Coffee roaster: Guide and types of roasting

We already know that getting a good coffee is not easy. We have seen on this blog how not only the way it is prepared in the coffee machine but also the grinding of the beans has an influence. And if we go even further back, we find the first stage of the process: the roasting of the coffee.

This is a step that is usually not visible to the consumer since the vast majority of us buy the coffee already ground or, at best, the beans already roasted to grind ourselves. However, as we will see throughout this guide, the roasting of coffee also greatly modifies the taste and aroma of each bean.

For all these reasons, more and more users are choosing to buy green coffee and roast it by hand. Getting a coffee roaster for your home is not easy, but there are several alternatives that we will get to know along these lines.

Let’s start at the beginning:

What is a coffee roaster?

A coffee roaster is a machine in which the green coffee beans are poured into and roasted to produce the coffee beans that are used to grind and make our favourite drink.

The methods for roasting coffee are very varied: there are gas coffee roasters, wood coffee roasters, air roasters, roasters for handcrafted and industrial coffee, among others.

Now that you know what a coffee roaster is, you should look at the options and models. In this guide, we are going to try to know all of them and to give a global vision about this process so important for coffee but so unknown for most of the consumers.

History of the coffee roaster

A bit of history never hurts to know the origins of this process and its tools.

It is known that in the 15th, 16th and 17th centuries, there were already some (scarce) sectors of coffee consumers who knew the importance of a good roasting of the bean—these used pans with holes, which they heated on a modest bed of coal. We can consider this rudimentary invention as the precursor of the coffee roasting machine, which would come later.

Coffee roasting machines began to be perfected and used massively during the 18th and 19th centuries. First, homemade and handcrafted, later, patented and industrial. Metal plates were used in their construction, mainly: brass, copper and iron.

The industrialisation of coffee roasting did not take place until the end of the 19th or beginning of the 20th century. In the 20th century, technological advances and the use of electronics came into play, allowing, above all, improvements in temperature control and therefore aiming at a much more homogeneous roasting of the beans.

As you can see, from the Renaissance to the present day, the evolution of coffee roasting has evolved at the same time as knowledge about the importance of coffee and the taste for consuming this infusion in the best possible way has grown.

coffee roaster

The coffee roaster and its parts

A coffee roaster has several components. The main one is the rotating drum: a metal roaster that turns inside the roaster and inside which the coffee beans are placed.

In an industrial coffee roaster, this rotating drum is usually replaced by a large metal container, which is heated by air (hence the name air coffee roaster) and which roasts the beans by direct contact.

In these cases, the movement function is carried out by large blades that spin inside the container, moving the beans as they pass by to prevent them from burning and to make the roasting more homogeneous.

How coffee is roasted (step by step)

As you can imagine, the process of how you roast coffee beans are absolutely critical to the taste and aroma of both the bean and the beverage that is made afterwards.

The aim of roasting coffee is to achieve a dark and homogeneous colour in the beans (no parts that are lighter than others). To do this, it is important to control the temperature well and devote enough time to the process. Between 15 and 20 minutes is recommended.

If an industrial coffee roaster (or air roaster) is used, the process usually follows a sequence of predefined steps:

  • Clean the toaster from any previous processes.
  • Roast the coffee using hot air, at a temperature of between 150º C and 220 ºC.
  • Select and mix the freshly roasted beans (blends or mixtures with beans from another roasting can also be made).
  • Cool or let the rest of the bean. Coffee continues to react to heat (because it is very hot) even after it has been roasted, so if you do not want to go overboard with bitterness, it is advisable to lower its temperature in the dry as quickly as possible.

If you use a home coffee roaster, the roasting process is much more controlled. We’ll see how this works later on, but roughly speaking, you need to put the beans inside and let the roaster spin for as long as you like.

Although many users do not know this, the green coffee bean undergoes significant changes when it is roasted.

Let’s try to summarize it in a schematic way. The longer the coffee is roasted, the better it is:

  • The more components are extracted.
  • Less acidity.
  • More body.
  • More bitterness.
  • More wear (loss of volume of the grain).

NOTE: the loss of weight of the bean is due to the expulsion of humidity and plays a decisive role in knowing how much we are roasted. That is why a coffee scale is usually used to weigh the beans before and after roasting so that we know whether we are doing it right or whether we are over-roasting.

In other words: the type of roast has a decisive influence on the taste of the coffee. Do you want to get a more acidic coffee? Then you should roast the beans for a short time. Do you like full-bodied coffee? Then you should start with a generous roast. And so on to an infinite number of nuances and variables.

Where can you buy a coffee roaster?

Nowadays, it isn’t easy to buy a home coffee roaster. The main models (such as the Behmor coffee roaster, which we will discuss later) are not sold on Amazon or in other online shops. Of course, industrial roasters are also not affordable for a particular user.

It is much easier to buy a coffee roaster in Peru, Colombia and other Latin American countries. There, fortunately for them, the process of roasting coffee at home is much more popular and in greater demand.

How to clean a coffee roaster

The maintenance of a coffee roaster is a fundamental job if we want to enjoy it for a long time and in perfect condition. If you don’t know how to clean a coffee roaster, this demonstration will surely clarify several concepts. In the example, they use an industrial coffee roaster, but the process is similar and can be extrapolated to other types of roasters.

The best home coffee roaster

Which is the best coffee roaster? When it comes to home roasters, this model is without a doubt the best. The Behmor 1600 Plus coffee roaster is the first home coffee roaster designed and built for roasting coffee beans at home. As you can see, it is very similar to a microwave or a tabletop oven.

The difference is inside, where a mesh roll serves to make the coffee beans spin and roast evenly.

Here you can see how it works:

This appliance, located inside the coffee roaster, is nothing more than a rotating roaster. Coffee rotary roasters can be purchased separately and installed in the oven, grill, or in a home roaster if we have one at home.

Of course, you can also roast coffee in a frying pan or a popcorn machine. These are valid solutions for beginners, but they give you very little control over the roast, and the results are not going to be 100% ideal: it is normal that the beans burn more in one place than in another, and if the roast is not homogeneous the taste of the coffee will not be either.

Coffee roasters for shops

These coffee roasting machines no longer have a place in a house, but we are still obliged to make room for them on this page.

How to make a diy coffee roaster

If you want to have a coffee roaster for your home, you don’t have to spend a lot of money. If you know the process, you can make one with your own hands. The concept is very simple, so the video is self-explanatory:

A homemade coffee roaster like this one can also be used to roast other types of beans: barley, malt, peanuts, etc. You have to research the right temperature and time for each one.

Artisan Coffee Roaster

If you don’t have the option of using an industrial coffee roaster or a Behmor roaster but don’t want to give up on roasting coffee at home, you can do that too. In this video, we show you how to roast coffee at home in just a few minutes:

NOTE: When you have roasted your coffee, don’t forget to store it immediately in a coffee can or with a vacuum packer. Freshly roasted coffee should rest for several days so that all the aromas and nuances of the bean can settle in.