Decaffeinated Coffee Pods: the Origins

To obtain a quality espresso coffee, and consequently also for decaffeinated coffee pods, one must always start with the choice of the origin of the beans. The origin is simply the place where the coffee beans come from, and it influences, along with many other important factors, the taste, aromas, and body that will be perceived in the cup.

As mentioned in the following paragraphs, it is easy to think that the quality of decaffeinated coffee depends greatly on the quality of the beans being decaffeinated. The richer and more aromatic they are, the less noticeable the difference will be to the customer compared to non-decaffeinated coffee. For this reason, our decaffeinated coffee pods ALWAYS contain four different origins with an unmistakable aroma blended together to create a blend:

• Brazil (Arabica) to give the blend roundness and sweetness, but above all, the distinctive cocoa aftertaste
• Colombia (Arabica) to bring its balanced taste and the unmistakable aroma of chocolate and caramel, with slightly citrusy notes of plum and peach
• Ethiopia (Arabica) thanks to which the blend acquires floral and citrus notes
• India (Robusta) which provides a velvety body and pleasant spicy notes

The Decaffeination of Decaffeinated Coffee Pods

To achieve the decaffeination of the coffee present in decaffeinated coffee pods, one must act on the green bean (not yet roasted). The first commercial process was developed and patented in Bremen, Germany, in 1905, and sold as Café Hag, a name still in use (2). The law requires that raw (unroasted) decaffeinated coffee must contain less than 0.1% caffeine on a dry basis (3). A solvent capable of extracting caffeine from the bean is used to remove the caffeine.

There are mainly four different solvents used to decaffeinate coffee, each with its own advantages and disadvantages. At the end of roasting, the residual solvent used must not exceed the technically unavoidable amount and must not pose risks to human health (5).

Ideally, the decaffeination process should remove caffeine from the bean cells without any alteration of the bean itself. Due to the very nature of the caffeine molecule and its position within the coffee bean cells, this removal faces great obstacles that can cause loss of aroma or aroma precursor molecules, changes in the structure and size of the beans, loss of mass, and changes in appearance (1).

During decaffeination, the beans are first brought into contact with steam and water to increase their moisture content from the initial approximately 10% to 25-40%. The beans are then decaffeinated through solvent-modulated extraction. At the end of the process, the residual organic solvent is drained and then removed using steam, followed by drying to return to normal whole moisture values (1).

The Solvents Used in Decaffeination

The first solvent that can be used is water, in use since 1941 for decaffeination purposes (2), a non-selective solvent solely for caffeine and therefore difficult to use. Since the solubility of caffeine in water increases with temperature, extraction is carried out with hot water for about 8 hours.

When the bean is brought into contact with water, it extracts not only caffeine but also various water-soluble components contained in the beans, inevitably leading to a “thin, light” flavor in the resulting coffee. Some strategies are used to attempt a resolution to this problem.

For example, the caffeine extraction water can be saturated with aroma precursors (chemical compounds naturally contained in the beans that evolve into coffee aromas during the roasting process) to reduce their extraction from the beans during the decaffeination process. However, exchanges between the precursors saturating the water and those present in the coffee are inevitable, causing a change in the composition of the decaffeinated beans.

A second strategy used involves having the water extract caffeine and water-soluble aroma precursors, removing caffeine from the resulting solution using a solvent or activated carbon, concentrating the caffeine-free solution formed, and then having the decaffeinated coffee beans reabsorb the aroma precursors present in the extraction water.

A second solvent that can be used is supercritical carbon dioxide. With the use of this solvent, carbon dioxide is subjected to high temperatures and high pressures (about 25-30 MPa and 100°C), thus obtaining properties intermediate between those of a liquid and a gas (supercritical state). In this state, carbon dioxide becomes highly selective in extracting caffeine. The costs for this type of processing are obviously very high, making it difficult to use for decaffeinating small quantities of coffee.

It is also possible to extract with liquid carbon dioxide at 6.5-7 MPa and 20-25 °C, but it requires longer processing times due to the lower solubility of caffeine. The main advantage, however, is the much lower processing temperature. Sometimes a “flat” taste may occur in decaffeinated coffees with carbon dioxide.

The third solvent that can be used is ethyl acetate. It is a selective solvent for caffeine, often naturally present (for example, it is frequently found in fruit). The main drawback is the flammability of the product used, which requires specific procedures in the decaffeination process. Tasting tests have often detected an enhanced fruity note in the treated coffee. Only if decaffeination is not performed under optimal conditions can a “cooked” taste result.

