Cacao bitter taste

Caffeine, the active substance responsible for the stimulant effect of the coffee plant s berry, is a methyl-xanthine, one of the family of stimulants present in more than 60 species of plants. The pure chemical forms white, bitter-tasting crystals, which were first isolated from coffee in 1820. Other family members are theophylline, found in tea leaves, and theobromine, found in the cacao pods that are ground to make chocolate. The most potent component in the coffee family by unit weight is theophylline, while theobromine, the weakest component by unit weight, stays in the body longer than does caffeine. 

Theobromine was isolated from the seeds of the cacao tree and then shortly afterward was synthesized from xanthine by Fischer.132 Theobromine is the primary bitter-tasting alkaloid found in cocoa and chocolate chocolate contains 0.5—2.7% theobromine. Theobromine is water insoluble and is an isomer of theophylline as well as paraxanthine. Theobromine is categorized as 3,7-dimethylxanthine while theophylline is 1,3-dimethyl-7f/-purine-2,6-dione and paraxanthine is 1,7-dimethylxanthine. Theophylline is known to be a bitter-tasting principle of green tea. Theobromine is used as a vasodilator (a blood vessel widener), as an aid in urination, and... 

Theobromine (3,7-dimethylxanthine, 3,7-dihydro-3,7-dimethyl-lW-purine-2,6-dione). C7H,N402, Mr 180.17 formula, see under theophylline. Monoclinic, bitter tasting needles, mp. 357 °C, sublimes at 290-295 °C, soluble in hot water, alkali hydroxides, concentrated acids, moderately soluble in ammonia, poorly soluble in cold water and alcohol. With acids T. forms salts which decompose in water detection by the murexid reaction. T. is the main alkaloid of cocoa (Theobroma cacao, 1.5-3 wt.-%), from which it is obtained - especially from the husks in which it accumulates during fermentation. The typical bitter taste of cocoa is the result of interactions between T. and the pip-erazinediones formed in the roasting process. T. has diuretic, vasodilatory, and stimulating effects on cardiac muscle. The activities are weaker than those of the structurally related caffeine (a methylation product of T.) with which it co-occurs in cola nuts. For further pharmacological properties, see table under theophylline. 

Fresh cocoa beans, the seeds of cacao tree (Theobroma cacao, StercuUaceae), have a sour odour and a sour, bitter and astringent taste. The main contributors to the bitter taste are purine alkaloids. The astringent taste of cocoa products is mainly influenced by oligomeric procyanidins, flavan-3-ol-C-glycopyranosides (see Section 8.3.6.2.2) and N-phenylpropenoyl amino acids (see Section 2.2.1.2.1). 

Theobromin—C1H8M4O3—occurs in the seeds of theobroma cacao in the proportion of about two per cent. It is a colorless crystalline powder, bitter in taste difficultly soluble in water, alcohol, ether, and chloroform soluble in acids, with which it forms salts. When heated with chlorin water so that the fluid gradually evaporates it leaves a red-brown residue, which turns to a fine purple-violet with ammonium hydroxid. 

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