Decaffeination. coffee

Fig. 10. Semicontinuous coffee decaffeination process using supercritical CO2 (1).

In all the above mentioned processes of coffee decaffeination, changes occur that affect the roast flavor development. These changes are caused by the prewetting step, the effects of extended (four hours plus) exposure at elevated temperature as required to economically extract the caffeine from whole green beans, and the post-decaffeination drying step. 

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... 

Coffee decaffeination (one plant, 1978) Processing/extracting/evaporating 1.4-115 Cohen etal. (1980)... 

Brewed coffee Instant coffee Decaffeinated coffee Black tea Cola drink Chocolate bar Over-the-counter stimulant Over-the-counter analgesic... 

Food and Pharmaceutical Applications These applications are driven by the environmental acceptability of CO2, as well as by the ability to tailor the extraction with the adjustable solvent strength. The General Foods coffee decaffeination plant in Houston, Texas is designed to process between 15,000 and 30,000 pounds of coffee beans per hour (McHugh and Kmkonis, op. cit.). See Fig. 22-22. The moist, green coffee beans are charged to an extraction vessel approximately 7 ft diameter by 70 ft high, and carbon dioxide is used to... 

Figure 10.5 Schematic representation of the coffee decaffeination process.

Beverages Brewed coffee Instant coffee Decaffeinated coffee Brewed tea Pepsi-Cola Coca-Cola Mountain Dew Dr Pepper... 

Supercritical fluid (SCF) food processing plants have become one of the more robust technologies for new applications within the food industry in recent years. The announcement of the construction and start up of a coffee decaffeination plant in Houston, Texas (X) has markedly heightened interest, resulting in increased awareness of the unique factors that apply to the design of the SCF processing plant and, more importantly, the considerations necessary to select equipment and components for installation in a SCF processing plant. 

Water has been shown to be an effective solvent in some chemical reactions such as free radical bromination. Supercritical fluids such as liquified carbon dioxide are already commonly used in coffee decaffeination and hops extraction. However, supercritical carbon dioxide can also be used as a replacement for organic solvents in polymerization reactions and surfactant production. Future work may involve solventless or neat reactions such as molten-state reactions, dry grind reactions, plasma-supported reactions, or solid materials-based reactions that use clay or zeolites as carriers. 

Supercritical fluid extraction offers several advantages over conventional extraction processes. The extraction is carried out at high pressures and then the extract is usually recovered by lowering the pressure, as the solubility is a strong function of fluid pressure. The compositions of the extracts are different from those from the liquid extraction. Supercritical fluid extraction has been well accepted for coffee decaffeination and is being applied in other food, cosmetics, and pharmaceutical applications. Supercritical carbon dioxide is an environmentally benign nonflammable fluid. 

Supercritical carbon dioxide has been industrially used in a variety of processes, including coffee decaffeination, tea decaffeination, and extraction of fatty acids from spent barley, pyrethrum, hops, spices, flavors, fragrances, com oil, and color from red peppers. Other applications include polymerization, polymer fractionation, particle formation for pharmaceutical and military use, textile dyeing, and cleaning of machine and electronic parts. 

The Katz patent states that about 15% of the coffee beans in the extractor are discharged and admitted during a semicontinuous pulse. To provide an estimate of the scale of the process we here calculate the amount of coffee beans moved during a pulse. The vessel is 70 ft tall X 7 ft diameter this equates to an internal volume of about 2500 ft. Coffee beans have a density of about 40 Ib/ft, so the extraction vessel holds about 100,000 lb of coffee beans. A 15% replenishment is a rate of 15,0001b per pulse, and the pulse happens about every 30 to 60 min—this is not laboratory scale operation. There are still many other hops extraction, coffee decaffeination, and spice extraction plants throughout the United States and Europe several of them operate at 30 to 60 million Ib/yr throughput, further exemplifying that SCF extraction is not just a laboratory curiosity. 

In this chapter the SCF processing of two natural products, coffee and edible oils, is described in some detail. The principles involved in the coffee decaffeination process are similar to those described for the regeneration of activated carbon and the extraction of ethanol from water. In the remainder of the chapter a variety of other SCF applications are presented. 

Coffee decaffeination with carbon dioxide has been the object of a large amount of effort in research and development at the Max Planck Institute for Coal Research in Germany and at other academic and industrial laboratories in Europe and the United States. An indication of the intensity of effort applied to this process comes from a review article that lists the United States patents on decaffeination granted up to the end of 1981 (Paulaitis et al., 1983a). Several earlier patents were inadvertently omitted from that list a corrected version is given in table 10.1. Research activity on supercritical fluid extraction of stimulants from coffee, tea, and cocoa has continued, indicated by the number of United States patents granted since that review article was published some of them are listed in table 10.2. 

Table 10.1 United States Patents on Coffee Decaffeination (1981 and Earlier)...

We summarize the data from one example of an early coffee decaffeination patent to highlight the specifics of the process (Roselius, Vitzthum and Hubert, 1974). Four hundred grams of rough-ground deoiled roast coffee is wetted with 200 ml of water and is treated with supercritical CO2 with an... 

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