Roasting, pt. 2: The Equipment and Roasting at Home

The first thing we have to think about is the equipment: what are you going to use to roast coffee? It’s true that you can roast coffee anywhere there’s heat, but I’m about as likely to try roasting coffee in a dryer as I am trying to cook a turkey in one, even if does kind of resemble the real deal.

Innovation is not always a good thing.
Picture by Damien du Toit is licensed under CC BY 2.0

A drum roaster is the most common type of roaster used in the craft coffee industry. They vary in size incredibly, from tiny, one pound tabletop test roasters to monsters that can roast a few hundred pounds of coffee at once. Generally a smaller batch means less inconsistency in the batch. They feature rotating drums that heat up to roast the coffee. They work through both convection and conduction, so some heat is transferred directly to the beans from the drum, but the air catches some of that heat, warms up, and helps roast the beans a little.

There are roasters out there that work exclusively by hot air. Some might have walked into a super market that roasts its own coffee to find something that looks like some kind of mechanical monster variety of a popcorn popper. Don’t trust those. Generally, the heating is uneven and the process automated.

Coffee is only kind of like popcorn, and this is just taking it too far.
Picture by pchow98 is licensed under CC BY NC ND 2.0

That being said, if you want to try your hand at roasting coffee at home, there are worse things you could do than trying to do it with a popcorn popper. So many people have done it by now that it’s basically a science, and some people have gone as far as adding modifications to their poppers. Even if you have an old fashioned stovetop popcorn popper you can manage some decently roasted coffee.

There are other ways if you don’t have a popcorn popper or feel like owning one. The oven is popular, preferably with a perforated pan or something else that has a lot of holes in it—like a mesh colander. You could even go back to the old days and just roast in a cast iron skillet, but be ready for smoke. Like lots of smoke. Like ninja levels of smoke.

Just train your other sense and you'll be fine. Or turn the exhaust fan on, if you want to be lame.
Picture by Martin Cathrae is licensed under CC BY SA 2.0

None of these methods are going to offer you the same quality you would get from a professional roaster. But this is more about process, adventure and bragging rights than making the best coffee in the world. So what’s stopping you? Go out, get some green beans and roast yourself some coffee.

What Happens When You Roast Coffee?

Maybe you wanted to make your own coffee, but growing is difficult and you don’t live on a mountain in the middle of Ethiopia, so you would only be able to grow poor little coffee plants. Or maybe you did grow some coffee but when you processed it you just wound up with a fermenting pile of mush. Either way, somewhere along the line you just gave up and decided to buy some green beans online. Roasting can’t be that hard, right? It’s just, what, baking?

Well, you’re in luck. Anyone with an oven or a stove, or (for the desperate folks out there, a popcorn popper, can roast coffee). Unfortunately, roasting good coffee can be tough. It’s not as simple as just tossing the beans in a heated drum and walking away.

No matter what you’re using, when you toss a bean in the heat, the beans will dry out before anything else happens. Even though some of that moisture was dealt with in the processing, there’s still a little hanging on. One surprising side effect of this is that drier coffee beans will actually roast quicker. So sometimes in the depths of our Maine winters the coffee will roast quicker, despite Jack Frost’s best attempts to cool the process down.

Once the beans are dry they will start to caramelize. That’s right, the same process that makes a decadent sweet is behind coffee’s awesomeness. Okay, maybe not so surprising. There are a lot of sugars in those green beans, but we don’t want them to just be sweet, we want them to be complex.

Coffee is not Kool-Aid
Picture by Arun Joseph is licensed under CC BY NC SA 2.0

Once the beans reach 394 degrees Fahrenheit (give or take a few) they will crack. Think popcorn. It’s an audible sound that is called first crack and is considered the point when coffee becomes drinkable, by most.

Coffee might be popcorn, kinda. Don't tell coffee I said that.
Picture by Janet Lackey is licensed under CC BY NC 2.0

If you keep the heat going until the beans reaches 437 degrees Fahrenheit (again, give or take a few—coffee is complicated), they will actually pop again. At this point, all of the sugars have been caramelized, most of the delicate flavors have been burned off, and there will be a lot of ‘darker’ flavors—think chocolate and smoke. This is also the end of a stage called pyrolysis, which began with first crack, for all of the science-y types out there.

Coffee: a more reasonable and fashionable outlet for the seasoned nerd

Picture by Andrea Allen is licensed under CC BY 2.0

A good roaster wants to balance a nice sweetness with a rich complexity. If you roast a bean too long you risk losing some of the bean’s more delicate flavors, and if you get crazy and decide to keep on going, all you will taste will be the roast. Some appreciate the darker roasts for their chocolate flavor and rich mouthfeel, but some consider dark roasts to be burnt, tasting like carbon and even plastic if the roast goes too far.

