The first thing you need to make a great cup of coffee is a way to roast the green coffee beans. There are at least three or four different ways to roast coffee.
Coffee roasters are very expensive, and most of them will roast more coffee than you can drink within the freshness limitation. I have tried roasting coffee in a crock pot, using an old cast iron skillet, and using a air popcorn popper. You need to get the coffee beans hot enough to smoke and crack.
The crock pot method of roasting beans worked pretty well, but it took a long time. I have the suspicion that I actually baked the beans instead of roasting them. The cast-iron skillet worked pretty well, it was much faster than a crock pot. But it was really difficult to really control the temperature of the skillet. The results were uneven.
Microwaving Green Coffee Beans
I also tried microwaving the green beans in a small portable microwave I have in my garage. A microwave cooks from the inside out so this is a rather unique method. The oils get pushed out to the surface of the bean much quicker than what happens when the bean is roasted from the outside in. It made a great cup of coffee, but it was a little uneven in the roast.
I suspect you could make a relatively cheap roaster that was pretty effective if you played with this concept a little. The time between first crack, and second crack was only about 15 seconds. An idea that could be patented?
Roasting Green Coffee Beans in Air Popper
Air poppers worked quite well. They were very fast , and they roasted the beans very evenly.
I have used several different kinds and brands. I’m pretty ambivalent about the brand to choose. I will not shill for anyone brand in particular.
I think that I get the best results from a rather large 1400 Watt air popper I picked up at a Goodwill store. This one is a little larger than most air poppers, I seem to have my best results with this one. I feed it about 1/2 cup of green beans per roast. Each roast takes about 3 1/2 to 4 1/2 minutes. Two sessions of 1/2 cup each in the popper, are enough to give me fresh coffee for up to three days. I never roast more than 2 cups in a session.
Experiment with the Popper
You will have to experiment with the popper you choose to find out what works best for you. If you use a 1000 or 1100 Watt popper you may have to roast in lots smaller than 1/2 cup. Alternatively, those less powerful poppers may take more time.
What I found, was that making the batches larger than a half cup tended to weight the beans down enough so that there was a permanent layer on the bottom of the popper that was burnt. Above that, the coffee was fine. Then, if you overfilled even more the popper tended to blow excess green beans out of the popper onto the table.
In other words, you wasted more beans if you overfilled the popper. When you roast coffee beans, the beans will expand and crack. Some of the beans will get blown out of the popper UN-roasted. The skin of the bean (it’s really a dried berry) will come off and be blown out of the popper as the coffee is roasted.
Roasting the green beans is a messy process. There is smoke, there are beans being blown around, and there is chafe that is blown around also. I strongly suggest you roast your beans outdoors. Remember, if you roast indoors your smoke alarms will probably go off! Avoid a visit from the fire department, and do your roasting outside! I do mine in the garage during really bad winter weather. Otherwise I roast outside.
Sieve or Colander
You will also need a colander or a sieve to pour the roasted beans into when the roast is done. The beans will still behind, in fact they will still be cooking. To stop that process you will need a way to cool the beans off. Putting them in a colander or sieve is a good start. Some people use a fan to cool off the beans.
Another way to do it is to simply spray them with a garden-variety spray bottle filled with water. The mist from the bottle hits the hot beans and is turned to steam. In the process of absorbing the latent heat of vaporization most of the heat energy in the beans is removed almost instantly. With practice you will learn just how much to spritz them to get them cool. This is my preferred method of cooling down the beans because it stops the roast almost instantly.
Timer
You also need a timer to time your roast accurately. There are literally hundreds of types of beans you can roast. With many of these varieties the length of the roast is absolutely critical.
30 seconds one way or the other can have a tremendous effect on the taste you get from the same batch of beans. You won’t believe how 30 seconds can change the color of a batch of freshly roasted beans either.
You could literally make up a color chart like the paint stores have full of samples of the same bean roasted to the 3 1/2 minute mark to the 4 1/2 minute mark in 15 second increments.
The change in color and taste is clearly discernible. Perhaps the funnest part of coffee roasting is taking a bean you like and really taste testing it until you get the exact taste that you prefer. Then switch to a different bean and do the same process over again. After a while you will have narrowed your preferences down to two or three favorite beans, and two or three favorite roasts.
