Scientists at the TU München detect glycidamid in crisps and French fries
The discovery of acrylamid in heated foodstuffs sent shockwaves around the world in 2002. Subsequent improvements in production methods enabled the food industry to reduce levels of acrylamid. However, further investigations revealed that the levels of acrylamid found in food has virtually no toxicological impact. In fact, the carcinogen glycidamid, a substance that is also generated when potato products are heated, is seen as a much greater threat. Now for the first time ever, scientists at the Technische Universität München (TUM) have shown the direct presence of glycidamid in crisps and French fries.
It has long been known that acrylamid is broken down in the liver to the highly carcinogenic substance glycidamid. And although scientists suspected that glycidamid is produced when foods are heated, its actual existence in foodstuffs has never been proven. But now, a team of experts headed by Dr. Michael Granvogl at the TUM's Chair of Food Chemistry has done just this. They have not only detected the dangerous substance directly in different types of crisps and French fries, but have also developed a procedure for measuring the amount of glycidamid present in these foodstuffs.
The scientists have thus far examined ten different types of crisps, three types of pre-cooked French fries as well as regular home-cooked French fries. In all of the samples tested, the team found levels of glycidamid ranging from 0.3 to 1.5 micrograms per kilogram. Although the same products typically contain 300 to 600 micrograms of acrylamid per kilogram, the scientists still see these comparably low levels of glycidamid as a cause for concern, as glycidamid is a significantly more dangerous substance. A similar study carried out by scientists at the University of Kaiserslautern revealed that even the smallest amounts of glycidamid triggered mutations in mammal cells.
Tests with different kinds of frying fats also led Granvogl to a further worrying discovery. The lowest concentrations of glycidamid were detected in slices of potato fried in saturated oils such as palm oil, a widely used fat for frying. In contrast, significantly higher levels of glycidamid were detected in tests with sunflower oil - an equally popular frying oil which contains unsaturated fats. Different studies have shown that unsaturated fats react with oxygen in the air to create hydroperoxides, which in turn react with acrylamid to produce glycidamid.
Since polyunsaturated fatty acids are regarded as being healthy, sunflower oil is frequently used for cooking potato chips and other potato products. The researchers' results now show that this may not be such a healthy option after all. "Many oils are labeled 'suitable for frying and baking', even oils that contain high levels of unsaturated or even polyunsaturated fatty acids," explains Dr. Granvogl. "Our initial results indicate that oils with saturated fatty acids are actually the better option here."
Improvements in industrial production methods led to dramatic cuts in levels of acrylamid in food. And now, TUM scientists are working on further developing this new process to make it available to standard commercial labs. The objective is to enable the food industry to reduce glycidamid levels to an absolute minimum. Prof. Schieberle, head of the Chair of Food Chemistry and the group's leader, has now created a PhD position to investigate the influence different types of oil have on glycidamid levels.
Published in: Journal of Agricultural and Food Chemistry, August 17, 2008
Source: TU Munich