Introduction: Roast Your Own Coffee at Home
Do you want to drink gourmet coffee at near-Folgers prices?
Are you ready for the freshest coffee available anywhere?
Do you want that special blend no one makes?
Want to help 3rd world farmers escape the tyrannical thumb of big-business coffee?
Would you enjoy one-upping a Starbucks connoisseur wanna-be who claims to drink 'good' coffee?
Are you ready to drink the absolute best coffee you can get?
Then come on in, and learn to roast your own beans.
Step 1: A Warning
There are a lot of ways to roast coffee, from an oven to a popcorn popper to a commercial roaster. This is the heat gun method (also called the heat gun/dog bowl method.) I use this most of the time because it can produce excellent results for very little investment and only moderate work.
Before you read further, I should warn you of a few things.
First of all, this is habit forming. Much like sleeping and breathing.
Second, we will deal with some 500 degree F temps here, so you might get burned.
And finally, you run a high risk of becoming a coffee snob. You may soon find yourself wondering how you could stand to drink that coffee from the wonderful locally owned micro-roaster down the street, even though at this very moment you think it is wonderful. You may start using fancy wine-tasting terms to describe how SHG Pocofundo differs from SHB FTO Likimpti. And you are pretty much guaranteed to stop considering Starbucks swill to be coffee, if you have not already. (Not that I'm biased, or anything.)
If you are willing to take these risks, then proceed.
Step 2: Roast! (but Not Before You Read the Following Steps)
Before roasting, you need to gather beans and gear, and prepare a place to roast. But if you are like me (and I know I am!) then you are too impatient to wade through that to get to the fun stuff. So first I'll tell you how, then I'll tell you all the hard stuff.
Roasting is actually really easy. You pour green coffee in a bowl, then heat it with heat gun for a while while stirring it with a metal spoon. When it is roasted enough, you stop and cool it off. Really, it is that simple.
Ah, but how much coffee? Well, that depends on the capacity of the bowl, and on how much you want to do. Each bowl has a maximum amount of beans you can reasonably stir before you spill all over. You need to find out by using a measuring device (I use a 1/2 Cup measure) to fill it. Usually about 1/2 to 2/3 full is all you can stir; measure and put in some green coffee and stir. When you start spilling, that was too much. :-) Since I measure in 1/2 cup increments, I then know that 3-1/2 cups was too much, so I call my maximum capacity 3 cups. Now the hard part. The maximum amount you can roast in that bowl is 1/2 the amount it can hold. Because here is unexpected coffee fact #1: coffee grows when it roasts. Some coffees grow only 25% larger, others (like most Kenya AA) will double in size. So if your bowl can hold 3 cups, and you expect the coffee to double in volume, you can only put 1-1/2 cups in when green. Got it so far? Good.
Bowls also have a minimum amount of coffee they can hold. Generally speaking, you have to cover the bottom about 1/2" deep. (For our non-US friends, that's about 15 mm. I have no idea how many liters are in a cup.) You know it is enough if the coffee beans fill in over the bottom of the bowl behind your spoon. Since most bowls (not all, see later steps) have a very limited range they can hold, I actually keep 3 bowls. One can do 3/4 to 1-1/2 cups, one can do 1-1/2 to 2-1/2, the other can do 2 to 3-1/2. If I need more, I swipe a bigger bowl from a Kitchenaide stand mixer. :-)
It is kind of hard to describe how to point the heat gun at the beans to cook them, so you'll have to look at my wretchedly cheeseball drawing below to understand. Basically, you point the gun down at about a 45 degree angle, towards and parallel with the side. This allows the air to swirl around the bowl, across the tops of lots of the bean at once. If you do it right, it should come shooting back up out of the bowl somewhere in the vicinity of the heat gun (though I rarely am that lucky.) This VERY HOT air will rapidly heat the surface beans. So, since we want all of the beans heated evenly, we start mixing immediately and don't stop until they are done. My roasting buddies and I discuss stirring methods occasionally, but the one that works best is the one that you find you can do for 15 minutes straight and actually mixes all the beans.
