I first began roasting coffee three years ago. My mother-in-law bought me a roaster for Christmas, and after I was finally able to source a regular supply of green beans, I fell in love, not only with the taste, but also with the addition to my morning coffee ritual.
The problem was that the roaster was a little delicate for life in our house. It made very nice coffee, and it also had a basket to catch the chaff, a reasonable timing system, and a cooling phase for after the roasting was complete, but the roaster itself always seemed to be breaking. The chaff basket was a bit top heavy, so the glass container beneath it would sometimes tip, and it broke twice and had to be replaced at a tidy sum. Then the element burnt out for no reason that I could figure, except maybe that our kitchen is plenty cold on a winter morning and the element may have had too extreme a temperature change. When I looked into the substantial cost of replacing the element and then added in the cost of replacing the glass holders occasionally, it was more than the price of a new roaster, so I thought that I would take a look at some other roasters that were hopefully a bit more durable. What I discovered, however, was that a special roaster is not at all necessary to roasting your own coffee. Not only are there several stove top methods, all of which seem to require a bit of practise, but there is also the standard air popcorn popper, which makes very good coffee with only a little practice, and which has been my primary way of roasting coffee ever since, something like a year now.
Besides making very good coffee, an air popcorn popper is relatively cheap, fairly durable, and widely available. Even good quality poppers can be purchased for under fifty dollars new, and they can often be found in thrift stores for next to nothing. They do not have a chaff basket, or a timer, or a cooling cycle, of course, but a large bowl in front of the spout will do to catch the chaff, and the time will depend on the temperature and your preference anyway, and air cooled beans taste no different than machine cooled beans, so the poppers have the advantage of the roasters in almost every way I can think. Besides, while I am certainly the sort of foodie who delights in preparing things at home, I am not the sort of foodie who expresses this delight mostly through acquiring specialty gadgets, and the popper lets me use something that I have already and lets me hack it for use in ways that it was never intended, all which pleases me very much.
Now, if you are interested in learning to roast your own coffee this way, which is an interest that many people have expressed to me in the last year, the process is fairly simple. First, you need to acquire an air popper if you do not have one already. Pretty much any air popper will do, but it does need to be an air popper rather than one of the mechanical poppers out there, because the beans need the air flow. The only other thing to keep in mind is that a higher wattage is probably better than a lower one, which may be another reason to try a thrift store where you might find one of the old high power, low efficiency, unbreakable units that they used to sell back in the day.
You will then need to find some green beans. This is not a simple thing here in Guelph. Though we do have several places that roast their own green beans, and though they can sometimes be badgered into selling some of them, none of these retailers sell green beans as a regular part of their business, which can be a bit frustrating. There are several options for ordering beans from Toronto, like The Green Beanery and Merchants of Green Coffee, but the closest and most customer friendly source I have found is Eco Coffee in Kitchener. I use them almost exclusively, and I have never been disappointed.
Once you have your beans, fill the hopper of the air popper up to whatever its regular capacity would be for popcorn kernels. Avoid the temptation to fill it too full, because the beans need to circulate freely. Replace the lid, place a bowl under the spout, and turn on the popper. The roasting time will be highly variable, not only because of air temperature and humidity, but because everyone likes their coffee roasted differently, so never just set a timer and walk away from the popper. Instead, do whatever else needs to be done in the kitchen and keep an ear on what the popper is doing, because the progress of roasting will be much more evident to the ear than to the eye.
After a few minutes you should begin to hear a distinct popping or crackling sound. This is called first crack, and it is the sound of the thin outer skins of the beans popping. About this time you should begin to see these skins, delicate, light brown husks, come floating out of the popper into the bowl, as the beans rub the skins off each other and the air blows them out of the hopper. These husks will be few at first, then there will be a bunch of them at the same time, and then they will dwindle again, much the same as popcorn pops, and once most of the husks are spent, the beans will be ready for those who like a light roast.
After a few minutes more, during which there should be very little sound, the cracking will begin again. This, logically enough, is called second crack, and those who like a medium roast should stop roasting just when they hear the first of these cracks. The second crack is caused by the centre part of the bean, where it used to attach to the cherry, popping off as the bean expands. These bits look like little black discs, and they will soon come floating out of the popper as well, slowly at first, then rapidly, and then slowly once more. Once the second crack is complete, the beans will be ready for those who like a dark roast.
Of course, there are those of us who like our beans darker even than a dark roast, who prefer a French roast or even better, and we will need to keep roasting for a few minutes even past the second crack stage, until the beans start to look very shiny and oily. At this point, you may even see a bit of a haze begin to emerge from the popper, like when oil is heated in an empty pan, which is essentially the case as the coffee bean oil hits its smoke point on the side of the popper. This is a good sign that the beans will be dark enough to satisfy even those with the most bitter palettes.
At whatever stage you think your beans are done, you should empty them from the hopper immediately, so that the beans on the outside are not left against the hot metal. Dump them into a bowl and leave them to cool. Ideally, they should sit for several hours, but I generally wait only until they are air temperature before grinding them and making that first perfect cup of coffee.
This may seem like a lot of work for your java, but if you turn the roaster on first thing in the morning and leave it to roast while you prepare the rest of your breakfast, the sound and the smell make for an anticipatory experience that more than pays for the time it takes. I highly recommend at least trying the experiment, and I will even volunteer my assistance if any of you need some help with your first attempt. It will only cost you a cup of your freshly roasted coffee.