Coffee starts as a fruit. A cherry, small and red when ripe. Inside is a stone and that stone is processed and roasted to become the coffee bean.

To get from cherry to cup, that stone needs to be extracted, dry out, and roasted. But the step in between (ie. how you remove the fruit from the stone) is where most of the flavor actually comes from. That process is called fermentation.

Microbes eat the sugary pulp that clings to the bean, producing alcohols and acids. Same basic chemistry as bread or beer. Which microbes, how long, how much oxygen, what temperature all of it changes the flavor. The practical upside: you don't need a flavor shot in your coffee. Just pick beans fermented in a way that matches what you want.

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The core processes

There are three classic approaches. Each leaves a different amount of fruit on the bean, which changes what the microbes have to work with.

Process	What happens	Time	Flavor result
Washed / Wet	Skin + pulp removed, thin sugary layer left, bean soaked in water	12–72 hrs	Clean, bright, acidic, clear fruit
Natural / Dry	Whole cherry left out in the sun to dry	Several weeks	Heavy, fruity, sticky sweet
Honey / Pulped Natural	Skin removed, some pulp left on, then dried	Varies	Between washed and natural more "body", less intensity

Washed is the most controlled. Natural is the most chaotic and most flavorful. Honey is the middle-ground. I'm somewhere between a Natural and Honey; Fruit and sour notes make my cup sing.

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Modern / experimental processes

This is where it gets a bit more niche. Producers have started borrowing techniques from winemaking and brewing to push flavors further.

Process	What happens	Flavor result
Anaerobic Fermentation	Cherries sealed in airtight tanks, oxygen depletes as fermentation runs	Syrupy, wine-like, very aromatic
Inoculated Fermentation	Specific yeasts added (wine, beer yeasts) to steer the flavor	Depends on the yeast is much more controlled and intentional
Carbonic Maceration	Sealed tanks filled with CO₂ instead	High intensity, very sweet

I'm definitly more interested to try out different and newer processes. I've had some interesting stuff from Vancouver's own FUNK coffee.

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What controls the fermentation

A few variables matter regardless of which process you're looking at:

• Temperature — warm speeds it up, too hot and you get bad/weird flavors
• Time — more time builds depth, too much and it goes sour or rotten
• Sugar content — the fuel. More pulp left on = more fuel = more potential flavor
• pH — shifts as fermentation progresses, affects which microbes thrive

The main thing I took from this: fermentation is a balance problem. Every lever has a point where it stops helping.

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Brewing to match the process

This the part I hadn't really thought about before. The way you brew should account for how the bean was processed to accentuate the characteristics.

Process	Flavor character	Brew approach
Natural / Experimental	Heavy fruit, intense	Lower temp (~90°C/194°F), coarser grind, faster extraction. V60 or cold brew. Espresso: 1:2.5 ratio, cooler water
Washed	High acidity, clean, delicate	Higher temp (~94°C/201°F), finer grind. Aeropress or thick-paper pour over. Espresso: 1:2 ratio
Honey	Balanced, creamy-ish sweetness	Flat-bottom dripper (Kalita), French press for body. Standard espresso ratios

The logic is: intense beans need a lighter touch in brewing to avoid over-extraction. Delicate washed beans can handle (and benefit from) more precision and heat.

Get out there and cup something new, especailly now you can order all the interesting pour-over choices they have at that fancy cafe downtown. You might find yourself down a fermentation rabbit-hole filled with delicious coffee.

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References

Recent developments in coffee processing: unlocking flavours — Efico

Understanding coffee fermentation: from classic to experimental — Royal Coffee

Coffee fermentation: dry vs wet coffee process — Low Key Coffee Snobs

Coffee fermentation: what is it and how can it improve quality? — Perfect Daily Grind