Find out how the process of roasting coffee transforms the green beans into the ready-to-brew coffees we enjoy daily.

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The Art of Roasting

What Happens when Coffee is Roasted?

The Art of Roasting

The green coffee bean is made up of fats, proteins, fibers, and miscellaneous chemicals. The coffee we enjoy so much does not actually come to life until the coffee is roasted. The heat of roasting forces the moisture out of the bean, and draws out of the remaining substance, various tiny fragrant beads of a volatile oily material. This substance is not actually oil, since it dissolves in water - but is the flavor essence that we prize as coffee.

During roasting, the oil gathers in little pockets throughout the heart of the bean. As the beans are roasted for longer periods and more moisture is lost, the oil develops further and begins to rise to the surface of the bean, giving dark roasts their characteristic oily appearance.

As the beans roast for a longer period, the bean begins to burn; creating the bittersweet flavor that is cherished by advocates of dark-roasted coffee. Dark roasted coffees also contain considerably less acid and caffeine - these are burned off during the roasting process.
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What Happens when Coffee is Roasted?

The coffee we enjoy so much is only a potential, and does not actually come to life until the coffee is roasted. The green coffee bean is actually a fruit/nut made up of fats, proteins, fiber, and miscellaneous chemicals. The heat of roasting forces the moisture out of the bean, and draws out of the remaining hard substance tiny fragrant beads of volatile, oily substance variously called coffee essence, coffee oil, and coffeol. This substance is not actually oil, since it dissolves in water - but it is that which we prize as coffee. This essence also evaporates easily, readily absorbs other, less desirable flavors, and generally proves to be as fragile a substance as it is tasty. Altogether, it makes up only 1/200th of the coffee bean's weight.

In medium or American roasted coffee, which is the roasting style we adhere to at Coffee Masters, the oil gathers in little pockets throughout the heart of the bean. As the bean is held in the roaster for longer periods and more moisture is lost, the oil develops further and begins to rise to the surface of the bean, giving dark roasts their characteristic oily appearance.

Meanwhile, as the bean roasts for a longer period, the rest of the bean begins to burn, creating the bittersweet flavor (albeit over-roasted) that is cherished by fans of dark roasted coffee. Frequently, this charred flavor disguises the unique flavor characteristics that different beans possess. Dark roasted coffees also contain considerably less acid and caffeine - these are burned off during the roasting process.

The roasting process itself is quite simple, however, there is a wide margin for error. The green coffee beans simply need to be evenly exposed to temperatures of at least 400f for 5 to 10 minutes and then be cooled at the right moment.

It sounds pretty simple, but there are factors that actually make coffee roasting a science.
   • You must roast the beans evenly.
    • Coffee roasts differently because of density. Higher grown beans are "harder" and require a higher temperature.
    • Older coffees can roast more quickly than new "moist" crops.

Coffees from different regions of a country differ in composition, size, etc. Roasting time has to be adjusted to compensate these characteristics to bring out the best in the bean.
    • There are about 30 different roasts, light to dark, to choose from, each which has its own length of roasting time.
    • Each roasting device creates different air convection.
    • Different sources of heat have different effects on roasting. (Gas, hot air, wood-burning)
    • Roasting at lower temperatures for longer periods of time affects the flavor.

Coffee Masters questions all of these factors and more when roasting a particular coffee for you. We're dedicated to shipping you fresh-roasted, great tasting gourmet coffee, and the kind you can't buy at a grocery store.
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