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Fermentation and Processing
Coffee processing is one of the most important single events that occurs in the entire supply chain. It alters coffee flavor through fermentation and technique, it preserves character through preparation and drying, and it readies coffee for export.
The classic dichotomy—washed and natural processing methods—continues to account for the vast majority of production style worldwide. Natural process (coffee dried without intervention, in the whole fruit) is the original style dating back hundreds of year, and still accounts for large portions of production volumes in locations like Brazil, Ethiopia, Yemen, and India. Washed coffee, however, is the standard bearer of modern specialty arabica production. By removing the fruit, fermenting, and washing the coffee and drying it in its protective inner shell (called “parchment,”) spoilage was minimized, qualities improved and homogenized, and flavors generally presented as milder, brighter, and cleaner.
Modern high-end specialty coffee production often leans into further “intervention” in the form of anaerobic fermentation environments (including carbonic maceration techniques), inoculating the coffee a specific yeast or bacteria strain, ecopulping or demucilaging to save water, and even adding ingredients to the fermentation tank or drying patios (often fruits or spices) to enhance flavor through co-fermentation and infusion.
Understanding Coffee Fermentation from Classic to Experimental
Fermentation is the key process shaping coffee flavor.
Traditional natural and washed methods rely on microbial activity. Naturals ferment in the whole cherry, creating fruit-forward flavors, while washed coffees ferment after depulping for cleaner, brighter profiles. Poorly managed fermentation can lead to the sensory defect known as “ferment,” marked by sour or rotten notes.
Additive Fermentation: “Infused” Coffee is Gaining Popularity—and Sparking Industry Debate
"Upon receiving a gift bottle of co-fermented apples and grapes recently, I thoughtlessly posed the question, “Is it a cider or a wine?” My friend responded, “It’s both!” Perhaps a purist would respond differently, saying, “It’s neither!” Fluid definitions in beverage-making constantly challenge traditional understanding of our crafts."
The Coffee Fermentation Continuum Ebook
This ebook maps how each fermentation method, traditional natural, traditional washed, honey process, multi-stage, anaerobic/carbonic, co-fermented, and inoculated, shapes coffee flavor, from clean and mild to fruit-forward or funky.
"Led by zeitgeisty processing methods such as anaerobic fermentation or carbonic maceration, new ways of developing flavor and removing fruit from coffee seeds seem to be emerging every day. Even relatively straightforward terms like “fully washed” or “natural” don’t fully convey exactly what’s happening when a coffee producer sends their coffee cherries from the tree to the drying tables. In anticipation of a class on fermentation and processing styles in coffee, I asked my colleague Evan Gilman to help me create a unique visualization tool to accurately and quickly convey what people mean when they say things like “pulped natural” or “triple washed.”"
Read"Fermentation in food and drink production predates recorded history. It has served as an integral factor in the creation of new flavors ever since some first bold soul tried a few grapes that were left out just a little too long."
Read"Two years later, Felix surprised me with another phone call. This time, it was to invite me to participate in this year’s Taza Presidencial – Bolivia’s coffee competition. To say I was thrilled is an understatement; I’ve dreamed of going to Bolivia for years; the opportunity to taste this origin’s best coffees and lead the tasting as Head Judge was simply a dream come true. Freshly back in the office from this adventure, I’m as excited as ever for the future of Bolivian coffee, and the opportunity to bring these coffees to roasters here in the US. Bolivia is full of passionate and consummate coffee professionals, and I’m looking forward to continuing to connect with this growing market. "
Read"What do you call a coffee that is neither fully washed nor dried in the cherry… and more importantly, what does it mean when we say Pulped Natural, Honey Process, or Semi-Washed? In the world of coffee, there are basically two ways to process post-harvest. You can minimally process before milling and export (i.e., natural, cherry-dried, and/or dry-process), or you can depulp, ferment, and wash the seeds before they dry."
Read"Upon receiving a gift bottle of co-fermented apples and grapes recently, I thoughtlessly posed the question, “Is it a cider or a wine?” My friend responded, “It’s both!” Perhaps a purist would respond differently, saying, “It’s neither!” Fluid definitions in beverage-making constantly challenge traditional understanding of our crafts."
Read"Virtually all supply chains have byproducts, waste that is a result of steps to obtain a final product. Coffee is no exception. Coffee is frequently grown and processed in extremely rural places in the world, with little access to healthcare, cell signal, fertilizers etc. Large estates in places like Brazil are the exception to this but not the majority. Because of the diversity of growing conditions, production methods can vary widely."
Read"Upon receiving a gift bottle of co-fermented apples and grapes recently, I thoughtlessly posed the question, “Is it a cider or a wine?” My friend responded, “It’s both!” Perhaps a purist would respond differently, saying, “It’s neither!” Fluid definitions in beverage-making constantly challenge traditional understanding of our crafts."
ReadFermentation is the key process shaping coffee flavor. Traditional natural and washed methods rely on microbial activity. Naturals ferment in the whole cherry, creating fruit-forward flavors, while washed coffees ferment after depulping for cleaner, brighter profiles. Poorly managed fermentation can lead to the sensory defect known as “ferment,” marked by sour or rotten notes.
Read"Coffee is a highly complex compound. With roughly 200 volatile compounds in green coffee and roasted expressing upwards of 1,000, there are so many factors at play that can alter the sensory experience of the final cup. The consumer-facing side of the coffee industry may roll its eyes at flavor notes like apricot, sweet pear and lemon, but these flavor notes are in fact not entirely subjective. Flavors are correlated to the sensory experience associated with certain molecules: tartaric acid to berries, citric acid to lemons, esters to florals and so on. "
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