Coffee Roasting

Coffee Roasting

Coffee Roasting and blending processes are essential for ensure best taste and quality and are typically done at the end after drying the coffee beans. Dried seeds “beans” are roasted, grounded and brewed to make one of the two most important beverages. Coffee drying can be done by either sun drying or mechanical hot air drying, and preferably on shade netting. By drying, 13% to 15% moisture content is reduced. Sun drying is cheap and makes a slightly higher-quality product but it requires much labour, space and time. The coffee must be laid 2,5cm thick and turned every hour.

The dry, green, hulled coffee beans are graded according to size and shape by means of a rotating sieve. In the first place, the beans are pushed along by a spiral plate, or moved along an inclined horizontal rotating sieve where holes or bars vary in size or width to allow the required sizes of beans to fall through into separate compartments as they pass from one end of a grader to the other.

The global trade in coffee is a two stage process. Although some producing countries have a
tradition of roasting coffee beans, approximately 90% of unroasted (green) beans are exported from tropical countries to Europe and the United States where they are blended, roasted and traded again as roasted beans or ground coffee. About 10% of this total is sold as soluble (instant)coffee.