UNDERSTANDING COFFEE

The Coffee Roasting Process

There’s a lot of thought that goes into your beloved jar of Nescafé. Our growers pick only the best of the bunch for your brew and these beans get put through a careful coffee roasting process to create the unique flavours which make every sip of Nescafé as memorable as the last.

If you want to know about how the humble bean turns into the iconic flavour in your mug, read on and find out all about our unique coffee roasting processes.

The reason behind coffee roasting

It may surprise you, but coffee beans aren’t beans at all. Rather, they’re seeds which are grown inside a coffee cherry. Prior to the roasting process these ‘beans’ are green and smell grassy, a far cry from the rich flavour you’ve come to associate with coffee! The roasting process is where the magic happens and the clever little beans develop between 800 – 1000 different aroma compounds to transform into the coffee you know and love.

It’s during the coffee roasting process that allows for different roast profiles and flavours to be developed and as such, the temperature and time it takes has a huge impact. Quick roasting can result in beans which are dark outside with green inners, which not only tastes bad, but too much chlorogenic acid is produced, a substance that can be unsettling for your stomach. On the other hand, if beans are roasted for too long, it results in a bitter and charred brew.

How is NESCAFÉ coffee roasted?

Across all roasting methods, the energy source for roasting coffee beans is hot air. There are currently three main coffee roasting processes used:

1. Direct contact

This is carried out by classic drum or centrifugal roasters which work by passing heat from the walls of the roaster to the beans by direct contact or conduction. Typically, the beans will be kept moving by a paddle or a rotating drum (sometimes both) to help ensure an even roast. Occasionally hot air will also be used with these roasters for a more balanced result; however, this process is known as roasting by convection.

2. Hot air

Hot air coffee roasting is done with a tangential roaster. This form is often favoured as it uses a mechanical paddle and hot air to keep the beans constantly moving which prevents burning.

3. Radiation

Roasting coffee beans via radiation is currently one of the most difficult methods and as such, it’s the least popular. This is due to the fact radiative heat is extremely hard to measure and next to impossible to control, so when this method is used, infrared heat will usually heat a barrel and air, rather than applying radiative heat directly to the beans. However, direct contact or hot air or a combination of the two are far more common processes.

The coffee roasting process

The entire coffee roasting process involves four carefully calculated steps which requires a master roaster to ensure each step is completed accurately and that the beans are heated evenly.

1. Drying stage

Coffee beans have a humidity of around 10% (give or take), which means they need to be dried prior to roasting. How long this takes will depend on the roaster in question, however the temperature at the end of this step should be around 160°C. There’s a very delicate balance here as it can’t be heated too quickly or too much as you risk burning the beans. It’s also during this stage that energy from the bean is collected.

2. Browning stage

From here the coffee beans will begin to smell a bit like hay or toast, losing their original grassy aroma – this is a sign that the aroma precursors are changing to compounds. It’s during the browning stage that an exciting process known as ‘the Maillard reaction’ happens. This is where the beans have absorbed enough heat which causes the amino acids and sugars to react to one another, creating the unique aroma profile for each bean.

At the end of the browning stage, you’ll encounter what’s known as ‘the first crack’, lighter roast coffees typically aren’t roasted beyond this point.

3. Development stage

The development stage sees an exothermic reaction occur and the coffee starts to crack due to the collected energy from the drying process. This is where the aroma compounds are developed and the total time it takes depends on the desired flavour profile or roast. If a dark roast is wanted, a second crack may occur.

4. Cooling

Once the desired roast has been achieved, the coffee beans need to be transferred to a cooler tray so they can be cooled quickly. The heat given off by the beans can cause them to continue to cook even after they’ve finished roasting, resulting in burnt and charred beans.

What is split roasted coffee?

Some of our instant coffees are made of two unique batches of specially roasted coffees. Each batch is individually roasted at a different temperature to bring out the very best flavours of both beans, and only then are they blended together to create one unique instant coffee. Our master roasters call this ‘split roasting’ and have a patent to protect the NESCAFÉ expertise in this coffee roasting process.

We do ensure that whilst some beans will be of a lighter shade when roasted, then others will be much darker and each cluster of beans will experience the optimal roasting to ensure a full and well-balanced aroma in the final blend of roasted coffee beans.

Interested in what split roasted coffee tastes like? Try our delicious NESCAFÉ GOLD Roastery Light and NESCAFÉ GOLD Roastery Dark blends.

Now you know the ins and outs of the coffee roasting process, why not find out about each roast profile with our guide?

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NEW COFFEE

NESCAFÉ GOLD Roastery

Crafted by our master roasters, our new range of premium instant coffees will transport you to our iconic Roastery from the comfort of your own home.

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