How does double washed coffee processing differ from K72?

Washed coffee processing, also called the wet process, removes the outer skin and mucilage before the seeds are dried. Kenya's double washed method repeats fermentation and washing steps, which can sharpen clarity and acidity. K72 washed and dry fermentation washed are variations that adjust soaking duration and fermentation frequency, and those variables shape the final flavor in the cup.

The wet process originated in the West Indies in the 19th century and developed in Jamaica, where it was known as WIP, the West Indian process, suited to humid and rainy regions. It contrasts with OIB, the traditional natural sun-drying method used before the 1850s. As specialty coffee drinkers ask more about traceability, producers add labels like double washed to signal how the coffee process was handled.

As one of the most traditional green coffee processing methods, the washed method significantly enhances coffee quality and cleanliness through its depulping and washing steps, earning deep favor among enthusiasts. With the rise of the specialty coffee wave, new terms like double washed, K72 washed, and dry fermentation washed have emerged endlessly—how exactly do they differ from traditional washed? From Front Street Coffee's perspective, this article first traces the historical origins and steps of traditional washed processing, then delves into the origins, operational details, and flavor expressions of Kenyan double washed, and extends to introduce the characteristics of K72 washed and dry fermentation washed, helping readers understand how variables such as soaking duration and frequency during fermentation shape the final flavor of coffee.

The washed method can be considered one of the most traditional and widespread green coffee processing methods. The two steps of depulping and washing not only greatly improve production quality but also allow the coffee liquid to exhibit excellent cleanliness, thus becoming a green bean processing method favored by many coffee enthusiasts—Front Street Coffee naturally among them.

As specialty coffee increasingly enters the public eye, more and more consumers begin to care about traceability information for single-origin coffee. Consequently, many producers, to highlight selling points, add modifiers before the processing method name, such as "double washed," "K72 washed," "dry fermentation washed," etc. So, what exactly is the difference between these names and conventional washed?

Before understanding these "new-style" processing methods, Front Street Coffee thinks it necessary to first review the ins and outs of traditional washed.

Washed Method

Also known as the wet process, English "Wet Process," refers to a method of obtaining green beans by removing the outer skin and mucilage before the seeds are dried.

According to relevant materials consulted by Front Street Coffee, this wet process originated in the West Indies in the 19th century and gradually developed in Jamaica, where it was then called WIP (West Indian process), mainly suitable for humid and rainy regions. In contrast is OIB (Oost Indische Bereiding, East Indian preparation), which is traditional natural sun-drying.

Before the 1850s, people always used the oldest natural sun-drying to process coffee cherries. It was not until the arrival of the Industrial Revolution that this "peel-first" coffee processing technology took the stage. In the mid-19th century, Jamaica was already one of the world's largest coffee-producing countries, with an annual output of about 70,000 tons of green beans. The local climate is insular, making it difficult for the fruit to dry, so natural sun-drying was not very advantageous in this land.

In 1845, James Meacock from Kingston, Jamaica, applied for a patent for the world's first coffee pulper machine. This machine could remove the outer skin of coffee cherries and also perform coffee screening. Thereafter, more and more inventions related to coffee pulpers emerged, and the washed method officially entered the coffee production process.

The steps of the traditional wet process are not complicated: flotation → depulping → fermentation → washing → drying → hulling → packaging. However, its implementation requires an ample water supply and relies heavily on mechanical assistance, so producers using washed processing must have sufficient funds to purchase equipment. The rise of the washed method coincided with early American plantations built by capital—these plantations had sufficient operating funds, and with various pulpers and hullers invented to meet the needs of the times, the washed method spread widely throughout the Americas.

Double Washed

In the original wet process, the fermented coffee beans are washed once with clean water, rinsed of mucilage, and then directly taken to the drying yard for drying and packaging. But in Kenya, the once-washed coffee is re-immersed in a pool of clean water, then removed for a second wash, and only then sent to the drying yard for dehydration.

Kenya initially changed conventional washed to "second soaking" not to pursue flavor, but out of necessity due to insufficient local drying yards. Kenya is a typical cooperative operation model in Africa. During each harvest season, smallholders bring freshly picked cherries to the processing plant all day long. The depulping 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 processing volume is too large, there is nowhere to dry the washed beans. So people had to pour the wet beans back into the pool, letting them "cool off" first to avoid spoilage or contamination, until the drying yard was free.

This form of secondary soaking in washed processing is called "Double Washed," also known in origin regions as "Fully Washed," "Double Fermentation," etc. Since Kenya was the earliest region where this processing method became popular, this type of washed is also called "Kenyan Process."

Later, everyone discovered that this locally adapted, twice-fermented washed coffee not only helped stabilize quality control in production but also brought layered fruity acidity to the coffee. For example, Front Street Coffee's Kenya Little Tomato uses double washed, and after brewing it often exhibits rich cherry tomato and preserved plum aromas, with a very unique flavor. Today, some American estates also use this Kenyan-style washed for their coffee.

K72 Washed Method

Also known as the Kenya 72-hour washed processing method, it can be understood as an additional extension based on ordinary washed and double washed.

This washed process emphasizes the control of fermentation time: first, a 24-hour water fermentation, then cleaning off detached mucilage, fermenting another 24 hours in a clean water tank, then again cleaning residual components, introducing into a tank with clean water for a final 24-hour fermentation, totaling 72 hours. This craft also gives Kenyan coffee a bright and clean high-quality fruity acidity. Front Street Coffee's daily offering Azalea uses this washed technique, making the brewed coffee present acidity like cherry tomato and smoked plum.

Dry Fermentation (Washed) Method

Since the initial wet process requires a large amount of pure water, the wastewater after fermentation has become acidic, and discharging it into rivers or soil can impact the ecological environment. To echo environmental protection and save water resources, the more water-saving dry fermentation washed method began to be advocated.

The so-called "dry fermentation" is when the depulped beans with parchment are directly poured into a fermentation tank and left to rest for about 6 to 8 hours. This step is actually quite similar to the more familiar honey process. The difference is that after dry fermentation, the coffee still needs to be rinsed with water to completely remove the degraded sticky substances. In terms of flavor, conventional washed often has a brighter mouthfeel, while dry fermentation washed coffee usually has a rounder sweetness than wet process (because it resembles honey processing).

It is not difficult to find that fermentation is an essential step in washed processing. So no matter which washed method, it is essentially just differences in soaking duration, frequency during fermentation, high or low temperature, aerobic or anaerobic, and whether additional additives are involved, etc.

The above content is compiled by CoffeeHunters, a coffee news website.