Formation of Strecker aldehydes between protein carbonyls – α-Aminoadipic and γ-glutamic semialdehydes – and leucine and isoleucine

The potential implication of protein carbonyls, α-aminoadipic (AAS) and γ-glutamic semialdehydes (GGS) on the formation of Strecker aldehydes from leucine (LEU) and isoleucine (ILE) was investigated in the present work. Solution mixtures containing the semialdehydes and each of the amino acids, were incubated at 80 °C and analysed for the volatiles in the headspace using SPME–GC–MS at sampling times (1, 12 and 24 h). The addition of the semialdehydes in solutions containing LEU and ILE led to a significant increase of the corresponding Strecker aldehydes, 3-methylbutanal and 2-methylbutanal. According to the present results, AAS is more reactive than GGS and the reaction of both semialdehydes with LEU is more effective than that with ILE. The ability of the semialdehydes to promote the formation of the Strecker aldehydes is inhibited by blocking their carbonyl moiety and significantly affected by the pH of the media. Beyond their role as protein oxidation markers, AAS and GGS may be active compounds in food systems and their interactions with other food components could lead to relevant consequences on food quality.