Irish scientists who put forward recommendations to lower potentially dangerous acrylamide levels in fried potatoes have found that potatoes purchased in supermarkets were unsuitable for frying or roasting.
Acrylamide is a chemical found in unexpectedly large amounts in starchy foods that have been cooked at high temperatures and can cause cancers in animals. It is labelled as a potential carcinogen.
Since its discovery, scientists have looked at ways to reduce its formation in cooked foods, where it is formed by a chemical reaction between asparagine, an amino acid, and certain sugars.
Scientists Dr Ronán Gormley and Dr Nigel Brunton of Teagasc and Dr Francis Butler of UCD found that storing potatoes at three degrees centigrade compared to eight degrees centigrade doubled the sugar levels and doubled acrylamide levels in crisps.
They recommended that before processing them into crisps, the potatoes should be stored at eight degrees centigrade to lower the sugar content.
They also found that the longer potatoes were stored over the winter, the higher the sugar levels found and consequently, the acrylamide levels when the potatoes were cooked.
"The acrylamide content of French fries made from Rooster, Record and Oilean potatoes bought in supermarkets was high," said the research.
"This related to high sugars because the potatoes were not conditioned at eight degrees centigrade and were therefore unsuitable for frying or roasting," said the researchers. They found that soaking and blanching the chipped potatoes before cooking reduced the sugar levels and the acrylamide in fried products.
"The high temperature cooking process that produces the browning and flavour sensation in French fries is also responsible for the formation of acrylamide," they concluded.
Work carried out by Dr Enda Cummins of UCD into a risk assessment study on the human intake of acrylamide from fried potatoes calculated that the intake from French fries averaged 0.27 microgrammes per kilogram of body weight per day for men and 0.20 for women.
The intake of acrylamide from crisps in Irish men and women averaged 0.052 and 0.064 microgrammes per kilogram of body weight per day and was within the recommended limit of one microgram per kilogram.