Caffeine, taste properties

How would you describe the differences between a cup of coffee and a cup of hot water What probably come to mind are the aroma, the dark color, and the taste of a good cup of coffee. Coffee s action as a stimulant is another obvious difference. These properties come from the chemical compounds that hot water dissolves from ground coffee beans. These compounds are molecules constructed from different atoms bound together in veiy specific arrangements. The molecule that makes coffee a stimulant is caffeine. Our background photo is a magnification of crystals of pure caffeine, and the inset is a ball-and-stick model of this molecule. 

The organoleptic properties of black tea depend to a considerable extent on the astringency resulting from the interaction of caffeine with the oxidized galloyl ester of the flavanols. The aroma components of black tea also constitute a unique flavor profile that blends well with the taste of the nonvolatile materials. The caffeine provides a moderate level of stimulation, which adds further to the appeal of the beverage, although tea has been shown to provide relaxation as well as revival of character.119... 

Two compounds that are used in some soft drinks formulations for specific purposes are caffeine, used in a range of beverages including colas for its stimulant properties, and quinine, used for its bitter taste. Traditional techniques for the analysis of these two compounds have often involved their extraction from aqueous solution into an organic solvent and then quantification by one of a range of methods. 

Benefits Japanese studies in the 1980s showed that the polyphenol components had antioxidant properties similar to superoxide dismutase (SOD), an enzyme that is a free radical scavenger and is thought to slow down the ageing process. The herb has less tannin than oriental tea, so tastes less bitter, and it is caffeine free. 

Caffeine is a bitter-tasting compound found in coffee, tea, cola beverages, and chocolate. Caffeine is a mild stimulant, usually imparting a feeling of alertness after consumption. It also increases heart rate, dilates airways, and stimulates the secretion of stomach acid. Caffeine is an alkaloid, a naturally occurring amine derived from a plant source. In Chapter 25 we learn about the properties and reactions of amines. 

One of the approaches found most suitable to explain the sensorial properties of sweet, bitter, and sweet-bitter substances proves to be the physico-chemical approach especially as concerns hydration and surface properties (DeSimone and Fleck, 1980 Funasaki et al., 1996 Fimasaki et al., 1999 Mathlouthi and Hutteau, 1999). Thus, solution properties of sweet and bitter molecules were found informative on their type of hydration (hydrophobic or hydrophilic) and on the extent of the hydration layer (Fiutteau et al., 2003). Physico-chemical properties (intrinsic viscosity, apparent specific volume, and surface tension) and NMR relaxation rates of the aqueous solutions of sucrose, caffeine, and sucrose-caffeine mixtures were used in the interpretation of the taste modalities of these molecules and to explain the inhibition of caffeine bitterness by sucrose (Aroulmoji et al., 2001). Caffeine molecules were found to form an adsorption layer whereas sucrose induces a desorption layer at the air/water interface. The adsorption of caffeine gradually increases with concentration and is delayed when sucrose is added in the caffeine solution (Aroulmoji et al., 2004). 

Aroulmoji, V., Hutteau, E, Mathlouthi, M., and Rutledge, D.N. Hydration properties and the role of water in taste modalities of sucrose, caffeine, and sucrose-caffeine mixtures, /. Agric. Food Chem., 49, 4039, 2001. 

Polycationic hydrogels swell less at neutral pH than at acidic pH thus they minimize drug release at higher pH. This property was applied to mask poor tastes of some drugs in the neutral pH environment of the mouth. When caffeine was loaded into hydrogels made of copol3miers of methyl methacrylate and AT -dimethylaminoethyl methacrylate (DMAEM), it was not released at neutral pH, but released with zero-order at pH 3-5 where DMAEM became ionized (18). 

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. 

C7H8N4O2, Mr 180.17, thin, bitter-tasting platelets, mp. 270-274 °C (monohydrate), moderately soluble in water, very soluble in hot water, alkali hydroxides, ammonia, dilute acids. A purine alkaloid from the leaves of the tea plant, also contained in matd (Ilex paragua-riensis and Paullinia cupana). The methylxanthines T., caffein(e), and theobromine are among the oldest known stimulants and drugs. Their pharmacological properties are compared in the table. In high doses T. can cause epilepsy-like convulsions. T. also exhibits antiasthmatic activity. ... 

Have you ever wondered about the origin of the saying, it s a bitter piii to swaiiow This saying is used to describe a situation that is difficuit to accept. Many medications contain bases, and a bitter taste is a property of bases. So, many medications actually have a bitter taste. If you look at the chemical formulas of the components of medications, you will see that they often contain nitrogen. One such component is caffeine, which acts as a stimulant on the central nervous and respiratory systems. Its molecular formula is C8Hio02N4- ammonia, caffeine has basic properties because it has a nitrogen that can accept a proton. 

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