What is Coffee Cleanliness? Cupping Cleanliness Definition and Coffee Roasting Considerations

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Introduction

When cupping each coffee bean, FrontStreet Coffee's baristas prioritize not the flavor, but its cleanliness. Cleanliness, as the first scoring item in COE cupping, demonstrates its importance. If cleanliness fails, subsequent scoring items will also fail.

What does cleanliness refer to?

Cleanliness means the absence of off-flavors, astringency, and other unpleasant tastes. Off-flavors are defined as those without a dominant profile, giving a chaotic and unclear sensation. The most common off-flavors include: earthy taste, woody taste, and grassy taste. Astringency refers to the unsmooth sensation when coffee enters the mouth, such as: bitter astringency and sour astringency.

Why is "cleanliness" so important?

Let's understand the emergence of "cleanliness" scoring

Cleanliness (Clean cup) is a crucial evaluation standard for specialty coffee. When the COE cupping standard was first introduced, cleanliness was the primary consideration due to Brazilian coffee beans. Why? Let's start with Brazilian coffee harvesting.

Brazilian Coffee Fruit Harvesting

Brazil produces over 30 million bags (60kg per bag) of coffee beans annually, making complete manual harvesting impossible. What's the solution? Machine harvesting! Due to the flat terrain, Brazil was the first country globally to use machines for coffee fruit harvesting. While efficient, machines cannot screen coffee fruits.

For a major producer like Brazil, coffee fruits are too common to warrant significant manpower and resources for individual screening. Consequently, whether coffee fruits are ripe or not, they are all piled together and sent for processing. Due to varying fruit maturity, each coffee bean has its own characteristics, leading to a very chaotic flavor profile in the coffee.

Brazilian Coffee Bean Processing

After harvesting comes processing. Before the definition of specialty coffee, everyone used sun-drying to dry coffee beans. However, unlike today's methods, the previous sun-drying process was simple and crude. Those with conditions would use concrete floors, while others would use dirt floors, spreading coffee fruits directly on the ground to enjoy "sunbathing."

Obviously, the latter was more common... While coffee fruits enjoyed "sunbathing" on one hand, they absorbed the essence of the earth on the other, making them prone to rotting during the drying process. After all, growing in soil, coffee beans naturally develop earthy flavors, known as "Rioy" flavor, which is the number one killer of coffee cleanliness.

Later, to solve this problem, the Brazilian Coffee Research Institute developed the pulped natural processing method based on Brazil's relatively clean climate. After removing the peel and pulp, the fruits with mucilage are exposed to the sun for 3 days, then machine-dried to 12% moisture content, thereby shortening the sun-drying time and reducing the chance of coffee beans acquiring off-flavors.

Defective Beans

After processing comes storage. Because uniform drying wasn't achieved during processing, the drying degree of each coffee bean varies. Some may not meet the moisture content requirements for coffee bean storage, or may have rotted during drying.

Rotting indicates over-fermentation of the coffee fruit, and the peeled coffee beans will also develop sour, rotten flavors... Beans that haven't been dried to storage requirements are prone to mold during storage or attract insects to feast until old age.

Although current coffee bean quality is much better than before, there are still many defective beans. FrontStreet Coffee selects raw beans before roasting and roasted beans after roasting.

In addition to problems with raw beans, roasting, freshness, and brewing also affect cleanliness.

Problems Caused by Insufficient Damper Opening

Silver skin: Before coffee beans reach the yellowing point, the silver skin begins to separate from the beans. At this time, the roaster contains large amounts of silver skin and water vapor. If the damper isn't adjusted promptly, the high-temperature environment in the roaster causes the silver skin to burn, producing fine carbon particles that attach to the coffee beans, bringing burnt and smoky flavors.

Smoke produced at first crack: When coffee beans reach first crack, they produce large amounts of smoke. If the damper isn't adjusted promptly, coffee beans will absorb smoky flavors. When entering second crack, more smoke is produced. If heat isn't adjusted, coffee beans will appear abnormally oily and develop severe smoky or even gunpowder flavors.

Low Roasting Temperature, Long Roasting Time

Too low heat during roasting extends the coffee bean roasting time. Even if they come out at the same temperature, they will develop some roasting flavors, like "toast flavor," and the flavor profile will be bland.

Brewing "Too Fresh" Beans

For better flavor performance, FrontStreet Coffee suggests resting medium-light roast coffee beans for 3-4 days, medium-dark roast for 5-6 days, and espresso beans for 7 days before brewing.

Freshly roasted coffee beans retain smoky flavors from high-temperature roasting internally, making the throat feel very dry when drinking. Resting beans means leaving freshly roasted coffee beans in their original packaging, allowing them to release gases quietly, and the flavors will gradually become rounded.

Under-extraction & Over-extraction

If coffee is under-extracted, the flavor will appear flat, even developing sharp acidity and green sensations. Over-extraction will extract large amounts of medium-to-high molecular weight flavor compounds, with woody and smoky flavors masking pleasant notes, making the coffee taste very bitter and astringent.

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