Coffee bean roasting: Dark secrets revealed

Whatever method you use to brew your coffee, it's the roasting that counts.

By Andréanne Hame

Coffee beans

Photo:Ben Frantz Dale
(from Wikimedia Commons)

After coffee beans have been processed, they look dull and unimpressive – nothing at all like the dark, glossy beans pictured here - the ones we associate with an aromatic cup of coffee. But beans can become all colors and flavors, depending on how they are treated during the commercial roasting process. Here, we'll take a look at what happens to coffee beans inside the roaster.

The roasting process

The green beans that will eventually someday grace your commercial espresso machine start the roasting process with a good screening, that is, the batch is sifted to get rid of anything that isn't a coffee bean. Then they are weighed and placed in storage until it's time for the roasting to begin.

People who oversee the roasting process use "roast profiles" to determine the length of time and amount of heat that is optimal to produce different flavors of coffee. Some roasters come with pre-programmed roast profiles. Typically, coffee beans are roasted in temperatures from 190° to 280° C (370° to 540° F) for about half an hour. A higher temperature and longer cooking time will result in a darker roast.

Which stages of the roasting process result in which types of coffee?

Light roast. This is the generic coffee you'll find at most fast-food outlets. The beans are roasted for about seven minutes, at which point they make an audible crack and expand to twice their original size. Their exterior remains dull, and they produce a rather weak and slightly sour cup of coffee.

Medium roast. This popular breakfast coffee is made from beans roasted for nine to eleven minutes. They retain a lusterless exterior that is light brown in color. The coffee they produce is full-flavored and less bitter than light roasts. Medium roasts are often found in specialty shops – the perfect complement to a cappuccino coffee espresso machine.

Coffee roasts

Photo from Wikimedia Commons

Dark roast. Beans cooked for twelve to thirteen minutes fall into this category. This sweet and potent roast includes Italian espresso beans and Vienna roast coffees. The beans are removed from the roaster after they make a second cracking sound. Their oils become visible on the beans' surface, giving them their familiar glossy finish. The picture (right) shows the difference in color between light and dark roasted beans.

French roast. This is the darkest roast available before the beans turn to ash. French roast occurs at about fourteen minutes into the roasting process. Little of the beans' original qualities can be tasted when the roast is this dark. The flavor is smoky, oily and very strong.

After roasting

When the desired roast has been achieved, the coffee beans are quenched with a cooling spray of water. Then they are screened once more to remove any fragments that got in during the process. After this is finished, the beans are stabilized, dried and made ready for packaging.

As you can see, there is a profile for any type of coffee you desire. Before you pick up a bag of coffee beans, make sure that they are made using the highest quality processing and roasting techniques. Even the best warranty automatic espresso machines can't make up for the flavor of inferior beans.

July 2008

Please note: Neither Veg World nor its contributors are qualified to give medical or nutritional advice. If in doubt, always consult a suitably-qualified professional.

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