Quinine taste properties

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. 

A first requirement for a substance to produce a taste is that it be water soluble. The relationship between the chemical structure of a compound and its taste is more easily established than that between structure and smell. In general, all acid substances are sour. Sodium chloride and other salts are salty, but as constituent atoms get bigger, a bitter taste develops. Potassium bromide is both salty and bitter, and potassium iodide is predominantly bitter. Sweetness is a property of sugars and related compounds but also of lead acetate, beryllium salts, and many other substances such as the artificial sweeteners saccharin and cyclamate. Bitterness is exhibited by alkaloids such as quinine, picric acid, and heavy metal salts. 

The physiological action of the cinchona alkaloids is that of an antipyretic or febrifugCj lowering the body temperature in case of fevers. Quinine retards the action of oxidase enzymes and acts as a poison to certain organisms, especially that of malaria. Its first use was as a specific for this form of fever. It has a very bitter taste and in common with other substances of like properties it acts on the alimentary canal causing increased secretion of digestive juices. 

Properties Yellow crystalline powder, contains 42% quinine bitter taste. Mp 185-186C. Moderately soluble in hot water or alcohol insoluble in cold water. 

Last but not least, quinine has also two unique properties a bitter taste and a strong fluorescence. The first is widely used in beverage and confectionary industry, which consumes ca. 25% of the world production of quinine [20], whereas fluorescence of quinine sulfate is routinely used in fluorescence spectroscopy as quantum yield standard [21, 22]. 

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