Coffee caffeine isolation

Tea yields better-quality caffeine than that obtained from coffee. Caffeine from tea is relatively colorless, whereas the caffeine extracted from coffee is highly colored. About 25 mg of caffeine is isolated in either case. Sublimation removes much of the color from the tea and coffee samples. 

Caffeine was conceived for a wide range of readers interested in the effects on human health, nutrition, and physiological function of the methylxanthine beverages and foods—tea, coffee, mate, cola beverages, and cocoa and chocolate products. These products supply one or more of the dietary methylxanthines—caffeine, theobromine and theophylline— and are an integral part of the diet of many people in many countries. The interest in the health effects of both the methylxanthines in isolation and in the products containing them has grown rapidly in recent years. 

The methylxanthines of interest are caffeine (1,3,7-trimethylxanthine), theophylline (1,3-dimethylxanthine), and theobromine (3,7-dimethylxanthine) and they occur in coffee, tea, mate, cocoa products, and cola beverages. This chapter is an introduction to their chemistry, isolation, and biosynthesis. While the class of methylxanthines is large and comprised of more members than these three, this chapter will essentially be limited to caffeine, theobromine, and theophylline. 

The experimental studies cited below have isolated and tested the impact of caffeine, different methods of preparation, and different chemical fractions of coffee beans on serum cholesterol levels over a varied range of time periods. 

Stimulants. From coca leaves chewed by native laborers in South America to brewed teas and coffees used across the globe, stimulants have been used since antiquity. In these essentially naturally occurring forms, coca and caffeine were long known to provide a boost of energy, focus attention, and decrease appetite. However, compared to today s refined stimulants, the effects were relatively mild. There is no clear evidence that these substances were used to treat the ancient antecedents of psychiatric illness in past cultures. The isolation of cocaine in the mid-1700s and the synthesis of amphetamine in the late 1800s dramatically increased stimulant use (and abuse) in society. 

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. 

Caffeine has been isolated from waste tea and from the decaffeiniza-tion of coffee by extraction at 70°C, using rotating countercurrent drums and an organic solvent, frequently trichloroethylene. The solvent is drained off, and the beans steamed to remove residual solvent. The extraction solvent is evaporated, and the caffeine is hot-water-extracted from the wax, decolorized with carbon, and recrystallized. 

Caffeine, the most popular natural stimulant, is found in a number of plants throughout the world. The drug was first isolated from coffee in 1821 and was named for that plant, but the effects of coffee and caffeine differ. In many ways coffee seems to be more powerful than refined caffeine or other caffeine-containing plants. 

Coffee and tea plants seem to contain a variety of N-methyltransferase enzymes that have varying substrate specificity (168, 169). For example, a caffeine synthase enzyme isolated from tea leaves catalyzes both the N-methylation of N-methylxanthine and theobromine (176). The substrate specificity of the methyltransferases can be changed by site-directed mutagenesis (177), and the crystal structure of two of the N-methyltransferases has been reported recently (178). 

Supercritical fluid extraction processes are particularly appropriate for the separation and isolation of biochemicals where thermal decomposition, chemical modification, and physiologically-active solvents are undesirable. Examples of these bioseparations include the extraction of oils from seeds using carbon dioxide (1), of nicotine from tobacco using carbon dioxide-water mixtures (2), and of caffeine from coffee beans again using carbon dioxide-water mixtures (3). 

Caffeine (1,3,7-triniethylxanthine) is the well-known stimnlant present in tea and coffee. Uric acid, the end product of nucleic acid catabolism in humans, birds and reptiles (nric acid was one of the first heterocyclic compounds to be isolated as a pure substance, by the Swedish chemist Carl Scheele in 1776) is formed by the action of the enzyme xanthine oxidase. In cases of excess uric acid, deposition of crystals of uric acid can occur, leading to the joint pain known as gout, usually initially in the big toe and usually in males. 

The most common use of scC02 is in the extraction of caffeine from coffee or tea, nicotine from tobacco, and essential oils from plants. The isolation of products is simple, with the evaporation of the solvent with no residue. Another important application is in supercritical fluid chromatography (SFC). 

Quantification of aroma-impact components by isotope dilution assays (IDA) was introduced in food flavor research by Schieberle and Grosch (1987), when trying to take into account losses of analytes due to isolation procedures. The labeled compounds have to be synthesized, the suitable fragments have to be chosen, and calibration has to be effected. A quantitative determination of ppb levels of 3-damascenone (Section 5,D.38) in foods, particularly in roasted coffee (powder and brew), was developed by Sen et al. (1991a). Semmelroch et al. (1995) quantified the potent odorants in roasted coffee by IDA. Hawthorne et al. (1992) directly determined caffeine concentration in coffee beverages with reproducibility of about 5 % using solid-phase microextraction combined with IDA. Blank et al. (1999) applied this combined method to potent coffee odorants and found it to be a rapid and accurate quantification method. They also concluded that the efficiency of IDA could be improved by optimizing the MS conditions. 

