What is K72 Washed Processing Method? What are Washed Process Coffee Beans?

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The washed process is one of the most traditional and common methods for processing green coffee beans. The steps of removing the parchment and washing not only greatly improve production quality but also give the brewed coffee excellent clarity, making it a favored green bean processing method for countless coffee enthusiasts, including FrontStreet Coffee.

As specialty coffee gradually becomes more popular, more consumers are beginning to pay attention to the traceability information of single-origin coffee. Therefore, to highlight certain selling points, many producers have added prefix modifiers to processing method names, such as "double washed," "K72 washed," "dry fermented washed," and so on. So how do they differ from conventional washing?

Before understanding these "new-style" processing methods, FrontStreet Coffee believes it's necessary to first sort out the origin of traditional washing.

Washed Process

Also known as wet processing, translated from "Wet Process," this is a method of obtaining green beans where the outer skin and pulp are removed before the seeds are dried.

According to relevant materials reviewed by FrontStreet Coffee, this wet processing method began in the West Indies in the nineteenth century and was developed in Jamaica, where it was called WIP (West Indian Process). It was mainly suitable for humid and rainy areas. In contrast was OIB (Oost Indische Bereiding), which referred to traditional natural processing.

Before the 1850s, people used the most ancient natural drying method to process coffee cherries. It was only with the advent of the Industrial Revolution that this "peel-first" coffee processing technology emerged. In the mid-19th century, Jamaica became one of the world's largest coffee-producing countries, producing about 70,000 tons of green beans annually. Because this area has an island climate, where cherries are not easy to dry, natural drying was not favorable in this land.

In 1845, the invention of the world's first coffee pulper machine was patented by James Meacock from Kingston, Jamaica. This was a machine for removing the outer skin of coffee cherries and could also perform coffee screening. Following this, more and more inventions related to coffee pulpers emerged, and the washed process was formally applied to coffee production.

The process of traditional wet processing is not complicated: floating → pulping → fermentation → washing → drying → hulling → packaging. However, its implementation requires an adequate water supply, and because it heavily relies on mechanical assistance, producers using the washed process must also have sufficient funds to invest in equipment purchase. The rise of the washed process coincided with early American plantations built by capital, which had sufficient operating funds, coupled with the invention of various pulpers/hullers that emerged to meet the demands of the times, which led to the widespread adoption of the washed process throughout the Americas.

Double Washed

The original wet processing method involved washing fermented coffee beans once with clean water to remove the pulp, then directly transporting them to the drying yard for drying and packaging. However, in Kenya, coffee that has been washed once is re-immersed in a pool of clean water, then taken out and washed again before being sent to the drying yard for dehydration.

The reason Kenya initially changed conventional washing to "secondary immersion" was actually not to pursue flavor but was due to insufficient local drying space. Kenya operates on a typical African cooperative model, where during the harvest season, small farmers deliver fresh cherries to processing plants throughout the day. The pulping and fermentation steps are relatively simple and not time-consuming, but drying each batch of fermented beans takes at least 5 to 7 days. Sometimes when the volume to be processed is too large, there's no space to dry the washed beans. Therefore, people had to pour the wet beans back into the pool to let them "cool down" to avoid spoilage or contamination until the drying yard was available.

This form of washed processing with two soaking periods is called "Double Washed" and is also known as "Fully Washed" or "Double Fermentation" at origin, meaning completely washed. Since Kenya was the earliest region where this processing method became popular and implemented, this type of washing is also called the "Kenyan Process."

Later, people discovered that this twice-fermented washed coffee, which was adapted to local conditions, not only helped maintain stable quality control in production but also brought rich, layered fruit acidity flavors to the coffee. For example, FrontStreet Coffee's Kenya Small Tomato uses double washing, often displaying rich cherry tomato and preserved plum aromas after brewing, with very distinctive flavors. Today, some coffee produced by American estates also uses this Kenyan-style washing.

K72 Washed Process

This refers to the Kenya 72-hour washed processing method, which can be understood as an additional extension of both regular washing and double washing.

This washing process emphasizes control over fermentation time. First, 24 hours of washed fermentation is performed, then the removed pulp is cleaned. In a clean water tank, it ferments for another 24 hours, followed by another cleaning of residual components, then introduction into a tank with clean water for the final 24 hours of fermentation, totaling 72 hours. This process also gives Kenyan coffee bright and clean, high-quality fruit acidity. FrontStreet Coffee's daily offering Assalia uses this washing technique, making the brewed coffee present acidity similar to small tomatoes and smoked plums.

Dry Fermentation (Washed) Process

Since the initial wet processing required large amounts of pure water, and the wastewater after fermentation has been acidified, discharging it into rivers or soil would impact the ecological environment. Therefore, in response to environmental protection and water conservation, the more water-efficient dry fermentation washed process has begun to be advocated.

What's called "dry fermentation" involves pouring the parchment beans directly into fermentation tanks after removing the fruit skin, letting them sit for about 6-8 hours. This step is actually very similar to the honey processing that people are more familiar with. The difference is that dry-fermented coffee still needs to be rinsed with water to completely remove the degraded and shed sticky substances. In terms of flavor, conventional washing often has a brighter taste, while dry-fermented washed coffee usually has a rounder sweetness than wet processing (because it's similar to honey processing).

It's not difficult to discover that fermentation is an essential step in washed processing. Therefore, regardless of which washing method is used, the differences are merely in the soaking duration and frequency during fermentation, high or low temperature, aerobic or anaerobic conditions, and whether additional substances are added.

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