If you’ve read even a few of our other blog posts, you’ve learned (if you didn’t already know) that there are a LOT of steps involved to get coffee to your mug. Any one of them could warrant an entire article (honestly, maybe even a whole book), and some of them have. From preparing the soil, to choosing a seed to place in it, tending a seedling as it transforms into a small tree, all the way through post-harvest processing, every single task becomes a variable in cup quality. And perhaps the most impactful of those tasks is fermentation.

fermentation tanks at Buchiro station, Muungano cooperative, Democratic Republic of Congo

In order for all the potential flavor within a coffee seed to develop into positive nuances we later notice in our cup, those freshly-revealed seeds should be fermented. We’re not talking about the same level of fermentation responsible for creating alcohol, as with wine, hard cider, beer or even some kombuchas. However, some level of fermentation—in which yeast causes a chemical breakdown of the seed’s components, creating more complexity—is important.

This step can occur naturally when raw (“green”) coffee is left in a tank exposed to open air; natural yeasts present in the environment will do their job. Some level of fermentation can also take place once coffee is raked out onto a drying patio, depending on the amount of mucilage or fruit still clinging to the seed and how much airflow is present. Any coffee production facility (usually called a “wet mill” or “washing station”) will have a system they use, timing the fermentation stage carefully with each batch.

my feet on a drying patio at Permata Gayo in Sumatra

Most coffees have their fruit removed as the first post-harvest step; this is called “washed” or “wet” processing. Coffees designated to be “honey processed” have their outer layer of fruit removed, but the sticky layer of pulp is left intact throughout fermentation and drying. And “dry” or “natural” coffees are left entirely intact as cherries, only having their fruit removed once the coffee is fully dry, somewhat like a raisin with a giant pit. Each of these processing methods presents even more variables for the fermentation stage: the more contact a seed has with its fruit throughout fermentation, the more sugars are present, and therefore the more potential for sweeter, fruitier flavors and aromas to be noticeable in the final product.

James Hoffmann. Photo credit: thefermentationproject.com

Coming up this fall, we have a unique chance to taste these fermentation variables in focus. James Hoffman, a well-known (at least in certain circles) coffee professional and YouTube personality, has sourced a coffee from Antigua, Guatemala, and enlisted support from Lucia Solis, a coffee fermentation consultant, to have that one coffee fermented four different ways. Roasting companies around the world have been invited to purchase the green coffee, roast it, and offer it to their customers in a sample set. Higher Grounds is lucky to be among the roasters who were able to purchase this coffee, and soon we’ll be opening up our pre-order sale so that you can participate with us in this unique globally-coordinated tasting experience.

In early October, there will be a virtual Fermentation Project event so that everyone who buys this coffee can hop on a giant video call and experience the tasting live, together. And in the Learning Lab, we’ll also host a tasting event (on a different day) to provide a guided tasting opportunity for those who don’t want to buy and brew the coffee themselves. If you’re interested, watch your email inbox—we’ll announce those details in our company newsletters.

We’re very excited about this chance to get up close and personal with the impact of fermentation on coffee. We hope you’ll join us.

This post was originally published on Coffee Lady Missives at coffeelearninglab.com.