SIMULATION EXPERIMENTS FOR DETERMINING THE USE OF ANCIENT-POTTERY VESSELS - THE BEHAVIOR OF EPICUTICULAR LEAF WAX DURING BOILING OF A LEAFYVEGETABLE

Laboratory experiments were performed using replica ceramic jars to si mulate ancient pottery vessel use. The aim of the study was to investi gate the behaviour of lipids, specifically, epicuticular leaf wax comp onents during the processing of foodstuffs in unglazed ceramic vessels to determine if the pattern of lipid accumulation in a vessel can be used as an indicator of the mode of use of individual vessels. Brassic a (cabbage) leaves were boiled in replica jars and the ceramic fabric sampled from different parts of the vessel profiles. Leaf wax componen ts were solvent-extracted from the fabric samples, and analysed by gas chromatography (GC) and GC/mass spectrometry (GC/MS) to determine the ir distributions and concentrations in different parts of the vessel p rofiles. The same lipid distributions were detected in the fabric of t he replica jars as occurred in the wax of the Brassica leaves. The pat tern of lipid accumulation observed in the experimental vessels, i.e. the relative concentrations of lipid at different points on the profil e, was analogous to that seen in two ancient vessels which had been sh own to contain Brassica leaf wax components. These results confirm tha t boiling a leafy vegetable in water results in mobilization of the ep icuticular wax and its incorporation into the porous ceramic fabric. T he boiling process is non-selective with respect to the major leaf wax components and leads to a characteristic distribution of lipid down t he vessel profile, with higher concentrations in the upper parts and g radually lower concentrations towards the base. This provided the firs t experimental evidence for the actual mode of use of individual vesse ls based on the results of organic residue analyses. (C) 1997 Academic Press Limited