Green Coffee Roasting: Coffee Roasting is a Blend of Art & Science
Coffee Roasters apply heat to green coffee in an effort to bring out a balanced taste and optimal flavor. The heat transforms the sugars, proteins, acids, etc to flavors of roasted nuts, malts, chocolate, fruit, berries, flowers and more.
Looking to learn how to roast your own beans? Keep reading.
Why Roast at Home?
Freshly roasted coffee tastes better!
Grinding coffee beans accelerates the loss of antioxidants, so brewing with freshly roasted coffee beans and grinding daily actually makes the healthiest cup of coffee.
Plus, green coffee beans are cheaper, so you can buy more and save!
Other factors also determine the coffee’s flavor. Country of origin or different growing environments will taste different even when roasted the same. The age of the coffee and the processing method will also affect the taste.
Air Roasters vs. Drum Roasters
Air Roasters are similar to hot-air popcorn poppers. Air roasters roast small batches, and are easy to clean. Drum Roasters have a rotating screen drum, allowing larger batches of coffee beans to roast more evenly. Air roasters typically take 8–12 minutes, whereas drum roasters might take 14–20 minutes.
Watch, Smell and Listen!
Ensure that the beans remain in constant motion so none of them become scorched.
Coffee will “pop” or “crack” twice during roasting.
The first crack is when the coffee expands and breaks its husk. Typically around 350°.
The second crack is when the collected moisture expands, and cracks the bean.
Light to medium roasts normally finish somewhere between first and second crack. Dark roasts typically finish after second crack.
You may be able to judge the correct roast level by deciding when you like the smell. But different coffees have different aromas. So it’s usually easier to learn to determine the correct roast level by eye.
• Allow the beans & equipment to cool down for handling.
• Rest/Degass the beans in an uncovered bowl or glass jar at room temperature with low humidity before grinding or storing your coffee beans. Most coffees reach peak taste profile if rested at least 1 day, some can be up to 3 days. Try some experiments and see what your tastebuds prefer.
• Store roasted beans in a cool, dry, dark place in a sealed container. They will begin to deteriorate and lose flavor in about six weeks.
• For medium or light roasts, brew within a month. For darker roasts, you’ll want to brew coffee a little closer to the roast date, no later than day 10 preferably.
• We describe coffee roast levels by color, ranging from light to dark. As the beans absorb heat, they become darker, and oils appear on the surface of the beans at higher temperatures.
Let’s break them down by roast level...
Lighter roasted coffee lends a much sweeter, brighter, tangy taste with a strong scent. The origin flavors of the bean will be more apparent. They are a brighter orange-brown in color, dry with no visible oils.
Light roasts also have higher concentration of antioxidants known as polyphenol chlorogenic acid (CGA), which helps protect against human cell damage and inflammation. This antioxidant is what creates the acidic taste of coffee.
Approximate roasting temperatures: 356°F – 401°F
Light roasted beans reach an internal temperature of 356°F – 401°F. At or around 401°F, the beans pop or crack and expand in size. This is the “first crack”.
The beans are roasted until the “first crack” is heard.
And if Light Roast coffee is not for you, continue roasting…
This is a good place to start experimenting.
Approximate roasting temperatures: 410°F – 428°F, roasted until after the “first crack” but before the “second crack”.
Turning to a medium brown color, medium roasts still have a dry surface. exhibiting more balanced flavor, and the aroma develops into a nutty, cocoa-like and malty character.
Your cup will have a more balanced and sweet taste. The glucose has been heated up and activated, but it also hasn't burned away yet.
Maybe a bit darker? Keep going…
Here you'll find a richer, darker color with some oil beginning to show on the beans, giving them a slightly shiny look. Medium-dark roasts have a heavy body in comparison with the lighter or medium roasts.
Approximate roasting temperatures: 437°F – 446°F.
The beans are roasted to the beginning or middle of the second crack.
The flavors and aromas of the roasting process become noticeable, and the flavors lean more toward spicy, chocolate, and dark berries.
Still not your palate? Almost there!
Dark roasts require careful monitoring to avoid burning the coffee beans; roasting goes much faster once you enter the darker levels.
Approximate roasting temperatures: 464°F – 482°F, about the end of the second crack, or a bit longer if you dare…
The darker roast will caramelize the sugars and the higher acidity will mask the sweetness. Aromas that are toasty, smoky and spicy develop. Sweet and acidic tastes are replaced by the development of bitters.
(note: they will begin to smoke in the roaster as the sugars carbonize.)
Beans are dark brown in color (sometimes almost black) and shiny from the oils.
You lose the characteristics of the beans themselves the darker they’re roasted, the origin flavors are covered up by the flavors of the roasting process. With dark roasts, you get more of a bitter and smoky flavor profile with a less complex/single note flavor and a richer taste.
The beans lose more moisture and the majority of the sugars break down, and as the roast progresses, the taste is increasingly bittersweet. The rich taste leaves the impression that it is a more caffeinated coffee, but the dark roasts have the least amount of caffeine.
Pick some of these amazing Green Beans, start roasting, and tell us about your journey!