Home ||  Back Issue Contents  || Search ||

Issue 18

Aussie bushfoods get the `all clear'

RIRDC Report authors - Drs M. & E Hegarty

Commercial Australian bushfoods have been given a qualified `'all clear' with regard to toxicity, although some precautions should be observed in a small number of cases, according to a new report from the Rural Industries Research and Development Corporation (RIRDC).

No adverse effects

The report, titled Food Safety of Australian Plant Bush foods, said that for the great majority of the bushfoods studied, there appear to be no reports of adverse effects following normal usage arid intake, despite inquiries throughout the period of the study, and no new evidence of unexpected chemical hazards has resulted from the analyses.

Bush fruits such as bush tomatoes (Solanum centrale) and seeds such as wattleseed (for example Acacia victoriae) have a reliable history of traditional use, and are especially favoured by the modern bushfood industry. Some, but not all, of the commercial bushfoods mentioned in this report have a history of traditional Aboriginal use, and/or use by early European settlers, however some traditional Aboriginal bushfoods required lengthy preparation to improve palatability and in some cases to remove toxins

Possible hazards

This report details possible toxicological hazards associated with bushfoods as: A major issue is that plant material being utilised is correctly identified. The available information on toxicity only applies 

to the nominated species and cannot be assumed to be relevant to even a closely related species.

Digestive or other problems may be associated with the consumption of particularly excessive quantities of unripe or very acid fruits, for example some of the aspens (Acronychia species), some bush tomatoes other than the popular Solanum centrale, some lillypillies (Syzygium species) and unprocessed Davidson's plums (Davidsonia species) or to excessive use of very strongly flavoured, peppery and potentially irritant spices (for example, Tasmannia species).

Harvesting, handling or preparation operations that vary from traditional practices can result in harmful or toxic constituents not being removed and included in the end food product. It is advisable for bushfood marketers to label their value-added products (and fresh material where practicable) with the name of the species used, and any advice as to requirements for cooking, removal of inedible parts, blanching, and a recommended maximum intake in the case of strong spices.

• free download from the RIRDC website:

www.rirdc.gov.au

(see `New Plant Products program

• online through our Eshop at www.rirdc.gov.au/eshop

• phone (02) 6272 4819 for a hardcopy

• email rirdc@rirdc.gov.au

• 2001, 8lpp. Pub no 01/028. $20 

Index: 18

From the Editor

Letters

Pharmaceutical properties of Qld Rainforest plants

Sunrise lime dieback

Toxicity results - 'all clear' 

North Coast Co-op 

Aboriginal use of Moreton Bay Chestnut 

Growth patterns in bushfoods

Lesser known species

Peak Body

Geijera sp

Back to the future

Native bees

Vale Denise Reason

Book Reviews

Recipes

Dangerous Bush Tucker

Products

Germination Trials

Emerging crops

TUCKOMBIL NATIVE FOODS

Wholesale suppliers of Native Food and Foliage Rainforest plants - Rainforest Fruits and Spices - Essential Oils

Plants for sale:

· Grafted Smooth Davidson Plum

· NSW and QLD Davidson Plum

· Grafted Illawarra Plum selections

· Cutting grown Illawarra Plum

· Cutting grown Riberry selections

· Cutting grown Lemon Myrtle

· Also Rosella plugs and tubes

· Plus various landscaping and rainforest regeneration trees and grasses

· All major macadamia cultivars.

All enquires to: Fax/Tel - (02) 6628 5558

PO Box 281, Alstonville.  NSW. 2477.

AUSTRALIA. Email -  tuckombil@nativefood.com.au

 

North Coast Native Foods Co-op Ltd

The North Coast Native Foods Co-op was formed in 1997 by growers of Australian native foods. The members of the co-op reside in the Camden Haven, Hastings and Macleay valleys of the mid-north coast region of NSW. The 21 current members are a multi-talented, skilled and resourceful group of growers committed to establishing markets for bushfood products locally and overseas.

