Should You Roast Coffee at Home?

Nick Cho

Should you knit your own socks? Should you remodel your own kitchen? Should you bake your own bread? Should you give yourself a pedicure? Should you perform your own appendectomy? The answer to each of these questions is fairly straightforward. If you have the wherewithal to do it, and you'd be happy enough with the outcome, the answer is yes, except probably for the appendectomy.

There are growing number of places that sell green (unroasted) coffee for those who want to roast it themselves at home, and a few options on the market for home coffee roasting machines. If you're considering taking up the hobby—or picking up a home coffee roaster as a holiday gift for someone you love, it's worth making an informed decision. Just because you can roast your own coffee at home, does that mean you should? I suppose the question at hand is ultimately, "Is coffee roasting more like knitting or appendectomies?"

A Quick Roasting Primer

At its most basic, roasting coffee is heating it until it turns brown. The thing is, those also make great instructions on how to take a beautiful prime-grade ribeye steak and turn it into cardboard, so you'll need to know more than that. A lot of us were eating cardboardy steaks back in the 70's and 80's when well-done was more the norm and coffee's been roasted for centuries with similar finesse. With most foods, cooking with heat was first about making it more digestible before it was about more palatable.

With roasting coffee, it's fundamentally about making it brewable, since brewing green coffee doesn't produce anything anyone really wants. A perfect roast is ultimately about the balance between flavors in the green coffee and those that develop during roasting.

Image from All About Coffee, by William Ukers, 1922.

Historically, roasting was done over an open flame in some sort of a pan, with some method of stirring to try to encourage evenness in the process. Mechanized roasting combined those two elements by putting the coffee in a metal contraption that you'd turn over the flame like a rotisserie. Different roasting machines performed the job in different ways, and as fossil fuel-burning roasters came into regular use, you saw a divergence in roasting dynamics depending on the tastes of your market.

American-built roasters were all about speed, which resulted in a more generic coffee flavor profile. Italian roasters were about slow, which maximized extractability while reducing burnt flavors, yielding roasted beans that were suited for the short brew-times involved in making espresso. German roasters, on the other hand, tended to be the most over-built and heavy, sort of like a massive cast-iron skillet for coffee roasting. Not coincidentally, Germany has historically enjoyed a higher quality coffee profile, developing what may be collectively the most picky coffee palates in the world. German-build roasters tend to be the most desired, and you can find many 100 year-old German-built roasters still in use today.

In essence, roasting coffee is a bit like popping popcorn, baking bread, and a little like grilling a steak. Like most of what we call "cooking," it's all about heat energy transfer. The majority of the energy is hot convective air, like a hot-air popcorn popper. "Air roasters" are designed to be purely convective, from modified hot-air popcorn poppers, to "fluid bed" roasters that continually tumble the coffee in a upward wind-tunnel of hot air. "Drum roasters," like those big German rigs, add a rotating drum that tumbles the coffee like a clothes dryer, with the drum itself being heated as well to add some conductive energy transfer. Gas-fueled roasters are the standard for commercial roasters, with temperatures in the roaster getting above 500°F (260°C).

So with that bit of background out of the way, let's get back to roasting at home.


Roasting at Home: Pros and Cons

Home coffee roasting machines are pretty much all electric, many sharing components with toaster ovens. There's a heating element, a fan, something that keeps the coffee moving, and a control mechanism. Different machines offer different levels of control over each variable, but none can directly compare to a commercial roasting machine.

"If a commercial drum roaster is like a cast iron skillet, most home machines are like cooking on aluminum foil."

Can't you just take that big German roaster design and just shrink it down to a 1-pound home roaster size? Well, try that with the giant 1000-degree oven from that popular Neapolitan pizza place in town. Can you shrink that down to toaster oven size? You've got a lot of the same challenges there, with the thermal mass of the machine being the main issue. If a commercial drum roaster is like a cast iron skillet, most home machines are like cooking on aluminum foil. Sure, you can get the job done, especially with a lot of practice, but you're always going to be missing out on the full potential of your raw materials.

Much like any DIY project, one of the main plusses to home coffee roasting is that green (raw) coffee beans are going to cost less per unit weight than roasted coffee—about 50-75% cheaper in fact. Green coffee also has a much longer shelf life than roasted coffee, which means you can stock up on green coffee once every 3 to 6 months rather than the "3 to14 days from roasting" rule of thumb I recommend for roasted coffee.

Do you love the smell of coffee? How about freshly ground or roasted coffee? Here's a little secret that very few people are aware of, unless you're a roaster: Roasting coffee is the best coffee aroma there is, and you only get to experience it if you're around when it's roasting. A sad fact about coffee is that most of the aromas are actually expelled during the roasting process and are essentially considered a waste product.

So home roasting is practical, it's aromatic, what else? How can I forget? It's FUN! Coffee is such a complex taste experience that little changes in the roasting process will result in noticeable changes in flavor. As you gain more experience, these relationships start making more sense, and it's always fun seeing your skills improve, isn't it?


The Verdict

I promise to be as straight-forward and blunt as possible in my articles here, while still presenting different perspectives.

No. You should not roast coffee at home.

The payoff for the trouble simply isn't worth it, especially when it's so easy to find coffee that fits your palate. Because of the smoke, it's a messy proposition, best performed in a screened-in porch or garage. A high-quality result requires a pretty significant equipment investment... which sounds suspiciously similar to performing an appendectomy!

Now if you've read this far and said to yourself, "That's good, because I wouldn't have wanted to roast my own coffee anyway," congratulations, you're a normal, reasonable person who's susceptible to a bit of coffee-expert persuasion.

But some of you are unconvinced. There's simply no dissuading some people, so if you're still committed to taking the home-roasting plunge, here are a few resources to steer you in a good direction.

Go here:

Sweet Maria's: Pretty much the of home coffee roasting. Find your roasting equipment and green coffee here, and delve into the infamous cacophony that is the Sweet Maria's Library, one of the best coffee informational resources you'll find anywhere. They sell Behmor, Gene Cafe, and HotTop roasting machines, any of which are a great choice.

Read this:

Home Coffee Roasting: A great book for beginner and intermediate home roasters alike.

Join the conversation:

Green Coffee Buying Club: If you're geeky enough to get in to coffee roasting at home, you'll probably appreciate this nerd-fest online forum for home-roasters. I know I do!

Have you considered roasting coffee at home? Tell us about your experience with it in the comments below!