Dry process coffee

The dry method produces green coffee beans much less expensively than the wet method. A high proportion of Brazilian Arabica coffee is processed in this way, and almost all Robusta coffees are treated in this way. The final beverage produced from dry-processed coffee has a full flavor that is often described as hard and sometimes is characteristic of a region, for example Rio coffees. 

Vilela, D. M., Pereira, G. V. M., Eerreira Silva, C., Batista, L. R., Schwan, R. R (2010). Molecular ecology and polyphasic characterization of the microbiota associated with semi-dry processed coffee Cojfea arabica L.). Food Microbiology, 27, 1128-1135. 

Freeze Drying. Commercial freeze drying of instant coffee has been a common practice in the United States since the mid-1960s. The freeze-drying process provides the opportunity to minimize flavor degradation due to heat (34). 

Includes soybean, rice bran, and dry-process com germ. Includes apples, carrots, coffee grounds, fish, grapes, pineapples, and tomatoes. Includes ABS, nitriles, styrene—butadiene mbber (SBR), natural mbber, and ethylene—propjdene- -diene mbber (EPDM). ... 

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. 

Roast style is a matter of personal taste, but for the most part the mildest Arabica coffees are the lightest roasted. Some Arabica coffees even become bitter if they are roasted to too high a temperature. Dry-processed Robustas and Brazilian Arabicas, on the other hand, benefit from deeper roasting. 

The coffees commanding the highest prices are also those with the most desirable taste quality. An order of decreasing value for some coffees follows wet-processed high-grown and then low-grown Arabicas, followed by dry-processed Arabicas and Robustas. Blends are made, in general, to reduce the cost. 

Belyaya, K. J., Clifford, M. N., Individual chlorogenic acids and caffeine contents in commercial grades of wet and dry processed Indian green robusta coffee, J. Food Sc 1. Technol, 32(2),104, 1995. (CA123 197159w)... 

Figure 2.3 illustrates a process in which the outer layer of a product is quickly frozen as a congealed crust. These CRUSToFREEZE plants have a capacity between 1500 and 5000 kg/h and require 0.5 to 0.8 kg LN2 pro kg of product, which has to be frozen totally on a conveyor belt. Figure 2.4 shows the product exit of the plant in Fig. 2.3. The freeze drying of coffee and tea extracts, fruit pulps or small pieces of meat require a multi- stage pretreatment. The granulated end product from coffee and tea extracts should have a defined grain size, a desired color, and a predetermined density. Fruit pulps should become granulated, with the appearance of fruit pieces, while meat pieces should not stick together like a small meat ball, but be recognized as single pieces when presented in a meal.

The freeze drying of coffee extracts has been, and still is, the most frequent application of this process in the food industry. For economic reasons it is best to start with 40 % solid content in the extract. The final product is judged by the following criteria ... 

The selected examples demonstrate that there is no ideal process for the freeze-drying of coffee extract. One must compromise in the various steps of the whole process, i.e. bean selection, roasting, extraction, freezing, freeze-drying and packing, to achieve the desired quality and cost of the freeze-dried coffee. 

Ancient peoples are known to have had dried fruits, vegetables, and meats. The pemmican of Native Americans and the jerky consumed by present-day campers and hikers are both prepared by drying. The drying process can include smoking, which may actually add antibacterial agents. The processes of dehydration and freeze-drying, used today to produce such foods as powdered coffee and soup, are variations of drying. 

Kerkhof, P. J. A. M. Preservation of aroma components during the drying process of extracts. (In 8th International Scientific Colloquium on Coffee ), 235-248 (1979)... 

Figure 21.2 Three different processing methods of coffee berries dry, wet and semi-dry processing.

For dry processing, the berries are often left on the coffee plants until overripe before harvesting. The berries are then dried in the sun to a moistme level of about 10-11%. Alternatively, the berries are dried directly after harvest by spreading in a... 

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