Once considered a poor imitation of the real thing, decaf coffee has come a long way since first invented. With more people drinking decaf than ever before, we wanted to dive into the processes behind the product.
In this blog post we’ll cover the science, history and taste behind your favourite evening brew.
A Brief History of Decaf Coffee
Decaf coffee has been around for more than a century. The first commercial decaffeination method was created in 1903 by German coffee merchant, Ludwig Roselius. Whilst transporting his goods, a shipment of coffee beans was accidentally soaked in seawater. When the beans were later dried and roasted, he noticed, whilst the flavour was mostly intact, the caffeine content had dropped dramatically. He later went on to develop a decaffeination method inspired by this event, involving water and a solvent.
Over the last century, a variety of different methods have been developed. From CO2 extraction to charcoal filters to a plethora of water-based techniques - these processes are more sophisticated than early attempts, removing caffeine more selectively and preserving more nuanced flavours.
How Is Decaf Coffee Made?
As with its caffeinated counterpart, decaf coffee begins its journey as a regular green coffee bean. The caffeine is then removed before roasting, using one of three main methods. It is then roasted as usual.
1. The Solvent Method
The Solvent Method is the oldest and most common decaffeination method. It is a highly regulated and extremely effective process, known for maintaining the natural character of the coffee.
How it works
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The coffee beans are steamed to open their pores.
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The beans are soaked in a natural solvent. The most common solvents are ethyl acetate (often derived from fruit or sugarcane) or methylene chloride.
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The solvent binds to caffeine molecules in the beans.
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The beans are then steamed and rinsed to remove the solvent and the subsequent caffeine.
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Finally, they are dried and roasted as usual.
2. The Swiss Water Process
Unlike other methods, the Swiss Water Process doesn’t involve the use of solvents or chemicals. It only uses water. Because of this, it tends to preserve the more delicate notes of the coffee.
How it works
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Coffee beans are soaked in hot water, which draws out the caffeine and flavour compounds.
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The water is run through a charcoal filter that catches the caffeine, but lets flavour compounds through.
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This flavour-rich, caffeine-free water is used to soak a fresh batch of beans.
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Because the water is already saturated with flavour compounds, only caffeine migrates out of the beans.
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The beans are dried and roasted.
3. The CO₂ Method
The CO₂ Method is the most modern technique and is favoured for large-scale production or coffees where strong, bold flavours must be preserved (such as espresso blends).
How it works
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Beans are moistened with water.
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They are placed in a high-pressure chamber.
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Pressurised CO₂ is pumped in, which binds to the caffeine in the bean.
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The caffeine-rich CO₂ is then extracted and separated.
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The CO₂ is recycled, and the beans are dried before roasting.
How Much Caffeine Is in Decaf Coffee?
Despite the name, decaf coffee still contains a tiny amount of caffeine. This is because it is impossible to completely remove all caffeine from the bean. By law, decaf coffee must have 97-99% of the caffeine removed - as a result one cup of decaf coffee contains 1-3mg of caffeine, compared to 70-140mg of caffeine in a regular cup of coffee.
Whilst these numbers may not mean much, it’s worth noting that a normal bar of milk chocolate contains around 10mg of caffeine - which can be 10 times the amount in a cup of decaf coffee.
Does Decaf Coffee Taste the Same as Regular Coffee?
Nowadays, many decaf coffees taste very similar or the same as their caffeinated counterparts. We’ve found that with our own decaf blends, many people in a blind tasting can’t tell the difference.
Ensuring a quality decaf coffee comes from a number of factors, including the processing method selected and the quality of the beans themselves (including their freshness). Additionally, medium to dark roasts work better for decaf coffee, as the longer roasting process creates more rich, deep flavours that are maintained even when decaffeinated.