What is a Master Roaster?

Are you a coffee lover and trying to learn everything you can about making that perfect cup of coffee? You may have come across the term “Master Roaster” and wondered what that exactly means.

A Master Roaster is a highly experienced coffee professional responsible for taking green coffee beans grown in various places and seasons and implementing roasting techniques to produce specific roast and flavor profiles. Much work is involved with the tasks of a Master Roaster.

Roasting coffee beans is both an art and a science. It can take years for an individual to become a coffee expert. Talent, skill, and a passion for coffee are all needed to be a great coffee roaster.

Although some programs offer classes and certification, a certificate is not necessary. To become a master roaster, you become an apprentice to learn the craft.

What are the Responsibilities of a Master Roaster?

As mentioned, a Master Roaster is a highly skilled coffee professional who affects how our coffee tastes. When the coffee beans come to the roaster, they are green and have no flavor. It’s only after the coffee beans are roasted that the flavor comes out.

When farmers ship out the coffee beans, the Master Roaster tests them to determine what the coffee tastes like and how they can enhance it through roasting. There are various ways coffee roasters can enrich the taste of the beans.

Every batch of beans requires a different temperature and time of being roasted. While some beans need to be roasted a little darker, others have to be roasted a bit lighter so the knotty characteristics of the bean are not lost.

Their primary objective is to create a stable and consistent blend. A Master Roaster often needs to make split-second decisions on the roast. If the wrong decision is made, it can ruin the entire batch of roasted coffee beans.

What does a Master Roaster Judge?

There are numerous characteristics that a Master Roaster looks at when creating an excellent coffee roast. Some of the traits they judge of a particular coffee bean and roast are the following.


Once the coffee bean is taken from the coffee cherries, they are green in color. Depending on their region, the color can vary from a greyish green to more of a yellow-green. This helps the Master Roaster make the determination on how best to roast them to produce the best-tasting coffee.

As the beans are being roasted, they go from their original green color to a tan color and then a brown. The color darkens more and more the longer the beans are roasted. If the beans are ever black, they are unfortunately burnt and need to be tossed out.


Aroma is one of the main characteristics denoting a coffee’s flavor and describes how the coffee smells. As the beans are roasted, there is a release of flavorful compounds from the coffee beans into the air. The fresher the coffee is, the more powerful the aroma will be.

As a general rule of thumb, the longer the coffee beans are roasted, the stronger the aroma will be.

Coffee can have a fruity smell to a slightly caramelized to a nutty aroma depending on its origin.

Acidity Levels

The master roaster can detect the acidity of a cup of coffee by merely tasting it. While sweetness is tasted on the tip of the tongue, acidity is tasted on the posterior sides of the tongue.

Think of when you eat something sour, like a lemon. You taste the acidity of it on the backsides of your tongue. Coffee beans grown in lower altitudes typically have fewer acids in them, so when they are brewed, they are classified as the least acidic coffees. If you are one whose stomach feels upset after drinking coffee, trying a lower acidic coffee is most likely your best bet.

In addition to the bean itself, acidity levels in coffee are also determined by how long the beans are roasted. The longer the beans are roasted, the more of the acids will burn off, therefore creating a lower acidic coffee choice.


The flavor of the coffee is determined primarily by the Master Roasters taste buds. Often, the overall flavor of the coffee is determined by the combination of the other characteristics being described, including acidity, aroma, bitterness, and sweetness.

Master Roasters look to create a coffee whose flavor is well-balanced, meaning one flavor or characteristic doesn’t overpower the others to the point where the flavor becomes unbalanced.

Similar to the coffee’s aroma, the coffee’s flavor can be described as having a fruity, caramel/chocolate, or nutty flavor.


This describes the texture of the mouthfeel. Master Roasters often use words such as “smooth,” “grainy,” and “creamy” to judge a coffee’s texture. These qualities are all affected by the bean, roast, and how the coffee is brewed.


A Master Roaster also judges the body of a cup of coffee, meaning they look at the coffee’s physical aspects, such as the weight or viscosity of the coffee on the tongue. The body of the coffee is greatly affected by the origin of where the beans were grown, roast levels, and the brewing method used.

A Master Roaster often uses terms such as “thin,” “heavy,” “watery,” and “syrupy” to describe the body of a cup of coffee. The body of the coffee is generally divided into three main classes.

  1. Light Body: The consistency is thinner, with minimal residue left on the tongue.
  2. Medium Body: More balanced and smoother mouthfeel.
  3. Full-bodied: Thicker mouthfeel while retaining more flavor.


I’m sure we’ve all taken a sip of a cup of coffee only to find ourselves complaining about how bitter it tastes. Now, bitterness is not always a bad thing. The problem arises when the bitterness of your coffee overpowers the other flavors of the coffee. Balance is what is needed.

That bitterness is tasted across the rear of the tongue. While overly bitter coffee is generally the result of a lower quality bean (usually robusta), it can also be due to roasting. When the roasting degree is high, you will taste more bitterness in the coffee.


The aftertaste of a coffee is different from the taste you get when drinking the coffee. Instead, it results from specific molecules remaining in your mouth longer than others after drinking the coffee. The compounds that dissolve in coffee oils carry some of the bitter and roasted notes in coffee.

Checking the Coffee They Make

Tasting is just one of the ways the Master Roasters test the coffees they make. Before they even begin the roasting process, they check the green beans to see if they have the correct moisture content and that are no defects, broken, or black beans. If found, these beans are removed from the batch since they can alter the taste of the coffee.

Once the coffee is roasted, the moisture content is again checked because it can now affect how the coffee beans are ground.

Checking the roasting degree is next. This is seeing how light or dark the bean is by using a reflectance color meter to measure the actual physical measurement of color.

Many Roast Masters will taste the coffee multiple times to ensure it is precisely how they want it. The overall goal of a roast master is to get a consistent taste of coffee.

Creating Coffee Blends

After the beans are roasted and inspected the last time, the Master Roaster can create different blends by combining 3, 4, and sometimes even mixing up to seven different coffees together. Each one is considered a new recipe.

Their unique expertise allows them to use their creativity to make all specialty coffees we enjoy today!

3 Main Types of Coffee Roasters

A master roaster typically uses one of the three main types of coffee roasters: a drum roaster, a fluid-bed roaster, and an air roaster (different methods include a centrifugal roaster and a tangential roaster).

Air Roasting

When using an air roaster, each bean is suspended in air to ensure a nice even roast, each and every time. The chaff of the bean is then vacuumed away from the final product, producing a smooth cup of coffee.

Roasting DrumĀ 

A drum roaster heats the coffee beans through the conduction of heat. Imagine a cement mixer with a flame underneath it. The flame heats the drum, which continually rotates with the coffee beans inside it ensuring they’re evenly roasted. The gas can be turned up or down to control the flames, which controls the temperature and speed of the roasting process.

Fluid-Bed Roaster

Fluid-bed roasters use convection rather than conduction to heat the beans. Imagine blowing a hot hairdryer up into a drum. The airflow heats and moves the beans around the drum. Roasting coffee this way is quicker than roasting in a drum roaster.

Final Thoughts

A Master Roaster is a highly rated coffee professional responsible for the quality of the coffees we buy in stores, online, and in coffee shops. Their abilities allow them to judge coffee beans by several coffee characteristics.

If you are still curious about the job of a Master Roaster, I highly recommend the book The Coffee Roaster’s Companion by Scott Rao.

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