Tuesday, April 14, 2015

Beware to Prepare when using Australian Bush Tucker ... Peas

Toxins and Tucker

Castanospermum australe
The black bean

Although no Australian member of this group has been seriously exploited as a food crop, some have been important as food for both aborigines and for the early European colonists. However, as some of the latter found to their cost, many of the native "peas" are also toxic unless the seed is prepared correctly. This usually involves soaking to leach out the toxin or heating to destroy the toxic chemicals.

Some of the species used for food include:
  • Castanospermum australe, the black bean. The seeds of this species are toxic when raw and are prepared by roasting or soaking in water.
    The Black Bean has also proved valuable as a timber species, it's seeds have been utilized - following extensive preparation as a food by Aborigines and it contains alkaloids which have been shown to have anti-HIV and anti -cancer properties.
    Castanospermum australe
    Coastal Jack, Canavalia rosea
    (toxin removed by heat).
    This plant was eaten by members
    of James Cook's expedition in 1770.

    Fabaceae>Canavalia rosea? Beach Bean DSCF5481comp
    Vigna lanceolata, maloga bean, from northern Australia

    Vigna lanceolata
    Vigna lanceolata
    • Mucuna gigantea leaf and buds
      Mucuna gigantea, burny bean.

    Burny Bean inflorescence
    Mucuna gigantea, burny bean.
    The toxic properties of some species have also had an impact on agriculture by other means; ie. by being implicated in livestock poisoning. Nervous system malfunction is seen in poisoning of livestock by some Darling peas. (Swainsona species), and by Gastrolobium species.The rattlepods, Crotalaria species, are also implicated in livestock poisoning. They contain pyrrolizidine alkaloids which accumulate in the liver and produce long-term damage which is often fatal.
    "Horses and cattle are more susceptible to poisoning than sheep, but sheep have been poisoned by bluebush pea (Crotalaria eremaea ssp. eremaea) in western Queensland. Poisoned horses develop a condition called "walk-about disease" or "Kimberley horse disease" in which they become unaware of their surroundings and wander blindly. A major cause of this poisoning is Crotalaria crispata, a small plant common in the Kimberley region of Western Australia. Other Crotalaria species cause the disease in the remainder of tropical Australia.
     In central and northern Queensland an unusual disease of horses is caused by two other species of Crotalaria, C. aridicola (Chillagoe horse poison) and C. medicaginea (trefoil rattlepod). Horses may develop a taste for these plants which damage the oesophagus (gullet) producing ulceration severe enough to stop the horse swallowing food."

     Crotalaria medicaginea var. neglecta - Trefoil Rattlepod
    Dr Ross McKenzie, 1993 Bill Tulloch Memorial lecture to the Queensland Region of the Society for Growing Australian Plants
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    Images @ Eminpee Fotography

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