May 31, 2023 5 min read

When you encounter a coffee roaster that prides itself on its freshly-roasted coffee beans and specialty coffee roaster knowledge, you may find yourself wondering what the coffee roasting process actually entails.

What kind of time, effort, and expertise goes into freshly roasting coffee beans? Why does a coffee company's roasting expertise spell the difference between a high-quality coffee brand and a brand known for pumping out over-extracted and bitter coffee beans?

Coffee roasting is so much more than browning raw coffee beans — instead, it's an art and a science overseen by skilled artisans. To produce a consistent and high-quality product, specialty coffee roasters rely on temperature control, a keen eye for detail, and an intimate knowledge of key roasting equipment.

As the customer and coffee drinker, acquainting yourself with the coffee roasting process will allow you to gain a better understanding of the roasting technique's impact on coffee aroma, acidity, bitterness, flavor development, and taste uniqueness.

With knowledge of the roasting process under your belt, you'll be better equipped to make smarter purchasing decisions when restocking your coffee bean supply. Not only will you be able to select coffee roasts according to your taste preferences and caffeine needs, but you'll never overlook the importance of purchasing from a specialty roaster again.

From Green Coffee Beans to Coffee Roasted to Perfection

After harvesting, raw beans need roasting before they’re brewed. The roasting process is what transforms green coffee beans and gives them that rich chocolate-brown color that's come to define the coffee bean.

During the roasting process, the heat-triggered chemical reactions within the bean alter its flavor and aroma. How a bean will roast is determined by the following factors: origin, altitude, and variety.

In striving for a high-quality and highly-coveted roasted coffee blend, temperature control and roasting equipment are the two key determinants of roasting success.

Importance of Temperature Control

Extreme high or low temperatures can negatively impact the critical chemical reactions that the coffee roasting process requires, resulting in underdeveloped or burnt-tasting coffee. Maintaining consistent temperatures throughout the roasting process ensures that all of the beans are roasted evenly and have a consistent flavor profile.

The Importance of Roasting Equipment Type

Specialty roasters hoping to assume greater control over temperature will use a drum machine with rotating barrels when roasting coffee beans. A drum machine facilitates even heat distribution, eliminates hot spots, and ensures uniformity across multiple batches.

Conduction roasters depend on cast iron for caramelization purposes, whereas those coffee brands looking to achieve a lighter-body roast will turn to a fluid bed roaster.

Other roasters rely on decades-old and customized roasters. For example, Mystic Monk's flock of roasting specialists achieve one-of-a-kind flavor profiles by using a 1950s Gothot, customized to provide ultra-fine control across various roasts.

The Three Stages of Coffee Roasting

Roasting coffee beans is a process that consists of three central stages: drying, browning, and developing.

Drying Stage

During this initial roasting stage, water is driven out of the bean as it heats up. This typically takes place at temperatures between 160°C and 200°C (320°F to 392°F). As moisture evaporates from inside the bean, it expands and cracks audibly.

Browning Stage

As temperatures rise above 200°C (392°F), chemical reactions begin to occur within the bean that results in browning — the roasting stage where the flavors associated with roasted coffee develop. Sugars caramelize, creating sweet flavor notes.

Developing Stage

More complex chemical reactions occur during this final stage of producing roasted beans, creating additional flavors and aromas. At this point, temperatures can reach upwards of 230°C (446°F). Without careful monitoring, there is potential for burning or scorching, and this could lead to an unpleasant taste in the roasted beans.

Types of Coffee Roasts

The length of time spent roasting the coffee beans distinguishes one coffee roast from another. 

  • Light roasts are roasted for a shorter amount of time, which results in a lighter color and a more acidic flavor. 
  • Medium roasts are roasted slightly longer, producing a darker color and a more balanced flavor with less acidity. 
  • Dark roasts are roasted for the longest period, resulting in a very dark color and a bold, smoky flavor with minimal acidity.

The longer a coffee bean is roasted, the more oils rush to the surface, affecting both flavor and caffeine content.

Light Roast

Light-roasted coffees typically have higher acidity levels due to less exposure time at high temperatures, allowing for the retention of some acidic compounds in unroasted beans. The presence of components like chlorogenic acid can result in sourness or tartness in the flavor profile or even unearth citrusy or fruity flavors like lemon or berries.

Medium Roast

Medium-roasted coffees strike a perfect balance between acidity and body. Medium roasts have a slightly lower caffeine content than light roasts due to exposure times. While it was originally thought that the longer a coffee bean is roasted at high temperatures, the more caffeine is burned off, more current research shows that  the beans expand in size the longer they are roasted, so a tablespoon of medium beans weighs less than a tablespoon of light roasted beans and therefore has less caffeine by volume.

Chocolate and nutty undertones are a staple of medium roast blends, making a medium roast coffee the ideal choice for coffee drinkers desiring rich flavor profiles.

Dark Roast

Dark roasted coffees lose much of their acidity during prolonged exposure times, leading to deeper flavors like smokiness or earthiness along with charred notes, which can lead to bitter taste characteristic of espresso or french roast blends. A cup of dark roast contains the lowest caffeine of the three roast varieties — light, medium, and dark, and that’s because the beans are larger and lighter. Much of the moisture in the bean has evaporated during roasting.

Mistakes Inexperienced Roasters Make When Roasting

While it'd be easy to assume that every coffee roaster works through the roasting process at the same pace and cadence, what sets apart an inexperienced roaster from a seasoned one is their understanding of roasting best practices.

Common roasting mistakes that can negatively impact the taste, body, and bitterness of a coffee roast include the following:

  • Not understanding the green coffee's origin story (variety, elevation, characteristics, etc.)
  • Not preheating the roasting equipment
  • Overloading or underloading the roasting machinery
  • No standardized protocol between batches, resulting in inconsistent batches


There’s real science behind the roasting process, and it doesn’t only affect the taste of your favorite brew. It also modulates the caffeine levels of a bean, which means that some drinkers will deliberately opt for dark beans over a medium or light roast if this matters more than other factors like taste and body.

And while the ultimate choice of roast type is up to you, choose Mystic Monk’s specialty beans andfresh roasted coffee options for your next cuppa. Infusing the very best and rigorous roasting standards with mystical, inspired gourmet blends, the Wyoming Carmelites give coffee aficionados everywhere a taste of the monk life. Take a sip and discover a hidden world of specialty roasts today.