Roast Your Own Coffee at Home

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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

This is going to be messy. Roasting coffee gives of a lot of smoke and a lot of chaff (the thin skin of the bean), so you probably want to do this outside, in a garage or shed, or anywhere else your wife does not mind you making a mess. Also, the surface you set the roasting bowl on should be heat-resistant if possible.

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.

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    52 Discussions

    For those beginning to roast at home, try the fresh roast 500. Its entry level and provides a great introduction. Also madbeanscoffee.com sells green beans.

    Roasting coffee beans is easy and simple but we should take precautions and read the guidelines carefully like in this post. Before doing anything at home you should be aware of the things that might happen while roasting coffee beans.

    I've been home roasting for a few years. Coffee Bean Corral is a great source. They carry ONLY green beans. Selection is good. They are not as pricey as some other sources I've used. I'm currently living on the East Coast, and my orders arrive within a couple of days. Visit their website at www.coffeebeancorral.com Enjoy your home roasting experience. You'll never go back to "regular" coffee again!

    As a roaster i can say that this method does work but should not be compared to commercially roasted coffee's. Modern day roasters are more like magicians. The reality of the coffee world is there is no such thing as consistency. With hundreds of thousands of farms in varying regions threwout the world, with variable weather conditions from year to year, its literally impossible to have the same output from one year to the next. Add variable change every few months the coffee ages and you can start to see some of the nightmares roasters have to deal with. The question now is how do roasters keep the same taste from one year to the next? The answer is comparable consistency. Depending how good a roaster is, they can substitute with other coffee's that match the prior coffee's taste profile to achieve a similiar cupping profile. Air roaster vs commercial drum roaster vs infrared roasting all bring different results...some good...some bad. All in all have fun with it and also have respect to people in the craft. Roasting may seem easy to some, but throw in a few more variables and you start learning how insanly complex it can become.

    1 reply

    I would say that this compares to, but is not the same as, commercially roasted coffee. It is different, as different roasters' coffees are different. It is not the same year to year, or batch to batch, because it is a variable product. Whether that's a good or bad thing is a matter of preference and perspective. (I think of it as very good.) The great thing about roasting for yourself is that you don't have customers expecting March's coffee to taste the same as last August's coffee. I get to change out varieties all the time, and get different flavors. I love that, but others prefer consistency. I am aware of how complex roasting coffee can become, and that as you scale up paying attention to those complexities becomes a requirement. But that's true in most any field I can think of. At the small batch size, taking care of 25% of the complexity takes care of 90% of the quality. So I keep it simple enough that I can enjoy it, and keep my batch sizes small enough that I can keep it simple. And I hope a few other folks can enjoy it that way as well.

    The Coffee Project gives out free samples and instructions to roasting newbies in the US. Email them at orders@coffeeproject.com with your name and address.

    According to other sources, this should take 10-15 minutes of heating; and hold the heat gun about an inch from the beans throughout. Thanks for inspiring me to try this. Results pending from my first effort.

    Quite an interesting method you have here. I'm proud to say I've taken your advice and tried your plan to the dot, and I must say, what a satisfying way to enjoy the freshest coffee you can get! I ordered my beans from The Coffee Project, which you have linked in the 'Ible. I started with one pound of Captain Cook's Kona coffee, which is a Hawaiian bean. I can't say I've ever had a fresher cup of coffee in my life. Wonderful Instructable and a wonderful idea. 5 stars/faved.

    3 replies

    Thanks! I really need to add another couple of steps, or new instructables. I still use the Poppery method for very small batches, and have upgraded to a breadmaker for the bowl/mixer. I'm kicking out much higher volume this way. I'm glad you enjoy it. I love sharing good coffee.

    I know it's been a while and this thread is kind of dead, but just wanted to add: Weissensteinburg, your father may be a vp, but does he actually know what's going on in the roasting plants? I worked for Sbux in management and am originally from York, PA, where the east coast roasting facility is located. I can't even begin to count all of the 5-lb bags I personally opened only to find blackened beans, oily and smelling burnt. I realize that Sbux was created in part to bring the dark roasts popular on the upper west coast to the rest of the country, but the older and more ubiquitous the company becomes, the worse their quality seems to be. (and don't even get me started on the new machines - any barista who doesn't know how to grind, tamp and extract properly doesn't deserve his/her apron, imo)

