Caffeine removing from coffee

Decaffeinated coffee satisfies people who like the smell and taste of coffee but cannot tolerate the caffeine. How is caffeine removed from coffee ... 

Table 11.5 Caffeine and chlorogenic acid removal from coffee beans extract...

Because of the central nervous system effects from caffeine, many people prefer decaffeinated coffee. The caffeine is removed from coffee by extrachng the whole beans with an organic solvent. Then the solvent is drained off, and the beans are steamed to remove any residual solvent. The beans are dried and roasted to bring out the flavor. Decaffeination reduces the caffeine content of coffee to the range of 0.03% to 1.2%. The extracted caffeine is used in various pharmaceutical products, such as APC tablets. 

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. 

Figure 25.16 shows how caffeine is removed from coffee. Coffee is mixed with CO2 at a temperature and pressure above the critical point of the CO2. The supercritical CO2 dissolves the caffeine (small black dots), decaffeinating the coffee beans. The fluid mixture of CO2 with caffeine then flows into a chamber where the pressure is lowered below the critical point so caffeine partitions into water. The carrier CO2 is recaptured and the caffeine is dumped in the aqueous phase. 

The dense fluid that exists above the critical temperature and pressure of a substance is called a supercritical fluid. It may be so dense that, although it is formally a gas, it is as dense as a liquid phase and can act as a solvent for liquids and solids. Supercritical carbon dioxide, for instance, can dissolve organic compounds. It is used to remove caffeine from coffee beans, to separate drugs from biological fluids for later analysis, and to extract perfumes from flowers and phytochemicals from herbs. The use of supercritical carbon dioxide avoids contamination with potentially harmful solvents and allows rapid extraction on account of the high mobility of the molecules through the fluid. Supercritical hydrocarbons are used to dissolve coal and separate it from ash, and they have been proposed for extracting oil from oil-rich tar sands. 

Another challenge is to develop methods to replace the volatile organic solvents that are used in many industrial procedures. One choice is water as a solvent it is easily repurified, and has a harmless vapor. Another choice is supercritical carbon dioxide, a good solvent for many organic substances. It is not as innocuous as is water, but carbon dioxide can be easily recovered and reused. It is currently used to remove caffeine from coffee, and is being developed as a dry-cleaning solvent to replace organic solvents (Chapter 9). 

Figure 5.8 Coffee is decaffeinated by constantly irrigating the ground beans with supercritical carbon dioxide schematic representation of a Soxhlet apparatus for removing caffeine from coffee...

Secondly, solid CO2 is relatively cheap. Finally, after caffeine removal, any occluded CO2 will vaporize from the coffee without the need to heat it or employ expensive vacuum technology. Again, we retain the volatile essential oils of the coffee. Even if some CO2 were to persist within the coffee granules, it is chemically inert, has no taste and would be released rapidly as soon as boiling water was added to the solid, decaffeinated coffee. 

Furthermore, supercritical CO2 does not behave as merely a mixture of liquid and gaseous CO2, but often exhibits an exceptional ability to solvate molecules in a specific way. The removal of caffeine from coffee relies on the chromatographic separation of caffeine and the other organic substances in a coffee bean supercritical fluid chromatography is a growing and exciting branch of chemistry. 

D. J. Adam, J. Mainwaring and Michael N. Quigley have described a simple experiment to remove caffeine from coffee with a Soxhlet apparatus see Journal of Chemical Education, 1996, 73, 1171. Their solvent was a chlorinated organic liquid rather than supercritical CO2. The abstract is available at http //jchemed.chem.wisc.edu/ journal/issues/1996/Dec/absll71.html. 

Caffeine can be extracted from coffee and tea using solvent extraction. A tea solution was mixed with the solvent ethyl ethanoate in a separating funnel and the funnel was shaken. The layers were left to settle and the lower aqueous layer was then removed and the ethyl ethanoate layer was drained and stored. 

Dichloromethane is used as a solvent to remove caffeine from coffee beans. 

Dichloromethane, CH2C12, is an organic solvent used for removing caffeine from coffee beans. The following table gives the vapor pressure of dichloromethane at various temperatures. Fill in the rest of the table, and use the data to plot curves of Pv ... 