In 1849, Payen again performed an isolation, a purification and an elementary analysis of caffeine, but the formula he proposed was wrong. He also attempted, unsuccessfully, to analyze chloroginic acid which he had isolated two years before. In addition, he resumed study of the aromatic essence of coffee . In the products of roasting he detected the presence of highly volatile hydrocarbons with an unpleasant empyreumatic odor. The aromatic essence isolated by Payen is also mentioned in the book of Pelouze and Fremy (1861) under the name of cafeone . 

Carboxylic acids with an amino group on the ct-carbon are commonly called amino acids. Amino acids are linked together by amide bonds to form peptides and proteins (Section 23.7). Caffeine, another naturally occurring amide, is found in cocoa and coffee beans. Penicillin G, a compound with two amide bonds (one of which is in a i8-lactam ring), was first isolated from a mold in 1928 by Sir Alexander Fleming. 

Caffeine is an alkaloid isolated from coffee, tea or the dried leaves of Camellia sinensis (Iheaceae), or prepared synthetically. 

In literature very little is published on the extraction of alkaloids on an industrial scale. The few papers available were published between 1950 and 1970 and concern the isolation of alkaloids from whole plants or plant parts 168,169). The extraction of catharanthine and vinblastine from C. roseus leaves on a pilot plant scale is described by Atta-ur-Rahman et al. (170). Svoboda developed a method for the extraction of ajmalicine, vinblastine, and vincristine which has been used by Eli Lilly Co. (169,171-173). Supercritical fluid extraction is a method which is used for the extraction of caffeine from coffee beans. This method also seems of interest for further studies of other alkaloids. 

In connection with plant breeding programs, cell and tissue cultures of Coffea species have been studied extensively. We do not deal with this work here, however, and the reader is referred to Baumann and Frisch-knecht for a review (740,741). Although caffeine (46) can be easily isolated from coffee beans at low cost, a number of studies have been made on the production of caffeine in cell cultures of Coffea. The biotechnological aspects of the caffeine production by means of cell cultures has been reviewed by Prenosil et al. (109). 

Purines also occur in common beverages. For example, it is customary to drink tea, coffee, cocoa, mate, guarana, and other related stimulating drinks in many places in the world. Coffee, red tea, green tea, and cocoa are representative drinks that are widely appreciated all over the world. Among these, coffee is prepared from the seeds of Cqffea arabica or Coffea robusta (Rubiaceae), and red tea and green tea are prepared from the leaves of Camellia sinensis (Theaceae). Cocoa is prepared from the seeds of Theobroma cacao (Sterculiaceae). These drinks all contain purine derivatives, i.e., caffeine, theobromine, and theophylline. The history of the research on caffeine and theophylline is old, and these alkaloids were isolated as long ago as 1820 by Pelletier and Caventou. Total syntheses of these alkaloids were attempted at the end of the nineteenth century [3,4]. 

Hermann found in coffee a resin (Harzstoff) and a soapy principle (Seifen-stoff). Chenevix found a bitter principle in coffee but did not isolate it. Cadet, who mentions Chenevix and Paysse, found what he thought was gallic acid and a peculiar acid, which Paysse had called acide cafeique. Thomson, who mentions Hermann and Cadet, says Paysse tried to show that Chenevix s bitter principle is a peculiar acid, cofEc acid which, says Thomson, reddens vegetable blues, but in other respects does not seem better entitled to the name of acid than tannin. Caffeine was perhaps first satisfactorily established and named by F. F. Runge in 1821, and independently by Pelletier and Caventou and Robiquet. The bitter principle (thein) of tea was isolated by Oudry (no initials are given). Berzelius s suggestion that theine and caffeine are identical was confirmed by Mulder and by Jobst. Theobromine was discovered in cocoa by Woskressensky. ... 

Some examples of successful commercial selective extractions are the removal of caffeine from coffee or the solubilization of nicotine from tobacco both accomplished on moist matrices to aid in selectively solubilizing the alkaloid component. Selective extraction has been demonstrated for the segregation of essential oil from other lipid components in natural extracts derived from fruits and for the separation of aroma components in cocoa butter from the base oil. Other enrichment SEE schemes that have been reported include the fractionation of carotenoid from leaf protein concentrate [25], the fortification of sterols in seed oils [26], and the isolation of lecithin (phospholipid-containing fraction) from triglycerides [27]. 

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