How is excellent decaffeinated coffee made?

Decaffeinated coffee is sometimes unfairly seen as inferior, lacking the flavour and aroma coffee lovers enjoy. In fact, decaf can be excellent. It lets people who are sensitive to caffeine, or simply enjoy an evening cup, savour the taste of coffee with far less caffeine.

The history of decaffeinated coffee began with Goethe

How can you enjoy coffee and still sleep well? In the nineteenth century, Johann Wolfgang von Goethe took an interest in this question. An enthusiastic coffee drinker, he is associated with the story of chemist Friedlieb Ferdinand Runge, whose work helped identify caffeine.

This became part of the early story of research into coffee and its stimulating component. Later commercial decaffeination methods included benzene — now recognised as hazardous — and processes involving water. Modern production uses different approaches.

Three main methods pursue the same aim but differ considerably. They normally treat green, unroasted beans, and water plays an important role because caffeine is water-soluble.

Caffeine can be removed using approved solvents, supercritical carbon dioxide or water-based methods. The water-based process discussed in our original guide is referred to as Swiss Mountain Water.

Water-based decaffeination

This approach aims to remove caffeine while preserving the coffee's characteristic flavour and aroma. We particularly value solvent-free, water-processed decaf, which is why coffees made by this type of process feature in our shop.

How does it work? Green beans are soaked in water. Caffeine passes into the water, along with compounds associated with flavour and aroma. The liquid then passes through an activated-carbon filter designed to remove caffeine while retaining the flavour-bearing components in the extract.

At this stage, the initial beans have lost both caffeine and flavour components. The important product is the caffeine-reduced, flavour-rich extract, which can then be used with fresh green beans. Because that extract already contains coffee solids, it helps remove caffeine while limiting the loss of flavour from the new batch.

The result is coffee that still tastes like coffee, with most of its caffeine removed. Water-based processes can achieve very high caffeine removal; the original guide cites up to 99.9%. The exact specification depends on the process and product, and decaf need not mean absolutely zero caffeine.

A key attraction is that no chemical decaffeination solvent is used in the extraction stage. Most importantly for your cup, a carefully chosen decaf can taste excellent.

Other decaffeination methods

Solvent-based processing uses an approved extraction solvent, commonly methylene chloride or ethyl acetate. It is widely used partly because of its relatively low cost. Depending on the method, the beans are moistened with water or steam before the caffeine is extracted. The solvent is subsequently removed, and the treatment may involve repeated stages.

These processes sometimes prompt concern because the same chemical names can appear in other industries. Food processing is subject to limits and controls, however; an industrial use alone does not establish the safety of the finished coffee.

Carbon-dioxide processing uses high pressure and controlled temperature, around 70°C in the example described here. Moistened beans are placed in a pressure vessel, where carbon dioxide acts as an extraction medium for caffeine. This method is particularly suited to processing large quantities.

Who is decaffeinated coffee for?

Many people enjoy two or three cups of coffee a day without difficulty. For most healthy, non-pregnant adults, 400 mg of caffeine daily is a commonly used upper guideline, although individual tolerance and the caffeine content of each cup vary.

Some people tolerate caffeine less well, and genetics can be one reason. The liver enzyme CYP1A2, part of the cytochrome P450 system, plays a major role in metabolising caffeine. Differences in its activity can help explain why some people process caffeine more slowly.

Those people may be more likely to experience irritability, anxiety or sleep problems after coffee. But decaf is not reserved for them. Anyone can enjoy a good-quality decaffeinated coffee simply because they want one, regardless of how quickly they metabolise caffeine.