WASHINGTON — Proline, an amino acid found in both wheat and rye flour, was the most potent of 10 amino acids tested in reducing the acrylamide levels during a study in the United Kingdom and appearing on-line in the Journal of Agricultural and Food Chemistry. Acrylamide, a probable carcinogen, has been shown to originate in high-temperature food production, such as in the Malliard reaction of the amino acid asparagine with reducing sugars.

Adding amino acids has been proposed as a way to reduce the levels of acrylamide in crisps, flat breads and bread crusts. United Kingdom researchers from the University of Leeds, the University of Northumbria at Newcastle and the University of Reading worked with sealed low-moisture asparagine-glucose model systems. They monitored acrylamide formation in sealed, low-moisture waxy maize starch heated at 160 degrees Celsius (320 degrees Fahrenheit) over 60 minutes. They added the amino acids aspartic acid, cysteine, alanine, glutamine, valine, leucine, tryptophan, proline, glycine and phenylalanine.

"We also report the significant mitigating effect of proline, which was the most potent amino acid in reducing the acrylamide levels in sealed low-moisture model systems," the researchers said, and added proline is present at significant levels in both wheat and rye flour.

At increased concentrations, proline and tryptophan reduced acrylamide levels by about 80% after 60 minutes of heating. Cysteine reduced levels by 55%, and glycine reduced levels by 45%.

The researchers said further studies would help to identify whether modulation of the amino acid content of bakery products to mitigate acrylamide formulation presents a realistic opportunity for the food industry. The studies could address proline’s effect on the acrylamide content and flavor profile of baked foods.