Most of the growers started as a means to diversify their farming interests. In 1996 when the bottom had dropped out of the beef cattle industry, many people were looking around for alternatives. Meetings were held to discuss the emerging bushfood industry and Co-op member growers decided to plant Australian native trees for the spice industry. Approximately 24000 lemon myrtle trees and 11000 aniseed myrtle trees have been planted, some now more than 3 years old.

Since then growers have also planted 27000 lemon scented tea trees, 1200 davidson's plum, and smaller amounts of riberries, brush cherries, cinnamon myrtle and several other varieties. All have been selected as they are well suited to our climate and soil conditions. From these, the NCNF produces spices, essential oils and teas and will be developing other products to utilise the fruits as they come on line. Management of the commercial bushfood plantations is designed on an environmentally sustainable system. The outcome is a chemical residue free product.

Most Australians think of bushfoods as emu, kangaroo and witjuti grubs, but that is only the sensationalised side of bushfoods. Australia has hundreds of unique flavours, which can all be incorporated into our existing diets and food habits. 

We currently only utilise a few of these. 

Bushfood ingredients can be used in a multitude of ways including ice cream, chutneys, soup, syrups, jams, fettuccine, tea, curries, on seafood and meat, stir fry, salad dressing and desserts. Lemon myrtle can be used as a substitute for lemon grass and aniseed myrtle as a substitute for five spice.

The latest flavour that is taking the imagination of chefs all over is lemon myrtle. Lemon myrtle has a superb fragrance and a delightful flavour of a blend of lemon, lemongrass and lime. The flavour blends beautifully in a variety of

culinary applications. It is exquisite in cheesecakes, desserts, breads, biscuits and chocolates and creates a superlative flavour for fish, sauces, pasta and beverages. It can be used instead of lemongrass in Thai cooking, and because of its ease of use is becoming a real favourite with the Asia chefs.

Aniseed myrtle is a very aromatic spice. It can be used to flavour pasta, seafood, stocks, sauces, breads, biscuits, chocolates, ice cream and liqueurs. It substitutes beautifully for star anise in any recipe. Some of the growers' products, under the "Barbushco" label, are available from The Olive Oil Shop at Timbertown in Wauchope, Sea Acres Rainforest Centre in Port Macquarie, The Clog Barn in Coffs Harbour, Laurieton Health Foods or The Lorne Valley Macadamia Farm. Some health food stores have a limited range of products, but are happy to get in other products if you ask. So if your local shop or restaurant is not stocking or using our unique Australian flavours, perhaps you should ask them.

To taste the Australian flavours at their best, try dining at Signatures Bar & Grill in Port Macquarie, where they have a new chef whose use of bushfoods is simply stunning, or in Wauchope, at Bago Woodworks Restaurant or Waterman's Cafe.

Anyone interested in Australian essential oils can find a wealth of information from a recently published book called Bush Sense - Australian Essential Oils & Aromatic Compounds by Mark A Webb. This 128 page book details over 20 species, extraction methods, chemical and aroma constituents, therapeutic properties and method of application of over 20 species including lemon, aniseed and cinnamon myrtles. Bush Sense is available from More Than A Bookshop in Wauchope. In researching the book, the author visited a number of local plantations.

Contacts

Barbara Barlin Director 02 6556 9656

Alan Campbell Chairman 02 6586 1180

Stephen Carle Director 02 6585 9284

Toni Park, Secretary

02 6556 5350

Pauline Voase Director 02 6567 1442 - marketing into Asia

Kerry Wheeldon Treasurer 02 6586 1180

Aboriginal Use of the Moreton Bay Chestnut

(Castanospermum australe)

Sean McBride is a lecturer in anthropology at the University of Queensland and teaches survival and bushcraft courses through Touch the Wild (www.geocities.com/touchthewild/) Ph. (07) 3822 8119.

Introduction

Plant use is an important part of Aboriginal economies. The Moreton Bay Chestnut (C. Australe) figured prominently in the diet of Moreton Bay Aborigines and elsewhere.

The large seeds appear to have been a staple food source, but required processing to remove toxins.

Replicative processing experiments have been conducted on Bungwall (Blechnum indicum) by Gillieson and Hall (1982), and Richter (1995), but until now, not on Moreton Bay Chestnut (except for ongoing traditional use in the rainforests of North Queensland).