Step 3: How to Know When to Stop
A 'green' coffee bean may be a number of shades of green, from a pure green to almost blue to a slightly greenish tan/yellow. Once you start roasting, they slowly change from green to yellow to mildly tan, then slowly darken through a series of browns. If roasted long enough, they turn very black and oily, though even Starbucks rarely overcooks them that far. The range of colors can be seen on the Degree of Roast Pictorial from Sweet Maria's.
Once the beans start turning from tan to a true brown, they will begin to make a cracking noise, known among roasters as "first crack". (Roasters are not always a creative lot.) It sounds like a mix between popcorn popping and walnuts cracking. The bean is rapidly expelling moisture, giving off a cracking noise. This happens at about the same time that the sugars in the bean begin to caramelize. First crack will begin with just one or two cracks, then will quickly gain momentum. Some batches will seem like only a few crack, while others will seem like every bean cracks twice, all at once. But after a few moments, the cracking will slow to a stop. At this point, if you want a light roast, stop roasting.
If you want a medium roast, keep going until you begin to hear another cracking noise, creatively dubbed "second crack". This one sounds like more of a snap, somewhere between snapping a pencil in half and tapping fingernails on a metal desk. This crack is due to the beans cellular structure cracking apart. When you first hear a second crack, you can pull the roast for a medium/dark medium roast. Or you can keep going. At this point you can bring it into a rolling (continuous) second crack, which gets you into the range of a dark roast. The outsides of the beans get oily at this point, and as you keep going you can go past dark to extra dark roast, then Vienna roast, then French roast, then pure charcoal, and finally on to a Starbucks roast. Eventually they can literally just catch on fire.
When you have reached the level you want, turn off the heat source, empty the bowl into a cooling device, and cool away. The next few steps will explain what sort of gear to use.
Step 4: Obtain Some Beans
In order to roast coffee, you will need to get some green coffee beans to roast. There are actually more types of beans than a person can reasonably keep track of, and they can be obtained from many different places.
Many local coffee roasters/shops (not chains) will sell you green beans if you ask. Typically they will charge you almost as much for the green ones as the roasted ones. This is not all that great of a deal, but it can be good to get you started.
I purchase all my beans online, or trade beans with a few roasting friends who also buy online. I get most of my beans from The Coffee Project because of the reasonable price, good selection, 1 pound increments but multiple pound discounts, and the cool burlap bags often they come in. I occasionally get beans from Coffee Bean Direct. One friend buys primarily from Green Coffee Buying Club, which has great deals and is very people-oriented, but also takes a lot more time and work. The Cadillac of online green coffee stores is Sweet Maria's; they carry more types of beans than anyone else, and have some of the highest quality beans, but they also are higher priced to match all that service. (They also have some of the best information available on home roasting anywhere.) There are many, many other places out there to get green beans, possibly including your local micro-roasting coffee shop.
The point is, you need beans to roast, and you will end up wanting a lot of them. I now buy about 3 kinds of coffee at once, and 5 or 10 pounds of each. Lots of coffee. The good news is that green coffee keeps a very long time, so long as it is kept dry and out of sunlight.
Step 5: Prepare Your Working Area
You will need to gather the following tools before you begin:
- a heat gun
- a metal bowl
- a stirring spoon
- something to cool the beans with
Step 6: The Heat Gun
A light (City) roast finishes at approximately 425 f. A true French roast can get as high as 475 f. In order to get to these temperatures, we need to have a heat source that can put out 500+ f heat. There are a variety of sources which can produce this, but none so inexpensive, portable, or prevalent as a heat gun.
If you don't have a heat gun already, you can purchase one at any hardware store. They range from about $15 US to well over $100. Mine cost $17 and has no troubles roasting a lot of coffee, so there is no need to buy the expensive one if you are on a budget. These are basically a serious tool version of a hair dryer; they kick out serious heat and a lot of air and suck a lot of electricity.
