What is the difference between double washed and washed coffee?

The distinction between washed and double washed coffee is less about a fundamental change in chemistry and more about a strategic refinement of the fermentation timeline. In a standard washed process, cherries are depulped and placed in tanks where microbial activity breaks down the sticky mucilage layer. Once the desired level of degradation is reached, the beans are washed and moved to drying beds. The 'double washed' method, synonymous with traditional Kenyan processing, introduces a second, distinct soaking phase. After the initial fermentation and wash, the parchment coffee is submerged in fresh, clean water for an additional 12 to 24 hours. A common misconception is that this is a 'second fermentation'; in reality, it is a soaking stage designed to leach out remaining fermentation by-products and ensure the bean surface is pristine. From a producer’s perspective, this method was historically a logistical solution: it allowed mills to hold washed coffee in cool, water-filled tanks when drying space was at capacity during peak harvest. Today, producers maintain the practice because the extended soak acts as a final quality control measure, allowing for further sorting and resulting in the hallmark citric brightness and 'clean' cup profile that defines the region’s specialty output. While it consumes significantly more water and labor, the process remains a gold standard for highlighting the intrinsic terroir of the bean without the masking effects of residual fruit sugars.