Moreton Bay Chestnut

The Moreton Bay Chestnut (also known as the Black Bean or Queensland Chestnut) is a large tree, up to 40m tall, growing in rainforest from the Bellinger River in N.S.W. to Cooktown in north Queensland, and up to 150km inland (Everist 1974).

It was, and is, plentiful, is available for most of the year and produces vast quantities of large pods containing large, poisonous seeds.

The seeds can be eaten after processing, but the poisonous compound is as yet unknown and produces vomiting, stomach cramps and diarrhoea. However, the Aborigines used a variety of techniques to remove this poison.

Methods

From the ethno-historic literature I have broken down the main processing methods into three groups: 1) cooked first, 2) processed first, and 3) dubious methods.

(see Table 1).

Those in the dubious section are there because of my belief that:

* Soaking a whole seed, without prior processing, will not allow for a sufficient surface area to be acted upon by running water, in order to remove toxins. It occurred to me that soaking the whole seed first may have softened it, making for easier processing. I tested this by soaking a whole seed for 4 days. It showed no sign of softening.

* Stirring the processed flour around with water, unless conducted for a long period of time (current estimate - 18 days), will not remove sufficient toxin, compared to using running water.

Cooking

The ground oven appears to have been the favoured method of cooking. This method steams the seeds making them soft and easy to process. Boiling for three hours will also produce the same result. I have also baked seeds in a domestic gas oven for two hours at 150O C but they develop a hard exterior that makes them difficult to process. I suspect that `roasting' and `baking' in the literature both refer to steaming in a ground oven.

A shallow pit, 10 cm deep and 60 cm in diameter, was prepared and lined with flat stones (not river stones). A tipi (conical) fire was built on top of the stones, out to the edge of the pit. The fire was lit and maintained for one hour. The coals were scraped out of the pit and paperbark (Melaleuca spp.) sheeting was placed on the stones. Five kilograms of seed were placed on the paperbark and sprinkled with 1 cup (250 mls) of water. The seeds were then covered with more paperbark and the whole oven was covered with soil, ensuring that heat was retained. The oven was left for seven hours and then the seeds were removed.

Cooking has the effect of loosening the brown, wafer-thin covering on the seeds. The covering is removed by compressing the seed between the thumb and forefinger of both hands, at the same time sliding the thumbs forward. This cracks the covering making it easier to remove.

Table 1. A breakdown of the main methods of processing Moreton Bay Chestnut from the ethnographic and ethnohistoric literature

Cooked first

Initial Step 

Processing  Soaking Reference
Baked 

Cut fine with

sharp shell 

 

Soaked (running water) at least 12 hours  Roth (1901:1)
`Baked

Baked Sliced with snail shell Soaked (running water)

"quite a couple of days" 

 

Roasted
Cooked in ground oven 
Processed first (initial step)

Roth (1901:10)

Roasted Pounded between Soaked (running water) Bundock 1885

stones 3-4 days (cited in McBryde 1978:204)

Roasted Broken up Soaked (running water) Bundock 1885

some days (cited in McBryde 1978:263)

Cooked in Sliced with Soaked (running water) Banfield (1932:260)

ground oven snail shell 2-3 days

Processed first

Initial step Processing Soaking Reference

Scraped with Soak Maiden 1898:352

jagged mussel (no other information)

shell

Cut into strips soak J.A.Boyd (in Maiden 1900:281)

(no other information)

Dubious

Initial step 2nd step 3rd step 4th step Reference

Baked soaked sliced with snail shell soaked Johnstone (1903:26)

Soaked Dried in sun roasted in hot ashes pounded Banfield (1932:260)

Baked in

stone oven pounded sifted stirred around with Colliver (1974:26)

water in a bark trough

An initial 10 kg of seeds were cooked in a ground oven in two batches of 5 kg. The first batch, although successfully cooked, was unable to be processed for 24 hours and in that time developed a blue grey mould over all the seeds, which resulted in the batch becoming unusable. The second batch was successful and did not develop the mould, despite attempts to reproduce it.

