Scientists are mining discarded potato peelings for biochemical treasure – bioactive substances that may be used in improving human health, writes CLAIRE O'CONNELL.
THEY SAY one man’s trash is another man’s treasure. But what sort of bounty could possibly lie in piles of discarded potato peelings or in heaps of spent grain left over from brewing beer?
A biochemical kind of treasure, according to two groups of researchers who are gearing up to mine such waste for bioactive molecules with the potential to control agricultural pests, improve human health and even combat cancer.
“We have been interested in by-products for quite a while now,” says Dr Nigel Brunton, a senior research officer with Teagasc who works with phytochemicals derived from plants. “They are mostly defence compounds the plants produce themselves that may have a beneficial effect for human health.”
Brunton and colleagues are currently looking for valuable chemicals in potato peels, which crisp manufacturers Largo Foods are only too happy to donate for the research.
The company produces around 30 to 40 tonnes of wet peel each week, and has to pay for its disposal, says Brunton. “So if we can do anything useful at all with the waste, that’s a good thing.”
Funded under the Department of Agriculture and Food’s Firm scheme, the scientists at Ashtown are starting to examine the peels for glycoalkaloid compounds, which can be toxic at high levels but have already proven their mettle when used as a topical treatment for skin cancer.
The project, which involves collaborators at University College Cork, will isolate glycoalkaloids from the potato waste and hopefully find some novel compounds in the process, explains Brunton.
GLYCOALKALOIDS COULD also help farmers to ward off nematode (roundworm) pests, he says, noting that collaborator Peter Jones at UCC is working on this. “Nematodes are present as eggs in the soil and the glycoalkaloids basically cause the nematodes to hatch out,” explains Brunton. “So at a time when there are no potatoes growing there you apply the potato peel waste or the glycoalkaloid to the soil, causing the nematodes to hatch out, and they have no food source so they die.”
And as the potato peels give up their biochemical secrets, another group of scientists will look to a different source of potentially useful chemicals – brewers’ spent grain (BSG), a solid leftover from the brewing process.
“There are significant volumes of this material produced annually,” says Prof Dick FitzGerald, from the University of Limerick, who estimates that about 150,000 tonnes of BSG are produced in Ireland each year. “But if you consider how much beer is consumed internationally that can be bumped up by several orders of magnitude worldwide.”
At present, the leftover material is usually diverted to animal feed, but the UL team and their collaborators at UCC are eyeing up other uses.
“We know BSG contains some potentially useful components of food interest, so it has an important application in human nutrition,” says FitzGerald.
The first step is to isolate the carbohydrates, fibre and protein from the cereal by-product, explains researcher Dr Charlie Piggott, with a particular eye to finding bioactive compounds such as anti-oxidants.
“There are known antioxidants found in cereals that have protective functions in the intestine,” he says, adding that the project hopes to find new beneficial compounds too.
The Firm-funded work will also mine the leftover grain for bioactive peptides (protein fragments) that could be added to functional foods to help manage health conditions in humans.
FitzGerald believes that isolating particular compounds or enriched fractions from the spent grain will add value.
“We may need targeted strategies to release these peptides so that they can then be available to interact with organs to bring about or mediate particular beneficial health effects,” he says.
The project, which has links with Diageo and Kerry Foods, will run for four years.