Anaerobic Washed

What Is Anaerobic Washed?

In anaerobic washed processing, cherries are usually pulped first, then the mucilage-covered beans ferment in sealed tanks without oxygen before being washed clean. Compared with anaerobic naturals, this method emphasizes clean, precise acidity and distinctive lactic aromas while keeping the clarity of a washed coffee.

How It Differs from Traditional Washed

Traditional washed fermentation happens in open tanks, mainly to break down mucilage for washing, and usually lasts 12–36 hours. Anaerobic washed treats fermentation as a flavor-creating step: in sealed, oxygen-poor conditions, lactic acid bacteria take center stage, producing more lactic acid and aromatic esters with yogurt-like or tropical notes.

Processing Steps

• Sort: select cherries of even ripeness
• Pulp: mechanically remove the skin, leaving the mucilage
• Anaerobic fermentation: seal in tanks with a one-way valve to vent oxygen, controlling pH and temperature, typically for 24–72 hours
• Thorough washing: wash off the remaining fermented mucilage with plenty of clean water
• Drying: dry on raised beds or mechanically to about 11% moisture

Flavor Profile

• Refined lactic acidity: an alluring yogurt-, cheese- or kefir-like acidity
• High clarity: well-defined flavors with bright, clean acidity
• Distinctive aromatics: cinnamon, gingerbread or delicate florals
• Tropical fruit: some lots show passion fruit or lychee

Anaerobic Washed vs. Anaerobic Natural

• Anaerobic washed: clean, bright and acidity-driven, with more restrained fermentation notes
• Anaerobic natural: heavy, sweet and boozy, with more intense fermentation notes

If you love the clarity of washed coffee but want more adventure, anaerobic washed is a great place to start.

Notable Origins

• Colombia
• Guatemala
• Rwanda
• Costa Rica

Brewing Tips

Anaerobic washed coffees suit light to medium-light roasts brewed as pour-over or siphon to show off their clarity and aromatics. Try 91–94°C water and a 1:15–1:16 ratio.