Coffee is also not plastic.
Picture by Brenda Anderson is licensed under CC BY NC SA 2.0

There’s not just the level of the roast to worry about, but also how it got there. If you don’t treat the coffee well, heat it gently and keep it constantly moving, you risk beans that are unevenly roasted. This could mean one side is burnt while the other is a nice rich brown, or that maybe the outside is just where you want it to be, but the inside is still green. The resulting coffee can taste, at the same time, burnt and vegetal, a kind of unfortunate conundrum.

Now you know the process: next time we will talk a little bit more about what roasters use on different levels, and how you might go about roasting coffee at home.

Processing, Pt. 2

So we've looked at how to get the bean out of the fruit, but once you have it, what do you do with it? The answer is not to grind and brew, or even roast. Those beans have a ways to go, and before they can even be shipped, they have to be dried to a low moisture content, because moisture, rot and bacteria are like a group of young hooligans that are always hanging out together. The beans are usually dried in beds outside, where they are shifted frequently to speed the process and prevent mold. 

(Photo by skinnydiver is licensed under CC BY-SA 2.0)

The process is also done partially or entirely by machine on some farms. It is important that the process is done properly, neither too quick nor too slow. If it's down too quickly, it risks damage to the beans, while if it's done too slowly unpleasantness may set in via rot or fermentation. Either way, you get some pretty nasty coffee.

I’m not pointing any fingers or anything 
(Photo by JeepersMedia is licensed under CC BY 2.0)

After the coffee has been dried, there's still the parchment around the bean, which is removed by dry milling. Some producers delay milling and let the beans rest with the parchment intact for a few months, which increases the shelf-life of the green beans. Once the beans are milled they must be sorted by density and color to insure consistency within batches. For a roaster, this means he doesn’t have to curse because half of the batch burnt before the other half could finish. For you this means if you buy a pound of coffee it’s going to taste basically the same throughout the whole pound. This can be done by hand, using density tables, and judging color by eye, but infrared is being used more frequently throughout the world.

(Photo by sarahemcc is licensed under CC BY 2.0)

Mostly, the beans are sorted to remove any defect beans, but they can also be graded into different batches labeled by number or letter, or separated into normal coffee beans and peaberries, which are smaller, round coffee beans that are the result of a genetic defect (which isn't to say there is anything bad about them, just to say that they are different; some even hold the peaberry in higher respect than the plain ol’ bean).

Roasted peaberries up close 
(Photo by Tschi is licensed under CC BY-SA 2.0)

After the beans are sorted, they are shipped to importers who distribute them, or sometimes even directly to roasters who have relationships with individual farms. The final step between these green beans and the coffee beans that most people think of is roasting, which we'll cover next post.

Processing, Pt. 1

Let's say that you decide to take everything into your own hands and grow your own coffee beans. You put in the effort of planting the trees, caring for them and waiting a few years, and finally you have some beautiful bright red coffee cherries. As proud as you are, now you must be wondering, how exactly do I turn these into coffee beans?

I bet if you just squeeze hard enough you’ll get coffee, right?
(Photo by skinnydiver is licensed under CC BY-SA 2.0)

Processing, which is removing everything but the sweet bean within, is an important, and sometimes overlooked part of the journey of coffee. There are a few main ways to go about it, and slight variations on them, some of which are associated with different growing regions, but as craft coffee becomes more prevalent this is changing.

Washed coffee is by far the most common processing method. It's consistent, risk free, and produces a clean cup with more crisp and simple flavors. Think of it as the safe sedan of the coffee world. For many people, this is the only type of coffee they've tasted. In washed processing, the cherries are thrown into a machine that removes the fruit,and then the mucilage, or the sticky scraps around the bean, is removed partially by bristles and then finished by fermentation in tanks of water.  The result is a coffee with a clean mouthfeel and clear flavor.

Cherry Pulper (Photo by Coffee Management is licensed under CC BY 2.0)

On the other end of the spectrum is the natural process, which was the first method used. Because it’s simpler than the washed process, it has been common in areas that can't necessarily afford all of the equipment required for washed coffee. All that must be done is pick the ripe cherries and then place them out in the sun until they're dried, like fantastic caffeinated grapes. The coffee is hulled, and voila, naturally processed coffee! The sugars of the cherry and mucilage give coffees processed this way a sweet and rich fruity flavor (like our Brazillian Mogiana). Why is the process uncommon if it's cheap and makes a uniquely delicious cup? It's somewhat of a gamble. Even assuming the weather agrees, there's such a variation in the fermentation that happens naturally that it's guaranteed that there is going to be a lot of inconsistencies within the same batch of coffee, and (unfortunately) at least a little rotting. It's not exactly like playing Russian roulette, but it's a gamble that means decently consistent natural coffees command a high price on the market.

