Classic Definitions of Roast Degree

These beans were photographed at 1-minute intervals during preparation of a French roast.

During roasting, coffee beans change from green to yellow to tan to brown, and, if roasted very dark, black. No universal system exists for naming different degrees of roast; what one roaster calls a "light roast" another roaster may label "full city.”

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 anextreme, 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.

Cinnamon *roastsare generally dropped, that is, discharged from the roaster, sometime very early infirst 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 producelight-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, winey, 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.

Roasts discharged just before second crack 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

Viennese roasts are those dropped in the early moments of second crack, when oil has just begun tomigrate 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.

The microstructure of green coffee is relatively organized and dense, with oils coating the cellulose matrix.¹⁰ As coffee roasts, the generation of steam and carbon dioxide (CO₂) increases pressure within the beans, forcing their structure to expand and pores to enlarge. A couple of minutes before first crack, beans expand enough to begin freeing the silver-colored skin, or chaff, trapped within the folds of their center cracks. When the cellulose can stretch no farther, fissures form within beans and on their surfaces, violently expelling water vapor and gases, creating the popping noises of first crack.

Specialty roasters seeking a light or medium roast typically drop beans between the end of first crack and the beginning of second crack. After first crack, gas production continues, rebuilding pressure within the bean cells. Simultaneously, the bean structure becomes more brittle, setting the stage for second crack. While the primary cause of first crack is the buildup of steam pressure, accumulation of CO₂ is the main driver of second crack. Just before or after the onset of second crack, oils bleed to the bean surfaces; almost all roasters would regard this as an objective indicator of a dark roast.

Bean expansion and the release of water vapor and gases during the cracking phases weaken beans’ cellulose structures and make them more porous and brittle. The darker, more porous, and more brittle the inner beans are, the more developed they are. Sufficient inner-bean development is a prerequisite for great grind quality, high extraction, and elimination of undesirable savory flavors.

Inner-bean development lags behind outer-bean development during roasting. A roaster must skillfully manage the process to ensure that the inner bean is sufficiently roasted by the time the outer bean reaches its intended color. Ideally, the final “spread,” or color difference, between the inner and outer bean should be negligible in a light roast. The darker the roast, the larger the acceptable spread, provided the inner bean has developed to a certain minimum degree. Throughout this book, I will discuss strategies to optimize inner-bean development.

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