What are the best Coffee Roasting Methods?

You’re a bagged coffee connoisseur, but you’ve decided that it’s finally time to take the next step and roast your own beans. You may be asking, what are the best coffee roasting methods? It’s a complicated question with different answers, but we’re here to help simplify it. In this blog, we’ll discuss different roasting techniques, including drum roast, air roasting, and infrared roasting, as well as how those different mediums can influence your brew’s flavor. 

Overview of the Coffee Roasting Process

Before we can discuss individual ways to roast beans, we should talk about the chemical process of roasting. In the next section, we’ll define the three phases of roasting, how the Maillard reaction affects flavor, and the different roast levels.

The 3 phases of roasting — drying, browning, and development

The scientific process of roasting coffee beans can be separated into three main phases: drying, browning, and development. We’ll address each phase and how it can affect characteristics like flavor and aroma.

Drying Phase 

• Humidity inside the bean must evaporate before flavors can be developed.

• Color will change from green to yellow at around 300 degrees Fahrenheit by the end of the phase.

• Length and momentum of the drying phase will determine the success of later phases.

• Slower momentum = slower roast/less heat

• Faster momentum = faster roast/more heat; possibility of less flavor if too fast

• Precise timing and temperature balance are necessary for each kind of bean

Browning Phase (Maillard Reaction and Caramelization)

• Consists of the Maillard reaction (discussed in the next section) and the caramelization of sugar in beans. 

• The Maillard reaction happens at around 248 degrees Fahrenheit.

• Caramelization occurs at around 330 degrees Fahrenheit. 

• Beans change from yellow to light brown

• It ends with the first crack (when the coffee bean cracks open, reminiscent of popping kernels), which leads to light and medium roasts.

• A combination of sugars, such as glucose and lactose, with amino acids results in different flavors.

• The degree of caramelization influences the final brew's sweetness, acidity, bitterness, clarity, and complexity.

Development Phase

• Lasts from first crack through the end of the roasting cycle

• Second crack - Oils within beans rise to the surface. Happens around 435 degrees Fahrenheit. Sounds more like crackling. 

• The period that is most responsible for flavor modulation and development

• Length of development time and temperature are the main factors

• The intervals between crackling will tell you when it’s done

• Shorter development time/lower temperature = Higher sweetness and acidity

• Longer development time/higher temperature = Higher caramelization/lower acidity

Flavor development and the Maillard reaction

We’ve previously mentioned the Maillard reaction, but let’s explain it in depth as it’s an instrumental piece of how flavors and aromas develop during the roast process. Named after its originator, Louis-Camille Millard, the Maillard reaction is a heat-induced chemical reaction between amino acids and reducing sugars that results in browning in a variety of foods including falafel, marshmallows, and steaks.

With coffee beans, the Maillard reaction can be understood this way:

• Crucial for browning the beans and releasing flavors and aromatics

• The length of the reaction and the rate at which it occurs are what change roast profiles

• Roast profiles are defined by total roast time and coffee bean temperature. You want a balance between acidity, sweetness, and bitterness.

• A longer roast time can add bitterness and smoky notes.

• A shorter roast time can lead to less complexity and balance.

• Lower temperatures can lead to fruity, floral, and nutty flavors.

• Higher temperatures can lead to bitter and acidic notes.

Roast levels and how they’re measured

Among other factors, the frequency of the Maillard reaction depends on the roast level - light, medium, and dark roasts. Roast levels can be identified by audible cues, color, and temperature. Let’s talk about each primary roast level.

Light Roast

• Light brown

• Retain most of the caffeine 

• Fruity or floral flavors

• Around first crack (Around 385 degrees Fahrenheit for internal bean temperature) 

Medium Roast

• Medium brown color

• Beans with more balanced acidity, aroma, and flavor

• Chocolate, caramel, and nutty flavors

• After first crack, before second (At least 401 degrees Fahrenheit)

Dark Roast

• Dark brown color, oily sheen

• Beans with low acidity and bitterness

• Bittersweet chocolate notes and drier nut flavors

• After the second crack (at least 435 degrees Fahrenheit)

Once you become more experienced, you can also start mapping out roast curves to help identify and track the phases that coffee goes through during the roasting process. By tracking the heat and intervals at which phases occur, you’ll have a reference point for your desired roast profile for that particular bean. The shape of a roast curve is determined by temperature, airflow within the roaster, and moisture.

When you’re ready to refine other parts of your coffee-making routine, explore the many high-precision, premium options from Pesado.

Coffee Roasting Methods Compared

In the next section, we’ll compare drum roasting, air roasting, and infrared roasting and discuss the best use cases for each method.

Drum roasting

Drum roasting is the most common method for coffee roasting. During drum roasting, the beans are placed in a rotating drum and heated by a direct flame for slow, full-contact roasting. 

In comparison to other roasting methods:

• Conductive heat from the drum and convective heat from the surrounding hot air

• It can have inconsistent heat distribution and can char the beans, leading to ashy flavor. Others are underroasted and have sour, grassy flavors.

• Offers strong development control, but is more challenging to master

• Adaptable for both delicate light and rich dark roasts, superior for dark roast

• More maintenance and a slower roasting process

Fluid bed (air roasting)

During air (or fluid bed) roasting, the coffee beans are roasted by a strong stream of hot air that lifts and rotates the beans in a suspended position. By tumbling each bean, that ensures uniform heat. 

In comparison to other roasting methods:

• Naturally removes the coffee chaff during the roasting process

• Slightly less expensive than a drum

• Faster roast times and with less energy

• Better for light roasts. Known for more consistency and retention of flavor. 

• Instant cooling

• Air roasting prioritizes even extraction.

• Less maintenance than drum roasting

Infrared roasting

Infrared roasting is when the coffee beans are heated internally directly through infrared radiation (a form of electromagnetic radiation). 

In comparison to other roasting methods:

• Heats the beans directly instead of relying on conduction or convection

• Potential for uniform roasting

• Faster roast times and more energy efficient

• Smoother, sweeter, less bitter brews

• Learning curve for temperature control

• Still a niche, expensive product

For more tools and accessories that can help you make smoother, more consistent coffee shots and better brews, investigate the many options at Pesado.

Which Coffee Roasting Method Is Right for You?

There isn’t a single answer for the best coffee roasting method. Different methods will yield entirely different flavor permutations and allow a range of control in terms of internal bean temperature and length of processes. Assess your own preferences and think about your ideal roast profile based on your budget and goals. Questions like, are you going to be using this at home or commercially, or do you want a brew that’s more bright or bold?

All of those questions will factor into your purchase. Or maybe you just want to whet your appetite and try DIY roasting through air poppers or pans. Your ideal roast will depend on your tastes and skills. But the key is to never stop learning and adjusting. There are so many tools and different kinds of equipment that you can use to create your perfect brew. With high-quality, ergonomic dosing, distribution, and extraction tools from Pesado, you’ll be empowered to create your perfect cup of coffee.