Why does coffee need a process before roasting?

Coffee starts as a red fruit on the tree, similar to a cherry, holding two seeds with flat sides facing each other. Processing removes the skin and pulp so only the seed remains, and it brings moisture down to a safe range for storage and transport. Without it, the fruit would spoil and no coffee green bean could be roasted.

Method drives flavor direction: the natural process leaves fruit and pulp in contact with the seed for intense fruity aromas and high sweetness, while the washed process removes the pulp first and delivers clean, bright acidity. The honey method sits between the two. The article also explains the fruit's structure, from silver skin and parchment to pulp and husk, and notes how roasters choose among these methods.

Coffee green beans don't look the way we know them as soon as they're picked. They first grow on the tree as red fruit that resembles cherries. From fruit to roastable coffee bean, a series of processing steps must take place in between, the purpose of which is to remove the skin and pulp, keeping only the seed, while also bringing the moisture content down to a safe range for easy storage and transport. Different processing methods directly affect the direction of a coffee's flavor—the natural process brings intense fruity aromas and high sweetness, while the washed process presents clean, bright acidity. This article will systematically outline the basic structure of the coffee fruit and introduce in detail the specific operational steps and flavor characteristics of the natural and washed methods, while also mentioning Front Street Coffee's processing-method preferences in product selection, to help coffee lovers build a complete understanding of processing methods.

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To understand what processing methods are all about, we first need to give a lesson to friends who are still unfamiliar with coffee: what exactly is coffee?

1

The Coffee Fruit

The coffee tree belongs to the Rubiaceae family and is a shrub or small tree. It usually doesn't flower for the first time until it has grown for about three years, and the flowers are white, giving off a delicate fragrance similar to jasmine. A few months after the flowers fade, the tree begins to bear fruit.

The newly formed fruit is green, gradually turns yellow, and becomes red when fully ripe, looking extremely similar to a cherry, which is why it is called a Coffee Cherry in English. At this stage it is ready to be picked.

A ripe coffee berry is bright red on the outside and cherry-shaped, concealing a pair of seeds inside—what we call coffee beans.

These two beans face each other with their flat sides, fitting snugly together. Each coffee bean is wrapped in a very thin outer membrane called the silver skin; outside the silver skin there is also a yellow layer called the parchment. Beyond that, the whole coffee bean is enclosed in a sticky, pulpy substance—this is the coffee pulp, soft in texture and sweet in taste. The outermost layer is the husk.

2

Common Processing Methods

From this we can see that coffee is far more than just beans. So why do we need to understand the coffee fruit before discussing processing methods?

There are two reasons. First, when coffee farmers pick it, the fruit looks like this—not the processed, roasted bean form we see later. What we need is only the coffee seed, so the role of the processing method is to remove the skin and pulp and keep the seed.

Second, at this point the coffee fruit is still a fruit, with a very high moisture content, and the pulp contains sugar. If stored improperly, it easily ferments, grows mold, or even spoils. Therefore, people must find a way to turn the coffee fruit into a form that is easy to store and transport.

Natural Process

The natural process is the most common coffee processing method. It involves drying the coffee fruit first and then letting the pulp and skin fall away. Among all processing methods, the natural process has the longest history, and a considerable portion of global coffee production uses this method, usually in countries that lack water and have little rainfall but abundant sunshine.

The Process

1. Sorting

The picked coffee cherries are poured into a water tank. Ripe fruit sinks to the bottom of the tank, while unripe fruit floats on the surface. Coffee farmers must first pick out these unripe fruits.

2. Drying

The sorted fruit is spread directly on the ground or on raised mesh beds to dry. The specific duration depends on the local climate and takes about 2 to 4 weeks. During this period someone must turn it regularly. Once the moisture content drops to around 12%, the dried coffee fruit can be gathered and stored.

3. Dehusking

After the coffee fruit has dried, the outer skin easily comes off in one piece. Local coffee farmers use a huller designed specifically for natural process coffee to strip the skin, leaving the coffee seed we need. After manual sorting and grading, it can then be exported around the world.

Flavor

Natural-process green beans tend to be yellowish in color. Because the pulp and green bean are retained during processing, fermentation of the pulp can give the coffee beans fruity and floral notes as well as the winey aromas produced by fermentation, with strong sweetness, a heavy mouthfeel, and complex aromatics—but at the same time it may also produce some off-flavors.

"Red Process, Ruby Process"

90+'s "Red Process" and "Ruby Process" use the natural method, but with even stricter standards during the selection of the coffee fruit.

Red Process

The so-called "Red Process" is a special processing method carried out by the 90+ team using their own patented drying technology. This process causes the parchment coffee beans to show varying degrees of red, from light red all the way to ruby red. This processing method can further enhance the coffee's own aromatic characteristics, while on the palate it displays an intense sweetness with obvious fruity flavors.

Ruby Process

The "Ruby" process is a more difficult and more extreme form of the red process. It pushes the sweetness and fruitiness of the red process to the extreme, but if it goes even slightly past the critical point, it turns into an unpleasant fermented flavor. This method also requires extensive manual selection. Every single green bean must meet the "ruby" standard before it can be called a "ruby" bean. After repeated elimination and repeated attempts, only the tiny remainder left at the end can meet the "ruby" standard, which is why it is expensive.

Washed Process

Because the West Indies region lacked sufficient sunlight, the Dutch introduced the "washed method" around 1740. The washing process first requires removing the pulp of the coffee fruit, then using fermentation tanks to remove the mucilage remaining on the parchment, after which the beans are washed and then dried.

The Process

1. Sorting

As with the natural process, the washed method also requires removing low-density unripe beans, likewise by soaking them in a water tank and picking out the unripe beans through sedimentation.

2. Removing the Pulp

A special machine is used to remove the skin and pulp, leaving only the coffee beans wrapped in parchment. But at this point, a thin layer of mucilage still remains on the parchment of the green coffee beans.

3. Removing the Mucilage

At this stage there is still sticky mucilage remaining on the surface of the coffee beans, which needs to be removed. This layer of mucilage adheres strongly and is not easy to remove, so it must be placed in a tank for about 18 to 36 hours to let it ferment, thereby breaking down the mucilage.

4. Washing

The fermented coffee is washed in a flowing water channel to remove the attached pulp and pectin. To create new flavors, some producers will place the washed coffee into a clean water tank once more to soak and ferment, producing even more distinctive acidic and aromatic notes.

5. Drying

At this point, the washed coffee beans have a very high moisture content. To prevent continued fermentation that would cause spoilage, they need to be dried, which takes about 1 to 3 weeks; sometimes a mechanical dryer is also used. Once the moisture content drops to around 12%, the coffee can be placed in a warehouse for storage.

6. Hulling

Before the parchment coffee is shipped out, it is sent into a huller to grind off the parchment, becoming the familiar pale green green coffee beans. After further sorting and grading, it can then be exported around the world.

Flavor

Clean, with prominent flavor and high acidity, but not as full-bodied as natural-process coffee.

In its bean list selection, Front Street Coffee also presents the flavor characteristics of different producing regions according to processing method. For example, washed-process beans often highlight clean acidity, while natural-process beans emphasize sweetness and fermented aromas.

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