Coffee Expert Kevin Sinnott Explains What You Need to Know to Home-Roast Your Own Coffeebeans

Written by
Kevin Sinnott, coffee expert and founder of CoffeeCon.
Kevin Sinnott, coffee expert and founder of CoffeeCon. (The original image is no longer available, please contact KCRW if you need access to the original image.)

Think you’re a coffee nerd? It’s hard to trump Kevin Sinnott. At any given time he has 20 coffeemakers in his kitchen. He is a coffee expert, author of The Art and Craft of Coffee and the creator of CoffeeCON, the world’s first consumer coffee conference and onsite brewing university. Lucky for us, he’s also a frequent guest on Good Food.

This year’s CoffeeCon takes places this Saturday, May 4th outside of Chicago. Coffee roasters, baristas, bloggers and enthusiasts can attend 40 different classes on topics such as the best pour over methods, olfactory development and siphon brewing. Since we in LA cannot attend, we asked Sinnott to give us a mini-lesson on what we see as a growing coffee trend: home roasting.

You can start with a simple air corn popper. Believe it or not, it’s a similar process. The trick is to put enough beans inside that a “floating bean bed” forms, where the beans stay airborne in a formation. They pop, or crack as it’s called in coffeedom, but instead of bursting into a puffed kernel they turn brown, then go darker as you roast longer. You can remove them any time you wish, but once they start cracking in double time, smokes gets heavy. Better be outdoors! Don’t singe them of you will have to start a multinational chain and, oh that’s right we already have one.

Do you start with “green beans?” Where do you order them?

There are lots of online green suppliers. You might even talk your local coffee roaster in town into letting you purchase some from them to a trial flight. One that I like is Green Buying Club . Their prices are reasonable, inexpensive enough to let you experiment and breath easy. You’re going to make some mistakes. I have – what an understatement!

How do you know when the roast you want is done?  By timing, color, aroma?

Timing works only if you’re experienced, but even the experienced roasters use their other senses. Color is perhaps ideal, but it requires a practiced eye and it’s hard to see the beans in detail while they’re being tossed around. Aroma is helpful. In fact, early in the roast, the aroma may not be pleasant, but as it goes along it gets sweeter. Sound is the most reliable, only made difficult because so many roast methods involve noisy fans. But, discerning the first crack is critical. Once I detect first crack, I use my eyes and nose to note minute differences between roasts.

Is there a different technique for roasting espresso beans than roasting coffee beans?

Espresso extracts differently and there’s no doubt that those differences change the flavor balance in the cup. Generally speaking, a lighter roast that tastes perfect in a Chemex will taste overbright and acidic as an espresso. The trick for the home roaster is to not go too far in the dark direction for espresso. A little bit goes a long way. Some advanced home roast machines offer roast temperature options to extend the time and flatten the bean brightness in order to optimize the coffee for espresso.

Describe the flavor differences between freshly roasted coffee and coffee that was roasted a week, month or even 6 months before.

Fresh roasted coffee is bright and can even have a slight carbonated quality you might describe as sparkling. In fact, a lot of carbon dioxide is released 24 to 48 hours post-roasting. Some home roast aficionados swear that you must wait a day or two before brewing. I think this is not settled law, but there is no doubt you will get some foaming if you brew right after roasting and a little resting definitely reduces this. Out about a week from roasting the beans will foam less, and this does improve the ability to brew and may actually result in a more flavor, because none of the grounds flee their responsibility by floating on the foam. Whether it’s science of conditioning I do agree some coffees taste better a week out. Two weeks out this advantage starts to disappear. The coffee is still good but little or foaming happens. A month out, the foam is gone, and the coffee, while delivering pleasant flavor, starts to taste flat. Six months out, I am no longer amused. It’s undrinkable to me, unless I simply need to stay up late and there are no alternatives.

We’ve noticed that some of the new, “boutique” roasters are roasting coffees that taste more sour and unexpectedly winey. Why is that? 

What a great question! Yes, we’ve swung the other way from the Starbucks roast. The current fashion is to roast just after first crack, which is quite light. Roasters are convinced that this maximizes the distinctive flavor notes generally known as acidity. I am also noticing the same thing. It’s like when someone gets a new home theater and they’re turning up the thundering bass. I’d like some balance. I agree. I used to enter a city and sniff the local roaster as I walked in and did a u-turn if I got too much roast, like wines that were over-oaked. Now, I’m turned in the other direction. I wish some of these folks would stay a little longer, let the natural sugars in the beans develop a bit. Like a crusty Italian Filone bread. Anyway, off the soap box. But you asked.

Once you’ve roasted your own beans, what device do you use to brew your coffee?

I have 20 coffeemakers in my kitchen. My wife has a rule, but she rarely counts so I have a lot of choices. I have a few favorites. For light roasts I urge folks to explore the vacuum or siphon coffee brewer. It gets everything. Coffee HD. Of course, there’s a new brewer that’s a hit among well-heeled enthusiasts – the Trifecta. I hate to name brands but it’s Bunn and it’s a no-brainer if you have the dough and want perfection.

Do you have any last tips for coffee lovers who want to start roasting their own beans? 

Roast with plenty of ventilation. I once ruined Thanksgiving because I roasted indoors using just the stove fan before friends dropped by. Smoke all over. My wife greeted people at the door with, “Welcome, you’re not just our friends, you’re witnesses! She was mad!!!

Pay attention. Seconds count. One reason I don’t predict roasting will ever become the bread machine is due to the finicky nature of coffee roasting. Ten seconds can take your perfect medium roast into a French roast, fine if you like it. Otherwise, instant compost! Pretend your driving. No texting.

Keep notes. No one remembers two roasts or more back what chant or dance they did to create the perfect alchemy. Once you’re drinking the coffee with a friend and they say, “Hey this is really good. What’d you do?” you’re sunk unless you have some notes. I’ve had the chance to read one or two logs of the great coffee roasters and believe me, Captain Kirk would be envious. Heck Charles Dickens would be. These guys record everything. But, they get results and repeatable results. But, I know many home roasters and some are really great. It’s a bit of an addiction. They compulsively roast. I guess it’s healthy as long as you can afford it. No different really from a gifted guitarist who plays for hours on end.