From Green Bean to Great Coffee: A Beginner’s Guide to Coffee
Ever wondered what actually happens between a coffee cherry growing on a plant and the coffee landing in your cup?
We talk about coffee being “freshly roasted” all the time, but roasting is actually just one part of a much longer journey.
Before a coffee bean ever gets anywhere near a roaster, it has already been shaped by where it was grown, the variety of coffee plant, the farmer who grew it, how the cherries were picked, how they were processed and how they were dried.
Then it gets to us.
And that’s when we get to play our part.
At Acorns, we roast coffee in small batches, aiming to bring out the character of each coffee rather than making every bean taste the same. We don’t believe there is one perfect roast for every coffee. A delicate Ethiopian and a chocolatey Brazilian coffee are very different things, and we think they should be treated that way. Why not come and see us in action at The Shed in Bordon, Hampshire - find us using this link.
So, let’s go right back to the beginning.
First things first: coffee doesn’t start as a bean
This might sound obvious to anyone who works with coffee, but it’s something many people don’t realise.
Coffee beans are actually the seeds of a fruit.
Coffee plants produce small fruits known as coffee cherries. When they’re ripe, the cherries are harvested and the seeds inside them are removed, processed and dried.
Those seeds are what we call green coffee.
At this point, they don’t look or smell much like the coffee you know.
They’re usually greenish in colour, firm and fairly unremarkable in aroma. There isn’t much of that familiar smell of freshly brewed coffee.
That comes later.
The journey from cherry to cup is a long one.
Where is coffee grown?
Most of the world’s coffee is grown in countries around the equatorial region known as the Coffee Belt.
This stretches broadly between the Tropics of Cancer and Capricorn and includes major coffee-producing regions across Central and South America, Africa and Asia.
But simply saying where a coffee comes from doesn’t tell the whole story.
A coffee’s flavour can be influenced by its:
- Country and region
- Farm and altitude
- Coffee variety
- Soil and climate
- Weather
- How the cherries are harvested
- How the coffee is processed
- How it is dried
- And, eventually, how it is roasted and brewed
That’s one of the things we love about coffee.
Two coffees can both be called “coffee” and yet taste completely different.
What happens after the coffee cherry is picked?
Once coffee cherries have been harvested, the fruit needs to be processed so that the seed can eventually be dried and prepared for export.
There are several different ways of doing this.
And this is where things start getting particularly interesting.
Washed coffee
With a washed coffee, the fruit surrounding the coffee seed is removed before the beans are dried.
The cherries are typically pulped to remove the outer skin and much of the fruit, and the remaining material is removed through washing and/or fermentation before the coffee is dried.
Washed coffees are often associated with a cleaner, more defined cup, allowing characteristics associated with the coffee’s origin and variety to come through clearly.
You might find citrus, floral, tea-like or crisp fruit characteristics in some washed coffees.
But it’s worth remembering that processing doesn’t work like a flavour menu.
“Washed” doesn’t automatically mean “citrus”.
It is one influence among many.
Our favourite washed coffee is our Brazil Santos, that we use in our shops.
Natural coffee
With a natural, or dry-processed coffee, the whole coffee cherry is dried with the seed still inside.
As the cherry dries, the fruit surrounding the seed has a much greater influence on the developing coffee.
Once drying is complete, the dried fruit is removed from the bean.
Natural coffees can often have a more pronounced fruitiness and sweetness, sometimes with flavours that remind you of berries, tropical fruit or dried fruit.
Again, though, there isn’t a simple rule that says every natural coffee will taste fruity.
The coffee’s variety, growing conditions, drying process and roasting all matter too.
Meet our washed Colombia Finca Sofia, Great Taste Award Winning Coffee Bean.
Honey processed coffee
Despite the name, there is no honey involved.
Honey processing gets its name from the sticky, honey-like layer of fruit — called mucilage — that remains around the coffee seed after the outer skin and some of the fruit have been removed.
The coffee is then dried with this layer still attached.
The amount of mucilage left behind can vary, which is why you’ll sometimes hear terms such as yellow honey, red honey or black honey.
Honey processing can create coffees with a combination of sweetness, fruit character and cleanliness that sits somewhere between some washed and natural coffees.
Wet-hulled coffee — Giling Basah
If you’ve explored our Coffee Knowledge Hub, you may have already come across Giling Basah, or wet-hulling.
This is a traditional processing method particularly associated with Indonesia.
Rather than drying the coffee all the way down while the parchment remains intact, the coffee is partially dried before the parchment is removed while the beans still have relatively high moisture content. The beans are then dried further.
