Light vs Dark Roast: What It Means

Light vs Dark Roast: What It Means

Ever looked at coffee beans and wondered why they can look so different? Some are light brown and dry, while others are much darker, sometimes almost black and with a noticeable sheen. What makes the difference, and what does it mean for the coffee you end up drinking?

It's easy to assume that a darker coffee bean means a stronger cup of coffee. But what do we actually mean when we say a coffee is “strong”? Are we talking about caffeine, flavour, or something else?

To understand the difference, it helps to start with where coffee begins.

Coffee starts as a fruit. The coffee plant produces small fruits called cherries, and inside each cherry are usually two seeds. These seeds are what we call coffee beans.

Before they are roasted, these beans are green, hard and quite unlike the coffee we come to know. They don't have the familiar aromas or flavours of the coffee we drink. We develop those through a process called roasting.

What is roasting?

Roasting is a carefully controlled process involving the management of heat, airflow, temperature, timing and the rate at which the coffee develops throughout the roast. These variables are adjusted at different stages of the roast to influence how the green coffee responds, before the beans are rapidly cooled to stop the roast developing further.

Every green coffee has its own chemical and physical structure. The variety, origin, processing method, moisture content and physical characteristics of the green coffee all affect how it responds to roasting. So two green coffees found in even two different parts of the same country can be fundamentally very different and respond very differently to the same roasting process. 

The differences between Arabica and Robusta are one example of how the type of coffee you're starting with can affect the finished cup. You can read more about this here: Arabica Vs. Robusta.

The important thing to note here is that neither will taste like a finished cup of coffee - the familiar flavours and aromas we associate with coffee are created through the changes that take place during roasting.

This is why roast level isn't simply a matter of how long we leave the beans in the roaster -  we don't simply roast coffee until it reaches a particular shade of brown, even though colour can be a useful visual indicator of roast level. As the roast progresses, heat causes a series of chemical reactions that develop new flavours and aromas. The further the coffee is taken through the roast, the more these roast-developed flavours begin to influence the character of the finished coffee. At lighter roast levels, more of the coffee's original characteristics can remain apparent, which can include floral or fruity qualities. At darker roast levels, the flavours created by the roasting process itself become increasingly prominent, which can often bring more pronounced toasted, caramelised, bitter and smoky notes.

Therefore, the flavours in the finished coffee are the result of both the characteristics of the green coffee and the chemical changes that take place during roasting. The 'roast level' describes how far the coffee has developed through the roasting process, and how much influence the roasting process has had on its final flavour. The way we manage this process for a particular green coffee is called its 'roast profile'.

How Do We Know What Works?

So, if roast level and roast profile affect the character of a coffee, how do we know which approach works best for a particular bean? One of the ways we find out is through a process called cupping.

Cupping is a simple, systematic way of tasting coffee that allows us to compare different coffees and different roast profiles side by side. By preparing and tasting them in the same way, we can assess how the roasting process has changed the flavour and decide which approach works best for that particular coffee.

When we cup coffee, we use the Coffee Taster's Flavour Wheel to help describe what we're tasting. It gives us a shared vocabulary for identifying and communicating different flavours and aromas, from broad categories such as fruity or sweet through to more specific characteristics.

Cupping isn't only something we do when we're deciding how to roast a new coffee. We cup our coffees regularly to make sure they continue to taste as they should. Green coffee naturally varies from crop to crop, and even as a coffee changes over time, regular cupping helps us monitor the flavour and make sure our roasting remains consistent. We work hard to ensure that you get a reliable, consistent cup.

So, What Makes a Coffee Strong?

When someone describes a coffee as strong, they might mean that it has a more intense flavour, more bitterness, more body, or simply that it contains more caffeine. These are different things, and a dark roast doesn't automatically mean a coffee will be stronger in any of them.

The amount of caffeine in a coffee isn't determined simply by whether it is light or dark roasted. The coffee itself, how much we use and how we brew it all affect how much caffeine ends up in the cup.

Roast Level and Brewing Method

Different roast levels can also suit different brewing methods, depending on the characteristics you want in the finished cup. How roast level and brewing method work together is a subject in its own right and personal tastes can vary wildly.

Read more about Filter Vs. Espresso for more on the differences and the impact of bean choice. If in doubt, you can always contact our expert team who will talk you through what to go for.