How Roasting Affects Taste of Coffee

Did you know that it is particularly important for baristas that the coffee they brew is perfectly roasted?

That’s why there are people in the coffee industry who only do one thing: roast coffee. But what exactly does that mean and what is the process they follow?

Most importantly, how does roasting affect the taste of coffee? This is what I will be talking to you about today.

Here’s an overview of what I will cover:

Definition of roasting

What is the meaning of roasting anyway?

According to dictionaries, roasting means “exposing a substance to high heat  for a long time without the addition of fat or water so that it is cooked, gets a brown crust, and becomes crispy”.

In the case of coffee roasting, this refers to the raw coffee beans. Roasting coffee is the process in which coffee beans are roasted and get this deep brown colour we all know and love. When roasting coffee, the so-called roast aromas are created in the coffee bean.

 

Why is roasting coffee so important?

The seeds of the coffee cherry are called coffee beans. These are processed and dried after the harvest, which also plays an important role in the flavor profile of coffee. 

Before roasting, the raw coffee beans are green and have a bean-like, grassy aroma. In fact, green coffee beans don't smell at all the way we imagine coffee to smell. This is because coffee only develops 800 to 1000 different aromatic substances when it is roasted.

And these substances give the coffee its unique taste. Depending on the type of roast, the roaster can influence the development of these aromatic substances and thus also determine the taste of the coffee.

Roasting process

Roasting coffee simply means that green coffee beans turn brown. The roasting process itself is a process that consists of different phases. Depending on what happens in these individual phases, this affects the taste of your favorite hot beverage.

So what exactly happens during the roasting process? There are three basic stages in roasting: drying, browning, and developing/roasting.

Drying

The raw coffee bean has a moisture content of 8-12%. Therefore, it is necessary to dry them before starting the actual roasting.
 
As a rule, the drying phase with a commercially available drum roaster takes about 4 to 8 minutes. Towards the end of the drying process, the temperature is usually around 160 ⁰C.

 
However, it is advisable to be careful, especially with drum roasters because if they are heated too much right at the beginning, the beans will burn.

Browning

From 160 ⁰C onwards the coffee begins to smell of toasted bread. From this moment on, the flavor precursors begin to transform into flavors. Even if the browning takes place after drying, the drying phase is also continued during browning.
 
Now the Maillard reaction sets in, which is responsible for the brown coloration of the coffee beans. In the Maillard reaction, sugar levels and amino acids react, creating hundreds of different flavor and color compounds.

 
These are known as melanoids. During this phase, the roasting process naturally slows down. Some roasters deliberately slow it down at this point to ensure that the flavor develops.
 
Towards the end of the browning phase, the coffee beans begin to burst. This phenomenon is called “first crack”. The development or roasting phase begins with it.

Developing/roasting

At the beginning of the development or roasting phase, the reaction of the coffee bean becomes exothermic. This means that the bean has stored energy during the drying and browning process, which now causes the coffee to burst.
 
In the development phase, the desired flavoring substances develop. If we do not slow down the roasting process at this stage, there is a risk that our coffee will taste smoky and become too bitter.

 
The development phase typically comprises around 15-25% of the total roasting time. However, the exact duration depends on the desired taste profile and degree of roasting.

Roast level

The so-called degree of roast is one of the most important factors when roasting coffee because it measures the various roasting results you can get when roasting coffee. 
 
The degree of roasting can be influenced by varying the temperature and roasting time and has a decisive influence on the aroma, taste and purpose of the coffee. You can actually measure the degree of roasting either with a color measuring device or by tasting.
 
Roasters usually want to intensify the coffee's own aromas and achieve a corresponding degree of roasting. Typically, light roast coffee is acidic, dark roast coffee is bitter. Fruity aromas are also more common in light roasts, while smoky aromas are more common in heavily roasted coffee.
 
As a rule of thumb, you can assume that a light roast brings out the character of the green coffee better. By the way, it is easier to distinguish light roasted beans from one another than dark ones.

The different degrees of roasting - an overview

Type of roast
Light Cinnamon Roast	extremely light roast that arises before the first crack
Light Roast	light roast, also called pale or cinnamon roast. It is ready around the time of the first crack. Light roasts taste more sour, but hardly bitter. They often have distinct citrus notes.
Medium Roast (American Roast)	medium-strong, medium-brown roast. It is traded as a breakfast roast or American roast, among other things. Very balanced with a full body.
City Roast and Full City Roast	medium to dark brown color. Arises between the first and the second crack.
Dark Roast (Vienna Roast)	dark roast, which can be recognized by the small drops of oil that collect on the coffee bean. It is also called Viennese roast or light French roast. Darker roasts taste slightly sweet, but bitter. They often have strong and chocolate flavors.
French roast	very dark roast. It is also called continental roast or double roast. The surface of the coffee bean is shiny.
Italian roast	very dark roast. By the way, it is also known as espresso roast. The surface of the coffee bean is very shiny.
Spanish roast (Neapolitan Roast)	the darkest roast that is still drinkable. The beans are almost black and the surface dull.
Torrefacto	With this type of Spanish roasting, the coffee beans are roasted with added sugar. The torrefacto coffee is usually mixed as a blend with a regularly roasted coffee. Torrefacto components in coffee blends reduce acidity and bitterness.

 

Roasting time

Even if the degree of roasting has the greatest influence on the aroma profile of the coffee, the total roasting time and the time that each individual phase of the roasting process takes are also important factors.
 
If you roast the coffee quickly, you get more of the desired aromas. The overall aroma of the coffee (fruity, berry-like, chocolatey, nutty) becomes stronger. Please click here to learn more about flavor profile. The number of flavorings that are created at the beginning of the development phase is also higher with fast roasting.

 
In some cases, however, quick roasting doesn't make sense. Because the quick roast enhances all the aromas in the coffee. If we don't want some aromas in our coffee, we have to adjust the roast profile accordingly.
 
For example, some acidity in coffee is usually desirable. In the case of espresso blends, on the other hand, customers often prefer a rather low acid content. Slow roasting gives the organic caffeic acids more time to break down. This makes the coffee less acidic overall. In such a case, slow roasting could be useful.

Final Thoughts

Well, one thing is for sure, roasting coffee is never boring. On the contrary, it helps you learn a lot about your favorite drink. It’s true that when it comes to roasting, things get a bit technical but the actual process is not that difficult to do once the roaster knows what kind of flavor profile suits the bean better.

And now that you know all about the different degrees of roasting, you can try a few different ones and see which ones suit your taste better!