Indigenous Detoxification Methods

This is part of Year 11 HSC Chemistry course under the topic of Chemical Reactions

HSC Chemistry Syllabus

  • Investigate the chemical processes that occur when Aboriginal and Torres Strait Islander Peoples detoxify poisonous food items

      Indigenous Detoxification Methods

      This video discussed various ways in which Australian Aboriginal and Torres Strait Islander peoples detoxify macrozamia cycads and utilise them safely as a food source. 

      Native Foods and Importance

      Native foods like the daisy yam, the bulbine lily, and the purple coral pea, play a crucial role in the diet of some Indigenous Australians. Among these native foods, the macromazia cycad stands out. 

      The plant is both toxic and carcinogenic yet for some Indigenous populations, it is a staple. The consumption patterns of the cycad vary with the fruit being favoured by some in the Southwestern Australian population, and others preferring the seed. 


      Detoxification Process

      There are two main detoxification methods which are employed to make the fruit safe for consumption; anaerobic fermentation and leaching. 


      Anaerobic Fermentation:

      Anaerobic fermentation is a process which involves soaking and burning the cycad fruit which helps in eliminating the macrozamin toxin which exists within the the macromazia cycad, a carcinogenic substance which is present in the flesh. Although the toxicity of the fruit decreases upon fully ripening, fermentation ensures that any remaining toxins are neutralised. 




      Eastern populations have a preference for the endosperm or seed of the cycad and consume it as a vital carbohydrate source, akin to bread. However, these seeds contain cycasin which is both neurotoxic and carcinogenic. The consumption of the seed poses serious health risks and can lead to the development of colonic cancer.

      These seeds undergo a process called leaching. This simple yet effective method involves cutting the seed open, and washing it with running water. Given that cyacasin is water-soluble, it dissolves when exposed to running water. For a detailed explanation of this mechanism, refer to the video "how indigenous people remove toxicity from food" in the module 5 HSC Chemistry playlist. 

      Once the toxins have been leached away, the kernels are then ground into flour and baked into a bush bread.