The INET contactors have also been applied to non-nuclear processes, such as the removal of a specific rare metal (yttrium) from other rare metals (Zhou et al., 2007), hydrocortisone from fermentation liquor (Zhou et al., 2006b), phenol from wastewater (Xu et al., 2006), and caffeine from coffee beans (Duan et al., 2006). As described by Zhou et al. (2007), the contactor rotor is driven by a motor that is not above the contactor. Instead, a belt connects the motor to the top of the rotor shaft. This design is possible because these materials are not radioactive, and hands-on maintenance is thus possible. 

Swiss company developed a distillation method to remove the caffeine from coffee, creating decaffeinated coffee without use of methylene chloride. 

In 1979, a Swiss company developed a distillation method to remove the caffeine from coffee, creating decaffeinated coffee. The Swiss water process proved popular among young urban professionals as it was considered to make a more natural product in comparison to the earlier method of making decaffeinated coffee,... 

Because of its low cost, nonhazardous chemical nature, and low critical temperature, carbon dioxide has been used in many applications. A commercial process to remove caffeine from coffee, using supercritical C02 as the solvent, is shown in Fig. 17. While actually a liquid-solid extraction process, it demonstrates principles involved in SCFE. A commercial SCFE process has been reported for recovery of hydrocarbon liquid from heavy oil. As compared with conventional propane deasphalting, this SCFE process can reduce capital and energy costs. 

Methylene chloride (CH2C12) and chloroform (CHC13) are also good solvents for cleaning and degreasing work. Methylene chloride was once used to dissolve the caffeine from coffee beans to produce decaffeinated coffee. Concerns about the safety of coffee with residual traces of methylene chloride prompted coffee producers to use liquid carbon dioxide instead. Chloroform is more toxic and carcinogenic than methylene chloride it has been replaced by methylene chloride and other solvents in most industrial degreasers and paint removers. 

By the late 1980s, technologies for the removal of cholesterol with supercritical carbon dioxide were offered by a number of companies (38). Commercialization was never attempted by any major food company for removal of cholesterol. Successful scale-up and commercialization was achieved by the General Foods Corporation for removal of caffeine from coffee (45). The primary disadvantages for the dairy industry were the low yields, low cholesterol removal, and the very high capital and operating costs of the equipment. 

Supercritical CO2 is used to remove caffeine from coffee beans. First, the green coffee beans are soaked in water. The beans are then placed in the top of a column that is 70 ft high. Supercritical CO2 fluid at about 93 °C and 250 atm enters at the bottom of the column. 

It can be argued that the first supercritical fluid extractions (SFE) were performed in 1879 when Flannay and Hogarth investigated the solvating capabilities of ethanol.28 However, it took roughly 100 years before supercritical fluids made any significant impact on industrial processes. The removal of caffeine from coffee beans was reported in the 1970s29 and led to... 

Among the practical applications of supercritical extraction is the use of supercritical carbon dioxide as the solvent in a number of processes. Carbon dioxide has several favorable properties as a supercritical solvent. It is nontoxic, low-cost, and noncorrosive. Its critical temperature is 304.2 K, which is near ambient. These properties are especially desirable in food processing, for the extraction of food components that must not be exposed to high temperatures. Examples are the removal of caffeine from coffee and the extraction of oil from beans and corn. 

One of the commercial methods for decaffeinating coffee is the direct-contact method. The unroasted coffee beans are first softened with steam and then brought in direct contact with a decaffeinating agent, such as dichloromethane (most often called methylene chloride in this context), CH2CI2. The caffeine dissolves in the dichloromethane, after which the dichloromethane/caffeine solution is removed from the beans. 

In the process depicted in figure 1.2, coffee beans charged to the extractor, 10, via line (18) are decaffeinated with supercritical carbon dioxide. The caffeine-laden CO2 stream leaving the extractor is passed into the bottom of a water-wash column where the caffeine is removed from the CO2. (Chapter 8 describes the thermodynamic equilibrium situation for the water-wash column.) The caffeine-free CO2 is recycled to the coffee bean column, and decaffeinated coffee beans leave the extractor via line 20. Let s now follow the water stream leaving the bottom of the CO2 scrubbing tower. The caffeine-... 

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