Coffee with caffeine versus decaffeinated coffee: the first is more widely drunk, but people also drink the second, especially after supper…explaining “if I drink coffee now I won’t be able to get to sleep.”
If we look at the statistics, decaffeinated coffee, is drunk regularly by roughly 12% of coffee consumers, while another 30% drink it occasionally… making for a turnover of 75 million euros a year, equivalent to 7% of the coffee market.
Everyone knows that caffeine is a stimulant that contributes to making us more mentally and physically active. But is it true that it makes it more difficult to get to sleep? And how is it eliminated from coffee? Let’s debunk a myth or two.
When was decaffeinated coffee invented?
The first decaffeination processes were implemented in the early 20th century.
The basic process was actually discovered in 1820 by the German chemist Friedlieb Ferdinand Runge, but the first to actually commercialise it – between 1903 and 1906 – was Ludwig Roselius, a German coffee merchant.
How is coffee decaffeinated?
Caffeine is soluble, and can be extracted from green coffee beans before they are roasted. There are five principal methods for decaffeinating coffee, differing only according to the extraction agent employed, apart from which the process is always the same.
The principal phases of decaffeination are:
- Swelling. In order to be able to extract the caffeine, the coffee beans are “swollen” by steam, which expands the beans’ cellular structure.
- Extraction. One kind of specific solvent or another is used to “capture” the caffeine and draw it out of the bean.
- Solvent recovery. The solvent is removed from the coffee bean and recovered. This is necessary both for economic reasons – the solvents are expensive and are therefore recovered for re-use, to save money – and for legal reasons – because the law requires that production waste be minimised.
- Drying. The moisture is removed from the beans.
- Packaging. The coffee is packed in sacks, ready for shipping.
- Analysis. Decaffeinated coffee must be tested to ensure that its residual caffeine does not exceed 0.1% of the coffee’s weight, that residual solvents do not exceed specific limits (depending on the solvents used), and that overall humidity does not exceed 11% (in Italian law).
Decaffeinated coffee: the solvents used
There are five main solvents employed to remove caffeine from coffee. They are all volatile, and so leave no trace in roasted coffee.
1. Supercritical carbon dioxide
The green coffee beans are moisturised by water and steam until they attain the ideal moisture percentage (maximum 40%). Then the beans are passed through the extractor along with the carbon dioxide, present in a particular physical state called “supercritical”. This state has the dual properties of spreading like a gas and dissolving like a liquid. The extraction takes place “gently”, at a pressure between 120 and 250 atmospheres. Once the beans have been deprived of their caffeine content, they are dried. CO2 decaffeination ensures a high level of extraction selectivity, leaving intact the other substances involved in determining the quality of the coffee. However, this method is expensive: the equipment needed costs a lot, because of the need to work at pressures up to 250-300 bar, and its running and maintenance costs are extremely high. The process also requires a lot of energy, which means it can only be used on large product quantities, since it would be uneconomical to use it on small amounts of coffee beans.
2. Liquid carbon dioxide
Liquid carbon dioxide is a less expensive and energy-devouring alternative than the supercritical version, because it works at much lower pressures and temperatures (65-70 bar, and 20-25°C). As with supercritical CO2, the beans are moisturised with water before the solvent treatment begins. The disadvantage of this method is that the extraction time is far longer, since it takes place at low temperatures.
Here too, the green coffee beans are steam-moisturised in the preliminary phase and then passed through the extractors where dichloromethane (an organic substance authorised under existing EU legislation) removes its caffeine. This substance is highly volatile (evaporating at 40°) and is this eliminated from the coffee via steam-treatment in the next phase. The roasting process subsequently eliminates the last residual traces.
Dichloromethane was one of the first solvents used to decaffeinate coffee at an industrial level, which is why it’s one of the best perfected over time, and also one of the most widely used. It is extremely selective towards caffeine, resulting in a high quality coffee which maintains all its desired sensorial characteristics intact.
4. Ethyl acetate
Ethyl acetate is a solvent present in nature – especially in fruit – which makes it an appealing organic choice, even though a synthetic version is often used. Like the dichloromethane, ethyl acetate is highly selective towards caffeine and thus makes it possible to obtain a high quality coffee. But unlike dichloromethane, it has two drawbacks: it is highly inflammable and has a fruity perfume. It therefore produces a decaffeinated coffee that has a characteristic smell and a slightly different taste: a solution that some people find unpleasant.