In between these two is semi-washed, also known honey process or pulped natural (it seems no one knows what to call it). Like washed coffee, the cherry is removed from the seed, but the mucilage is left on, so that, like natural coffee, they can be left to dry in the sun or on drying beds. They retain some of the sweetness and mouthfeel of natural coffee, but are a little more refined and a little more stable.

Too much information for you? Relax by looking at these puppies in coffee cups. Next time when we finish talking about processing.

Growing and Picking Coffee

The world’s insatiable need for coffee (or perhaps just caffeine) has to be met somehow. Last post I mentioned that coffee spread pretty quickly, but where did it go, and how much of it?

Coffee is grown in more than 60 developing countries by around 25 milling farmers. Most of those farmers are still small family businesses, but you can find large coffee plantations in the countries with higher production.

There are two types of coffee plants out there, robusta and arabica. Robusta has the benefit of being a little more, well, robust, so it can handle more temperature fluctuation and harsher climates. It has more caffeine, so why do we mostly drink arabica coffee?

Well, that too, but that’s not what I meant exactly

Beans from the Arabica plant taste better. Much better. So much that it’s harder to find a brand that will openly admit to using large amounts of robusta.

There’s also another explanation of robusta’s caffeine content. The caffeine in coffee occurs as a natural defense against getting eaten. So more caffeine might mean more of a buzz for you, but it also means more death for most other things.

Even the smaller farms will generally need some help come harvest time, and some farms also grow other crops in conjunction with coffee. Coffee plants will begin producing fruit three to five years after planting. The fruit itself takes about nine months to ripen.

Don’t worry, the coffee will be ready in about six years. A cup of water while you wait? (Photo by jakeliefer is licensed under CC BY 2.0)

The plant is harvested by hand by necessity. Coffee plants can flower multiple times throughout the year, so this means there will be a mixture of ripe and unripe berries, so pickers have to be careful not to steal from future crops. It's common for the pickers to pass though several times to pick all of the ripe cherries.

(Photo by mckaysavage is licensed under CC BY 2.0)

After the cherries are picked, the have to be processed before they’re of any use to us, a step we’ll learn about in the next few posts.

What Exactly is Coffee?

Coffee is inescapable. You can find it in McDonald's and five star restaurants, the break rooms in offices and just about every gas station around the world. It exists as a simple beverage or a borderline dessert, from whole beans or instant powder. A coffee addiction is an expectation in certain lines of life, and practical necessity for others. But despite it's constant presence in our lives, very few of us know the story of where it comes from or how it got into your cup. Our hope is to change that.

It might be surprising to you that coffee comes from a fruit, though we’re not talking apples or oranges here. 

Pictured: Not coffee
(Photo by atomicbre is licensed under CC BY 3.0)

The coffee cherry is the fruit of a shrub native to Africa and parts of Asia, requiring a mild climate, lots of rain, and if you want to make a decent cup of coffee, a high elevation. 

(Photo by Ignatio Icke is licensed under CC BY 3.0)

1. center cut             2. bean,           

3. silver skin            4. parchment  

5. pectin layer         6. pulp             

7. outer skin                    

We get coffee from the seed, which we call the coffee bean. As you can see to the right, there’s a lot going on in this humble cherry. The bean inside is surrounded by parchment, mucilage and the fruit itself. How exactly do we get the nice brown beans you know and love? It’s complicated, but we’ll get into that later.

No one really know why some humans saw a fruit and decided to take its seed, roast it, and then make a drink out of it, but there is a myth about it. Sometime around the 9th century, a goatherd in Ethiopia was watching over his animals when he noticed that they would become energized and excited after eating the fruit from a certain plant.

Some say that he then decided that he wanted in on that action and ate the fruit as well, then spread the word around to his tribe. Others say that he reported his findings to an abbot at the local monastery where it became used to stay alert during prayers.

Whatever the truth story, we know that by the middle of the 15th century it had made its appearance in Yemen, and from there it spread to the rest of the Middle East, then to Europe, and from there it spread all over the world, imperialists planting it wherever it could grow, most likely because conquering countries takes a lot of energy. It quickly became the drink of choice by everyone from American revolutionary soldiers to the Pope himself. 

This is mow much of the world runs on coffee.
(Photo by Bamse is licensed under CC BY 3.0)

Skip ahead a few centuries and most of us can't face the day without it. Good things spread quickly. Catch us next time to find more about how coffee trees go from seed to tree to bean!