Anaerobic Fermentation

A line of sealed plastic yellow barrels for anaerobic fermentation at Punta del Cerro mill in Huehuetenango.
A line of sealed plastic yellow barrels for anaerobic fermentation at Punta del Cerro mill in Huehuetenango. Drying naturals in greenhouse. 25 days to dry inside. Washed coffee dries on patios. 200q per 100. 5.35 to 1 cherry to green or parch?. 670q is base parchment price locally.
A line of sealed plastic yellow barrels for anaerobic fermentation at Punta del Cerro mill in Huehuetenango.
A line of sealed plastic yellow barrels for anaerobic fermentation at Punta del Cerro mill in Huehuetenango.

Anaerobic simply means “without air”, which makes this term that describes what has become quite a craze in the coffee world a bit confusing. Generally speaking, all coffee fermentation occurs in the absence of air. But when you see coffee’s marketed as “anaerobic fermentation”, they are referring specifically to fermenting in airtight tanks, either whole cherry, or depulped coffee with fruit mucilage intact, for a duration of time before moving on to the next processing stage. During anaerobic fermentation, yeasts and bacteria break down carbohydrates such as sugars, resulting in organic compounds that affect flavor and aroma. With standard wet fermentation, the main goal is to break down the fruit layer that’s stuck to the coffee beans in a day or two so that it can be removed before drying. In contrast, flavor is the driving factor behind anaerobic fermentation, and duration and temperature play a big part in the outcome. Anaerobic coffees tend to have wild fruit flavors that, in our experience, often edge into ascetic, vinegar, and alcohol territory.

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