Strecker degradation
Japanese: ストレッカー分解
A stage of the Maillard reaction where amino acids are converted to aldehydes. An important source of aroma compounds in fermented foods.
Strecker degradation is a reaction occurring in the intermediate stage of the Maillard reaction. α-Dicarbonyl compounds react with amino acids, which lose CO₂ and are converted to aldehydes. Discovered by Adolph Strecker in 1862.
The resulting aldehydes often have strong aromas, significantly contributing to fermented food fragrance. For example, leucine yields cheese-like 3-methylbutanal; phenylalanine yields rose-like phenylacetaldehyde.
Strecker degradation is triggered by α-dicarbonyl compounds—Maillard reaction intermediates—and is therefore promoted under conditions where the Maillard reaction advances: high temperatures and long aging. Behind miso's complex aroma lies this chain of stepwise chemical reactions.