Tweaking the Coffee Roasting Curve

Coffee Roasting by Stockton GrahamPerhaps it’s because the Specialty Coffee Association of America almost canceled our regional trade competitions (they’ve since been reinstated by popular demand), but I’ve been recently thinking about those competitions and I’m reminded of what a competitor once said during his presentation.

He discussed this philosophy of how, after harvesting, all a roaster does is take away from the coffee’s natural flavor. He talked about how the role of the farm, the roaster and the barista is to keep the quality of the coffee.

This is speculative since it infers that a coffee bean has a maximum flavor potential, a destiny of sorts, but it’s also literal. We take away the cherry that the coffee beans come from; we take away inherent sugars, proteins, and even caffeine when we roast; and when we brew coffee, we dispose of the grounds after a solution is created.

What I like about this philosophy, though, is that it reminds us of the necessary steps in keeping a coffee’s integrity, its flavor, from farm to processing, roasting and all the way to brewing. Any lack of attention to detail could diminish the flavor, hurt a farm’s credibility, decrease coffee sales, or, more broadly, not provide a consumer with an enjoyable coffee experience.

It helps me realize the importance of our roasting job at Stockton Graham & Co. Our responsibility is to balance the roast of each coffee so it is a product our customers want and also shows off a particular coffee’s natural flavor.

A good question from here though is what is the best approach to achieve this balance? Because coffee is continually changing flavor from the moment it starts growing until the moment it is consumed (due to growing climate, processing, aging, roasting, grinding, brewing and so forth) and can change even drastically from harvest to harvest, should we seek to maintain a consistent flavor from year-to-year? Or, should a coffee always be changing to match each harvest?

How much variation should we give a particular coffee?

For us, it’s a mix. At Stockton Graham & Co., our roasting team looks for coffees they enjoy and know to be high-quality examples of a particular coffee’s natural flavor. But they also pay close attention to the needs of our customers, which may be looking for consistency from order-to-order and from harvest to harvest.

As a coffee drinker and patron of many coffee shops in the Raleigh area, consistency is something I’ve never paid much attention to before I started at Stockton Graham & Co. But it makes sense: If a coffee is always different, how will I know if I will enjoy a cup of coffee at my favorite coffee shop every time I buy it? To some coffee shop patrons, and so also to some of our customers, consistency is king.

It makes me realize how a roaster can be skilled in many ways. While one roaster may always look to change a roast depending on their current preference, I see Brandon Riggs, Roastmaster at Stockton Graham & Co., really take each consumer’s interests and their coffee preferences to heart so that both are respected.

The Roasting Process
Roasting coffee is our specialty here at Stockton Graham & Co. We obtain coffee once it is processed, and it’s our job to make the coffee taste great. Green coffee, before it is roasted, has higher levels of caffeine, proteins, and natural sugars, but has the density of a small pebble. We take the green coffee (harvested from a coffee cherry) and heat it till the coffee bean is brittle enough to break apart and be diluted/absorbed into hot water.

As coffee reaches the right temperature (around 375-400F), you can hear it start to break open. This noise is referred to as the “first-crack.” It’s then that the coffee beans are ejected out of the chamber and air-cooled.

httpss://www.youtube.com/watch?v=_354ufdgffQ

There are actually a few different ways this process can occur. The standard is a drum roaster, where the coffee swirls in a barrel with a controlled fire underneath. The second most common amongst roasters would likely be a fluid bed roaster, which uses superheated air to suspend the beans and roast them. Each method can create subtle differences in the coffee.

Generally, when the coffee beans are introduced to heat, a roaster will monitor, or program, the temperature of the coffee. Typically, roasts occur at a rounded, steady increase or an “S” curve, consistently warming. While the flavor is always developing, it isn’t until the last minutes of the roast, around 400F, that a roaster is keen to either under develop or burn the coffee. Darker roasted coffees will roast longer while lighter roasts will come out earlier. This is because some coffees develop better with more heat as compared to other coffees that will lose its flavor if exposed to any higher temperatures.

Fine-Tuning Our Coffees
One way to maximize the quality of the coffee and any particular bean’s flavor is to adjust the temperature and length of the roasting. While some adjustments are made to enhance certain aspects of the flavor profile, our roasters also will adjust roasts as coffee moves further off harvest, ensuring that the coffee we deliver to customers is consistent from order to order.

“Within the last 6-months, we’ve been fine-tuning our roasting process more than ever before to ensure that each bag that a customer buys is as consistently good as the last,” said Roastmaster Brandon Riggs. “There are two things a roaster can manipulate, and those are time and temperature. When you plot these factors on a scale, you end up with an S-shaped curve. Thing is, you don’t want your ‘S’ curve to be too drastic—meaning, you don’t want the coffee to gain excessive temperature at the end of the roasting cycle.”
It’s these nuances that help adjust the flavors of the coffee so that the bean’s natural flavor is optimized and the coffee meets the needs of our customers.

Our Papua New Guinea, for example, is one coffee that we’ve been fine tuning in the roasting process.

“We’ve had a consistent roasting profile for about 3 to 4 years,” Riggs said. “This year, we needed to change it up a bit. By adjusting the temperature at the end of the roast in our latest profile, we noticed it holds a bright body well and has a clean, sweet finish.”

Brandon strives for consistency and quality; so while coffee is constantly evaluated, it is not always changed. This was a good instance in which we’ve done justice to the coffee’s flavor and see good feedback from our customers.

“With the Selva Negra, which just recently came back to us, we’ve adjusted the roast three to four times based on tasting evaluations to make sure it’s back to the same quality our customers have come to expect,” Riggs said.

These are a few ways our coffees have been closely monitored and adjusted at our roastery so that our coffee is both consistent and enjoyable. You can get a close look if you try our new Selva Negra and can compare it to the last time you had it. Maybe it’ll still have that zing you were looking for or maybe it has a lighter finish. Being a discerning coffee taster is just as important as being an expert roaster.

To talk to our roasters or to order coffee, call our Customer Care Associates at 800 835 5943.

Article contributed by Clayton Johnson, coffee roasting assistant at Stockton Graham & Co. in Raleigh, NC.