What Affects Coffee Cleanliness? What Are the COE Cupping Evaluation Items? Why is Brazil the World's Largest Coffee Producer?

The Importance of Coffee Cleanliness

"Cleanliness" (sweetness aside) is the first scoring item in COE cupping. If a coffee fails on cleanliness in the initial evaluation, it fails across the board — which shows just how decisive cleanliness is for a cup of coffee.

What is Coffee Cleanliness?

In coffee, cleanliness means the absence of negative flavors and sensations that disturb the tasting experience. Earthy, hay-like, and woody notes are the classic negative flavors; astringency and roughness are the classic negative sensations.

Causes of Coffee "Uncleanliness"

Coffee can turn "unclean" for many reasons. Harvesting, processing, roasting, and brewing all weigh on cleanliness. Start with harvesting and processing — COE's insistence on cleanliness owes much to how Brazilian coffee was harvested and processed in the era when the program was conceived.

Brazil, as we know, is the world's largest coffee producer: roughly one-third of global output, over thirty million bags (60kg each) a year. Volumes like that simply cannot be hand-picked as fully ripe cherries — a concept that barely existed then. Conveniently, most Brazilian plantations are flat, so Brazil invested in mechanical harvesting. Machines can't judge ripeness the way people can, so ripe and underdeveloped cherries come off the tree together.

And everyone has eaten unripe fruit — that obvious, prominent astringency and flat taste applies to coffee too. But at the time, coffee in Brazil was an ordinary commodity crop that wasn't treated specially. There was no sorting after harvest: everything went straight to the processing plants for a quick sun-dry before export. How quick? Spread the cherries on the ground and let the drying begin. Before specialty coffee existed, most producing countries dried cherries this way, and this crude sun-drying loads the cherries with dust, breeding earthy and hay-like negative flavors. (For more on crude natural drying, see our earlier articles.)

Post-harvest storage was little better — mold and insect damage were common, each adding its own undesirable notes. Coffee then relied on the bitterness of deep roasting to mask these flaws. But as roasting advanced and the mainstream shifted from dark to lighter roasts, the shortcomings came into the open. Producing countries began re-examining the upstream industry, improving harvest and processing, and bean quality rose. Even so, some defective beans always slip through. So before roasting, we hand-sort out the defects first. Now, how do roasting and brewing affect cleanliness?

How Roasting Affects Coffee Cleanliness

During roasting, beans release a great deal of steam as internal moisture evaporates, and the expanding volume forces the silver skin to flake off. The roaster must increase airflow to expel steam and chaff. Left unadjusted, that thin, cicada-wing silver skin scorches in the high heat and becomes tiny carbon particles that cling to the beans — think of charcoal sticking to food, lending burnt, smoky flavors to the cup.

Under-roasting can also cause underdevelopment, bringing green and hay-like negative flavors. And freshly roasted coffee, still loaded with internal gas, both hinders hot-water extraction and creates a rough, scratchy sensation in the throat. All of these count as roasting-imparted flaws that reduce cleanliness.

How Brewing Affects Coffee Cleanliness

This one is easier: under-extraction and over-extraction. Beyond its desirable flavor compounds, coffee contains negative ones as well. Those compounds do release during extraction, but at lower efficiency — with a properly calibrated extraction, positive flavors keep them in check. Under-extract, and they dominate: sharp acidity, greenness, and hay are the telltale flaws of an under-extracted cup.

Over-extract, and those background flaws keep accumulating until they exceed what the positive flavors can mask — the whole cup fills with woody, smoky unpleasantness. Cleanliness, in other words, is the product of every link in the chain. The cleaner the cup, the higher the bean quality, the more accurate the roast, and the more disciplined the brew.

FrontStreet Coffee Recommendation

Brazilian coffee, with its moderate acidity and excellent balance of sweet, bitter, and body, suits medium roasts beautifully — nutty aromas, a mellow cup, just a whisper of acidity, and equal talent as single origin or blend component. Three picks:

FrontStreet Brazil Cerrado Red Bourbon: The classic introduction to Brazil. From the Cerrado region, this pulped-natural Red Bourbon at a medium roast shows creamy peanut, toast, caramel, and hazelnut, with a rounded, non-acidic body and a touch of pleasant bitterness. Great for pour-over and equally at home in a moka pot, espresso SOE, siphon, or French press.

FrontStreet Brazil Queen Estate Yellow Bourbon: From Mogiana near southern Minas, where fertile red volcanic soil builds a full aroma. This rare Yellow Bourbon — a mutation of Red Bourbon — tastes cleaner and fruitier, with sugarcane sweetness plus fruit and chocolate through pour-over, moka pot, or home espresso.

FrontStreet Espresso Blends: Brazil is the first choice for low-acid, balanced espresso formulas. FrontStreet's crema-rich Classic Blend, nutty Specialty Blend, barista-favorite Black Cocoa Blend, and café-oriented Commercial Blend all include Brazil components — chocolate and cream aromas, gentle sweet-sour-bitter balance, and a stability that makes extraction easier to repeat.