The escaping, and expanding gas in the beans causes the foam. This coffee most people will find more tasty than brews made from coffee that is old enough to have the gas already escaped during storage.
Basics of Air Popper Roasting
With an air popper, the basics of roasting are quite simple. Measure out about a half cup of green beans, and place them in the popper like they were popcorn.
Generally air poppers don’t have an on-off switch. You will need to take note of the time, or start your timer at the time you turn on the machine or plug it in. The air popper will start to do its job and heat the beans by blowing hot air on them.
Generally the beans will be somewhat lighter than popcorn kernels. That means the beans are a little more likely to blow out of the popper than popcorn is. Again, let me remind you that this is a slightly messy process. Generally I try to catch the chafe, and non roasted beans in a large bowl I position outside the popper. Do not overfill your popper. It is pointless to do so. The excess will be blown out, and the beans on the bottom will be over roasted, while beans and the top will be blown out or under roasted.
Not much will happen initially when you turn the air popper on. Usually at about the three minute mark you will start to hear a few cracking sounds coming from the popper. This will be the green beans cracking as the oil inside the bean heats up and expands. There are two definite separate intervals during which you will hear the cracking sound. Usually by this time you will note that the beans are smoking and smoke is coming from the air popper. The smoke will have a nice coffee smell to it that is not at all unpleasant.
Cracking Period
Coffee roasters call that first time you hear the cracking sound city roast or first crack. Stopping the roasted this point will give you a lightly roasted, highly caffeinated bean that contains all the delicate nuances of the bean you just roasted.
There will not be much evidence of oil on the outside of the bean If you roast your beans further you will go through the various roast levels you see coffee at.
After the second cracking period you start to get into the dark roast, or French Roast type of coffee. Some people do like dark roast coffee. With this kind of roast the caffeine content is reduced somewhat as the bean has been roasted to the point that the sugars and some of the other chemicals in the bean have been caramelized or burnt off. The length of the roast all depends on your palette.
What is Your Type of Roast?
If you are a sugar and cream type of coffee drinker there is another viewpoint to consider. What type of roast goes best with what you like to drink in your coffee? You have to decide this. That is why I recommend initially keeping it simple and sticking with the same bean. Roast that bean into about four different cups of coffee reflecting roasts of increasing lengths of time. One of those four brews, you will end up having a preference for.
You may end up discovering that your real preference is for cream and sugar and not coffee. And, you may find out your real preference is for the charred taste of a dark roast coffee. You may discover that your preference is for lightly roasted black coffee. If you discover that you fall in the first two preferences as far as coffee goes.
There may not be anything for you to gain by roasting your own beans. If that is the case, just make a point of grinding your own beans and forget about roasting them yourself. I am going to go out on a limb and say that roughly 2/3 of most coffee drinkers will fall in that category. That last third is the group that would get the most out of roasting their own beans.
With an Air popper you will go through the four main types of roast very quickly. Those are light roast, medium roast, medium dark roast, and dark roast. The difference in time for each category is perhaps only about 30 seconds of timing for each category.
Everything happens so fast that you need to watch your timer, and once you shut off the popper you need to move expeditiously to get the beans out of the popper and into your colander. The beans will still be hot and they will still be roasting and smoking. To prevent them from going to the next roast stage you need to shut the roast down immediately. To do that you need to put the fan on them, or spritz them with missed from your spray bottle. This is my preferred method of stopping the process rapidly. With a little practice you will quickly learn how much spray to use for each batch to stop the roast and not over wet your beans.
At this point, take a look at your beans and see how they look. They should be warm still, but not hot. Look at how much oil is on the outside of the bean. Is it commensurate with the kind of roast you wanted?
As the length of the roast goes up the amount of oil on the outside of the bean increases. Light through medium roast coffee has almost no oil on the outside of the bean. Also look to see if you have uniformity of color in the beans. If they are not uniform in color then you may have overfilled the popper, and may need to reduce the size of the batch the next time you roast.
One thing I have noticed is that if I under roast my beans they are much harder to grind. It takes longer in the grinder and the beans sound different in the grinder when they are under roasted. As the length of the roast increases the amount of time required to grind the beans seems to go down.