How to Roast Coffee Beans
Want to know how to roast coffee beans to make the best tasting coffee? Then this article is for you!
In our previous article Where Do Coffee Beans Come From? we finished with our precious beans awaiting export to the country where the coffee will be produced.
To refresh your memory, the basic process was: harvesting the coffee cherries; processing of the cherries; different de-pulping methods; the fermentation process; washing and drying the beans and sorting through the beans.
Let’s skip ahead, the beans have now arrived at the roaster, awaiting roasting. Once the beans have been roasted, there’s an expiry date on them. They need to be sold as soon as possible. In your panty or on the shelf of coffee seller, they can last for about six months. But this basically means that they need to be sold quickly, because once you’ve bought them, they will still be sitting in your pantry for a while.
Tip: roasted beans can last up to two years if stored in your freezer.
The Fine Art of Roasting Coffee Beans
Roasting is the process of transforming green beans into those delicious aromatic brown beans. Most roasting machines maintain a temperature of about 550°F (287°C). The beans are kept moving throughout the process to prevent burning.
When the beans reach an internal temperature of about 400°F (204°C), they start turning brown and the caffeol, a fragrant oil locked inside the beans, emerges. This process is called pyrolysis and it’s at the heart of roasting, it produces the flavor and aroma of the coffee. Afterwards the beans are immediately cooled either by air or water.
Roasting requires a skill found somewhere between art and science. A few important skills for roasters include a strong attention to detail, excellent sensory skills and sensory memory as well as a passion for all things coffee. The good roasters and the great ones are separated by the level of these skills.
The main goal of coffee roasting, is to enhance the green coffee beans’ qualities and to develop them to their fullest potential. For instance, we might try to tame a coffee’s level of acidity while accentuating its citric flavor, or we might try to enhance the mouthfeel in a coffee while also focusing on its natural chocolate notes.
Roasters will tell you that the process is both challenging and tremendously rewarding. Each batch of roasted coffee is tested with an Agtron roast analyzer, scientifically testing the classification of the roast.
The Agtron system works from 0.0 points for the darkest roast to a 100 points for the lightest roast. These samples are also “cupped” to ensure that the flavor matches the customer specifications with consistency.
The following are the various roast levels that can be achieved. Currently there’s a trend that’s leaning towards coffee connoisseurs preferring dark roasts, but some people will argue that too much of the finer nuances are lost with dark roasts. In the end it all boils down to personal preference.
Light roasts have a light brown, tan color and it is generally preferred for milder coffee varieties. They are the brightest of the coffee roast varieties and have the highest level of acidity. As these coffee beans are roasted for the shortest amount of time, the oil does not have chance to break through the surface of the bean as they are not roasted long enough to crack.
A few light roast types:
– Light City Roast
– Cinnamon Roast
– Half City Roast
– New England Roast
A medium roast has a slightly darker color than the lighter roast and with a stronger flavor. At this roast level, the flavors and aromas start to create a balance between the acidity and body of the coffee beans. Often referred to as the American roast, this coffee is popular in the United States.
A few light roast types:
– Regular Roast
– American Roast
– Breakfast Roast
– City Roast
Medium Dark Roasts
This roast has a rich, dark color because it has some oil on the surface and it has a slightly bittersweet aftertaste. The taste can be somewhat spicy with the beans roasted to the beginning or middle of the second crack, around 225°C (437°F) to 230°C (446°F).
– Full City Roast
– After Dinner Roast
– Vienna Roast
At this roast level shiny dark brown, sometimes almost black, beans are produced that resemble chocolate which have an oily surface and a distinct bitterness. Overall the darker the roast, the less acidity will be found in the coffee.
A few light roast types:
– French Roast
– Espresso Roast
– Italian Roast
– Continental Roast
– New Orleans Roast
– Spanish Roast
How Does Good Coffee Taste?
Coffee tasting is another fine art form and there are people that dedicate their lives to finding that perfect cup and learning how to distinguish it from a bad cup, as well as how to describe it to others. You’ve heard some people talking about an undertone of chocolate, or a hint of caramel?
Brightness or Acidity
The first impression of a cup of coffee, is the brightness or acidity. The acidity can be described as that crisp sensation on the tip of your tongue. This is not talking about the pH of the coffee.
Pleasantly acid flavors are perceived almost instantly on the tongue’s tip and front corners, just behind the upper teeth. Various acids are found in coffee, to name but a few – citric, lactic, malic and acetic. These contribute to the many bright, sharp flavor notes found in a cup of coffee.
A few factors influence the acidity of the beans, if they are grown at higher altitudes and processed by washed methods, they generally have a greater perceived acidity then those lower-grown or naturally-processed beans – even if they are from the same origin and region.
Heat during the roasting process causes acids to be formed and consumed, as well as converted into sugars and other flavor combinations. During the roasting process, the roaster manages the roasting time, the roast profile and outturn temperature to control acidity and balancing it with body, providing specific flavor notes.
For instance, dark roasts have lower acidity then lighter roasts of the same origin. Furthermore origins or blends roasted on short roast times will cup brighter than the same origin or blend roasted to the same level on longer times.
Other internal changes to a roast profile will also change the relative levels of acids in a coffee, it will result in a cup with considerably different flavor notes.
Next time you take a sip of coffee, ask yourself “How full of flavor does my mouth feel? And for how long?” This is one way how roasters and cuppers learn to evaluate body, of course together with perspective acquired from hundreds of tasting trials.
On the technical side, laboratory testing quantifies other components such as levels of viscosity, oils, sugars and dissolved solids like cellulose, suspended particles and more. But sensory evaluation is a matter of perception and practice.
It’s important to use a consistent brewing method to evaluate coffees and this has a profound effect on the coffee’s flavor profile and body level.
An example, coffee brewed by French press shows a more complete flavor profile and significantly fuller body when comparing the same coffee with a drip-brewed method with a paper filter. The problem is that the filter traps oils and solids that are part of body as well as fine particles that carry darker flavors.
Another factor to keep in mind, the green bean processing methods intensely affect a coffee’s body. If the beans were wash processed, the sugary fruit pulp is completely removed from the coffee beans and it produces coffees with a light to medium body and clean, bright flavors.
In contrast, dry processing is more natural and dries the beans and fruit together to produce coffees with a deeper tone and more diverse flavors plus a heavier body.
The roasting process also affects the body. Usually longer roasting times build a coffee’s body, while shorter times will accent the acidity. But this is only true to a point. A too long roast will cause a coffee to lose both acidity and body. This fault is known as baked or “bakey”. A “bakey” coffee will produce a cup that is bland and lifeless.
There’s more to your cup of coffee…
So, there you have it, a little more inside info to make you sip that next cup of coffee a little bit slower. I’m a lover of sugar in my coffee, and I know it’s a horrible habit, killing the actual flavor of the coffee. But it’s so nice… You? Are you brave enough to drink your coffee straight up – black, without any sugar?
Talking about sugar, caffeine has also been the talking point of many health debates, is it good or bad for you? Next time we’ll investigate the effects of caffeine on your body.