Czech J. Food Sci., 2009, 27(10):S207-S210 | DOI: 10.17221/1092-CJFS

Advances in Chemistry of Isothiocyanate-derived Colourants

K. Cejpek^*, J. Velíšek

Department of Food Chemistry and Analysis, Institute of Chemical Technology in Prague, 66 28 Prague, Czech Republic

This study is focused on the reactions of isothiocyanates (ITCs) in the presence of amino compounds leading to coloured structures via substituted 2-thiohydantoins. A series of complementary experiments has been done and appropriate reaction conditions and structural prerequisites have been defined. Low-molecular colourants isolated and characterised from the model systems can be sorted into three groups. Yellow to red diastereomeric dehydrodimers of 2-thiohydantoin derivatives that contain an acidic methylene group are formed in mixtures consisted of ITCs and amino acids with α-methylene group in mild acidic to mild alkaline systems. The condensation products of the 2-thiohydantoins with reactive aromatic or heterocyclic carbaldehydes from the Maillard reaction, essential oils etc. comprise a heterogeneous group of mostly yellow colourants. Blue compounds of two types are structurally more complicated structures that arise from N-substituted amino acids and ITCs in alkaline media.

Keywords: isothiocyanates; amino acids; 2-thiohydantoins; carbaldehydes; colour; pigments

Published: June 30, 2009  Show citation