    This is the coolest instructable I have seen so far. It's bulletproof: saves money, really fun, tastes better, opens you up to a whole new world. My comment is about the grind. If you're making espresso, it turns out that the grind is just as important as the roast. Research it a little, and you'll find that a flat burr grinder is best for a consistent grind. I have to wait for christmas to get something like this, but I wanted a fix that would cover me until then. This technique allows me to have tons of crema and perfect flow every time: If you have a spinning blade type of grinder, you can grind the beans until they have a (ballpark) espresso grind, but there will be large bits in there. Use a fine wire mesh colander (a sieve is too fine), dust the ground coffee into a bowl, and all the chunks are removed. Now it's just a matter of tamping the espresso to a consistent density, which to me seems to be a matter of practice. I am still getting a flat burr grinder. I think I am overgrinding at least 20% of the coffee in order to get the majority of it to an epsresso consistency, and I wonder how this is affecting the taste. At least the espresso flows perfectly now. Maybe I should make an instructable from this - I don't know. If it's a harmful technique, let me know.

    4 replies

    I'll back you up on the importance of the grind. I was blessed to stumble on a cheap burr grinder years ago, accidentally, at Target of all places. Even stranger, it is a Mr. Coffee and only ran $20. I've looked for them again in the years (5? 7? Was it really four houses ago?!?) since, hoping to give them as gifts, but never found any. But mine still kicks out so long as I clean well. I can't say enough about the quality that a consistent grind imparts, though I must admit that I didn't notice till I had to use a blade grinder again. Wow. Espresso comes out richer because all of the pieces are equally minuscule. Drip coffee is better because you don't get those powderized bits from the shattering of the beans on the blades, thus keeping the "mud" out of the cup. And you can also dial in the courser grind for a french press, which is even worse on the mud factor with small pieces. As for your method: I've no idea. I can see how it would work, and can't see a problem to the coffee. Seems a bit tedious to me, but I'm potentially overestimating the actual work involved. So long as you aren't doing days' worth at once; coffee should always be ground at the last practical moment to minimize oxidation. (It's a lot like cutting apples; don't expect the ones from yesterday to still be good.) In other news, I've been hoping to either update this Instructable or create one or two new ones on this. I really want to cover the popcorn popper method better to show how ridiculously easy it is, plus a roasting buddy has yet another popper method, plus I've recently started a heatgun/bread maker method! Should I expand this, or do new ones?

    Oh please, Sysi, tell us how to roast coffee with the popcorn popper. I have been tempted to toss mine but have held on in case something came up...(or someone).. and there was a real need for it.

    Man, that would be awesome if you did one on the popcorn popper method. It would save time for me because I roast two handfuls each night for the next day's espresso. Malabar Gold is my favorite so far...

    I found a small cast iron mortar:
    http://www.amazon.com/gp/product/B0009XHDP8
    that has a nice interior curve to it which makes it easy to focus the heat on the beans. I place mine on the back of a 2" thick cutting board.

    The method for screening out chunks is quite easy, as long as you have a mesh colander as opposed to a sieve. A sieve would take several minutes, leaving you a teaspoon of fine dust, while a mesh colander takes a few seconds and gets all the chunks out.

    In that case, I'll take a few photos when I roast this weekend, and try to get an Instructable up. The popper method is sooo easy. ;-)

    Excellent instructable! I'm deffinately going to try this, I think home-roasted coffee (even my first newbie attempts) would make great Christmas gifts for my coffee-loving family. Any suggestions on what to package it in for gifting? I'm thinking 1/4 pound increments sent Priority mail (probably the day after roasting, with hopes that the beans won't go more than a week before they have a chance to be brewed). Little wax-paper or parchment bundles? Brown paper bags? Ziplocks? Vaccume-packing is out of my price range for now, unfortunately. Any suggestion would be appreciated. Thanks!

    3 replies

    I know that a lot of the green coffee sites I mentioned sell 1# or 1/2# bags that may work for you. I've sent very small batches across the country in Ball jelly jars (from the canning section of your local grocery or mega-store) but I can't guarantee the glass won't break when you get them there. In a pinch, you could actually use ziplock (or whatever branded) sandwich bags. They seal tight, and you can pinch most of the air out first.

    Whetever you do, make sure it is airtight, and you might want to let the beans sit 24 to 48 hours before sealing them up. If you don't they will be more pressurized from the CO2 that they release, and if all the CO2 stays around them they can take on a very flat taste.

    Also, you might not have to worry so much about super freshness. While many people are very particular about the coffee, most people still drink Folgers and the like. To them, 2 month old home roasted coffee is still gourmet.

    Cool, thanks! I found some 1/4 pound bags at Sweet Maria's (I think) that look nice for presents, but I might end up using sandwich bags.