Effects of nitrogen nutrition, fungicide treatment and wheat genotype on free asparagine and reducing sugars content as precursors of acrylamide formation in bread

Acrylamide, a monomer with neurotoxic and potential carcinogenic effect, is formed via the Maillard reaction in heat-treated carbohydrate-rich foods. The major acrylamide precursors are reducing sugars and the amino acid asparagine. The aim of this study was to analyse effects of nitrogen nutrition, leaf disease control, wheat genotype and their interactions on acrylamide precursors content in wheat flour. Asparagine content was generally increasing at higher nitrogen doses, and nitrogen dose increase from 0 to 180 kg/ha increased the asparagine content to about 250%. The highest asparagine levels were determined at early spring nitrogen application. In the year 2006 with high leaf disease infestation, fungicide treatment decreased asparagine content particularly at higher nitrogen doses. In 2007, the effect of leaf disease control did not express in respect of very low infestation level. Close relationship between protein content and free asparagine in wheat flour was determined when leaf disease stress (fungicide treatment) and drought stress (year) were constant. Asparagine content was strongly influenced by wheat genotype and the differences between genotypes exceeded 200%. Effect of higher intensity was lower as compared to nitrogen nutrition, with regard to compensatory effect of fungicide treatments. Glucose content in wheat flour decreased both with fungicide treatment and total intensity level. Nitrogen dose increased glucose content up to 120 kg N/ha. Higher nitrogen doses decreased glucose content to initial level.