Mechanism of coloring reaction caused by heating Tutankhamun's peas

Abstract

Tutankhamun's pea has the unique characteristic of turning from green to reddish brown upon heating. However, the coloring mechanism underlying this process is unknown. The precursor and pigment were identified here and the coloring mechanism was investigated. The precursor was determined through cleavage reactions between flavans and liquid chromatography–mass spectrometry; the source was a dimer of epigallocatechin comprising (–)-epigallocatechin (mass: 610)—a type B prodelphinidin. The colored component produced by heating had a mass of 608, consistent with the mass of the oxidized dimer of (–)-epigallocatechin. The same phenomenon was confirmed for the colored component produced by heating a synthesized dimer of (–)-epigallocatechin, suggesting that the colored component was a dehydrogenated oxide of this dimer. To our knowledge, this is the first report on the coloring mechanism of Tutankhamun's pea; the dimer of (–)-epigallocatechin is responsible for the unique coloring characteristics of pea.

Keywords

• Tutankhamun's pea
• Heating
• Precursor
• (–)-Epigallocatechin
• Dimer
• Prodelphinidin