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Understanding the Finer Points of Coffee Bean Roasting

Scott Rao, an authority on coffee, explains how bean roasts affect flavor, body and caffeine content of a cup of coffee.


From the coffee drinker’s side of the counter, brewing receives the majority of the credit, or blame, for how coffee tastes. Drip, pour over, siphon, French press, etc. — making a cup at work, the average drinker can only choose the method by which water interacts with coffee grounds, and maybe how the whole beans are ground; these are the factors on which things like acidity, sweetness and body are blamed. But roasting, the process that transforms beans from green and soft off the branch to brown and brittle in the bag, is the true genesis of these flavors, upon which brewing can only tinker. To understand how roasting impacts the taste in your cup, we spoke to Scott Rao, the author of multiple books on coffee, including The Professional Barista’s Handbook, Espresso Extraction: Measurement and Mastery and Everything but Espresso.

Below, in an excerpt from his book The Coffee Roaster’s Companion, Rao makes sense of the range of whole beans you can buy to help control your morning cup before the beans are even ground. But he warns that “while all professionals label roast levels based on bean color, there is no consensus on exactly what roast level each name indicates,” so there will always be a bit of variance from roaster to roaster, and the following are by no means the legal definitions. – J. Travis Smith

From The Coffee Roaster’s Companion

Notes on Roast from Scott Rao

Color Changes: The first stage of roasting is commonly known as the “drying phase,” although beans lose moisture at similar rates throughout most of the roasting process. During the first few minutes of roasting, degradation of chlorophyll causes beans to change color from green to yellow. As roasting progresses, the beans change from yellow to tan to light brown, primarily due to Maillard reactions. Late in a roast, as the beans approach first crack [the point at which enough water has evaporated from the beans that they emit a cracking sound], the brown color deepens due to caramelization. In a dark roast, carbonization may turn beans black.

Classic Definitions of Roast Degree: Light roasts offer acidic, floral, and fruity flavors, more delicate aroma, and less body than dark roasts. Dark roasts develop smoky, pungent, bitter, and carbonized flavors. If one takes roasting to an extreme, burnt flavors dominate and body declines.

The coffee industry’s lack of an agreed-upon nomenclature for degrees of roast causes confusion among roasters and consumers alike. I don’t claim to offer the “correct” definitions for different roast levels, but I believe the following descriptors represent common and reasonable interpretations of various roast degrees and bean colors.

The Roasts

Get Crackin’



Cinnamon* roasts are generally dropped, that is, discharged from the roaster, sometime very early in first crack. Few consumers desire the green, grassy, often “peanutty” flavors of a cinnamon roast. However, some larger companies selling beans to cost-conscious consumers favor the very low weight loss of cinnamon roasts.

In the cup: Very acidic, often “green” or “peanutty,” with grassy and floral aromas and very light body.



City roasts are those dropped during the last stages of, or just after, first crack. Such roasts produce light-bodied coffee with very high acidity. City roasts are the current fashion among more progressive, or third-wave,** roasters and have historically been the standard in Nordic countries.

In the cup: Acidic, wine-y, sweet (especially if developed well), and juicy, with floral and fruity aromatics, hints of caramel, and light body. Can be grassy, lemony, and tart if not developed adequately.

Full City


Roasts discharged just before second crack [the temperature at which the beans emit another cracking sound, this one signifying the beginning of their collapse] and the appearance of surface oils are known as full city roasts. Many consumers prefer full city roasts because they offer a pleasing balance of moderate acidity, mellow caramels, and medium body.

In the cup: Caramelly, with ripe fruit and medium body.



Despite what almost everyone has heard, darker roasting does not decrease the caffeine content of coffee beans. Caffeine levels are virtually unchanged by roasting, as caffeine is stable at typical roasting temperatures. Given that beans lose mass during roasting, their proportion of caffeine by weight increases during roasting. Therefore, assuming one brews coffee of all roast degrees with a particular ratio of water-to-ground-coffee mass, rather than volume, darker roasts will yield brewed coffee with higher caffeine content.



Viennese roasts are those dropped in the early moments of second crack, when oil has just begun to migrate to bean surfaces. The standard roast degree offered by Starbucks Corporation is an example of a darker Viennese roast.***

In the cup: Bittersweet, caramelly, pungent, and often nutty or spicy, with heavy, syrupy body.



French roast indicates oily beans with pungent, bittersweet, and carbonized flavors. Such a dark roast makes it difficult to detect a bean’s unique character.

In the cup: Burnt, bitter, and smoky, with hints of caramel; body may be heavy or medium, as body peaks at a lighter French roast and declines with further roasting.



Most Italian roasters drop their coffees at medium roasts, but somehow the darkest, oiliest, and most bitter and carbonized roast level has come to be known as Italian roast. Almost all Italian roasts are rancid by the time they are consumed because their degraded cellulose structures allow rapid oxidation and staling.

In the cup: Burnt, smoky, rancid, and carbonized, with medium body.

* “Cinnamon” relates to the color of the beans at this roast level and has nothing to do with the flavor of cinnamon.

** Coffee importer Timothy Castle coined the term “third wave” in 2000 in reference to a movement refocusing on coffee quality. Castle described the first wave as the emergence of pioneering, quality-obsessed coffee entrepreneurs in the 1960s, ’70s, and ’80s who offered the first modern alternatives to large, institutional roasters. The second-wavers were a group of skilled businesspeople in the ’80s and ’90s who offered quality coffee but were more business savvy and profit oriented than the first-wavers. The third wave developed as a rebellion against the compromises of the second wave and offers a renewed commitment to coffee quality. Common usage of “third wave” has evolved away from Castle’s original definition and now typically refers to companies favoring lighter roasts and brewed-to-order coffee made by hipsters.

*** I think of full city and Viennese roasts as the “crowd pleasers,” though most connoisseurs and third-wave companies frown upon such roasts. Critics contend that a lighter roast highlights a bean’s uniqueness, while a full city or darker roast blunts too much of a coffee’s acidity and delicacy.

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