How Does Processing Green Coffee Impact its Taste and Acidity Levels?

Before the coffee arrives to your doorstep or is poured in your cup, a great deal of processing must occur both, here in the United States, and in the coffee bean's country of origin. How that coffee is processed, can affect not only its taste by its acidity.

Coffee Processing 101: Post Harvest

In this article, I will be sharing with you the various methods of processing coffee for export in the Specialty Coffee Industry. How the coffee is processed has a major impact on its quality, price, and taste.

Lets begin with the most common methods of processing and then I will include a couple bonus methods at the end, including my favorite method; European Preparation (EP). Most of the coffees which you will find in our inventory at Mavericks are EP.

First a word about quality, will be discussing processing methods of the coffee bean post-harvest. This article does not speak to other quality factors namely:

• Genetic Variety

• Climate

• Soil

• Geographic Origin

• Cultivation Practices

The aforementioned factors are contributors to the coffee quality prior to harvesting, the post-harvest process cannot make-up for what the cultivation lacks.

Types Of Coffee Processing: A Common Processing Method of Coffee.

This is the 1st step after harvesting the coffee bean. Processing cannot change the underlying quality issues mentioned above. However, processing can modify or fine-tune the intrinsic quality of the bean itself. The processing of the coffee is more a like a revelation, revealing what is already in the bean. So, it is important to start with a coffee bean that has been cultivated to specialty grade standards.

Two Methods of Processing Coffee

There are two general methods used to obtain a stable condition of the coffee, the dry and wet process.

• Wet Process

• Drying Process

Within these two types of board categories of processing methods there are several variations of each, such as: Honey, Pulp Natural, and Wet Haul. In the case of Honey Processed, variations occur such as Honey White, Yellow, Red, and Black.

The point is that while coffee process can generally be divided into wet of dry processed coffees their exist many nuances to handling the coffee at origin. I have just identified a few categories of processing here to give to you insight.

The larger point is this: each process has the same goal of removing the coffee seed from it's fruit flesh, mucilage, silver skin and bring the coffee bean to a stable moisture content. How that is acommplished is quite different.

Anatomy of the Coffee Bean

For quick anatomy of coffee bean; the coffee bean is actually the seed of the coffee. Mucilage is the gooey layer between the outer shell of the coffee bean and a fruity layer of the fruit flesh.

Approaches to Green Coffee Processing

Interestingly, whether wet or dry, similar approaches to processing the coffee bean can impart it's own unique flavor profile to the final cup of coffee. Some of the most common types of coffee processing include:

1. Washed Process (Wet Process) - This method involves removing the outer layer of the coffee cherry (the "pulp") before the beans are dried. The beans are then fermented to remove any remaining mucilage before being washed and dried. Washed coffees are known for its clean, bright, and acidic flavor profile.

2. Natural Processed Coffees (Dry Process) - This method involves leaving the coffee cherries to dry naturally before removing the outer layers. The drying of the beans inside the cherry imparts a unique sweetness and complexity to the final cup. Natural processed coffee is known for its fruity, berry, and wine-like flavor profile.

3. Honey (Semi-Washed) - This method involves removing the outer layer of the coffee cherry while leaving some of the sticky and sugary mucilage that surrounds the coffee beans. The beans are then dried with this mucilage still on them, which will also deliver a unique sweetness and complexity to the finished coffee. Honey processed coffee is known for its notes of fruit, honey, and caramel.

4. Pulped Natural (Semi-Washed) - This method is similar to honey process, but it's more common in Brazil and Ethiopia. In this method, the outer layer of the coffee cherry is removed while leaving some of the sticky, sugary mucilage that surrounds the coffee beans. The beans are then dried with this mucilage still on them, which imparts another form of sweetness, complexity, and body to the coffee. Specifically, Pulped Natural coffees are known for their notes of fruit, honey, and caramel.

5. Wet Hulled - This method is primarily used in Indonesian countries such as Sumatra, it involves removing the outer layer of the coffee cherry's skin (called the "pulp") while the beans are still moist, rather than waiting for them to dry first. This results in a coffee that has a unique flavor profile characterized by earthy, herbal, and sometimes spicy notes, as well as a heavy body. I can attest to the processing method with our own Sumatra, which carries a spice note. (This is the one coffee that we carry that are not washed coffees or EP)

   

Washed Coffee Processing Methods

The Washed processing, also known as the wet processing method, is a method of preparing coffee beans in which the outer layer of the coffee cherry (fruit) is removed before the beans are dried. This method is known for producing a clean and bright cup with a high level of acidity and a distinct flavor profile.

The process typically involves the following steps:

1. Picking: Coffee cherries are hand-picked when they are fully ripe.

2. Pulping: The outer layer of the cherries fruit is removed using a machine called a pulper. The pulper separates the beans from the fruit and removes the mucilage. The mucilage is the sticky layer surrounding the bean.

3. Fermentation: The beans are then placed in tanks where they ferment for up to 48 hours. Fermentation helps to remove any remaining bits of fruit and break down the sugars in the beans.

4. Washing: After fermentation, the beans are washed to remove any remaining fruit and mucilage.

5. Drying: The beans are then spread out on raised beds or patios to dry in the sun. Depending on conditions this process can take anywhere from several days to a few weeks. Beans must be rotatd to ensure uniform drying.

6. Hulling: Once the beans are dry, the parchment (the dry outer layer of the bean) is removed using a machine called a huller.

