Why Everyone Should Roast Their Own Coffee

Once you go home roast you never go back.

I started roasting my own coffee two summers ago. Now I’m hooked. In fact, I think everyone should roast their own coffee. Not only is it possible to roast your own coffee at home — this may itself surprise some readers — it’s actually fairly simple. In fact, home roasting can be done with as little as a toaster oven, or frying pan and stove. I discuss a recommended method below. But, first I address why anyone would bother with this in the first place.

Why Bother?

1. Taste
What first attracted me to home roasting is the difference in taste. Honestly, if you haven’t tasted freshly roasted coffee, you really don’t know what you’re missing. I can’t overstate this point. Of all the ways to improve your cup, this is by far the most effective I’ve seen. I still remember being startled by my first taste of freshly roasted coffee. I was awe-struck, thinking:

What the hell have I been drinking all this time?!

Coffee is often treated like a non-perishable food-product, stuck next to cans of soup on the shelf (or — god forbid — half open in the freezer). But it really is a fresh food. And, like all fresh foods, it goes bad fairly quickly. After about a week roasted coffee quickly starts decaying into bland, lifeless caffeine-water. Basically, as soon as the beans are roasted, they start releasing aromatic compounds (think “flavor particles”). These compounds smell delicious. But, the more you smell, the less you taste. So, the more time beans spend roasted, the less flavorful they are. (Check out this TED talk for more on the importance of freshness.)

Since a commercial product typically sits around for weeks after leaving the factory and before being used by the customer, the coffee industry spends boatloads of money trying to combat this inevitable result. (Anyone for a nice nitrogen flush?) I’ve even seen a whole PhD thesis about trying to improve methods for industrial roasters to delay staleness. One of the main conclusions of the dissertation is that it’s really really hard to delay staleness. And delay is all you can do. Blandness is inevitable.

But, there is a much simpler and cheaper way to get fresh, delicious, vibrant coffee… roast your own beans at home!

2. Price
A second reason to roast at home is the fact that it’s cheaper than buying roasted beans. Prices vary widely. But, if you buy something decent from a typical retailer, you can expect to pay around $10/lb for roasted coffee. (For instance, Peet’s Major Dickason’s Blend on Amazon.) On the other hand, a pound of good quality, green coffee beans can be found for under $6. One of my favorites, Sumatra Peaberry, sells on Amazon for $7.50/lb.

(Aside: when comparing prices by weight between roasted and unroasted coffee, it’s important to keep in mind that the roasting process dries the beans out, resulting in a 15-20% reduction in mass. The point above stands, however, as it’s typically still cheaper to buy unroasted beans, even with the loss of mass.)

3. Ethical Sourcing
One of the big ethical issues for all coffee drinkers is the exploitation of coffee producers, the farmers who grow the beans. (See here for example.) This is, of course, just one instance of the very large and deeply troubling issue of global trade inequalities, and the exploitation of laborers in developing countries.

You’ve probably heard of “Fair Trade” coffee. Of course, it’s very easy for a company to put the label “Fair Trade” on their product, without it meaning anything. (That said, “Fair Trade Certified” does mean something legally, and is worth looking for.) But, far better than Fair Trade, is what’s called “Direct Trade”. Direct Trade is not a legal category or label. But what it means is that the coffee is not passed through a series of middlemen, each of whom takes a cut. Unroasted coffee can be purchased directly from cooperatives of coffee producers. In other words, by buying unroasted beans, you can know that the farmers are getting a fair deal because you are giving it to them.

Of course, you still ought to be attentive to the reputability of the people you’re buying from. But, buying unroasted gives you much more information. When you buy roasted beans you don’t typically know anything about how the beans were sourced by the roaster. You may not even know where they are coming from. Home roasting therefore helps coffee drinkers to make more informed and more ethical purchasing decisions.

Ok, so let’s say you’re sold. How exactly do you do this?

How To Do It

First of all, you’ll need to buy some unroasted beans. This can be done, as I indicated, on Amazon, or other websites like Sweet Maria’s or Pachamama. A lot of places offer sampler packs, so you can try your hand at different varietals.

Next, you’ll need to pick a method of roasting. You can roast with as little as a pan on the stove or a toaster oven. The weakness of these “you’ve already got everything you need” options is that it’s hard to get a consistent roast. Some beans will come out a little scorched, others blonde. It works, but it’s not ideal. Thus, my recommendation is a hot air popcorn popper.

