For instance, the heat-initiated Maillard reaction of reducing sugars and amino acids forms the initial basis of methional's composition.

The formation of methional stems from the interaction of α-dicarbonyl compounds (intermediate products in the Maillard reaction) with methionine (Met) by the Strecker degradation reaction:[1] Methional easily degrades into methanethiol, which then oxidizes into dimethyl disulfide.

Furthermore, the methionine resulting from the Strecker degradation reaction produces alkyl pyrazines, which contribute to the flavors in roasted, toasted, or thermally processed foods.

Due to the ease of its decomposition, a large portion of methional is lost during potato processing.

Similarly, in the presence of flavin mononucleotide (FMN) and light, methionine is nonenzymatically oxidized into methional, ammonia, and carbon dioxide.