Processing is a short, but by far the most critical step in the journey of coffee which determines the final flavor profile of the berries. Rewinding a little, we’ve learned about the different types of coffee, such as Arabica and Robusta, and we’ve learned that the varietal plays an important role in determining the base quality to start with, which, when combined with good agricultural practices, will provide us with a good quality of bean to begin processing with.
Since the developed sugars within each individual cherry have a significant role to play in developing the end flavor profiles, we must ensure that the harvest is done to the best of our abilities. Because coffee is an agricultural product, we must remember that each individual cherry is unique in its own way, whether in terms of shape, size, or the development of the berry itself over the course of 7-9 months while being nurtured by the plants.
The goal is to homogenize the berries so that they work in harmony with one another. This can be accomplished by ensuring that the berries ripen uniformly, which is a challenge because most farmers rely on rain for blossom. Irrigation is one of the most controllable ways to address this problem. But this could also be induced by shade management and inducing stress to the plants by handling/Pruning before the Blossoming of the flowers.
We will most likely end up with a homogeneous lot of coffee if we harvest the coffee at the right stage of ripeness, preferably cherry red. which is then processed.
Processing In India
In India, farmers traditionally use either “natural processes,” also known as “dry processed,” “cherry coffee,” “sundried coffee,” or the “washed process,” also known as “wet processes.”
Traditionally, the farmer harvests the ripe cherries, cleans the lot of all foreign matter, and places it out on the patio to dry in the sun. This process is carried out primarily because the farmer has limited or no access to water resources and lacks the financial means to invest in machinery.
Washed process, on the other hand, is when cherries are harvested and put through machinery called “Pulpers”, which removes the cherry’s outer skin, followed by washing the beans to remove the mucilage that covers them. At this point, some farmers alter the process by allowing the pulped beans and mucilage to ferment for a period of time ranging from 8 to 36 hours, then washing and sun drying the beans, depending on the profile they wish to develop.
Popular Types of Coffee Processing
1. Natural/Dry Process
Today, the best and most reliable method of processing Naturals is to harvest the cherries when they are deep red in colour and then immerse the whole lot in water to remove any floaters. This ensures that any faulty beans are removed and the cherries are thoroughly cleaned before drying. The importance of drying cannot be overstated. When we naturally process coffee, we are allowing the sugars in the cherry to ferment and react positively with the bean. If done incorrectly, the coffee will become phenolic and over ferment.
It is always preferable to slowly dry the coffee rather than exposing it to direct sunlight. Maintaining a maximum temperature of 28 -30 degrees at the peak of the day aids the development of the coffee.
The end result is usually a well-balanced fruity cup of coffee. Regardless of the variety or region, Natural Processes add flavor to the coffee, such as fruitiness and sweetness. Common flavour notes include blueberries, strawberries, tropical fruits, and honey, and they are often compared to red wine profiles. Fermented flavors can sometimes go out of hand with alcoholic-like notes, while natural processes offer the consumer a range of new & exciting flavor notes.
2. Washed/ Wet Process
The wet process involves mechanically removing all of the fruit’s skin from the coffee cherry. Once the coffee cherry is harvested, it is passed through water to remove floaters and then through a de stoner to remove heavier particles to avoid damaging the depulper. Once depulped, the farmer can either ferment or wash their coffee immediately, depending on their goals. After that, the coffee is washed and prepared for drying. To ensure hygiene, drying is done well-clean patios or evenly raised beds. Raking the coffee is necessary in both processes to ensure even drying and balanced development.
Washed & Fermented: If fermentation is used, it is usually done in vats with or without water, depending on the desired end flavor – typically, for a period ranging from 12 to 72 hours. The same washing & drying process is followed as above.
Washed coffee usually has a bright and acidic flavor in the end cup, which is preferred due to its consistency and much cleaner profile with little complexity. Washed coffee tends to fetch higher prices due to its consistency and ability to sell not as a blend, but as a single variant because there is so much that can be done with this clean balance profile. Wet processing reduces the likelihood of defects in the batch as a result of the processing method used, and thus commands higher prices.
3. Honey Processed/ Pulped naturals
Honey processing is a popular specialty coffee processing method that originated in Costa Rica and El Salvador and is now used all over the world. The cherry is depulped mechanically here, with a certain amount of pulp/flesh leftover on the beans. The beans are then dried on patios or raised beds. Because there is less flesh, the risk of overfermentation is low.
Honey-processed coffee comes in a variety of colours, including black, red, yellow, and white. The colour refers to how much fruit flesh is left on the bean after it has been depulped. The amount of flesh left behind in black honey is the most, while the amount of flesh left behind in white honey is the least, and the physical appearance reflects the amount of flesh left behind. When compared to a fully washed coffee, this process produces a mellow yet bright cup profile with natural sweetness and good body.
4. Anaerobic Fermentation
This is similar to fully washed coffee, but the fermentation takes place in a closed container with no oxygen. While this is still an experimental process with limited results, it is gaining popularity in coffees used for competitions and high-end auctions. This process creates coffee with a distinctly bright, fruit-forward taste.
5. Carbonic Maceration
When coffee is macerated (fermented) in a carbon dioxide-rich environment, it is known as carbonic maceration. Coffee cherries are typically placed into airtight stainless steel barrels after being picked. CO2 is pumped into the barrel after it has been placed inside, allowing the coffee cherries to break down different levels of pectins. This method produces coffees that are bright and winey, with strong notes of red fruits and is a popular process in the wine & whiskey making industry.
6. Giling Basah
This popular Indonesian technique, which literally translates to “wet grinding,” is similar to the fully washed process, except that once the lot reaches a moisture content of 30%, it is hulled, and the final protective parchment layer is removed. The beans are slightly polished before being dried to a moisture content of 10-12%, which is ideal for storage. This process produces an earthy profile with notes of wood, mustiness, and tobacco. Although not widely known or liked by many, coffee enthusiasts will undoubtedly enjoy it.
Is the Lead for Coffee Academy & Flavour Science at Humblebean
He was the Quality assistant manager at Tata Coffee, and Lead production-in-charge for Roast & Ground and Starbucks operations. He holds a Masters in Coffee Economics and Science (University of Trieste, Italy) Scholarship from Ernesto Illy Foundation. Gaurav will help set up Humblebean’s Coffee lab & academy, and expand our blend development initiatives.