|
|
2003 Deakin University Research Report |
| Research Stories | |
| Report Contents | Research Output Contents | School Output by Year | Search for a Researcher |
Lupin Foods for Health
The name derives from the Latin for “wolf”, but there is no longer anything feral about the sweet lupin - decades of careful breeding have tamed it and made it an indispensable crop in Western Australia's sandplain wheat belt.
Now, food scientists want to complete the metamorphosis of the sweet lupin, Lupinus angustifolius, by making it a healthy, nutritious part of the Australian diet - a sort of home-grown equivalent of the soybean.
Australians can already buy a few boutique products made from lupin flour, like breads, biscuits and pasta, but Deakin University food scientist Dr Stuart Johnson believes the time has come for the sweet lupin to make its presence more strongly felt on supermarket shelves.
"Western Australian farmers produce around a million tonnes of sweet lupin grain per year," he said. "That's many times the figure for any other Australian legume crop, like soy, chickpeas or field peas.”
"But very little goes to human consumption - no more than a few thousand tonnes. Most lupin grain is fed to animals."
Dr Johnson says lupins were traditionally grown as a nitrogen-fixing crop in rotation with wheat. Plant breeders successfully reduced levels of toxic, bitter alkaloids in their seeds to the point where they could be safely eaten by sheep and cattle.
The latest generation of sweet lupins contains virtually negligible levels of alkaloids, and is recognised by Food Standards Australia New Zealand as fit for human consumption.
Agriculture now faces the challenge of ensuring it can produce enough food to feed the world’s still expanding population in the new millenium. With animal protein likely to become increasingly expensive, and in short supply, Dr Johnson says underutilised grain legumes like sweet lupin could be an increasingly important, alternative source of nutrients.
"My interest is in finding ways to use sweet lupins in food products that will be acceptable to consumers, palatable, and with desirable nutritional properties," he said.
"I'm working with a team of food science and nutrition researchers to investigate ways in which palatable food products can be developed from lupin and what happens when healthy human subjects are given diets high in lupin-derived products.”
"We hope to develop the nutritional understanding of the effects of lupin in the human diet that could assist the Australian food industry in its promotion of lupin to consumers in Australia and overseas."
Climatic and soil conditions permit a far greater production of lupin in Australia than soy, and much of the soy-based foods available in Australia are derived from imported soy-derived ingredients, so import replacement is a further incentive to develop a local equivalent.
What is known about lupins is that, like soybeans their kernels are comparably high in protein - about 40 per cent by weight - lower in oil (9 per cent vs 20 per cent), with about 30 per cent by weight of dietary fibre.
Dr Johnson previously worked in the food industry, where he was developing purified kernel fibre from lupins as an ‘invisible’ dietary fibre ingredient for foods.
He is now developing foods derived from lupin kernel fibre and flour such as high-fibre bread, muffins, pasta and breakfast bars.
Dr Johnson and his Deakin University colleagues Associate Professor Gwyn Jones, Dr Stuart Smith, Ms Helen Devereux, Mr Ramon Hall and Ms Amynta Baxter in collaboration with Food Science Australia, Agriculture Western Australia and several food companies have been funded by the Grains Research and Development Corporation, and the Australian Research Council to develop these foods, design diets around them and in collaboration with Prof Madeleine Ball of the University of Tasmania, to investigate the physiological effects of a diet high in lupin flour and purified lupin fibre in humans.
This includes effects on such things as bowel function faecal chemistry and microbiology, blood lipids and hormones, and appetite, factors related to the risk of bowel cancer, cardiovascular disease risk, non insulin-dependent diabetes and obesity.
Lupin fibre is a pale, bland powder that absorbs many times its own weight in water. There is evidence in pigs that lupin fibre may reduce total food intake. Dr Johnson and his colleague Ms Devereux are investigating whether lupin fibre, when added to other foods, can create sensations of "fullness" or satiety in humans, quelling hunger without reducing the palatability of the foods.
If the end result is that people don't eat as much, lupin fibre could become a valuable adjunct in diets for treating obesity and overweight – important given that almost 40% of adult Australians are considered overweight with a further 18% classified as obese.
"My own research interest is developing palatable, nutritionally balanced food products containing physiologically useful levels of fibre," he said.
"In our sensory evaluations of lupin fibre-enriched bread, muffins, breakfast bars and orange juice, we asked members of a taste panel to rank the acceptability on a line scale that ran from extremely acceptable to extremely unacceptable.”
"The fibre-enriched orange juice was the only product not to fulfill pre-set acceptability criteria though on average it was still rated better than ‘neither acceptable or unacceptable’ on the scale used for evaluation.”
"That result was interesting, because people were able to detect the texture of the fibre in the juice, and identify it as different from orange juice without fibre. We may be able to solve this problem by modifying the fibre particle characteristics."
Dr Johnson says that as a source of dietary protein for humans, sweet lupins are not yet in the class of soy, which has an amino-acid composition more like that of meat from animals.
Lupin protein is low in sulphur-rich amino acids like methionine and cysteine, as well as lysine, which are all essential in a healthy, balanced diet.
Dr Johnson says molecular geneticists could directly modify the crop's existing amino acid balance with genetic engineering, but given consumer uncertainty about genetically modified crops and foods, this might be a barrier to successful marketing. Instead of using genetic engineering the lupin industry may opt for the longer conventional breeding route, to avoid any risk of consumer resistance.
Dr Johnson says he isn't out to convert Australians into vegetarians. "I see lupins not as a replacement for meat in the Australian diet, but more as a way to a more varied diet that is higher in whole grains and dietary fibre and lower in saturated fat, with all its health implications of reduced risk of cardiovascular disease and colon cancer for instance," he said.
Australians could benefit from more fibre in the diet, while as long as essential amino acid requirements are carefully considered though appropriate food combinations, consumers could benefit from lupin as a relatively inexpensive extra source of dietary protein.
|
|
|
| Report Contents | Research Output Contents | School Output by Year | Search for a Researcher | |
| 2003 Deakin University Research Report |