Soil condition crucial in acrylamide production, study

The study, conducted by a team from Reading University and Rothamsted Research, tested three varieties of wheat and found low sulphur content was directly linked to high acrylamide production levels.

The research is part of a bid by the food industry to reduce the potential for acrylamide formation by examining source ingredients.

As the use of sulphate enriched fertilizers has declined and crop yields increased, the mineral content of soil has gradually been depleted. The UK's Home Grown Cereals Authority estimates that 23 per cent of land devoted to cereal crops is now at risk of sulphur deficiency.

Acrylamide first hit the headlines in 2002 when scientists at the Swedish Food Administration reported unexpectedly high levels of the potential carcinogen in carbohydrate-rich foods.

The chemical can be found in a wide range of heat processed foods including crisps, biscuits and crisp bread at levels between a few parts per billion (ppb) to over 1000 ppb.

Acrylamide appears to form as a result of a reaction between specific amino acids, including asparagine, and sugars found in foods reaching high temperatures during cooking processes. The process is known as the Maillard reaction. This occurs at temperatures above 100C (212F).

According to the research, published in the Journal of Agricultural and Food Chemistry, soil nutrition is a crucial factor in the formation of acrylamide as wheat low in sulphur contains higher levels of asparagines.

The scientists grew three varieties of winter wheat and found the amino acid content of flour made from sulphur-deprived grain was up to 30 times higher in some cases.

When the amino acid rich flour was heated to 160 degrees for 20 minutes the acrylamide content was between 2,600g to 5,200g per kg compared to normal levels of 600g to 900g.

Since acrylamide was uncovered as a food contaminant a global effort has been underway to amass data about this chemical. More than 200 research projects have been initiated around the world, and their findings co-ordinated by national governments, the EU and the United Nations.

Last month, the EU Confederation of Food and Drinks Industry (CIAA) released new guidance on how manufacturers can limit their risk of acrylamide formation during processing.

The CIAA will update the guidance as new processes are discovered or achieve trial stages. The final goal is to find appropriate and practical solutions to reduce the overall dietary exposure to acrylamide.