Green potatoes have always been off the menu, but a Tasmanian researcher is looking at how we can reduce the occurrence of greening to ensure more of the starchy root vegetable make their way on to our plates.
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After spending so much time growing underground, potatoes turn green when exposed to light, Tasmanian Institute of Agriculture PhD candidate Sabine Tanios said.
“In just a few days of light exposure they turn green,” Ms Tanios said.
“This causes big losses for industry and growers,” she said.
To find the cause of greening and how to eliminate the number of potatoes lost to green tinge, Ms Tanios has undertaken a research project through the institute and funded by Woolworths.
“What we are looking for is the genes involved in greening. If we can identify those genes and try to silence those genes we can reduce greening,” she said.
Ms Tanios’ research involves investigating the type of light that causes greening, the impact of nitrogen fertilisation on greening levels and greening susceptibility for different potato varieties and maturity levels at the institute’s Southern Tasmanian research facilities at New Town and Sandy Bay.
“As part of this project we screened 105 varieties of potatoes, and there’s big differences between them. What we are trying to do is understand why that is, so we found components – a lipid – in the skins which can act as a barrier and reduces light penetration, which reduces greening.”
“We are trying to understand the physiology behind that.”
Ms Tanios is two years into the three-year project, but can already see some relevant applications of her research.
“In the field we have to control the planting depths, take into consideration irrigation practices and we have to keep hilling. If we don’t hill the potatoes they get exposed to light in the field,” she said.
“Part of the work is focused post harvest, so we’re looking light type in the supermarket and intensity of light.
“The main idea is to protect them from light, but in the supermarket you can’t do that because people need to be able to see.”
The impact of light can be reduced by using opaque packaging to filter the “offending light wave lengths”, like a brown paper bag.
Blue light causes more greening than green light.
When it comes to storing potatoes after they have been purchase at the green grocer, supermarket or farmers’ market, “they need to be kept in a dark place and covered”.
“If there is no light you will not have any greening,” Ms Tanios said.
Johanna Baker-Dowdell
Johanna has more than 22 years experience as a journalist for newspapers, magazines and online publications.
Johanna has more than 22 years experience as a journalist for newspapers, magazines and online publications.
