Epsilon Open Archive

Abstract

Acrylamide is found at concentrations up to a few mg/kg in a wide range of foods, mainly carbohydrate-rich foods subjected to high thermal processing. Acrylamide is formed in foods via the Maillard reaction with free asparagine and reducing sugars as the precursors, with the former generally being limiting in cereal-based products. Bread is among the products that can contain high levels of acrylamide, so this thesis investigated factors affecting acrylamide formation in bread. A robust extraction procedure coupled with the chromatographic method from Ez-Faast® technology was set up and validated to analyse free amino acids in cereals, cereal fractions and products. Free amino acids were found to be mostly concentrated in the bran fraction. Asparagine was a major free amino acids in the cereals analysed. A major decrease in asparagine was found to occur during yeast fermentation. The content of acrylamide in rye crispbread was found to be mainly controlled by the time and temperature of baking and the level of asparagine present, but not by the fructose level. Studies on interactions between added asparagine, glycine and fermentation time on the formation of acrylamide in soft wheat bread showed that fermentation time has a reducing effect on acrylamide formation, which was governed by the level of asparagine present in the system. Glycine addition significantly decreased acrylamide depending on the initial levels of asparagine in the dough, and increased the colour intensity of the bread. Tests on the effect of storage conditions on acrylamide content showed that storage temperature affects its disappearance from the bread. Acrylamide levels were more stable at cold temperatures up +6 °C. A significant decrease in acrylamide was found at warmer temperatures (+20 and +40 °C). Reduction of acrylamide was greater in closed containers, with most reduction taking place in the early stages of warm storage. Increased moisture content resulted in a major decrease in the acrylamide content during storage.