Lamb, Jenna (School of Social Science, University of Queensland)

The Raw and the Cooked: A Study on the Effects of Cooking on Three Aboriginal Plant Foods in Southeast Queensland

Cooking is an essentially human activity, embodying the transformation from the natural to the cultural and increasing the palatability and availability of food resources. Plants probably formed the major part of the hunter-gatherer Aboriginal Australian diet, and plant-residues on stone-tools used for processing have been identified by Australian archaeologists. Ethnographies also record the cooking and processing of plants by past Aboriginal people, but very little direct archaeological evidence of plant-food cooking has been confirmed. In this vein, replicative cooking and stone-tool processing of three ethnographically-recorded starchy plant-foods from southeast Queensland (Alocasia macrorrhiza [native taro], Blechnum indicum [fern-root] and Castanospermum australe [Moreton Bay chestnut]) was undertaken. The resulting residues were compared using microscopy and a biological stain, in order to test the effects of cooking on starch-grains, since starch-grains are the only archaeological remains that demonstrate irrefutable changes after being affected by heat. Results revealed that the main morphological effects of cooking on starch are swelling, and disruption of the extinction cross; and that Congo Red dye stains gelatinised, and otherwise damaged, starch in such a way that raw grains are distinguishable from cooked grains. The Congo Red staining method applied to three bevel-edged artefacts (traditionally associated with B. indicum processing) produced consistently reliable results, allowing identification and differentiation of cooked, damaged and raw starch-grains, and several starch-grains observed on these artefacts were similar in size and appearance to those in cooked B. indicum samples. This represents the first thorough evidence of the effects of cooking on starchy plants known to have been cooked and processed by past Aboriginal people. The results of this study may be used by archaeologists to infer archaeological residues deriving from cooked starchy foods and thus identify cooking as a specific form of activity in past subsistence behaviour.

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