This is a surprisingly effective—and cheap—method. A hot air popper will roast a batch of beans in about 10 minutes. Hot air poppers can be found at thrift shops for about $5. In fact, old poppers from the 80’s (like the one on the left) are ideal because they run hotter than new ones, some of which don’t get quite hot enough. Of course, plenty of new models work just fine. They sell for about $20–30. (Here’s the one I use.)

If you get serious about home roasting, and do want to buy a purpose built roaster. There are a variety of options. The FreshRoast SR500 is a good, and not too expensive ($179) option. The roasting method is similar to the hot air popcorn popper (i.e., hot air blown through a bubbling bed of beans). But it allows for much more control, and so greater precision. I’ve used it with excellent results.


Things You’ll Need:
1. Popper
2. Colander
3. Spoon
4. Scale
5. Meat thermometer
6. Timer
(These last three are optional, but nice for keeping data. This will help you to replicate results if you find something you really like.)

I recommend that you roast outside. Or, if you live in a cold climate, in a garage or somewhere that you won’t mind getting messy. When coffee beans roast they shed a skin, called the “chaff”, which has a tendency to blow all over the place.

I start by measuring my beans by mass. This step isn’t strictly necessary — but I like precision! I like to roast batches that will work out to a whole number of cups of coffee. So, if I’m making coffee one cup at a time with an Aeropress (highly recommended by the way), using 16 grams of beans per cup, then I want final product to have a mass of some multiple of 16 grams. Let’s say 80 grams for 5 cups. The beans will lose moisture in the roasting process, leading to a 15–20% reduction in mass, depending on the darkness of the roast. I typically prefer a medium roast, so I’d estimate 17% loss of mass. Thus, for 5 cups of coffee, at 16 grams per cup, I’d want to roast around 96 grams. That’s a good size batch for a hot air popper.

Next, load your raw beans into the popper — start your timer and stick the thermometer in, if you’re using them — and fire it up! When they’re cold, the beans may not want to roll over each other. So, for the first few minutes of the roast you may need to agitate them using the spoon. My technique is to scoop the beans from the bottom to the top every 15 seconds or so. The idea is to try to keep all the beans moving. You want them all to get roasted perfectly evenly.

After a few minutes (around 400º F, if you’re using a thermometer) you’ll hear what’s called “first crack”. This sounds almost like popcorn popping (appropriate, no?). The cracking indicates that the internal temperature of the bean is rising and all the wonderful flavor-producing chemical processes are taking place.

After the first crack you’ll want to watch the beans for your preferred color. At this point the beans will make drinkable coffee, so it’s up to you — the roaster — to decide how dark you want your roast. A minute or two after the first crack ends, you’ll begin to hear the so-called “second crack”. This takes place at around 450–460º F. At this point you’re well into dark roast territory. Be careful not to go much beyond this, or you’ll be left with mere charcoal.

(Here is a really helpful guide for monitoring the roasting process. I’ve also summarized the phases of the roasting process below.)

Once you have reached your desired darkness, dump the beans in the colander and swirl them around. You want to cool them off quickly, so that they don’t continue to roast. After they’ve cooled to room temperature, seal them up in an airless container (a ziplock bag works just fine) and you’re good to go!

That’s it! There are lots of refinements to technique (a YouTube search will find you lots of videos). But, this should be sufficient to get you started. I hope you give this a try, and happy roasting!

For reference, here’s the roasting process phase by phase:
1. Yellowing phase: The beans turn from green to yellow, and smell a bit like grass or grains.
2. Cinnamon (a.k.a. the baked good) phase: This is where the beans start to turn beige and then cinnamon colored. There are some wonderful smells during this phase: baking bread or croissants and later cookies. It’s the best.
3. First Crack: This is the popping popcorn sound. The beans should be a light brown color. Oil from inside the bean starts moving towards the surface. After the first crack is finished, the beans are usable, though it will be a very light roast.
4. Intermediary phase: This is the period between first and second crack. Caramelization is continuing, and oils are continuing to move towards the surface of the bean. I usually stop the roast sometime in this phase.
5. Second Crack: The second crack is a little quieter than the first, more like rice krispies in milk. Unless you like a really dark roast, I’d recommend stopping before second crack finishes. Remember, the darker the roast, the more you taste of the roasting process, and the less you taste of the bean itself. Of course, plenty of people like the roasted taste. Just keep this in mind.
6. Charcoal phase: It is possible to drink coffee that has gone all the way through the second crack. But, you’re getting dangerously close to drinking charcoal-water at that point. Beware! At this point the sugars are burnt/burning and the beans quickly turn into horrible nastiness.

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