PhD project of the University of Naples Federico II carried out the complete cataloguing and classification of milk-boilers and multi-perforated lids, and collected about forty samples for organic residue analyses. The analyses were funded by the PRIN HERDS project and carried out at the Laboratory of Analytical and Isotopic Mass Spectrometry of the University of Salento. A combined analytical approach based on High Temperature Gas Chromatography- Mass Spectrometry (HTGC-MS) and Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS) was adopted to identify lipids absorbed by the ceramic fabric and to investigate artefacts’ function. Lipid profiles and compound-specific stable carbon isotope ratios allowed the distinction between ruminant dairy fats, adipose fats, and mixed residues, offering direct insights into the nature of the substances processed or contained in these ceramic artefacts. All analysed samples indicate residues from ruminant fats and none of the samples showed values that indicate the presence of subcutaneous fat from non-ruminants such as pigs. In several cases isotopic signatures consistent with ruminant dairy products were present, confirming that part of this ceramic assemblage was involved in milk and dairy processing. Other samples show evidence of mixed lipid input, suggesting complex processing practices or occasional reuse. Lastly, some samples were restored so contaminations are present. Overall, this study demonstrates how the integration of chemical analyses and ceramic typology can significantly refine our understanding of food processing technologies and dairy exploitation strategies in Bronze Age Italy.