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My procedure for roasting coffee with a popcorn popper and a gas burner.

In a previous post, I discussed my experience with starting to roast coffee using the side burner of my gas grill and a crank-style popcorn popper.

Now I will describe in greater detail my procedure and process for roasting great-tasting coffee at home.


You will only need a few things to get started:

  • A crank-style, stove top popcorn popper,
  • A colander or large strainer (for cooling),
  • A source of heat (a natural gas or propane flame is best)
  • Some green coffee beans

And that’s about it.

I use a “Back to Basics” brand crank-style aluminum popcorn popper.  The one I have has a plastic window on one side of the lid.  The window is nice, but probably not completely necessary.   Target and Amazon both have a number of poppers that would work fine.

Apparently there are some poppers that have plastic gears, and that sounds to me like a bad idea, so I’d look for one with metal gears.

In addition to the popper, I use a regular old colander.  I’m pretty sure it came from a garage sale, or possibly a general retail store.  There is certainly no need to spend a lot on this.


Fire up your flame, and set the popper on top of it.  You’re going to want to let the interior, especially the floor of the pot get nice and hot before you toss the beans in.  I usually give the empty pot about 4-5 minutes over a high flame to warm up.

Loosely measure out a third to a half-pound of beans.  You want all of the beans to remain in contact with the floor of the pot throughout the roast.  I use a small water glass which I think is about 8oz, fill it with beans, and that’s my measure.

Drop the beans in quickly, and immediately start cranking.

Now start watching, sniffing and most importantly, listening.

Very shortly, you will start to smell the coffee beginning to roast.  At first, the scent is very earthy.  It reminds me of the smell of the stalk of a plant, and isn’t all that pleasant.  The good news is, it doesn’t last long.  As the beans roast, they start to smell more like coffee, with notes of burnt oil.  This is good.

Keep cranking the pot, and eventually —within a couple of minutes— you will start to hear a sound like popcorn starting to pop.  This is the “First Crack”.  Just like with popcorn, the first crack will eventually slow and stop.  This is the point where the coffee becomes drinkable.  If you are going for a very light roast, you are very close to finished.

If you are looking for something other than the lightest roast possible, then keep cranking, and keep your ears open.  Within another minute or so, you will start to hear a sizzling sound, often described as sounding like Rice Crispies in milk.  This is the “Second Crack”, and regardless of how dark a roast you are looking for, you are almost finished.

Sometime before the end of the second crack, quickly remove the roaster from the flame and dump the beans into the colander.

In the course of roasting, the beans will shed chaff, and some of it will find its way into your colander.   You don’t want this stuff, since it will detract from the flavor of the coffee, so we’ll separate it in this step.  Once the beans and chaff are in the colander, swirl and toss the beans around.  When they come out of the roaster, they are still roasting, so you want to cool them as quickly as possible.  They will lose heat into the metal of the colander, as well as the surrounding air, so I like to keep them moving for a few minutes.  Agitating the beans also helps more effectively separate the chaff, so give the a toss and keep them swirling.

By the time the beans have cooled, you will almost certainly notice that they are a little bit darker than they were when you pulled the roaster off of the flame.  Keep this in mind when you’re timing the end of your roast.

Let me interrupt here for just a second to talk about roasts.

There are a lot of factors that go into the art of  selecting and achieving a particular roast, and a full discussion is beyond the scope of this little post.  I will vastly oversimplify the question and say simply that a lighter roast will preserve the subtle flavor notes of the particular bean, but will lack boldness and fullness of body.

On the other hand, a darker roast will have the opposite effect, sacrificing delicacy of flavor in favor of boldness and a more full body.

The good news is that there is a reasonably well-defined window, in which just about anything will be at least drinkable.  Assuming the beans are actually roasting, rather than baking (your roaster needs to be hot!), the entry point to drinkability will occur just after  the first crack.

If you keep the roaster on the flame through the end of the second crack, you are very likely to end up with charcoal.

So in general, the “window of drinkability” during roasting goes pretty much from the end of the first crack to somewhere toward the end of the second crack.  Of course, this depends greatly on the beans in question, so should be considered a loose guideline rather than a rule.

Okay, where were we?  Oh yes, the beans were cooling.

There is still one more step:  The beans still contain certain gasses which will affect the flavor of the coffee, so they will need to “Off-Gas”.  Depending on who you ask, the type of bean and roast, the cooled beans should be allowed to off-gas for anywhere from as little as four hours to as much as twenty-four.   I generally put the cooled beans into a mason jar and leave the cap off overnight.

That’s my basic process for roasting green coffee beans.  Nothing here should be taken as a hard and fast rule, it’s just one method that I have found that seems to work well for me.  I would encourage anyone reading this to experiment, and figure out what I have overlooked!

I hope this guide has been as enjoyable to read as it was to write, and anyone has anything to add, or suggestions to make, I’d love to hear them!


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