The Impact of Roasting on Coffee Flavors & Taste

Roasting is the final stage of a coffee’s complex journey from an agricultural product to a roasted bean. We refer to un-roasted coffee beans as green beans, which get their name from their greenish hue. Before roasting, these green beans are dense, nearly flavorless, and smell like grass. The coffee flavors and aromas we cherish are unlocked until heat is applied during the roasting process, and the coffee becomes more soluble and ready for consumption. Roasting is integral to our pursuit of deliciousness that balances art and science.

Loading the raw green beans into the hopper at Sightglass Coffee, photo by Michael O’Neal

Roast Profile: A Recipe for Coffee Flavors

Variables in the roasting process, like time and temperature, significantly influence how acidity, body, and taste are perceived. How a roaster applies these variables is referred to as a roast profile. A roast profile is a recipe created and followed by roasters to achieve a targeted flavor profile. A roaster uses time and temperature to manipulate flavor and highlight a coffee’s true potential. The coffee flavor will ultimately depend on the bean’s chemical makeup, but a roast profile can significantly affect the beans' expression. Even the most experienced roaster can make a low-acid, earthy coffee taste bright and fruity. This is because coffee's flavor compounds are already ingrained in the beans based on environmental factors and the selected processing methodology. However, a roaster can use the roasting process to encourage a coffee to taste more or less acidic and have more or less body, balance, mouthfeel, bitterness, or sweetness.

A roaster’s recipe, or roast profile, is tracked on a graph that measures time in relation to bean and air temperature within the roasting machine. Below is an example of Spyhouse Coffee’s Orion Espresso roast profile. The red line shows the bean temperature in relation to time. The rate of rise (RoR), drawn in blue, shows the rate or speed at which the coffee beans increase in temperature. For example, a RoR of 10 in 30 means the temperature will increase by 10 degrees every 30 seconds. This RoR can be seen on the graph below at 7 minutes into this particular roast. By changing the rate of rise and applying heat at different times throughout the roast, the bean curve (red) and the flavor profile will change. These changes are how roasters can influence and manipulate flavor. 

Roast recipe for the Orion Espresso from Spyhouse Coffee Roasters

This particular roast makes for a highly well-balanced cup that is rich and silky in body. The blend covers a range of chocolate coffee flavors, with balancing notes of dark berries and citrus fruits that round it out. If the roaster had chosen to speed up their rate of rise early on and shorten the roast time, this coffee could shift from a balanced and rich profile to bright and crisp. When brewed as an espresso (a more concentrated brew), it could taste somewhat sour in comparison. In contrast, roasting too slowly (17:00+ minute roast duration) could lead to a flat-tasting or uninteresting coffee.

Roast Degree

When we refer to a coffee as a light, medium, or dark roast, we are talking about its roast level or degree. The visible color of the coffee beans is directly related to the caramelization of sugars that occurs the longer they are exposed to heat. The darker the roast appears the more caramelization has taken place in that coffee. Finding your preference for a certain roast level can be crucial to enjoying your coffee experience. This is because the same coffee can taste dramatically different depending on the degree of its roast. For example, two of the same coffees from Evan’s Brother’s Coffee are sourced from the CODECH cooperative in the Huehuetenango region of Guatemala. This green coffee is higher in acidity than most Central American coffees, which gives the roaster more complexity and allows it to roast at a higher degree without having the taste fall flat. The only difference between these two coffee flavors is the roast degree:

Guatemala Huehuetenango medium roast vs dark roast

Evans Brothers' goal with the medium roast coffee is to showcase the acidity and sweetness in this coffee, highlighting the blackberry, citrus, and milk chocolate flavors. To do this, they roast in slightly smaller batches, add a little more convection (movement of air), and lower the end temperature, increasing sweetness and body. The goal of the dark roast version is to achieve a richer body that balances notes of bittersweet chocolate and mild citric acidity with pleasant smokiness. They do this for the dark roast by increasing the batch size, lowering the airflow, and roasting for longer. It is the exact same coffee that has different taste expressions based on the roaster’s recipe and roast degree.

Finding Your Roast Preference

There is no ideal roast level when it comes to coffee. Your satisfaction will depend on your taste preferences and how you take your coffee. A light roast may taste sour if you like rich, intense, and roasty flavors. A dark roast may be too bitter and intense if you enjoy delicate and nuanced flavors. Generally speaking, the lighter the roast, the easier it is to pinpoint acidity, citrus, and/or fruity flavors. These delicate flavors will present themselves in various ways at different roast levels. When coffee is roasted darker, it will inherit more roasty-taste characteristics.

Try thinking about roasted coffee in relation to toasting marshmallows. A lighter roast is less roasted (toasted) tasting and leaves more raw grain, sugar, or plant tastes and aromas intact. A darker roast has less of the inherent flavor compounds and instead has more toasty characteristics. These roasty flavors result from sugar browning, caramelization of sugars, and dry distillation (the breakdown and burning of plant fibers) due to extended exposure to heat.

