Scientists said Monday they have uncovered clues to how a chemical reaction during heating may result in the buildup of a possible cancer-causing agent in such favorite Western foods as french fries, chips, crackers, breakfast cereals and other fried, roasted, grilled, toasted or baked plant-based treats.
The new experiments identify a basic building block of life -- the amino acid asparagine, which occurs naturally in potatoes and numerous other vegetables -- as a key ingredient for cooking up the compound of concern, called acrylamide.
Acrylamide -- used in the production of plastics and dyes and in water purification -- has taken center stage in food safety research since the surprising discovery last spring that it exists in elevated levels in certain everyday victuals.
The latest research, which helps explain why the compound occurs in some cooked foods but not others and why, even within the same type, its levels can vary, points to possible ways to reduce acrylamide production during the heating process, investigators told United Press International.
The U.S. Food and Drug Administration is testing different brands to determine their acrylamide content.
Acrylamide -- which has been shown to cause cancer in animals but not humans -- is formed when heating causes asparagine to combine with sugars.
To scientists, this is known as the Maillard reaction. But to cooks, it is the aromatic, flavor-enhancing browning of gastronomic fare, which typically takes place at temperatures between some 300 and 500 degrees Fahrenheit, the investigators discovered in independent studies.
The worrisome substance was not found in boiled food, which is cooked at lower temperatures.
"(The finding) explains why acrylamide forms only at higher cooking temperatures and offers a possible explanation as to why it is more prevalent in potato and cereal-based foods," said Donald Mottram of the School of Food Biosciences at the University of Reading in England.
He is lead author of one of two independent studies on the same topic that will be published in the Oct. 3 issue of the British journal, Nature.
The journal permitted early release of the information to coincide with reports of similar findings by Canadian government scientists.
"The results demonstrate that temperatures in excess of 100 degrees C, which are associated with frying, roasting and baking, are necessary for acrylamide formation," he explained.
"We show that it can be formed by reaction of natural components of foods. The reaction involved is the same reaction which provides color and flavor in cooked foods ... We highlight the particular amino acid -- asparagine -- which can produce acrylamide."
Asparagine is particularly plentiful in potatoes and in some cereals, explaining why the highest levels were found in chips and crackers -- especially those containing rye flour -- said Richard Stadler of the Nestle Research Center in Lausanne, Switzerland, who led a second team conducting similar research. The center is the research arm of the international food giant with a wide array of offerings on its marketing menu, from chocolate and confectionery to frozen roasted potato side dishes.
"The findings could be used to investigate how changes in processing conditions could be applied to minimize acrylamide production in manufactured food products," Mottram said.
Apart from certain groups of industrial workers, the average person is not exposed to any significant source of acrylamide other than food, scientists pointed out.
"The research findings are important in that they indicate a possible formation pathway for acrylamide in food," Carolyn Vickers of the International Program on Chemical Safety at the World Health Organization in Geneva, told UPI.
The findings point to a possible approach of lowering acrylamide levels in food by reducing the duration and temperature of cooking, Peter Spencer, professor of neurology and director of the Center for Research on Occupational and Environmental Toxicology at Oregon Health and Sciences University in Portland, told UPI. He was a member of an international advisory panel that assessed the acrylamide risk last summer.
This research will need to be duplicated, and built on by others in order to fully elaborate the pathway(s) by which acrylamide is formed (there may be more than one)," Vickers told UPI.
"We are aware of other groups working on the issue and encourage publication of results as soon as feasible," she urged.
"This work will assist with identifying other foods that should be tested, and consideration of what could be done to decrease acrylamide levels in processed foods."
The findings offer the first important insight into the process since the surprising announcement last spring by Swedish scientists of high levels of acrylamide in everyday foods. Scientists stress that although the compound has been shown to cause cancer in animals, there is no scientific evidence it does so in humans.
Humans were roasting/frying/grilling/baking potatoes long before the likes of McDonald's appeared on the scene, yet the identification of the presence of acrylamide in certain cooked foods was not made until now for several reasons, scientists told UPI.
Probably no one thought of looking, and the initial studies conducted by the University of Stockholm were actually focused on investigating biomarkers of exposure in workers exposed to acrylamide (occupational exposure), Stadler told UPI.
Groups, including the FDA and WHO, are taking the findings seriously enough to make assessment of the acrylamide risk a top research priority. For now, the FDA has shied away from issuing any formal warnings or advice or avoidance of acrylamide, shown to be present in a wide range of eatables that even include roasted banana chips.
The 700-member Snack Food Association on Monday voiced strong support for the FDA's risk assessment plan.
"The FDA is asking the right questions about how much acrylamide is in a broad range of foods that are processed at high temperatures," Jim McCarthy, the association's president and chief executive officer, said in a statement.
"The FDA is asking the right toxicological questions about how the body metabolizes acrylamide and how toxic it may or may not be. And FDA is moving to determine whether any additional steps are necessary."
Stadler said that for now, consumers should follow WHO recommendations but added there is no need for a change in dietary habits. He did note consumers should avoid overcooking food.
The researchers are pursuing studies to learn how acrylamide is formed in various food categories and to identify ways to limit such production in food processing.
"Mankind has been eating cooked foods for hundreds or, perhaps thousands, of years," Mottram told UPI. "We should not let the present acrylamide issue detract from the enjoyment we derive from such foods, but it is so important that we have a balanced diet without excess of fatty and high sugar foods.
"The importance of fresh fruits and vegetables and exercise cannot be overstated."
