Light vs Medium vs Dark Roast Coffee

By Robert Parsons October 2, 2020

Roast level is the subject of long-standing debate among coffee connoisseurs. In the battle of light vs dark roast, everyone has an opinion about which produces the most flavorful joe, but ultimately, the only point of view that matters is yours, so let’s look at the roasting process and how it affects acidity, body and taste — the three dimensions that most influence how satisfied you’ll be with your brew.

Roast Level

Roast level reflects both the time beans spend under heat as well as the internal temperature they reach. During the process, beans change chemically through caramelization — known as the Maillard reaction — as well the through the absorption and release of energy called cracking.

Cracking is a two-stage process — called the first and second crack — during which heated beans expand and burst, releasing moisture. The time at which the roasting is stopped in relation to cracking in large part determines the final the roast level.

Acidity

Acidity refers to the flavors the acids in coffee produce. There are more than 30 types of acid in green coffee beans, and while some don’t survive roasting, others profoundly affect how brew tastes. From the chlorogenic acids that make breakfast blends taste bright and energetic to the quinic acid that give dark roasts a smooth finish, acids give coffee much of it’s characteristic flavor.

Body

Body describes how coffee feels in your mouth — its texture, weight and richness. It’s the combination of oils, acids and natural fibers in coffee, and it has a striking impact on flavor. Brewed coffee can be light-, medium-, or full-bodied, and a range of factors from the type of bean used to the way it’s brewed contribute to the final result, but how beans are roasted can either accentuate or soften it’s effect.

Taste

A coffee’s taste is built on acidity and body. The term differs just a bit from flavor — a word that is also used to denote the full sensory impact of coffee from aroma to aftertaste. Each of the five distinct human taste sensations — salty, sweet, sour, bitter and umami — may be impacted by roast level. When comparing light vs dark roast coffee taste, there’s a wide range of diverse flavors.

Light Roast

Light-roasted beans endure the shortest heating time. They reach an internal temperature between 350-400 degrees Fahrenheit, and the roasting process is stopped before or just at the start of first crack. Beans are light brown in color and denser than dark beans because they still retain significant moisture. As a result, they also contain more caffeine.

Light roasting generally preserves acidity. With more types of acid present, lighter roasts tend to retain more of the characteristic flavors associated with varietal beans. Chlorogenic acids, for example, are responsible for creating brightness and deteriorate rapidly under heat as do some of the acids that give coffee fruit-like flavors. Quinic acid, however, develops as other acids degrade and give darker roasts a cleaner finish.

Acidity

Light roasting generally preserves acidity. With more types of acid present, lighter roasts tend to retain more of the characteristic flavors associated with varietal beans. Chlorogenic acids, for example, are responsible for creating brightness and deteriorate rapidly under heat as do some of the acids that give coffee fruit-like flavors. Quinic acid, however, develops as other acids degrade and give darker roasts a cleaner finish.

Body

Body reflects the concentration of dissolved solids in brewed coffee and is affected more by the brewing method than how it’s roasted, but because lightly roasted beans are less oily than darker roasts, the final cup will tend to have a thinner texture.

Taste

Light roast retains a raw earthiness. It’s taste is often described as grassy or wheat-like with notes unique to its origins.

Who will enjoy light roasts?

Light roasts are bright and cheerful due to higher acidity. Their eye-opening nature makes them perfect for the breakfast blends morning people love. They also reflect more of the delicate flavors associated with where beans were grown, so if you like to experiment with coffees from Kona to Kenya, light roasting lets you appreciate their nuances.

Medium Roast

A medium roast is stopped when beans reach an internal temperature of 427 degrees Fahrenheit — just before second crack. Beans become deeper in color and more of their oils are released, but because they also lose more moisture, ounce for ounce, they have less caffeine.

Acidity

Medium roasts have somewhat less acidity. On the pH scale where 0 is the most acidic, water scores a 7, and 12 is the most alkaline, acidic breakfast blends might garner a 4.5 while medium roasts will earn a 5.

Body

More dissolved solids are released when medium roasts are ground, resulting in deeper body. Oils and other volatile compounds contribute to a thicker texture and clingy mouthfeel.

Taste

Oils and other compounds make medium roasts feel more substantial and for some, it improves the way complex notes linger and develop in the mouth. Flavors are more developed and lack the raw acidity of lighter roasts while still being vibrant enough to reflect the beans’ varietal origin.

Who will enjoy medium roasts?

Medium roasts are the go-to for a balanced cup of joe. The lower acidity is a blessing for those for whom coffee causes an upset stomach, and the flavors are impartial enough to match with a variety of foods at different times of day. Breakfast lovers might find it a little tame, and dark roast aficionados may call it downright dull, but for most, in the battle between light vs dark roast, it’s a perfectly happy medium.

Dark Roast

Dark roasts undergo longest heat. The roasting process is stopped at second crack, and the beans are dark enough to look like chocolate and are covered by an oily sheen. Surprisingly, they also have the least amount of caffeine.

Choosing darker roasts can be confusing. French roast, Italian roast and Continental roast are among the dozen or so designations that might label dark coffee beans, but the roasting times differ and so will the taste.

Acidity

As beans roast, the acids that contribute most to coffee’s taste degrade with one exception – quinic acid. This is the acid responsible for giving dark-roasted coffee a cleaner finish, but it’s also the most likely to give drinkers an upset stomach. Concentration reaches its peak in French roasts, then decreases as roasting progresses, giving coffees in the dark-roasted spectrum slightly different levels of acidity.

Body

Roasting releases oils that add heft to brewed coffee. Expect a thicker brew that approaches syrupy and helps flavors stick to the palate.

Taste

At this stage of roasting, brightness is overwhelmed and notes of origin disappear, but as more oils are released, they add to the texture of dark roasts and contribute to the overall depth of flavor. When comparing light vs dark roast coffee taste, connoisseurs describe dark roasts as bold, smoky and sometimes even sweet, while those favoring light roasts call it heavy and charred.

Who will enjoy dark roasts?

At this level, anyone expecting to taste the difference between varietal beans may be disappointed, but if you need a brew that stands up to lots of cream and sugar or just enjoy deep-roasted flavor, darker roasts are for you.

It’s important to remember that roast level is only one factor that shapes the flavor of coffee, so choose one that reflects your preferences, but don’t be afraid to trial lighter and darker brews. Like fine wine, it’s the differences that make coffee grand.