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A Glimpse Into Coffee Roasting

patrick smith
patrick smith
 

I take for granted that I watch coffee roast every day. I always enjoy it, but often fail to remember that it is really quite novel & interesting to many people. I was thinking about blogging this week. It occurred to me that I should compose a brief write-up of the roasting process & include some photos so that you could get a glimpse of what coffee roasting is like. It’s fun. The smells range from the chlorophyll-dominated scent of green coffee (think: fresh grass clippings in spring) to spicey cinnamon-esque aromas ¾ of the way through the roast to the final stages when the smoke intermittently stings your nose if you really breathe it in & the smell is that of toasted bread &….well, roasted coffee. I know that last one’s a cop out, but there’s nothing else really like it—it just smells like roasting coffee.

So the work begins by scooping & weighing green coffee.
Bag of green coffee beans

This involves nothing more than a scale, a bucket, green coffee of course, and my beloved scoop. We typically shy away from blends in favor of single-origin coffees. There is SO MUCH work that goes into cultivating & processing the caliber of green coffees we purchase that it’s really a disservice to them & the farmer behind them to obscure them in a blend. George Howell says it best, “blends hide the famer.” That said, the weighing of coffee rarely involves different coffees in one bucket. We account for nearly 20% weight loss during the roast, so if I need to yield 20 lbs. I’ll drop 25 lbs. Once it’s weighed out, I take it to the pre-heated roaster & pour it in the big funnel on top.
Measurning the beans

Then, down they go into the roasting drum. Just prior to a full roast, the drum is preheated to around 420 degrees F. Obviously when 25 lbs. of room-temperature green coffee hits the drum, it siphons off a good bit of that heat. Over the next minute & a half or so, the beans absorb a bunch of heat from the drum & the two “meet” in temperature at about 190 degrees F. Then begins the steady climb toward ±15 minutes & ±430 degrees F.
The roaster

As the roast progresses, it is important to monitor the heat transfer carefully & adjust the amount of natural gas going to the burner accordingly. In addition to watching the time & temperature relationship, there are a number of visual & fragrance cues available during the roast.

A look at the coffee just a minute or so into the roast:
Sample pull
These are samples I pulled from the roaster with the trier at various points throughout the roast:
beans during the roasting process
Maybe a more informative perspective:
another look at beans during the roasting process
Nearing the end of the roast:
Pull near end of roast
It reached the desired roast depth & now is cooling.

Once the coffee is cooled to room temp, we package it as quickly as possible & either ship or deliver it……but in the interest of disclosure, we typically set a little aside, let it rest 5 or 6 days, & enjoy the fruits of our labor!
Tamping the ground bean for espresso
Espresso being pulled
fresh cup of espresso