Water was among the first solvents to be used in coffee decaffeinating. It has the advantage of boasting a great commercial image, but unfortunately it is not very selective about its purges, which complicates its usefulness. There are two possible methods for reducing the impact of aroma loss in water decaffeination processes:
- firstly, the aqueous extraction can be saturated by standard coffee aromas beforehand, so that when it passes through the coffee beans it “captures” as few aromas as possible. The problem with this method is that it still features modified coffee aromas, caused by the molecule exchange between water and coffee.
- secondly, the aqueous extraction can be made to pass through the beans and to absorb both caffeine and aromas, but it is then decaffeinated using extraction solvents or active carbons, and finally reintegrated with the coffee beans via a molecular process.
The raw product obtained through this procedure is extremely dark even before roasting… so it has to be toasted very carefully, bearing in mind the particular characteristics of the altered product.
A new frontier: genetic engineering to create decaffeinated coffee.
The most recent frontier in coffee decaffeination is genetic engineering, i.e. producing coffee plants with no caffeine content.
In 2014, the genome of Robusta coffee was identified, a key discovery in many ways, helping us understand the origins of coffee and its kinship with other plants, and so improve the resistance of its plants against parasites and search for a coffee that is “decaffeinated from birth”.
This last aim, in particular, is being studied by a Brazilian researcher, Paolo Mazzafera. In 2003 Mazzafera discovered an Arabica variety with an extremely low caffeine content… roughly 15 times less than that of most coffee varieties.
The main problem with low caffeine coffee plants, like those discovered by the Brazilian researcher, is that caffeine increases their resistance to parasites. If deprived of their caffeine, the plants have to make themselves “less appetising” by reducing their size and growing more slowly. The challenge faced by genetic manipulation, therefore, is to succeed in developing a “decaffeinated coffee plant” suitable for large-scale cultivation. An extremely complicated task: Mazzafera did succeed in producing a laboratory plant with only a tiny amount of caffeine, but in its second generation the plants all returned to their natural levels of caffeine content.
To develop stably reproducible non-caffeinated coffee plants, therefore, many genetic components will have to be modified: a highly difficult and costly process not currently viable. But tomorrow… who knows?
What is caffeine exactly?
Caffeine is a substance that is found in the seeds and leaves of the coffee plant, but also in tea, cocoa and other plants.
In combination with caffetannic acid, it acts on nerve centres, provoking a sense of general wellbeing, stimulating people to feel more alert and active, both physically and mentally. It affects the lungs, because it provokes dilatation of the bronchi and pulmonary ventilation, it effects the muscles because it increases the capacity of muscular contraction, the heart as a cardiotonic, the stomach walls by favouring the secretion of gastric juices and thus improving the digestive process.
A cup of coffee contains between 50 and 150 mg of caffeine, depending on the coffee-making method used. Filtered coffee, for example, contains more caffeine than espresso, because during a slower filtering process the water dissolves a greater amount of caffeine from the coffee grounds.
Does caffeine create dependency?
People often say they are affected by “caffeine dependency”, but this usage resembles claims of being shopping dependent, work dependent or TV dependent. Actually, most medical authorities affirm that caffeine does not create true dependency.
In certain particularly sensitive subjects, the interruption of habitual caffeine consumption can cause headaches, tiredness or drowsiness. Normally these symptoms last for only a few days and can be avoided if caffeine consumption is reduced gradually and not suddenly.
There is no “standard” suitable quantity of caffeine for our organisms: the degree of tolerance varies according to physique and habits. Like all food, it is wiser to avoid excessive consumption, also to avoid unpleasant effects like tachycardia.
In general the effects of coffee on the heart are totally secondary and are not evident with “normal” coffee dosages such as 2 or 3 cups per day.
Is it true that decaffeinated coffee has less aroma?
“Decaffeinated coffee doesn’t taste as good real coffee!”. How many times have we heard that?
In reality, the taste of coffee depends on the concentration of aromatic substances developed during roasting, and has no connection with the presence or otherwise of caffeine, which is eliminated before the beans are roasted.
We can state this clearly: decaffeinated coffee has exactly the same taste as “normal coffee”. If it doesn’t taste good… that’s the fault of the coffee, not the caffeine!