| The chemical constituents of the pungent principle of Capsicum fruits were investigated. This principle consists of several vanillylamides of fatty acids called capsaicinoids. High pressure liquid chromatography analysis showed the presence of nordihydrocapsaicin, capsaicin, dihydrocapsaicin, two isomers of homocapsaicin, two isomers of homodihydrocapsaicin, octanoic acid vanillylamide and decanoic acid vanillylamide. Four major capsaicinoids, namely nordihydrocapsaicin, capsaicin, dihydrocapsaicin and homodihydrocapsaicin were isolated and their chemical and sensory properties examined. The isolation was achieved by low pressure liquid chromatography (flash chromatography) using C18 reversed phase packing material combined with (1) bromination of the unseparated NDC + C mixture and separation on a low pressure column or (2) semi-preparative high performance liquid chromatography of the unseparated NDC + C mixture without bromination. The purity and the identity of the isolated compounds was determined by high pressure liquid chromatography, mass spectrometry, infra-red spectroscopy and ultra-violet spectroscopy. Sensory evaluation of isolated capsaicinoids showed significant differences between their pungencies. Linear relationship between pungency and concentration was found. Pungency threshold values of individual capsaicinoids were established. Total pungency of a mixture of capsaicinoids was found to be correlated with the sum of pungencies of individual compounds. The determination of the total pungency of Capsicum extracts can be accomplished by adding the pungencies of individual capsaicinoids obtained by multiplying their threshold pungency values by the respective concentrations. |
