coffee roasting level: How does the roasting level affect the taste and caffeine content?

When green coffee beans undergo roasting, it triggers both chemical and physical changes, and unlocks the aromas and flavours inherent to the raw coffee. The characteristics and flavors of each roast can vary based on the specific roast level and the roasting process applied.

Coffee can develop between 800 and 1000 unique flavor compounds during the roasting process, and several factors influence which flavors emerge in the final cup. However, the roast level and the roasting process are among the most important factors. The roast level chosen accentuates particular flavors. There can be a significant difference in taste if an individual coffee is roasted in to different roast level.

Let's take a look at what coffee roast level is, how many roast levels there are, and how roast level affects the taste of your coffee and its effect on caffeine content.

What is coffee roast level?

Coffee roast levels refer to the degree of roasting the coffee beans undergo. Roasters determine the roast level based on a combination of factors such as roasting temperature, aroma, color, and cracking sounds. It goes without saying that in many cases, the level of roasting is determined solely by color. However, a visual assessment of roast level is rarely accurate.

There are 4 common roast levels widely used by roasters- light, medium, medium-dark, and dark. Light roasts are roasted for a shorter period of time and at lower temperatures, resulting in a lighter brown color, higher acidity, and a more pronounced expression of the origin (growing region) and processing method of the raw coffee.

Medium roasts have a more balanced flavor profile, whereas medium-dark roasts tend to have lower acidity and chocolate notes, at the expense of some of the fruitiness and brightness of light roasts.

Dark roasts, on the other hand, have a robust, full-bodied flavor that is predominantly bitter. Dark roasted coffee lacks all of the delicate and distinct characteristics of coffee, and all coffee tastes almost identical - bitter when roasted dark.

Below are detailed list of roast levels for each of the four major roast level categories. It is important to note that there is no hard and fast rule, and not all of these terms are used or applied consistently.

Light roast (roasted to 196-205 °C)

Here are the lists of popular light roast coffee types.

• Cinnamon Roast
• New England Roast (aka Half City)

Each of these roasts gives the coffee experience its own unique touch.

Cinnamon Roast 196 °C

It gets its name from its light brown color, which is reminiscent of cinnamon. Cinnamon Roast is a very light roast level that is pulled directly from the roaster at first crack at roughly 196 degrees Celsius. Sweetness is underdeveloped, and it is characterized by sharp acidity. Though not widely used for brewing, cinnamon roast is the first stage at which coffee becomes actually drinkable. A roast this light is normally used for cupping and analyzing samples by professional roasters.

New England roast 205°C

New England Roast, also known as Light City, is characterized by its light brown color. At this stage, the roast temperature is around 205 degrees Celsius, nearing the end of the first crack. Coffee is frequently roasted to this level for cupping because the origin can be tasted clearly with little "roast" flavor. It is also a preferred roast for some specialty roasters, highlighting origin characteristics and complex acidity.

A New England Roast gives the coffee a fruitier flavor, but it's not for everyone. For example, the fruity and citrus flavors of light roasted Yirgacheffe might be overpowering, especially if you're used to dark roasted coffee. This roast is generally preferred for milder coffee varieties.

Medium roast (206-2021 °C)

As the roasting process progresses, it reaches the medium roast level. Medium roast is known for its balanced acidity, medium body, and well-rounded flavours that appeal to a wide range of coffee enthusiasts. It is a versatile roast option that can be brewed with various brewing methods. Some common names for medium roast include American roast and city roast. 

Here are some popular medium roasts:

American roasting (206 - 210 °C)

When the roast temperature reaches 206 to 210 degrees Celsius, the coffee beans are at the American roast level. The American roast has a medium brown color, more body with acidic undertones, and is slightly sweeter than the light roast.

At the American Roast level, each individual coffee origin will be at its most distinct flavour. For instance, Burundi coffee will exhibit spicy flavours with chocolate undertones; Sumatran coffee will have earthy taste with a subtle nutty note, and Ethiopian coffee will exhibit a bright, citric acidity along with a fruity flavour.

City roasting (2011-2021 °C )

It is usually roasted at temperatures between 2011 and 2021 degrees Celsius and has a medium brown color. The roast character is slightly noticeable at this point, but the coffee's origin character remains intact. City Roast is often considered the "perfect middle ground" between light and dark roasts . It offers a balanced flavor profile with lower acidity than light roasts and more body and sweetness. Most specialty coffees are roasted at this roast level.

Medium-dark roasts (2021 - 225°C)

A medium-dark roast refers to coffee that is roasted just to the second crack, marked by the initial few cracks. This roast level result in a bolder flavor profile, reduced acidity, and often features hints of chocolate and caramel with a slight bittersweet aftertaste.

Here is the popular medium-dark roast type:

Full City Roasting (2021 - 225°C)

Full City Roast coffee beans are roasted until they reach first few snaps of 2nd crack, a stage occurring between 2021°C - 225°C. It is characterized by a medium-dark brown color with some oil on the surface. At full city, the acidity of the beans is significantly reduced. This is a key factor why they are preferred, particularly among espresso enthusiasts.

The body is fully developed and the flavours become bolder, often with hints of chocolate, caramel with a slight bittersweet aftertaste. 

Dark roast (2030 - 235°C)

Dark roast coffee is characterized by its dark brown color, shiny, oily surface, and roasting past the second crack at temperatures ranging from 130 to 135 degrees Celsius. Dark roast leads to loss of origin characteristics and complexity in coffee, diminishing the unique and interesting flavors that are typically found in lighter and medium roasts. Here in EastAfro Coffee we do not roast our coffee dark. Here are reasons why you should avoid dark roasts.

