Nonenzymatic browning reactions are produced during food processing and have important consequences on nutritional and sensory properties of foods. Many of these consequences are related to amino acid degradations. Thus, amino acids can suffer a Strecker degradation to produce many flavors, including Strecker aldehydes, pyrazines, pyridines, pyrroles, and oxazoles, among other compounds. On the other hand, amino acids can also suffer a decarboxylation to produce biogenic amines in a first step, which can be then converted into vinylogous derivatives such as styrene or acrylamide. The objective of this study was to determine the reaction conditions favoring the formation of either Strecker aldehydes or biogenic amines. Studies were carried out with phenylalanine, as a model amino acid, which was heated in the presence of different primary, secondary, and tertiary lipid oxidation products. The formation of phenylacetaldehyde and phenylethylamine was studied as a function of pH, concentration of reactants, water activity, atmosphere composition, time, temperature, and the presence of other amino acids as potential competitors. The obtained results showed that it is possible to promote either the oxidative decarboxylation of the amino acid, to produce flavors, or its simple decarboxylation, to produce biogenic amines, as a function of reaction conditions. The reaction conditions that favor the different alternative pathways were identified.

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