The last solvent that can be used is dichloromethane, a widely used solvent for decaffeination, among the first to be used industrially. Like some substances already mentioned, it acts selectively on caffeine and is highly volatile (boiling point at atmospheric pressure at 40°C). Again, imperfect decaffeination can impart a “cooked” taste.

The formation of aromas in coffee occurs mainly during the roasting process, which takes place after decaffeination. This is a great advantage, even though caffeine extraction processes can obviously influence aromatic components. The reduction of caffeine in coffee does not alter its flavor; what can alter it are the decaffeination processes, especially if performed under non-optimal conditions.

Current decaffeination processes have a limited impact on taste if properly conducted, and only slight changes in flavor can be noticed, such as, in most cases, increased acidity.

So, which is the best process? There is still no definitive answer, as taste differences can be very subtle, and it is complex to compare decaffeinated coffees with their counterparts that have not undergone any caffeine removal process, as decaffeinated coffees often require different roasting curves compared to their “original version” (1), inevitably leading to the development of different, non-comparable flavors and aromas on the same comparison scale.

For decaffeinated coffee pods, ethyl acetate is always used for the decaffeination process, resulting in a pleasant acidity in the cup, a delicate taste with fine aromaticity, a full and velvety body, and chocolate notes in the aftertaste.

Solvent Residues in Decaffeinated Coffee

The allowable residual amount of solvent varies depending on the substance used. Water and carbon dioxide do not require special attention as both are always present in the coffee bean after roasting, even if not decaffeinated.

Regarding ethyl acetate, there are no specific regulations on residue, as it is a substance already naturally present in some foods, such as fruit.

Dichloromethane, on the other hand, as a substance classified as “probably carcinogenic to humans” (7), requires non-carcinogenic reference values (safety values) and is limited to a maximum residue of 2 ppm (2 mg/kg) in roasted coffee (6).

The Roasting of Decaffeinated Coffee Pods

The step preceding the creation of decaffeinated coffee pods obviously involves the roasting process.

As mentioned above, decaffeination causes changes in the structure and composition of the bean, so it is necessary to create a careful and personalized roasting curve for the coffee that has undergone this process, in order to maximize aromaticity and taste.

Roasting times may be, for example, shorter or longer, and the final color of the beans may differ from non-decaffeinated beans of the same blend. Therefore, maximum attention must be paid to this process because this is the moment when, starting from aroma precursors, the true aromas of coffee are formed.

The Grinding and Packaging of Decaffeinated Coffee Pods

Immediately after roasting, the coffee needed for the preparation of decaffeinated coffee pods is ground. The time between grinding and packaging is crucial because the faster it is, the more coffee aromas are preserved in the ground coffee pod.

The powder obtained from grinding the roasted coffee beans is dosed in the amount of 7 grams and pressed.

The pressed ground coffee is then enclosed between two sheets of compostable food-grade filter paper.

The obtained decaffeinated coffee pods are packaged in single-dose sachets from which oxygen, a great enemy for the proper preservation of coffee, is removed and replaced with nitrogen, the noble inert gas par excellence.

The control of decaffeinated coffee pods ALWAYS takes place at the end of the packaging phase, on a sample basis, with the analysis of the ground coffee and subsequent extraction.

The packaging material, aimed at reducing environmental impact, has been designed to ensure the proper preservation of the pods and save 30% in weight of material compared to the market average.

Home Extraction

Home extraction is the culmination of the series of processes listed above. It is important to know that in coffee extraction, you can decide which tastes and aromas to enhance from those present in the decaffeinated coffee pod.
A shorter coffee extraction will highlight the acidic and intense taste, while a longer duration will decrease acidity in favor of bitterness. In between, you will find the heart of the always blend, a balance marked by a pleasant acidity.

BIBLIOGRAPHY:
1- Pietsch A., The craft and science of coffee (2017)
2- R. J. Clarke, Encyclopedia of Food Sciences and Nutrition (2003)
3- Ministerial Decree May 20, 1976, and subsequent amendments
4- Decree January 23, 1991, No. 87
5- DECREE August 4, 2011, No. 158
6- European Directive 2009/32/EC
7- P. M. Schlosser, A. S. Bale, C. F. Gibbons, A. Wilkins, G. S. Cooper – Human Health Effects of Dichloromethane: Key Findings and Scientific Issues (2014)