The Mad Barista

The roasting of green coffee beans is the first step in creating the perfect coffee flavor.

The end-goal of roasting varies with each individual bean type because beans grown in different regions and under different conditions come to the roaster with certain inherent flavors. There are, however, several tactics that can be employed during the process to extract specific flavors.

As the master roaster at Bow Truss Roasting Works in Chicago, Dennis Jackson roasts about 15 batches of coffee per day. He uses what is called a drum roaster, in which green beans are dumped and then rotated inside the drum using a series of paddles. The first step, he says, is heating the drum. "It's like pre-heating an oven - you never want to start with a cold drum. That will actually spur some chemical reactions that you don't want."

Once the drum is at the appropriate temperature, Jackson drops the beans inside. Immediately, the drum starts rotating, keeping the beans moving and triggering airflow. Because the roasting process is incredibly precise, Jackson uses the built-in timer and thermometer on his Probat-brand roaster to measure his pace and heat. "There's conductive heat and convective heat," he says. "Right now, the coffee is absorbing the heat."

Jackson says the coffee still has about 9 percent moisture and will continue absorbing heat throughout its first minute of roasting. The temperature inside the roaster, initially at around 420 degrees Fahrenheit, drops as a result. "If the beans absorb the heat too fast, the outside of the coffee can actually be compromised," he says. "The inside of the coffee will still be hard."

Once the temperature inside the drum drops below 165 degrees, the chemical reactions, for the most part, cease. The coffee is still absorbing some heat and gently releasing some moisture, Jackson says. At this point, he increases the airflow to fan the flame inside the drum and once again increase the internal temperature.

"I can do a lot with the air and the flame," he says. "I can build body with the air. I can take body out of it. I can build acidity or I can take acidity out. I can build sweetness. All that stuff plays into [the flavor of the coffee]."

As the roast continues, the beans turn a bit opaque. Jackson says this is a sign that they're taking on heat well. The next step is evaluating the aroma from the beans; at this first stage, there is a "vegetal, green pea-type of smell," he says. He continues to increase the temperature until the drum reaches 270 degrees Fahrenheit, the point at which all of the coffee's free moisture - the moisture outside of the cell itself - is gone, and the beans start to tan in color.

The next step is what Jackson refers to as "the golden point." At this stage, the roasting beans smell a bit more like baking bread. To prevent them from burning, Jackson increases the airflow and keeps the beans circulating within the drum. He then cuts the flame completely, throwing the beans into an exothermic condition, which means they have their own heat energy. Carbon dioxide is released, and Jackson says it is important to keep the roast moving at this point so that it doesn't stifle the roast.

"Right now, you can smell some of the acidity, but you also smell the sweetness. I'm trying to develop the sugars. The sugars are browning," he says. "I don't want to go too fast, so I slow the roast down [by increasing airflow and turning the flame off]."

Because the roast is now an exothermic process, the beans will keep cooking despite the lack of flame, Jackson says. The last step is to increase the airflow just slightly to eliminate any smokey flavor and develop the body, he says. He then lets the beans out of the roaster to cool.

While the roasting process is very holistic in its effect on the taste of the beans, certain aspects can manipulate certain taste profiles. For example, if the flame is too high inside the roaster, the outside of the bean will char, resulting in a burnt, bitter flavor, Jackson says.

Additionally, dramatically increasing airflow could completely remove the acidic notes from the beans. "If you've got a ton of airflow moving through the coffee, it literally knocks [the flavors] off and what you have is a bland, flat coffee. It also knocks out some of the body just because there's too much momentum and the coffee never gets a chance to really roast. It's more baked, if that makes sense," he says.

The roasting process is very much a product of time, patience and developed expertise. "Drum roasters take a long time to learn because there are so many aspects that you can manipulate to get the things you want out of the coffee," Jackson says. "Air manipulation, flame manipulation, your time - it all plays into what you want to do with the coffee."

The Roast Levels

The beans progress through various roast levels during the process, Jackson says. While some are generally more popular, several options exist for the discerning drinker.

Baristas call finding the perfect spot or grind setting "dialing in," but be careful turning that dial: Grind fineness greatly influences your brew.

"It affects however much flavor you can taste and what there is to taste, either positive or negative," says Jeffery Batchelder, a barista trainer at Intelligentsia. Adjusting your grind setting will also affect how the coffee extracts, i.e., what percentage of the grounds are dissolved in water. "There's a small window that you want to aim for when you're extracting, and that's between 18 and 22 percent of the coffee dissolving," Batchelder says. "If it tastes sour, you haven't hit that 18 percent yet. If it tastes really bitter, or really savory and astringent, you probably went over 22 percent." The ideal, he says, is when the flavor is delicately balanced. "Whenever it tastes sour, but kind of sweet, and also [has] a little bit of bitterness to round everything out - that's probably right in the mark."