7. Grading and Sorting: The beans are then graded and sorted according to size and quality.

8. Bagging: The beans are then packaged and shipped to the buyer.

Washed coffees produce a wide range of flavor profiles depending on the factors such as the coffee variety, the ripeness of the cherry, the fermentation time and temperature, and the drying conditions.

Dry Coffee Processing Methods

Dry methods are less depended on water to process the coffee beans and lean more to fermentation of the coffee bean in the wet methods.

Natural Process

Natural processed coffee is a way of handling coffee beans in which coffee cherries are left to dry naturally before their outer layers are removed. It adds sweetness and complexity to the coffee, with flavors of fruit, berry, and wine, which can also enhance the coffees body. This is a popular in countries such as Ethiopia, Brazil, and Yemen.

Honey Processed coffee

Also known as "pulped natural" or "semi-washed" coffee, Honey processed coffee, as a method involves removing the outer layer of the coffee fruit from the coffee bean. This is called "pulping". Honey processed provides for leaving the mucilage on the coffee even after the bean is pulped and dried.

The mucilage is a sugary and sticky substance that encirlces the green coffee bean between the bean and the fruit. The amount of mucilage left on the beans can vary "from light to heavy" and is usually scored on percentage basis for residual mucilage. This a popular method in Costa Rica, Honduras, and Nicaragua.

Wet Hulled Coffees

Wet hulled coffee, is a processing methods primarily used in Sumatra and other parts of Indonesia. The method involves removing the outer layer of the coffee cherry (called the "pulp") while the beans are still moist, rather than waiting for them to dry. This results in a coffee that has a unique flavor profile characterized by earthy, herbal, and sometimes spicy notes. Wet hulling can also add to enhancing the heavy body of the coffee. Interestingly, in the Specialty Coffee Industry, wet hulled coffee is considered to be of lower quality. I might comment that in the case of the Sumatra we carry at Mavericks, I thoroughly enjoy the spicy notes that coffee carries.

European Preparation Processed coffee

European preparation coffee, also known as "EC" or "European Coffee," is a method of processing coffee beans that is used in countries such as Ethiopia, Yemen, and Brazil. The method involves removing all the outer layers of the coffee cherry, including the parchment, and then polishing the beans to remove any remaining silver skin. The beans are then sorted by size and shape, and finally, they are graded according to the percentage of imperfections.

The European preparation method is considered to be one of the highest standards of coffee quality, as it ensures that the beans are free from defects and have a consistent size and shape. This uniformity, is size and density, makes the finished product after roasting very uniform. EP coffees tend to have a clean, bright, and balanced flavor profile. This method is often used for high-quality specialty coffees and is favored by so many specialty coffees, coffee roasters and competitions.

Carbonic Maceration

Barrowed from the wine industry the concept of Carbonic Maceration (CM) involves fermenting whole grapes or berries without crushing or pressing them, but by placing whole grapes in a sealed fermentation tank. Carbon dioxide is pumped into the tank to create an anaerobic environment, which causes the grapes or berries to ferment. So slow the fermentation this process is done at cooler temperature, which helps to preserve the fruity aromas and flavors of the grapes.

In the coffee world, a similar process of CM or "coffee carbonic maceration" or "anaerobic fermentation" is used to create unique and complex flavor profiles in coffee. The process starts with whole coffee cherries being placed in sealed tanks to ferment. I have not tasted a coffee processed in this manner, however, I have been told the result is a very fruity and like taste profile.

CM is still in its developing stages and is not widely used in coffee, but the potential is great.

Processing effects on Taste and Acidity of Coffee Beans

Processing techniques at origin can effect the taste of the coffee bean, but also its acidity. Fir acidity in cupping attribute and acidity as it relates to level of acid concentration.

Coffee Processing Methods: Affect Taste

The coffee processing method used can have a significant impact on the taste of the final cup of coffee. Different processing methods can bring out different flavors and characteristics in the coffee beans.

Washed coffees (wet process) coffee is known for its clean, bright, and acidic flavor profile. The removal of the outer layer of the cherry and fermentation before drying removes impurities and unwanted flavors from green coffee, highlighting the acidity and sweetness of the beans.

Natural (dry process) coffee is known for its fruity, berry, and wine-like flavor profile. The beans are dried inside the cherry, which imparts unique sweetness and complexity to the final cup. The drying process can take longer and the beans can be exposed to the sun and air, which can affect the beans' flavor.

Honey (semi-washed) and pulped natural (semi-washed) coffee is known for its notes of fruit, honey, and caramel. The beans are dried with some of the sticky, sugary mucilage that surrounds the coffee beans. This imparts a unique sweetness and complexity to the final cup brewed coffee. The degree of fermentation and drying time can affect the coffee's flavor profile.

Wet Hulled coffee is known for its earthy, herbal, and sometimes spicy notes, as well as a heavy body. The removing of the outer layer of the coffee cherry while the beans are still moist, rather than waiting for them to dry first, results in a coffee that has a unique flavor profile.

European preparation coffee is known for its clean, bright, and balanced flavor profile. The beans are sorted by size and shape, and finally, they are graded according to the percentage of imperfections, which result in a consistent, high-quality cup.

In summary, coffee producers, whether producing washed and natural coffees, regardless of the fermentation process utilized can play a significant role in determining the final taste of the coffee. Although, wet processed coffee is more to my liking for, consumers that favor that fruity taste from natural processing, there are many options available.

Wait you say! What about processing methods affect on acidity levels. While the processing method can have a potential slight effect on the pH of a coffee. Slow roasting is the single most effective means to turn any coffee into a very low acid coffee.

- Ryan