The reaction kinetics for the formation of Strecker aldehydes in low moisture model systems and in plant powders

The Strecker aldehydes, acetaldehyde (AA), 2-methylpropanal (2-MP), 2-methylbutanal (2-MB) and 3-methylbutanal (3-MB), are regularly found in processed foods of plant origin. They are produced by Strecker degradation of the amino acids, alanine, valine, isoleucine and leucine. The observed reaction of their formation in a low moisture model system and in commercially available plant powders turned out to be pseudo zero order. The activation energies for their formation, in a low moisture model system containing glucose and alanine, valine, isoleucine and leucine, ranged from 115 to 124 kJ/mol. Using a model system containing glucose and leucine it became possible to interpret the kinetics of the formation of Strecker aldehydes in relation to the formation of Amadori rearrangement products (ARP), the decrease of leucine and the formation of brown pigments as a function of heating time.