Roasting at Home

Roasting your own coffee at home is quite simple. Plus you get that extra satisfaction of being a little more neurotic about your coffee. In this article I show you how I roast my own coffee at home.

Roasted coffee only has a shelf life of about 2 weeks. After that time, you may as well throw it out. It won't be tasting any good. Worse than that, ground coffee only has a shelf life of about half an hour! I recently did a course on coffee and if the lecturer wanted to get across just one point, it was always use fresh coffee. Buying your coffee already roasted can be a nightmare. There are so many traps you have to look out for. How do you know how long the coffe has been sitting on the shelf? How can you tell exactly when it was roasted?

It was after this course I decided to give roasting at home a go. In the course we roasted some coffee ourselves so we knew how to do it when we got home. And we used a really expensive piece of roasting equipment...a popcorn maker. That's right, a $30 popcorn maker. The method for poping corn and roasting coffee is very similar. Both require a few hundred degrees of temperature, and both require the product to be moved around so it doesn't burn on one side. A popcorn machine is perfect for starting out roasting at home.

I've been told there are 2 main kinds of popcorn makers you can buy in Australia. One is good for roasting, the other is too hot. The right machine has a rounded top, whereas the machine which is too hot has a squarish shape. I have the squarish shape (as you'll see in the photos below), and yep, I reckon I'd get a better flavour with a different machine. I reckon this one might be too hot. But I'm still learning too.

Equipment

So let's have a look at what you need to get started. Of course you'll need a popcorn machine, and most importantly, some green coffee beans. They're quite easy to find on the internet. The bonus of green beans is they really do last a long time unroasted. If you're in Australia, give Coffee Snobs a go.

Equipment for roasting coffee at home

Figure 1.0: Equipment for roasting coffe at home.

  1. Popcorn machine
  2. Green coffee beans
  3. Dimatese cup (for measuring)
  4. Spoon
  5. Metal bowl
  6. A few plates
  7. Some roasted coffee (for color reference)

Method

I highly recommend doing this outside or in the garage. Green beans can have a lot of husk still on them, and this husk will come off during roasting and fly around in the air.

First of all set up your roasting area. Place your popcorn machine on a flat surface. During roasting the coffee beans will expand to about double their original size. Popcorn machines are designed to tip out the cooked product when it gets close to the top. If you find your coffee beans keep escaping out the top of the machine, you may have to prop it up with a plate of something.

Popcorn machine proped up to prevent spillage

Figure 2.0: Popcorn machine proped up to prevent spillage

Place some of the already roasted beans on a white plate near the machine. You can use these beans as a reference when trying to get the color of your roast right. Place about a dimatese cup of beans in the machine, and switch if on. The air flow through the cooking chamber will cause the beans to rotate in a whirlpool fashion. Savour the aroma. It is absolutley nothing like coffee at the moment, but that aroma...

Green beans compared to roasted beans

Figure 3.0: Green beans compared to roasted beans.

During the roasting process the beans will double in volume. The color of the beans will also transition from green, to yellow, to orange, to cinamon, then through the depth of colors you're used to in roasted coffee. The figures below show this transition.

Roasting has begun

Figure 4.0: Roasting has begun.

Starting to change color

Figure 4.1: Starting to change color.

Building more color

Figure 4.2: Building more color.

Almost done

Figure 4.3: Almost done.

Roasting complete

Figure 4.4: Roasting complete.

Is it snowing? No, that's just the husk of the beans coming off.

The aim here is to match the color of your reference beans as much as possible. During roasting, use the spoon to pull out a few beans from the cooking chamber and place them close to the reference beans to make it easier to compare the color. Total roasting time will vary but should usually be between 8 and 12 minutes. As I mention above, the popcorn machine I use is hotter than other kinds and so the beans roast faster. I find my roasts usually taje between 4 and 7 minutes. (This is probably way to fast and I'm killing the true flavours and aromas of the beans...)

At some point you should hear the beans start to "crack". This sounds much like corn poping. You can use this as a milestone in the roasting process. However each bean is different in how much time you need to continue to roast after you hear that crack. I roasted some El Salvadore recently that needed to come off very soon after the crack, but the Indian I'm roasting right now stays on a fair bit after.

Knowing when to stop just comes down to feeling and experience. Matching the color to the reference beans, as well as keeping an eye roughly on the time, and when the crack occurs are all good indicators to use. But you will probably be able to tell more drinking the coffee brewed from this roast. It will be quite obvious if this bean needs to be roasted more or less.

Comparing the color

Figure 5.0: Comparing the color.

Once you're confident the beans are done, switch off the machine and pour the beans into the metal bowl. Move the bowl in a circular motion to keep the beans moving. Use the bowl to toss the beans in the air and catch them again. This helps to dislodge any remaining husk. You don't want too much husk ending up in your coffee. Once all the husk is gone pour the beans into a ceramic bowl to cool down.

Cooling the beans

Figure 6.0: Cooling the beans.

Once the beans are cool, store them in an air tight container in a cool dark place. It's also a good idea to let the beans mature for a few days after roasting. The flavour can change quite a bit over that time.

Now all that's left is to enjoy your roast!

The final product: Latte

The final product: Latte.

There are many other methods for roasting your own coffee at home. I've heard of people doing on the stive top in a saucepan or wok, and even actually roasting them in the oven. Whatever method you choose, you'll find roasting your own coffee at home it so easy. And above all, you can roast the beans to your liking, and know exactly how fresh they are.