Roasting Methods for Coffee Beans
www.coffee-paradise.com

Defined Tag: Coffee Roaster.

Coffee, as air-dried green beans, smell of earth and has a different physical composition.  The heat during the roasting process sparks chemical reactions within the coffee beans that burn off waxes and release the oils to develop that characteristic coffee flavor and aroma we know.

For centuries, coffee was roasted at home using an ordinary flat pan over fire. Today, some coffee lovers successfully home roast their beans using popcorn makers. On the other hand, commercial coffee roasters use equipment powered by either gas or electricity.

The earlier gas-fuelled roasters ran at 1000° Fahrenheit, but the heat was uneven and occasionally charred the beans.  As a result the coffee had a burnt taste. Later models required much lower temperature, about 500° F, did not scorch the beans and retained the essential flavor components. Despite their efficiency, these large gas roasters fell out of favor because of the pollution caused by the smoke, chemicals and chaff given off.

The latest technological development in coffee bean roasting is the use of electric powered hot air. With the convection method, the beans move in a fluid bed of hot air which ensures uniform roasting without any charring.  These machines are also available in more compact models for small scale operations.

The beans lose about 10 to 20% of their weight during the roasting.  As the beans absorb heat, the sugars in them caramelize resulting into the dark colors of the beans. Also, the beans get brittle and the darker the roast, the more brittle the beans are. This aspect translates into the strength of the coffee.  You will be able to extract most of the flavors as more water is able to penetrate the coffee grounds made from darker and more brittle roasts.

With darker roasts, the chaff is released in the bean’s crevice making it more prominent.

The whole roasting process greatly influences the quality of your coffee. Roasting time varies in lengths to develop a particular flavor as acids and oils in the beans are burned off and released at different stages.  Longer roasting yields a stronger coffee flavor as there would be lesser acid but may be duller or flatter in taste.

Upon further heat treatment, the bean’s surface breaks down releasing more oils from the inside.  This is the reason why darker roasts appear oilier than the drier mild roasts.  Another effect of longer roasting is the loss of caffeine.  Darker roasts contain lesser caffeine although the difference is not that significant.

Roasted beans are cooled either by water-quenching or air-cooling.  Using water may add moisture back to the beans and washes away flavor. More roasters prefer the air-cooling method as the coffee beans are not compromised and the flavors are kept intact.

Roasted coffee beans emit carbon dioxide. This results in loss of flavor and a slight weight reduction of about one percent. This process continues until the beans become stale after two weeks.  For storage purposes, roasted beans should be properly packaged and frozen to avoid staling.

Copyright 2007 www.coffee-paradise.com