Anatomy of a Roaster

I get this often; ‘I love your logo, but what is it?’. Luckily it’s a simple answer; a coffee roaster.


Most people have not seen a coffee roaster before. Which is striking considering how many people drink coffee. The roaster is the equipment used to turn dried, green coffee beans into roasted, brown, aromatic little beauties. Roasting is one of the crucial processes in coffee production. This step allows for these plain, bland beans to be transformed so they can brew an amazingly complex cup of coffee.


Roasters are designed to apply controlled heat to the coffee beans, causing them to undergo a series of chemical reactions. These chemical reactions are known as the Maillard reaction and caramelization. Specialty coffee roasting requires a knowledgeable eye and a great deal of skill. It is not simply plug and play. So let’s look at the structure of the most common type of roaster, a drum roaster.

Bean Hopper:

This large funnel is the starting line of the roaster. Green beans are dumped into the hopper where they will sit until the roaster is preheated and ready to start roasting.


The trier is a small ‘scoop’ that extends into the drum of the roaster and catches a

few beans that the roaster can pull out and examine throughout the roast.

This is critical for the fine tuning of the roast process. It allows the roaster to monitor the chemical reactions taking place and determine if the roast is going too slow or too fast.


Chaff Cyclone:

During the roasting process the beans dry out, expand in surface area, and crack. One of the many outcomes of this is that the beans shed their outer skin. Have you ever eaten peanuts from the shell? Remember that red skin they have on them? That is the same type of substance that covers the coffee beans. Once that skin sluffs off, it needs to be removed from the drum or it will catch fire and disrupt the roast flavors. The chaff cyclone uses the heat from the roasting process to suck the chaff out of the drum. It is then spin in a cyclone where the solids settle to the bottom of the chamber and the heat escapes through a vent. It is VERY important that the chaff cyclone is cleaned regularly to avoid a fire in the roaster.

Roasting Drum:

This is where the magic happens. The drum is a metal (most of the time cast iron) barrel that rotates over gas burners (in the case of a gas roaster, which is what I roast on). The drum needs to be preheated just like your oven at home. Once heated the beans fall from the hopper into the rotating drum and start the roasting process. The drum usually has disruptive paddles inside of it that helps to stir the beans as they rotate ensuring an even roast. You can imagine this as a popcorn popper turned on its side or a rotisserie chicken roasting.


Cooling Tray:

Lastly, the roasted beans are dropped into this tray where spinning arms agitate the beans while air is pulled over the beans by a fan to cool them down.


They're Works of Art

These machines are incredibly complex and there are other parts and variables to roasting, but this is a fairly good synopsis. I am mesmerized by these machines that are works of art in and of themselves. The craftsmanship and detail in them is a remembrance to all that even something as mundane as your morning coffee has craft, has art, and has intentionality behind it.


So there you have it. The anatomy of a coffee roaster. If you’ve stuck with the blog post this long, then you have learned something new today. You should also understand the image within our logo a little better.

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