S-Substituted cysteine derivatives in production of flavour and colour

A brief review of our continuous investigations on S-substituted cysteine derivatives is presented herein. It comprises a summary on nonenzymatic (thermal) decomposition of these amino acids as well as on their role in the formation of blue and pink pigments during processing of garlic and onion, respectively. The emphasis is put on four most common derivatives, namely S-methyl-, S-allyl-, S-1-propenyl- and S-propylcysteine sulfoxides (methiin, alliin, isoalliin and propiin, respectively). Our results demonstrate that these sulfur-containing amino acids are the key primary precursors in the formation of both flavour and colour of alliaceous plants.