Caffeine water process

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,... 

In the common Swiss Water Process, coffee beans are soaked in hot water. This dissolves the caffeine and the flavouring compounds from the beans. The liquid is passed through activated carbon filters. The filters retain the caffeine, but let the flavouring compounds pass through. The filtered liquid, now caffeine-free, is sprayed back onto the beans. The beans reabsorb the flavouring compounds. Now they are ready for roasting. 

Note that decaffeinated coffee is not inert. In addition to small amounts of caffeine (enough to stimulate sensitive individuals), it contains other active substances from the coffee bean that can be irritating to the nervous, gastrointestinal, cardiovascular, and urinary systems. This is true of water-processed decaf, as well as die less safe solvent-extracted brands, which may contain residues of toxic chemicals. 

Today caffeine extraction using SCCO2 is the most commonly operated technology and, besides the more expensive Swiss Water process (using only water - saturated with the coffee s own sugars and pephdes - as an extracting agent [12]), it is the only one which is considered to be sustainable. 

Adsorption and Desorption Adsorbents may be used to recover solutes from supercritical fluid extracts for example, activated carbon and polymeric sorbents may be used to recover caffeine from CO9. This approach may be used to improve the selectivity of a supercritical fluid extraction process. SCF extraction may be used to regenerate adsorbents such as activated carbon and to remove contaminants from soil. In many cases the chemisorption is sufficiently strong that regeneration with CO9 is limited, even if the pure solute is quite soluble in CO9. In some cases a cosolvent can be added to the SCF to displace the sorbate from the sorbent. Another approach is to use water at elevated or even supercritical temperatures to facilitate desorption. Many of the principles for desorption are also relevant to extraction of substances from other substrates such as natural products and polymers. 

The basic process outline is depicted in Figure 5.2 moist un-roasted coffee beans and CO2 are fed counter-currently into the extractor under supercritical conditions. Caffeine is selectively extracted into the CO2 and this stream is led to a water-wash column to remove caffeine at a reduced pressure, the CO2 being recycled back to the extraction column. Extraction of the caffeine into water is necessary to avoid dropping the CO2 pressure too low, since compression is energy-intensive. There is now the problem of separating the caffeine (which is used in soft drinks and pharmaceu-... 

Tea is second only to water in worldwide consumption. Annual production of about 1.8 million T of dry leaf provides world per capita consumption of 40 L of beverage (Table l).1 The scientific interest in tea is due in part to the unusual chemical composition of its leaf and the complex series of reactions that occur when these components are converted to those found in commercial dry tea. Many of the reaction products interact with caffeine, modifying flavor and contributing to the technical problems of tea processing, as will be shown later. 

Instant tea produced as described above will dissolve completely in hot water but not in cold water, as the caffeine-polyphenol complexes are insoluble under those conditions. Since virtually all instant tea manufacture in the U.S. is for iced tea preparation, process modification is required. This initial extract may be cooled to 5 to 10°C and the cold water insoluble material or cream be allowed to precipitate. Under these conditions, 20 to 35% of the extract solids may be separated by centrifugation. The supernatant solids will reconstitute in cold water after concentration and drying.105 It is also possible to process the cream to make a portion of it compatible with the product and thereby retain the caffeine and some polyphenolic components that are present in this fraction.106 Commercial use of the enzyme Tannase, which removes gallic acid from gallated tea polyphenols107 and reduces cream formation108 can be used to reduce cream losses and manufacture instant teas retaining more of the natural polyphenol content. 

Decaffeination of green coffee beans is most usually carried out with a water/solvent partition system. The green coffee beans are first steamed until they are hot, wet, and swollen, to make the caffeine available. Solvent is then used to extract the caffeine out of the aqueous phase of the beans. Finally, the beans are steamed to drive off residual solvent. The coffee beans lose their wax surface covering in the process, as well as some flavor components. For this reason, the Robusta and Brazilian Arabica coffees that are dry-processed and have the most powerful flavors are usually the types that are decaffeinated. They become milder in the process. Mechanical polishing is used to improve the appearance of decaffeinated green coffee beans if they are not to be roasted immediately. Extra care is required, however, to store these decaffeinated beans since the loss of wax covering as well as caffeine renders them much more susceptible to fungal attack. 

The alternative approach draws form the experience of coffee decaffeination. The currently practiced process is carried out on a massive scale using scC02 to extract the caffeine from the coffee beans. The caffeine is not precipitated from the scC02 by decompression, but is extracted into water from which it can be separated. The great advantage of this process is that it can be operated at essentially constant pressure and... 

A further method separates the extracted substances by absorption. Basic for this method is that there should be a high solubility of extracted substances in the absorption material, and that the solubility of absorption substance in the circulation solvent should be as low as possible. Further, the absorption material must not influence the extract in a negative way and a simple separation of extract and absorption material has to be available. An ideal absorption material is therefore a substance which is present in the raw material. Most plant-materials contain water, which can act as a very successful absorption material. An ideal example is the separation of caffeine for the decaffeination of coffee and tea. On the one hand, water has a low solubility in CO2, and on the other, water-saturated CO2 is necessary for the process. The extracted caffeine is dissolved into water in the separator and caffeine can be produced from this water-caffeine mixture by crystallization. One advantage of this separation method is that the whole process runs under nearly isobaric conditions. 

The separation in the isobaric decaffeination processes is executed with absorption of caffeine, that means, the caffeine dissolved in CO2 is carried over into water by means of a packed washing column, or by adsorption with activated charcoal, but without recovery therefrom. Other separation methods under investigation are the use of membranes, since the difference in molecular weight between extract and solvent is high enough, or by the addition of substances of low solvent power. It is questionable whether the advantage of the possible isobaric process can compensate for the investment for the additional process steps required. 

Metabolic processes speed up appreciably under the influence of caffeine. Fatty acids are released into the blood, and a general increase in metabolism is evident as there is increased muscle activity, raised temperature, or both. More calcium is made available through caffeine s action in the muscles for contraction, but this effect is evident only at caffeine doses higher than people commonly use. Gut motility and secretion increase with a release of stomach acid and digestive enzymes. Urination is also stimulated caffeine directly affects the kidneys, cutting into their ability to reabsorb electrolytes and water. For every cup of coffee or two to three cans of caffeinated soft drink consumed, about 5 mg of calcium is lost in the urine. 

Sublimation is a process that involves the direct conversion of a solid to a gas without passing through the liquid state. Relatively few solids do this at atmospheric pressure. Some examples are the solid compounds naphthalene (mothballs), caffeine, iodine, and solid carbon dioxide (commercial Dry Ice). Water, on the other hand, sublimes at — 10°C and at 0.001 atm. Sublimation temperatures are not as easily obtained as melting points or boiling points. 

The story of coffee starts with the coffee berry. First the pulp of the berry is removed. This leaves two beans, each containing 1% to 2% caffeine. The beans are soaked in water and natural enzymes to remove the outer parchment husk and to start a slight fermentation process. Once the beans have been fermented, they are dried and roasted. Then the coffee is ready for grinding. Grinding increases the surface area of the coffee. Thus, finer grinds make it easier to dissolve the coffee in hot water. 

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