It is quite different from the washed, natural and honey processes you might commonly see described elsewhere.
It can contribute to the distinctive character found in some Indonesian coffees, including deeper body and earthy, herbal or spice-like characteristics.
Our Sumatra Mandheling Coffee is a superb example of a delicious wet hulled coffee bean.
What is fermentation doing in all of this?
This is another part of coffee processing that has become much more talked about in recent years.
Fermentation can occur naturally during certain processing methods, as microorganisms interact with the sugars and other compounds present around the coffee seed.
Today, some producers also deliberately control fermentation to influence the flavour of the finished coffee.
You may come across terms such as:
Anaerobic fermentation, where coffee is fermented in an environment with little or no oxygen.
Carbonic maceration, a process borrowed from winemaking terminology where coffee cherries are exposed to carbon dioxide in a controlled fermentation environment.
These processes can produce some wonderfully unusual coffees, with flavours that can be intensely fruity, wine-like, floral or sweet.
But they aren’t simply “better” ways of processing coffee.
They’re different tools.
And ultimately, what matters is what ends up in the cup.
So what is green coffee?
Once coffee has been processed and dried, it becomes what we call green coffee.
This is the coffee that roasters buy.
It can be stored, transported and eventually roasted.
And this is the point where the coffee arrives at our door looking very different from what most people imagine when they think of coffee.
It’s green.
It smells grassy, earthy or cereal-like rather than like your morning espresso.
It is also extremely hard and nothing like the brittle brown beans sitting in your grinder at home.
That’s because roasting hasn’t happened yet.
And roasting changes almost everything.
What actually happens when coffee is roasted?
Roasting is essentially a controlled transformation.
We’re taking a dense, relatively bland green seed and applying heat to it until it becomes the aromatic, brown coffee bean we recognise.
As the coffee heats up, moisture is driven from the bean and a huge number of chemical reactions begin to take place.
The colour changes.
The structure of the bean changes.
Aromas develop.
Sugars and amino acids react.
The bean expands.
Eventually, the pressure created inside the bean produces the familiar sound known as first crack — a series of popping sounds as the beans release steam and gases and their structure changes.
From there, the roast continues to develop.
And this is where the skill of the roaster really starts to matter.
We’re not simply trying to make the beans brown.
We’re trying to decide how far to take them.
Light, medium or dark roast — what’s the difference?
You’ll often see coffee described as a light roast, medium roast or dark roast.
These aren’t completely standardised categories, so what one roaster calls “medium” another might call “medium-dark”.
But as a general guide, roast level changes how much of the coffee’s original character remains alongside the flavours created and developed during roasting.
Light roast
A lighter roast generally allows more of the characteristics associated with the coffee’s origin, variety and processing to shine through.
You may find:
- More noticeable acidity
- Floral characteristics
- Citrus or other fruit flavours
- Lighter body
- Greater emphasis on origin character
This is one reason lighter roasting is often popular with coffees from origins where the natural characteristics of the bean are particularly interesting.
Medium roast
A medium roast sits more towards the middle of the spectrum.
It can offer a balance between the character of the original coffee and the flavours developed during roasting.
You might find:
- Chocolate
- Caramel
- Nuts
- Brown sugar
- Fruit
- Balanced acidity
- More body than a very light roast
For many people, this is a really comfortable place to start exploring different coffees.
It’s also where you’ll find plenty of the flavour profiles we love at Acorns.
Dark roast
Take the roast further and the influence of the roasting process becomes increasingly prominent.
Dark roasted coffees can have:
- Fuller body
- Toasted flavours
- Dark chocolate characteristics
- Smokier or roasty notes
- More bitterness
There is nothing inherently wrong with a dark roast.
It is simply a different style.
The important thing is that darker roasting can eventually overpower some of the characteristics that make a particular coffee unique.
That’s why we don’t believe every coffee should simply be roasted dark.
And here’s an important one: dark doesn’t mean strong
This is one of the biggest misconceptions about coffee.
Someone will often say:
“I like strong coffee, so I want a really dark roast.”
But “strong” can mean several different things.
You might mean:
- Strong flavour
- More bitterness
- Fuller body
- A heavier roast character
- Or simply more caffeine
They’re not the same thing.
A darker roast isn’t automatically higher in caffeine, and a lighter roast isn’t automatically weak.
At Acorns, when we talk about a coffee being strong, we’re usually talking about its flavour and intensity, not simply how dark the beans look.
If you want something darker and more roasty, though, that’s absolutely something we can work with.
Why don’t we roast every coffee the same way?