Processing

Four methods of processing the seeds were tested:

* Grating with a jagged mussel shell (A. pertexta). (fastest method)

* Slicing with a freshwater mussel

shell (Alathyria pertexta); (second fastest method)

* Slicing with a snail shell (Xanthomelon pachystylum) (third fastest method)

* Pounding between stones; (slowest method)

The stones were used as is, but the mussel shells and snail shells were initially ground down to an edge, using an industrial grinder, followed by hand grinding on sandstone.

The average time taken per kilogram for collecting seeds, preparing the fire, arranging the ground oven, removing wafer covering after cooking, and preparation for soaking, was 17 minutes (this did not include processing of the seeds).

One kilogram of seeds were processed by pounding between stones. The snail shell and mussel shell were used to process 1.5kg each, and 200g were processed by jagged mussel shell for comparison.

Times for processing 100g samples were recorded to achieve an average processing time. The times for processing 1kg of Moreton Bay Chestnut to a raw, inedible state prior to soaking vary from 70 minutes to 120 minutes. After processing, water was used to leach toxins from the material.

Poisoning

The toxic effects of Moreton Bay Chestnut on humans, cattle and horses have been documented since the nineteenth century. According to Cribb and Cribb (1987)

"... three of the slices, resembling a nutty potato in flavour, produced intense griping which lasted several hours". This was after soaking thin slices in running water for two days, then boiling for three-quarters of an hour in three changes of water.

Queensland Herbarium records mention three servicemen in southern Queensland in 1968, who ate small amounts of raw seeds and became seriously ill within two hours. They were admitted to hospital with symptoms of vomiting, severe abdominal pains and dizziness, but recovered overnight (Everist 1974:284).

Although saponins and Castanospermine have been suggested as possible causes of poisoning, McKenzie (1996) states that "the toxic principle in human poisoning has not been identified, and the effects on humans cannot, at this stage, be attributed to Castanospermime or saponins".

My experiments produced the following results:

* Sample 1 - 100g of cooked grated seed was placed in 1litre of water. The water was changed daily. It had a greasy/soapy feel which remained until the 18th day (even though saponins may not be the toxic agent they may be useful as an indicator of when to remove the material from water). On the 18th day the seed sample was strained and dry roasted. One teaspoonful (5g), equivalent to 11g of fresh bean, was ingested, as this was roughly equivalent to the three slices mentioned by Cribb and Cribb above. No ill effects were experienced.

* Sample 2 - 420g of pounded seed was placed in a cloth bag and left in a gently running stream, where water trickled through it constantly. The bag was tied in place and held down by a rock to make sure that the seed material was totally submerged. This was the closest approximation to traditional methods, where string bags or cane baskets were used. The sample was left for four days (96 hours), removed, dry roasted, and again one teaspoonful ingested. No ill effects were experienced.

Cribb and Cribb (1987:96) put a sample of seeds through a blender, then left it in running water for 14 days, followed by baking. The final product had no flavour, but was harmless. Much more research is needed on the poisonous aspect of Moreton Bay Chestnut but it appears that leaving the mashed or sliced seed in a flowing creek for 4 days is the best way of removing the poison. Warning: I tested the poisonous aspect on my own body which is not a recommended method. The Moreton bay Chestnut starch that I produced was not tested in a lab for poison content, so it is possible that some toxins remain in this food after processing. In the interest of safety I suggest toxicology tests be initiated on this food if you have any interest in trying it or marketing it.

Energy returns

After the material was leached of toxin, it was dry roasted to remove any water left over from the leaching process. The dry weight was converted to a fresh bean weight, and then this figure was subtracted from the weight of the initial sample. The difference was the amount lost through leaching.

When this fresh bean weight was subtracted from the initial sample weight, the loss from leaching averaged 52.2 % which effectively doubles (2.09 times) the processing time per kilogram of final product.

According to Brand-Miller (1993) the average energy return from 1 kg of Moreton Bay Chestnut is 873 kj/100gr or 8730 kj / kilogram. If we consider daily calorie requirements we find, "a daily 2172 calories (9014 kilojoules) ... necessary for the average adult to sustain health" (Boyer 1986:4).