Here are popular types of dark roasts.

• Vienna Roast
• Italian roast
• French roast

Light, medium and dark roasted: what do they taste like?

The flavor notes in coffee are influenced by a combination of factors, including the coffee variety, the origin of the coffee bean (terroir), the altitude at which it was grown, freshness of the coffee bean and the coffee processing method. However, roast level is equally important and has a significant impact on the flavor and aroma of the resulting brew. The level of roast will not tell you everything about how the coffee will taste, but it will give you an idea of what flavour profile to expect.

This graphic from Ikawa shows how flavours characteristics of the coffee change during roasting.

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Light roast

Light roast coffee frequently exhibits delicately fruity and floral flavors with accentuated acidity, which can be perceived as sour coffee at times. This is especially noticeable in East African coffees, where the combination of high-altitude cultivation and volcanic soil produces higher acidity in coffee beans than in coffee grown other regions such as Brazil. Acidity in coffee is a highly valued quality, and it is typically attributed to the presence of certain acids such as citric acid. These acids are found in high proportions in East African coffee, contributing to its bright and intense flavor profile. However, if roasted very light they tend to taste sour.

Characteristic flavor profile of a light roast

• Lighter body,
• higher acidity, which can sometimes be perceived as sour
• pronounced fruity and floral flavours

Medium roast

Medium roast coffee is distinguished by a well-balanced flavor profile, medium acidity, and medium body. Because the natural sugars have been caramelized further on medium roast, it gives maximum sweetness with a perfect balance of acidity, while retaining many of the coffee's unique flavor characteristics.

Characteristic flavor profile of medium roast

• medium body,
• Medium acidity
• natural sugars are caramelized, achieving maximum sweetness
• more developed fruit and floral flavours

Medium-dark roast

Medium dark roast is distinguished by lower acidity. As roast progress the natural acids diminish. It has richer body, and often features hints of chocolate with a slight bittersweet aftertaste.

Characteristic flavor profile of the medium-dark roast

• strong body,
• low acidity
• Hints of chocolate notes are common
• Bittersweet aftertaste.

Dark roast

Dark Roasted coffee has a robust, full-bodied flavor and tends to have a smoky or burnt taste and has a dark and shiny or oily surface. Dark roast leads to loss of unique flavors of the coffee's origin and complexity, reducing the unique and interesting flavors in coffee.

Characteristic flavor profile of the dark roast

• full-bodied
• lower acidity
• bitter and lacks complexity
• the unique flavors of the coffee's origin are difficult to recognize
• Bitter and burnt tones become more dominant

Which roast level has more caffeine: light or dark roast?

Does dark roast coffee have more caffeine than lighter roasts? Or do lighter roasts have more?

There are some misconceptions about which roast grade contains the most caffeine. Some people believe that the darker the bean, the more caffeine it contains. Others believe that roasting degrades caffeine, so light roasts contain more caffeine.

Caffeine levels are not affected by the level of roasting or the roasting process itself. Caffeine remains stable throughout the roasting process, despite physical and chemical changes in the coffee beans. Caffeine begins to decompose at 285 °C. Because roasting temperatures do not usually exceed 235 °C, the caffeine content remains constant across all roast grades.

 Therefore, if we are talking about individual beans, the caffeine level is the same whether it is light or dark roasted. So, how does the roast level then, affect the caffeine content in a cup of coffee? The impact of roast grade on caffeine level comes from the measuring method used for dosing during the brewing process. In other words, the caffeine level can vary depending on how you measure your dose – spoon or gram – for light or dark roasted coffee.

Let’s clear the confusion. Coffee beans undergo physical and chemical changes during roasting—they lose weight as they lose water and expand in size due to the formation of CO2 pockets inside the beans. The longer the roast time the more pronounced these effects are. Dark roasted beans will thus weigh less and are larger in size than light roasted beans. On the other hand lighter roasted coffee weight more and are smaller and denser. If you ground the dark-roasted coffee bean, each small coffee ground would have less caffeine than a lighter roast of the same bean ground to the same size.

So, how does this affect the caffeine content of a cup of coffee, whether it is light or dark roasted?

Because lighter roasted coffee is denser, if you weigh out 40 grams of coffee for a French press, you will have fewer light roasted beans than dark roasted. Therefore, when brewing coffee by weight, a darker roast requires a greater bean count or volume to equal the same weight as a lighter roast. And if the caffeine content is the same per coffee bean, the dark roast will have more caffeine simply because there are more beans in 40 grams of coffee.

Alternatively, if we measure using a spoon, you will get the opposite effect. Because of their greater size, dark-roast coffees contain fewer coffee beans when measured by volume with a spoon, resulting in a brew with less caffeine per cup than light-roast coffee measured in the same way. In other words, for a lighter roast, you can fit more of the smaller beans in a spoon, resulting in a higher caffeine level.

Essentially, the caffeine content in a cap of coffee is determined by the quantity of coffee used during brewing. Simply increase the amount of coffee if you want more caffeine.

To Summarize :The caffeine content is primarily determined by the amount of coffee used in brewing. If you measure your coffee by weight, a darker roast will contain slightly more caffeine because you use more beans. Light roasts, on the other hand, contain slightly more caffeine than dark roasts when measured by volume (spoon) because they are denser and heavier. Therefore, the difference in caffeine content between light and dark roasts is minimal and depends on how the coffee is measured.