Batchelder says "dialing in" is an arbitrary art, especially because the grind setting options change with every machine. Because there are no universal metrics for each grind, it can be difficult to determine grind setting.

The best tool to use in choosing a grind setting, then, is simply expertise. "I look at it and I feel it. I can tell by feeling it - where I need to go, whether [it needs to be] coarser or finer," says Brian Frain, premier barista trainer and wholesale operations manager at Bow Truss, which is nestled in Chicago's Lakeview neighborhood. "It's really hard to tell someone: 'Oh, just use medium grind,' so I'll usually send them home with a grind sample," he says. "I don't know what their grinder looks like, I don't know how many settings it has, so I'll say, 'This is what it should look like.'"

Frain's best piece of advice to new brewers is to literally lay their grinds out in a spectrum. He tells customers to get a blank piece of paper and trail out the sample he gives them. Then, they can grind their coffee, put it next to the sample on the piece of paper and compare the two. "I know that's not an exact science," Frain says, "but that's really what we do."

Temperature and dosage both affect your beverage's depth of flavor.

Temperature

"The temperature of water used to brew coffee using the pour-over method can affect the beverage's depth of flavor," says Dr. Shelby Hatch, a lecturer in the chemistry department at Northwestern University. "Water that is too cold might not extract enough of the beans' intricacies when it is poured over. Chemical reactions take place very slowly at cold temperactures, and extraction is a chemical process," she says. "If something isn't very soluble in cold water, it won't get extracted into [the coffee]."

Hatch, who conducted extensive research on the chemistry of coffee brewing, worked with a student research assistant to test various variables. The student's notes confirmed Hatch's hypotheses. "If you look at her notes, you'll see that as the temperature goes down, you're not able to really extract much of the compounds into the water. Caffeine is really soluble in water, so it's easy to extract that, but some of the other compounds are not [present]," she says. "If you don't have the water hot enough, you're going to get a more bitter tasting coffee because you're just going to be pulling out the caffeine, not the oils and other things that are less soluble in water."

Conversely, water that is too hot might ruin any delicate flavors in the coffee that were developed through the roasting and grinding process. "You don't want to use boiling water because it will extract flavors you don't want," Hatch says. For the Chemex method, she uses water that is heated to 94.6 degrees Fahrenheit.

There are more than twenty different ways to transform ground coffee into a deliciously drinkable cup of joe.

Some methods, like a pour-over, use a filter to siphon out oils and residual grind from the brewed cup, while using a French press involves saturating the grinds directly with boiling water without a filter. Because grinds can pass through, this often results in a rougher texture, but some argue this actually makes for a stronger and bolder cup of coffee.

Whether to use a filter depends both on your brew method and overall personal preference for the texture of your drink. "In brewing a cup of coffee, you have a set of variables," Frain says. "My job is to eliminate every single problem that I can [so that] I'm left with a hopefully perfect cup of coffee," he says. The pour-over method is the easiest and most common method for manually brewing coffee, as it only requires either a V60 dripper (for a single cup) or a Chemex. A V60 dripper is a portable cone-shaped device with a small hole on the bottom through which the coffee drips, and it can be placed directly on top of a mug for easy preparation. A Chemex, on the other hand, is a larger flask with a cone-shaped top and a rounded bottom. A filter is placed inside the cone on top of the flask, and the coffee drips directly into the bottom half of the container.

After you've chosen your preferred method and acquired a filter, the next step is to fill a kettle with boiling water. The kettle must have a long and narrow spout to ensure precise and controlled pouring - a key factor in coffee preparation, as even saturation of the grinds is crucial.

There are three main steps to the pour-over process:

To fully appreciate the complexities of the flavors in the final product, slurp it.

While it's not graceful, it is effective. Grab a spoon and scoop up bit of liquid. Using circular breathing, which allows you to breathe through your nose and mouth simultaneously, try to smell and taste the coffee at the same time. "I'm pulling in all of the flavor nodes from this coffee," Frain says.

Of course, if you're just trying to have a casual sip and get your required caffeine buzz, you can just sip the coffee normally. Keep in mind that the volatile compounds in the cup will keep reacting with the oxygen, which alters the taste of the coffee as it cools, so best practice is to drink up within 20 minutes of brewing your coffee.