J&A Report: Coffee Processing: How Washing Affects Taste
The process of washing coffee consists of removing its fruit layers before drying. Coffee is washed with water to remove the mucilage after the beans have been fermented. Mucilage is the soft, sticky layer that is responsible for sweetness.
Washing coffee beans results in a clean flavor profile. It is an ideal processing method for mild and bright brews. Removing as much mucilage as possible produces coffees with a light body and a bright, clean cup. The result is a fruiter, acidic flavor, while unwashed methods yield a heavy, smoother, and sweeter bean.
Washing Coffee Process
Before starting the process, weighing raw coffee cherries is necessary to calculate the yield in volume and weight. Then the pulp is removed using mechanical pulping machines. Inside the machinery, a blade cuts the cherry open, extracts the seeds, and discards the empty cherries. The coffee beans are set aside for mucilage removal.
The mucilage is composed of different sugars and alcohols that affect the flavor of the bean. Leaving this layer entirely or partially intact produces sweeter flavors. After the removal of the mucilage layer, coffee dries to prepare for the roasting process.
FIGURE 1: Coffee Washing Process
Washed Versus Unwashed Coffee Taste
Washed Coffee
Washed coffee has a cleaner taste than unwashed coffee. After the removal of the mucilage layer, the focus is drawn to the actual bean’s flavor. The result is a fruity-tasting coffee with a slight, fresh acidity. Specialty coffee experts prefer clean coffee because its flavor reflects that of the real bean. Properly washed coffee develops fundamental flavors, which vary based on the origin of the coffee bean.
Unwashed Coffee
In unwashed coffee, processing methods alter the taste of the bean. Unwashed coffee has a heavier body; it produces complex and smooth-tasting coffee. Due to its dense body and sweet characteristics, the taste often has hints of berries or tropical fruit.
Other Processing Methods
Honey Process
Central America is known for the use of the honey process. Beans are left with some mucilage when drying. Honeyed coffees taste naturally sweet and bright—a combination of unwashed and washed coffees.
FIGURE 2: Classification of Honey-Processed Coffee
Unwashed Coffee
In unwashed coffee, processing methods alter the taste of the bean. Unwashed coffee has a heavier body; it produces complex and smooth-tasting coffee. Due to its dense body and sweet characteristics, the taste has hints of berries or tropical fruit.
Anaerobic
Anaerobic means without oxygen. Anaerobic coffees are renowned high-end coffees that undergo a process similar to the washed process, but the fermentation happens in sealed tanks. Anaerobic-processed coffees have wild, unexpected, and complex flavor profiles.
Carbonic Maceration
This is similar to the wine-making process; the fermentation of the cherries happens during the harvest in carbonic maceration. The process breaks down the cell walls of the fruit flesh from inside out. Beans get soaked in all the flavors from the mucilage during the fermentation. Carbonic maceration yields varying flavor profiles and aromas like red wine, whisky, banana, and bubblegum.
Giling Basah
The Giling Basah method is typical of Indonesia. Giling Basah is a similar process to the washed process, but the beans are dried partially only. After 35 – 40% drying and elimination of the mucilage, the coffee beans need to be dried again. Giling Basah yields earthy flavors like wood, mustiness, spice, and tobacco.
Washing Coffee Beans to Improve Taste
A variety of flavors result from minor alterations in the duration of each step. Sorting and pulping remain the same for the various methods of the washing process. It is during the fermentation phase when flavor profiles develop, depending on the amount of mucilage left to react on the bean and the duration of fermentation, and form new flavor compounds. After being washed, the coffee beans now have distinct tastes based on these stages, their origin, and their variety.
Sources: Coffee Cartel, Coffee Wiki, Paulig