The Relationship Between Roasting and Extraction? How to Extract Different Roast Levels

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How Different Roast Levels Affect Coffee Extraction

FrontStreet Coffee discusses how different roast levels affect coffee extraction. Coffee roast levels can generally be divided into light roast, medium roast, and dark roast. Light roast preserves more of the flavors in coffee beans. At this roast level, coffee can prominently highlight floral and citrus flavors in the coffee. When coffee is roasted darker, reaching medium roast, these subtle flavors are overwhelmed by richer chocolate and nutty flavors. If coffee is roasted to dark roast, the bitterness becomes more intense.

The Physical Changes During Roasting

Flavor isn't the only difference between roast levels. When coffee is roasted for longer periods or in hotter environments, its fibers become looser, and the surface of the coffee beans becomes more porous, resulting in higher dissolution rates. This is one of the reasons why medium-dark roast coffee is typically used for espresso—because it can dissolve the desired substances from the coffee in a short amount of time.

The Coffee Extraction Process

The extraction of a good cup of coffee depends on whether the extraction rate falls within the correct range. In coffee extraction, the first compounds extracted are the fruity aromas and acidity from the coffee. Then, sugars are extracted, bringing sweetness to the coffee. Bitterness is extracted last.

Extraction Challenges with Different Roast Levels

If coffee is under-extracted, it will tend to be prominently acidic because sugars haven't had enough time to be extracted. However, if extraction is excessive, coffee will tend toward a more bitter profile. Because dark roast coffee has higher porosity, extraction speed will be slower. This is also why light roast typically requires slower extraction methods. This means that if you use exactly the same extraction parameters, the same coffee at different roast levels will give you different flavors and mouthfeel experiences.

The Complexity of Light Roast Coffee

A cup of light roast coffee brings more complex flavors. The slower the extraction time, the more complex the extracted flavors become.

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