When it comes to coffee, if you enjoy lighter, brighter, and more complex tastes, then shoot for a lighter roast. Shoot for a darker roast if you enjoy rich, roasty, toasted, or even smoky flavors. A medium roast might be for you if you want balance or the best of both worlds.

It’s worth mentioning that there are no industry standards for these roast degrees, and everyone has a slightly different definition and spectrum. What may be described as a medium roast by one roaster may be too light for you. To try to keep things as simple as possible, we have developed our own objectively calibrated system of scoring coffee roasts so that we can try to reduce confusion and make sure that we are sending the correct roast levels for each coffee drinker. How do we do this? We analyze every new coffee using a colorimeter, which uses near-infrared light to measure the roast color of the whole-bean coffee and the ground coffee. The tasting notes are then compared with these scores to create the final roast level.

Light Roast Coffee

Light roast coffee should have no visible oils and is light brown or tan in color. Generally, light roasts:

• Contain more perceived acidity (flavor sensation of brightness or pop in a coffee)
• Highlight the complex and nuanced flavors inherent to the bean. 
• Are lighter-bodied and lively; typically containing citrus, fruity, and floral flavors. 

Why drink a light roast? You like a lively, bright, or nuanced cup of coffee. You want to taste the coffee for what it is, how it was grown and processed. You enjoy a unique or interesting coffee experience.

Browse our light roast coffee options.

Medium Roast Coffee

Medium roast coffee is medium brown in color with little or no oils present on the surface of the beans. Medium roasts range from medium-light to medium-dark and are the middle ground between light and dark. Generally medium roasts:

• Combine nuanced flavors inherent to the coffee seeds with roasty caramelized sugars to create a more balanced cup.
• Offers a balance of chocolate and caramel-like flavor characteristics with soft nuanced flavors like citrus or a fruit-like acidity.

Why drink a medium roast? You like a balanced, smooth, rich, complex, or lively cup of coffee. You like some surprises but also enjoy the comforting flavor of bold coffee.

Browse our medium-roast coffee options.

Dark Roast Coffee

Dark roast coffee is dark brown, and the oils within the beans have surfaced from the amount of heat applied in the roasting process. Generally, dark roasts:

• They are lower in acidity; roast characteristics mask the acidity. 
• Reach deeper levels of sugar browning and dry distillation.

Why drink a dark roast? You like a rich, bold, or intense cup of coffee. You love the roasty, bittersweet flavors that make coffee taste like coffee. A dark roast makes the perfect companion if you like your coffee with cream or milk.

Browse our dark roast coffee options.

Tasting notes you’re likely to encounter with different roast levels

An espresso roast is not a degree of roast (light, medium, dark) but a roasting method that suits the espresso brewing process. Espresso is a coffee beverage that results from a unique brewing method. This method uses pressure to extract a small yet concentrated amount of coffee. Espresso will always refer to the brewing method (using an espresso machine), and roasting for espresso is intended to help a coffee taste its best when brewed with an espresso machine.

Why Roast for Espresso Differently than Filter Coffee?

Due to the concentrated nature of espresso, flavors within a specific coffee are intensified through this brewing process. Extraction occurs over several minutes with filter coffee as it drips through a filter. Brewing espresso takes a matter of seconds and thus extracts coffee flavors differently.

Generally speaking, acidic and fruity flavors are extracted first during the brewing process, followed by sweetness and bitterness. Because extraction happens so quickly in espresso, the flavors are more intense, and there is less room for error. For this reason, coffee brewed as espresso may taste brighter, more acidic, or even sour than if it were brewed as filter coffee. To combat “sourness,” some roasters roast darker for espresso, which typically helps diminish acidity. Others choose to preserve flavors that might get lost at a darker roast profile and manipulate or diminish acidity in other ways. Changing the roast recipe and using a slower rate of rise (RoR) might help reduce acidity and increase body, which could translate to a balanced and tasty espresso.

A great example is the medium-light roasted Mass Appeal Espresso from Ceremony Coffee Roasters. Rather than roasting it darker, Ceremony used sourcing and roast profiling (alterations to their RoR and bean curve) to reduce acidity and enhance notes that milk will complement. Ultimately, coffee intended for espresso brewing is typically roasted with balance in mind. In addition, roasters might choose green coffees that are inherently lower in acidity in the first place. If you love a balanced taste, any coffee roasted for espresso will also be a great option for brewing using drip or filter methods.

Roasting has a significant impact on the final taste of coffee. Roasting is the stage in our seed-to-cup journey where green coffee is transformed from an agricultural product into the beans we use for brewing. American small-batch, specialty coffee roasters like Spyhouse, Evans Brothers, and others work hard to experiment and innovate with their sourcing of coffee and how they roast it to build trust with their customers and bring us some of the best coffee on the planet, no matter our preferences.