The landmark study by the Swedish scientists in April 2002 identified higher levels of the potential carcinogen acrylamide in crisps, chips and some snacks, in stark contrast to meats, fish, vegetables and some nuts that demonstrated low levels. Recent findings suggest that the free amino acid asparagine, found in potatoes and cereals, could play a key role in the formation of acrylamide.
DSM applied genomics technology to degrade the free amino acid L-asparagine. "Since acrylamide is formed from L-asparagine when food is processed at temperatures exceeding 1200C, DSM experts reasoned that converting L-asparagine in dough prior to baking would prevent acrylamide formation," said the firm in a statement this week.
This involved screening the 14,000 genes of the Aspergillus niger genome - a commonly used micro-organism in the food industry and for which DSM determined the DNA sequence in 2001. A gene encoding L-asparaginase was cloned from food-grade Aspergillus niger and expressed in its native host. The resulting strain was fermented, and the asparaginase subsequently purified before being added to the dough.
"The result was a significant reduction in acrylamide levels in end-products such as bread and Dutch honey cake," said the Dutch firm, adding that it has filed a patent for the technology and is investigating its potential for application in other areas, including potato crisps.
Professor Don Mottram at the University of Reading, in conjunction with B L Wedzicha at the University of Leeds, last year provided an important breakthrough into the understanding of the origin of acrylamide in cooked food (Nature 419, 448-449, 2002). Theyshowed how acrylamide could be formed from food components during heat treatment as a result of the Maillard reaction.
"We found that asparagine, a major free amino acid in potatoes and cereals, is a crucial participant in the production of acrylamide by this pathway," Mottram told a conference at the Fie in Germany last year.
"Asparagine is essential for the plant to grow. There are high asparagine levels in some plant foods, but low in animal foods. For potatoes levels reach 940mg per 100g - 40 per cent of the total. This could explain why higher levels are found in plants, as opposed to meat foods," he said, adding that asparagine will react with reducing sugars to give acrylamide.
High temperatures also seem to play a key role in acrylamide formation. According to Mottram, temperatures in excess of 125°C are required for the formation of acrylamide in the asparagine and glucose model system.
DSM will present the technology at the ICC Cereal and Bread Congress, in Harrogate, UK running from 23-26 May.
Research on acrylamide is still at a nascent stage, despite a global effort that sees the World Health Organisation (WHO) co-ordinating scientists on acrylamide research projects across the world.
The European Commission and the European Food Safety Authority (EFSA) have developed a database to summarise the research activities in the EU and the Commission's Joint Research Centre is co-ordinating work on analytical methods and is collecting data on the levels detected in different foods. For 'long-term research needs,' the Commission has included the topic in the 6th Framework Programme for research and technological development.