Learn About Coffee Processing by Tasting Irving Farm’s ‘Experiments’


A number of factors affect the taste of your morning coffee (milk and sugar included — although that ubiquitous profile-altering duo is eliminated for the purposes of this article). For example: The ripeness of the cherries (coffee is a fruit seed, not a bean) when picked, the type of coffee variety farmed (think pinot noir versus cabernet sauvignon), and where it is grown (compare pinot noir from cooler, wetter Burgundy to sunnier, drier Santa Barbara) all play a role in cup profile. Also, roast levels heavily influence the end result; styles range from light, embraced by Scandinavians and growing in popularity, to extra dark and oily (think French roast, Italian roast, Vienna roast), rapidly (and thankfully) becoming obsolete as it masks flavor and hides flaws.

However, there’s another, often unknown, step in coffee’s journey to your nearest brew bar: the process of fermentation and drying, which adds or accentuates different inherent flavors in the fruit and its seed, colloquially called the bean, depending on the type and length undertaken. Again, one can draw parallels to the wine world here. Since few consumers know much about wine fermentation, let alone coffee, local NYC roaster Irving Farm has launched an educational effort with a taste demonstration, a four-part experiment using coffee sourced from El Salvador.

Consumer palates have grown significantly more sophisticated in the past decade; specialty coffee (about 10 percent of the world’s production) makes up a growing segment of the industry. Thus, both new and traditional farms are seeking ways to improve their product and differentiate it from the rest of the nut-and-chocolate-filled, smooth-profiled pack. This involves experimenting with different coffee processing methods, fermentation times, and techniques to amplify fruit, highlight acidity, and fatten or lighten the body.

For its “Los Niños Experiments,” Irving Farm engaged La Finca Talnamica (“finca” means farm in Spanish), and its owners, the Ortiz Herrera family, to attempt the labor-intensive process of separating one hand-picked harvest into four lots. The controls — same farm, variety, harvest, and mill — allow the variable (four different processes) to demonstrate the effect each has on taste.

For those interested in the details, keep reading. If the technical nuances induce glazed-over eyes, you can either buy the twelve-ounce bags for $15.50 online at, and at any of their five cafés, or taste them as pour-overs and single-origin espresso options in the shops. Irving Farm will also showcase the coffees in its monthly Intro to Cupping and Tasting classes ($30), while supplies last.


Back to the experiment: They selected the coffee variety “bourbon,” grown at an elevation of 1,360 to 1,400 meters (that’s less than a mile high) in the region of Ahuachapan, El Salvador. The four processes used were natural, honey, washed, and wild honey. The first three reflect traditional practices, washed especially, but the last one, wild honey, was developed in partnership between Irving Farm, Talnamica, and the Cuatro M. coffee mill, and has never been commercially produced before.

What do all these terms mean? First, a quick note about fermentation. During the process, yeasts and bacteria break down the sugars found in coffee mucilage, the seed’s (think bean) opaque, sticky, sweet, and protective encasement that lies within the coffee’s skin or pulp. (Click here for more on the anatomy of a coffee cherry.) The sugars, which can be measured in Brix like wine, produce acids and fruit notes during fermentation, lending complexity to the coffee.

Natural coffees are fermented and dried whole, meaning no layer of the cherry is removed, and fermentation takes place inside each individual bean. Naturals have their own fan club, myself included, made up of drinkers who love the vivid, sometimes wild, fruity, wine-like notes they produce. Have you ever had a coffee that reminds you of overripe blueberries? It was likely a naturally processed coffee. Ethiopian coffees are often natural. Of all the methods, this requires the least amount of water. Fermentation can be difficult to control, however, resulting in exaggerated or off flavors.

In the honey process, the skin or pulp is removed, but a percentage of the next layer enclosing the seed, mucilage (called honey, hence the name), remains. The mucilage will continue fermenting on the bean while it dries. Honeys are often creamy and sweet. Costa Rica has embraced this process, and the trend is spreading fast through Central and South America.

For the washed process, beans are pulped from their skin and fermented in a tank that might be stainless steel, cement, or even a plastic bucket for small farmers. The mucilage is intact, and fermentation runs somewhere between twelve hours and several days. Then the mucilage is removed — potentially using a tremendous amount of water — and the beans are dried. The key difference here is that during the drying process, no further fermentation with the mucilage occurs. This method is a conventional form of processing used all over the world. It delivers a clean, terroir-driven cup. Regions with scarce water resources, like Yemen, can’t (or at least shouldn’t) use this method.

Irving Farm’s coffees were processed using these three methods, plus a “wild honey,” with the variations outlined below.

The natural process, used in Experiment #1, entailed drying the coffee whole. Rather than doing so outside, which requires a reliably warm and dry climate for evenness and mold prevention, the coffee was dried in a mechanical dryer at a very low temperature for 60–70 hours.

The honey process, Experiment #2, entailed de-pulping the cherry but leaving some of the sweet mucilage stuck to the bean to dry in the sun.

Washed process, Experiment #4, required de-pulping the fruit, fermenting the beans in tanks without water overnight, then cleaning it fully of all mucilage in a mechanical washer, before drying it in the sun.

The wild honey, Experiment #3, is a blend of a honey and a washed process. The coffee was de-pulped and placed into fermentation tanks without water, like above. Once the pH reached 4.5, which took 12–16 hours, the coffee was dried in the sun. Unlike above, the mucilage was not washed off.

For a consumer, science and technique are only as fascinating as the results they produce. Irving Farm sent the Village Voice samples of all four coffees to see if their efforts were worth the labor. Do distinguishable — and worthwhile — taste differences exist between the coffees?

While my tasting notes didn’t align with theirs exactly — for example, I couldn’t find flavors of “maple granola” in #2 — I did detect distinct differences between the coffees. The natural had telltale blueberry notes and an exaggerated fruitiness compared to the other three. It was also the least delicate. The washed was also easy to identify with its benign chocolate tones and balanced body, both fairly characteristic of the processing style. The honeys, however, provided an interesting glimpse at the level of detail and nuance achievable with different processing methods. The honey, Experiment #2, showed crushed rose, banana skin, and pleasing acidity with a creamy, sweet finish. The wild honey, Experiment #3, had even brighter acidity and mandarin notes.

The best way to learn about coffee, or wine, or even chocolate, is to taste comparatively. Consumers infrequently have that opportunity, so get to Irving Farm and take advantage of this generous experiment before the coffees are gone. Keep in mind, the point of this exercise isn’t to make coffee more confusing, complex, or daunting, but rather to show the amazing range of taste potential held within a humble fruit.

Irving Farm was founded in 1996. Owners Steve & David opened their first café in Gramercy Park while learning to roast coffee in a converted carriage house in the Hudson Valley. They approach their twentieth anniversary with the opening of two new venues: the Loft, a state-of-the-art training and education facility in Manhattan, and a sixth café (location to be announced soon). Hint: It will reside within a contemporary architectural NYC landmark. The Irving Farm Roastery & Tasting Room opens in Dutchess County this year.

Lauren Mowery is a drinks and travel writer based in NYC.