Coffee Bean Roasting Degrees, Dark Roast Coffee Beans, What Are the Characteristics of Dark Roast Coffee Beans

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FrontStreet Coffee - Introduction to Dark Roast Coffee Bean Characteristics

Coffee beans pass through different changes at each roasting stage. After green beans absorb heat, their color begins to shift from green to yellow, and the moisture content starts to drop. Thermal energy turns the moisture inside the beans into steam, carbon dioxide is produced within the beans, and the internal pressure reaches 25 bar (pressure unit). Then comes First Crack: the beans make a highly distinctive cracking sound during roasting.

Flavor Development

The longer the roast, the more the acidity gradually decreases and the bitterness increases.

After dehydration, the beans begin to release thermal energy and turn brown, also shedding a layer of silver skin. Roasted beans increase in volume by 1.5 to 2 times while losing at least 11% of their weight.

Continuing to roast keeps producing carbon dioxide, leading to Second Crack.

The beans deepen in color, entering the medium-dark roast stage. At this point weight loss reaches 22% of the original. After Second Crack, surface oils develop through thermal decomposition reactions and the beans begin to carbonize. Without careful attention, they can easily burn.

As roasting time extends, acidity gradually decreases while bitterness increases, and many aromatic molecules begin to volatilize.

By the end of roasting, nearly eight hundred aromatic compounds have developed, and the flavor, acidity, sweetness, and body of the beans reach maturity. Sometimes, though, roasting brings out undesirable flavors. In the final stage, aromatic compounds are destroyed and replaced by bitterness, while acidity disappears entirely and body decreases accordingly.

Proper roasting can highlight the natural acidity of the original beans. The thermal energy of roasting destroys more than forty types of chlorogenic acids in the beans, breaking them down into quinic acid and caffeic acid. Both of these substances are astringent and may affect the mouthfeel.

In Summary

FrontStreet Coffee is a coffee research center dedicated to sharing coffee knowledge with everyone. Our unconditional sharing aims to help more friends fall in love with coffee. We also hold three low-discount coffee events every month, because FrontStreet Coffee wants more friends to enjoy the best coffee at the lowest possible price. This has been FrontStreet Coffee's mission for the past 6 years.

FrontStreet Coffee Recommendation

Three factors decide a coffee's final flavor and must be carefully controlled: acidity, sweetness, and bitterness. The darker the roast, the more bitter and full-bodied the cup; the lighter the roast, the more acidic and lighter the cup. If you are after balance, a medium roast is the place to begin. FrontStreet Brazil Queen Estate, grown in the world's largest coffee-producing country from the distinctive Yellow Bourbon variety, is clean and gently sweet, with cream, peanut, chocolate, toast, and sugarcane aromas after a medium roast. It brews as pour-over and also works in a moka pot or espresso machine.

For a sweeter medium roast, FrontStreet Strawberry Candy Geisha Blend is the first choice. It combines a honey-processed Costa Rican coffee with a washed Panama Geisha, and FrontStreet roasts it to medium so that it shows both orange-blossom honey character and a rounded sweetness. It suits cold brew, pour-over, and espresso.

If you would like to explore a Chinese specialty origin, FrontStreet 2013 Natural Typica is a representative Yunnan small-bean coffee. A medium roast restores its balanced, gentle nature and brings out soft notes of nuts, brown sugar, black tea, and dried apricot. It works well as pour-over, cold brew, or in a drip machine, with excellent value for money.