Amino acid decarboxylations produced by lipid-derived reactive carbonyls in amino acid mixtures

• Amino acids degradations by reactive carbonyls depend on the amino acids present.
• Arginine, lysine and cysteine promoted the formation of amino acid-derived amines.
• Cysteine was the amino acid that most increased the amine/Strecker aldehyde ratio.
• Their contribution seems to be related to a modification of the reactive carbonyl.
• This modification changes the ratio among products but not the reaction mechanism.

The formation of 2-phenylethylamine and phenylacetaldehyde in mixtures of phenylalanine, a lipid oxidation product, and a second amino acid was studied to determine the role of the second amino acid in the degradation of phenylalanine produced by lipid-derived reactive carbonyls. The presence of the second amino acid usually increased the formation of the amine and reduced the formation of the Strecker aldehyde. The reasons for this behaviour seem to be related to the α-amino group and the other functional groups (mainly amino or similar groups) present in the side-chain of the amino acid. These groups are suggested to modify the lipid-derived reactive carbonyl but not the reaction mechanism because the Ea of formation of both 2-phenylethylamine and phenylacetaldehyde remained unchanged in all studied systems. All these results suggest that the amine/aldehyde ratio obtained by amino acid degradation can be modified by adding free amino acids during food formulation.