Step 7: The Roasting Bowl
You will need a decent bowl to roast the coffee in. Given the high temperatures, stainless steel is the material of choice. Additionally, the steel helps spread the heat and roast the beans more evenly. The real trick is in getting the right shape and size bowl.
The most common name for this method is the heat gun/dog bowl method, because so many people use metal dog bowls to roast in. These bowls are great because they are readily available, come in various sizes, and, because of the shape, they don't transfer heat directly to the surface below them like other bowls do. However, I personally don't use one because I get annoyed with how much the beans spill out of them, and how few beans they hold compared to how much they look like they should hold.
I usually use a stainless steel mixing bowl most of the time. I got a set of 4 sizes for cheap, and they work great. The straight sides aid in keeping all the beans in the bowl when stirring, and I can estimate easily how much can fit in a bowl. There are downsides to a bowl like this; the large, flat bottom easily transfers heat to the surface below it. This can result in burned tables and decks (yep, done both) unless you have a steel-topped table (as I now have) or use a trivet or hot pad or thick cardboard or set it on concrete. Additionally, these bowls (like dog bowls) have a very exact amount of beans that you can roast in them; if you want to do other sizes you need another sized bowl. I have 4 of these, use 3, and keep a dog bowl for mini-batches!
The best bowls I have found are the ones with high sides that slowly taper and round down toward the bottom in a sort of egg shape. The tapered shape allows for a variety of different batch sizes, and the near-vertical high sides strongly resist spilling. The shape also seems to work well to direct the airflow and focus the heat onto the beans. A friend of mine has one that scales from a 3/4 cup batch to a 5 cup batch! When I need a particularly large batch, I swipe the 4.5 quart mixing bowl from our Kitchenaide, and it works wonders, but my wife won't let me keep it for everyday mixing. The only real problems with tapered bowls are the slight tendency to tip (easily remedied a variety of ways) and the probability of burning the surface below if you don't adequately protect it. (A Kitchenaide stand mixer bowl has an extra thick base that slows the heat transfer almost enough to prevent burning.)
Step 8: Stirring and Cooling
You will need something to stir the beans with while they are cooking. While some people have hacked together various automated methods (and I have considered making something based on a power mixer for drywall mud) I still use the same thing most people use: a wooden spoon. They run about $2 anywhere you can buy basic kitchen stuff, though you will probably want to opt for a longer handled one. You will need to dedicate a spoon to this task, because the spoon will turn black. It never catches fire, but after just one batch it will be permanently darkened, and after 5 batches it will impart a slightly smoky taste to your favorite dishes. (And it is not a good kind of smoky taste, trust me on this.) Your best bet is actually to steal your wife's current mixing spoon, and buy her pretty new ones. That way she lets you have them because she gets new ones, and you don't have to ask to buy more. :-)
I also recommend gloves, especially for the mixing hand, and especially in the summer. This is going to get HOT, and you need some protection. Plus the gloves come in handy when dumping out the super-hot bowl.
You will also need to cool the coffee when you finish. There are tons of ways to do this, from carefully hitting them with a slight mist in a very controlled environment (way beyond me) to just setting them on a cookie sheet outside in the winter. When I first started, I would dump the hot beans into a metal colander (did I mention it was metal?) and flip them around a lot until they were cool enough to touch. Then I would spread them on a cookie sheet to cool more while I roasted another batch. A friend actually has a wicker harvesting/chaff sorting thing that is used for rice harvesting; he puts the beans in and flips them in the air till they cool. Nowadays I use the contraption in the photo, which is a metal screen (did I mention metal? That's pertinent!) stapled to the bottom of a 2x4 frame, with small cross bracing under that in the corners. I put that on a box fan which I have elevated off the ground, then blow air up through the beans. It cools very fast.