This is where coffee roasting gets really interesting.
Imagine you’ve got a delicate Ethiopian coffee with floral and fruity characteristics sitting next to a Brazilian coffee with chocolate, nutty and caramel notes.
Would you really want to treat them identically?
Probably not.
Different coffees can behave differently in the roaster because of differences in:
- Bean size
- Density
- Moisture
- Variety
- Processing
- Origin
- Structure
And, just as importantly, they have different things worth highlighting.
A good roaster isn’t trying to make every coffee taste like their house roast.
They’re trying to understand what is already there and make sensible decisions about how to develop it.
That’s the bit we love.
Roasting isn’t about making coffee taste “roasted”
It might sound strange, but one of the easiest things to do to coffee is simply roast it too far.
The darker and longer you take a coffee, the more the flavours created by roasting can dominate.
You can end up tasting the roast rather than the coffee.
Our aim is different.
We want the roasting process to complement the coffee.
If a coffee has beautiful chocolate and nutty characteristics, we’ll want to develop those.
If another coffee has exciting fruit or floral notes, we don’t want to roast all of that character away.
It’s about finding the balance.
And that’s why roasting is as much about listening to the coffee as it is about applying heat.
Why does freshly roasted coffee need to rest?
Now we’ve roasted the coffee.
Surely it’s ready to drink immediately?
Well… sort of.
This is another one of those coffee things that can seem slightly backwards.
Freshly roasted doesn’t always mean ready to drink.
During roasting, gases — particularly carbon dioxide — build up inside the coffee beans.
After roasting, those gases gradually escape.
This process is known as degassing.
And it matters because coffee that’s extremely fresh can behave differently when you brew it.
You might find that espresso is difficult to dial in, the extraction behaves unpredictably, or the flavours simply haven’t settled into the balance you’re expecting.
Give the coffee some time, though, and things start to change.
The coffee settles.
The flavours develop.
The brewing becomes more predictable.
And, importantly, the coffee can simply taste better.
What about that little valve on the coffee bag?
If you’ve ever looked at one of our coffee bags and wondered what the little round valve is for, now you know.
It’s a one-way degassing valve.
It allows gases produced by freshly roasted coffee to escape without allowing air to freely enter the bag.
You’ll sometimes hear customers call it the “smell valve”.
And, to be fair, that’s not a terrible description.
Give the bag a squeeze and you can often get a lovely hit of freshly roasted coffee through the valve.
So how long should coffee rest after roasting?
There isn’t one magic number that applies to every coffee.
It can depend on:
- Roast level
- Coffee origin
- Processing method
- Bean structure
- Brewing method
- How the coffee is stored
- Personal preference
Very fresh coffee can be particularly lively and gassy, while coffee that has rested for a little while can become more balanced and easier to brew.
This is why we don’t subscribe to the idea that “the fresher, the better” automatically means coffee roasted yesterday is the best coffee you can drink today.
Sometimes a little patience pays off.
At Acorns, we deliberately allow our roasted coffee to rest before we serve it.
We’d rather serve a coffee that’s had time to settle into its best than rush it from the roaster to the grinder simply so we can say it was roasted yesterday.
From a coffee cherry to your cup
And that’s the journey.
A coffee starts life as a fruit growing on a plant somewhere around the Coffee Belt.
The cherry is harvested.
The coffee is processed and dried.
The seed becomes green coffee.
It is transported to a roaster.
The roaster develops it through heat.
The freshly roasted coffee rests and degasses.
Eventually, the beans are ground and brewed.
And finally…
you drink it.
That cup might have travelled thousands of miles and passed through the hands of farmers, processors, exporters, importers, roasters and baristas before it reached you.
When you think about it that way, your morning coffee becomes quite a story.
So, what makes a good roast?
There isn’t a single answer.
A good roast isn’t necessarily the lightest.
It isn’t necessarily the darkest.
It isn’t necessarily the roast that produces the biggest hit of bitterness or the most dramatic flavour.
For us, a good roast is one that lets the coffee taste like itself — only better.
The origin matters.
The processing matters.
The green coffee matters.
The roasting matters.
The resting matters.
And finally, the brewing matters.
Every stage has a part to play.
That’s what makes coffee so fascinating.
And that’s why, even after all these years of roasting it, we’re still learning.
From tiny acorns mighty oaks grow.
And from a tiny green coffee seed, an awful lot can grow too.
Want to learn more about coffee?
If you’ve enjoyed following the journey from coffee cherry to roasted bean, there’s plenty more to explore.
Learn from the people who roast it.