Depending on the method of processing used, the amount of time required to produce 1kg of edible Moreton Bay Chestnut varies from 163 minutes to 268 minutes using traditional methods. At worst taking the longest processing time (268 minutes/kg) as an example, the daily kilojoule requirement (9014 kj) will be returned in 277 minutes work— roughly four and a half hours. Using the best time (163 minutes/kg) it would require 168 minute to supply daily requirements—two and three quarter hours work. Processor experience could cut this time down considerably.

Storage

From personal observation the seeds last for many months on the ground. Roasted samples of leached and unleached processed seed have been kept without refrigeration for the duration of this experiment (three months) without any sign of deterioration. The mould that destroyed the first batch, was I believe, a result of the fact that the seeds were still hot and damp from the ground oven, and left in a pile exposed to the air. The attempt to reproduce the mould may have failed because the second sample used was smaller and cooler when left out overnight. It appears that a dry product will keep quite well for months.

Conclusion

As my interest in wild foods stems from my background as an anthropologist and a survival instructor, I consider the Moreton Bay Chestnut a good survival food (although not necessarily in the short term) due to its abundance and high carbohydrate content. However, a survivor would have to be knowledgeable in the method of processing and be willing to wait 4 -5 days for any return, so perhaps for longer-term survival processing Moreton bay Chestnut would be a worthwhile undertaking (it obviously worked for the Aborigines).

Those involved in the bush food industry may be put off by the dangers of poisoning and therefore careful testing of the final product would be important. Utilising machine methods of processing, large amounts could be processed fairly quickly. Its taste is bland so those of you in the bush food industry will have to weigh up the pros and cons. Even allowing for a 50% leaching loss of carbohydrate Moreton Bay Chestnut provides an abundant return, considering its ease of gathering.

REFERENCES

Banfield, E.J. 1994, Confessions of a Beachcomber. St. Lucia, Queensland: University of Queensland Press.

Boyer, J.C., 1986 Capitalism, campesinos and calories in Southern Honduras. Urban Anthropology 15:3-24.

Brand-Miller, J. , 1993 Tables of Composition of Australian Aboriginal foods. Canberra: Aboriginal Studies Press.

Colliver, F.S., 1974, Some plant foods of the Queensland Aborigines. Naturalist 21(1-2):22-31

Cribb, A.B. and Cribb, J.W.,

1987 Wild Food in Australia. Sydney: Fontana.

Everist, S.L., 1974 Poisonous Plants of Australia. Sydney: Angus and Robertson.

Gillieson, D.S and Hall, J., 1982 Bevelling Bungwall Bashers: a use-wear study from southeast Queensland. Australian Archaeology 10:79-85.

James, K.W., 1983 Analysis of indigenous Australian foods. Food Technology in Australia 35(7):342 -343.

Johnstone, R.A., 1903 Spinifex and Wattle, Queenslander, Dec.19, p. 26.

Maiden, J.H., 1898 Some Plant Foods of the Aborigines. Agricultural Gazette of N.S.W. 9:350-356.

Maiden, J.H., 1900 Native Food Plants, Agricultural Gazette of N.S.W. 10(4):279-290.

McBryde, I., 1978 Records of Times Past. Ethnohistorical essays on the culture and ecology of the New England tribes. Canberra: Australian Institute of Aboriginal Studies.

McKenzie, R.A., 1996, personal communication. Principle pathologist, Animal Research Institute, Brisbane.

Pedley, H., 1992, Aboriginal Life in the Rainforest. Cairns: Department of Education.

Richter, J., 1994, `A pound of Bungwall and other measures'. Unpublished Honours thesis, Department of Anthropology and Sociology, Faculty of Arts, University of Queensland.

Roth, W.E. ,1901 Food, its search, capture and preparation. North Queensland Ethnography 3:1-31.


Reselling  Bushfoods mag.

The magazine is still not big enough to be in newsagents - so I need distributers/wholesalers!

If you'd like to know more, contact Sammy at the magazine:

Ph: 07 5494 3812

email:sammy@ausbushfoods.com

TOP