Thermally Generated 3-Aminopropionamide as a Transient Intermediate in the Formation of Acrylamide

On the basis of the recent findings that "biogenic amines" can also be formed during thermal food processing from their parent amino acids in a Strecker-type reaction, the formation of 3-aminopropionamide, the biogenic amine of asparagine, was investigated in model systems as well as in thermally processed Gouda cheese. The results of model studies revealed that, besides acrylamide, 3-aminopropionamide was also formed in amounts of 0.1−0.4 mol % when asparagine was reacted in the presence of either glucose or 2-oxopropionic acid. Results of a second series of model experiments in which [13C415N2]-asparagine ([13C415N2]-Asn) and unlabeled 3-aminopropionamide were reacted together in the presence of glucose revealed a >12-fold higher efficacy of 3-aminopropionamide in acrylamide generation as compared to asparagine. Both [13C315N2]-3-aminopropionamide and [13C315N1]-acrylamide were formed during [13C415N2]-Asn degradation in a ratio of about 1:4, supporting the idea that 3-aminopropionamide is a transient intermediate in acrylamide formation. In this study, 3-aminopropionamide was identified and quantified for the first time in foods, namely, in Gouda cheese. Although the fresh cheese contained low amounts of 3-aminopropionamide, its concentrations were much increased to ≈1300 μg/kg after thermal processing. In isotope labeling studies, performed by administering to the cheese [13C415N2]-Asn in a ratio of 1:2 as compared to the "natural" concentrations of asparagine, similar ratios of unlabeled/labeled 3-aminopropionamide and unlabeled/labeled acrylamide were determined. Thus, 3-aminopropionamide could be verified as a transient intermediate of acrylamide formation during food processing. Keywords: Labeling experiments; 3-aminopropionamide; acrylamide; asparagine; Strecker reaction; Gouda cheese