The Quest for Coffee Perfection
Sponsored Content by BRITA
There is an incredible selection of coffee beans, roast levels, blends, and preparation methods to experiment with on your quest for the perfect coffee. However, using water with an unfavorable chemical composition can negate the time, money, and effort you have invested into achieving your desired flavor. Water filtration is the answer, but how does it work and how can you use it to your unique advantage?
Read on as we examine (and demystify) the main water filtration technologies but first, let’s not forget the sensory aspects of this delicious beverage and how your brain actually knows if the cup of coffee/espresso meets your individual seal of approval.
Aroma, Taste, Body, and Flavor: Senses of Perception
We use five senses to perceive food and drink: sight, hearing, smell, touch, and taste. In the case of coffee, three are particularly important: smell, taste, and touch:
• We use the olfactory bulb, a brain structure at the back of the nose, to sense the aroma of coffee. Aromas can also be perceived retronasally: when we take a sip of coffee, the aromas migrate from the oral cavity into the nose and reach the olfactory bulb via this route.
• We use our tongue and its receptors to detect the five basic tastes: sweet, sour, salty, bitter, and “savoriness” (often called by its Japanese name, umami). Together they define the taste of a food or beverage. If coffee has a chocolate-like aroma we don’t taste it but only smell it (an example of retronasal perception).
• The surfaces of the mouth have tactile nerve endings that let us feel the consistency of a food or beverage, which is called mouthfeel. With coffee, body is one of several tactile sensations. It is usually defined as the perceived viscosity, weight, or fullness of the coffee as we swirl it around in our mouths.
These three sensory inputs combine to create the overall sensory impression of a coffee’s flavor.
Everybody's preference is different: some prefer a coffee with more dominant acidity, while others favor a coffee with more bitterness. However, coffee experts agree that a brewing approach that brings aroma, taste, and mouthfeel into equilibrium is most likely to please the largest number of coffee-drinkers. In this case, no single attribute (acidity, bitterness, fruitiness, or roasted aroma) should dominate, and the coffee's body should neither be too thin and watery or nor too thick and heavy.
How Do Filtration Technologies Influence My Coffee?
Figure 2: How different water treatment technologies can affect the chemical composition of water.
Figure 3: The sensory impact of different water treatment technologies on coffee depending on the composition of the initial water.
The use of activated carbon reduces substances that can affect the aroma. In addition, decarbonization, total demineralization, reverse osmosis, and mineralization share the ability to improve the water and give the coffee a balanced flavor. Both decarbonization and mineralization support the ideal development of the coffee’s sourness; the first by enhancing it and the second by inhibiting it.
Softening amplifies the roasted aromas and increases the coffee’s bitterness, an effect that is typically associated with Italian coffee. Let’s further investigate these filtration technologies and see just how they influence black coffee and espresso.
Activated Carbon
Activated carbon is porous, fine-grained carbon. It is obtained by charring a natural carbonaceous material such as wood, peat, anthracite, or coconut shells and then “activating” it in a thermal process. This causes it to develop a large number of pores, increasing its internal surface area to attract and hold large amounts of substances.
“The internal surface area can comprise more than 1000m2, the size of four tennis courts, per gram.”
BRITA uses foodsafe activated carbon made from coconut shells which reduces the organic substances in water that have an unpleasant odor, like chlorine, which is often added to tap water to disinfect it. Chlorine has a distinctive odor and can be perceived in coffee. But even when the chlorine content is low enough not to be sensed, reducing it is vital as it combines with substances in the coffee, altering their structure and sensory properties.
Figure 4: Activated carbon can reduce substances in the water that could otherwise detract from the desired and expected aroma profile of the coffee.
Decarbonization
Decarbonization, also known as partial demineralization, is a term applied to all water treatment methods that reduce carbonate hardness.
Decarbonization reduces carbonate hardness, buffer capacity, and the alkalinity of the water.
Figure 5: The most commonly occurring mineral composition of European tap waters.
Acids, including those in coffee, possess and emit hydrogen ions. If the water were not filtered or decarbonized, the hydrogen carbonate would react with the hydrogen ions of the acids in the coffee. The remaining negatively charged part of the (coffee) acid left after shedding the hydrogen ions can lose its sour taste in the process. The more hydrogen carbonate is available to react with the hydrogen ions of the coffee acids, the more the coffee loses its sourness. Conversely, if less hydrogen carbonate is present, it reacts less with the coffee acids, which are therefore retained.
Figure 9: Balanced taste: The ‘right’ amount of hydrogen carbonate (HCO3-) results in a coffee with a desireable balance of sourness, aroma, body, and bitterness. To achieve this, coffee associations recommend brewing with water that has a carbonate hardness of 2-6 *dH. Although this parameter plays an important role in achieving great-tasting coffee, it isn’t the only factor. Unbalanced taste: Too little or too much hydrogen carbonate can increase and decrease, respectively, the coffee’s sourness, which can also impact other flavour parameters in unpredictable ways.
Figure 8: Decarbonization reduces the amounts of calcium (Ca2+), magnesium (Mg2=) and ultimately also hydrogen carbonate (HCO3-) present in the water. This can result in increased perception of the acids and improve the flavour balance of the coffee.
Softening
Softening reduces total hardness (the sum of carbonate hardness and permanent hardness) using a cation exchanger to which sodium ions are bound. After filtration, the water is almost free of calcium and magnesium ions. The hydrogen carbonate in the water reacts with the sodium ions exchanged for calcium and magnesium ions, to form sodium hydrogen carbonate.
Figure 10_option a: A cation exchanger with two bound sodium ions (Na+) exchanges these for a calcium ion (Ca2+)
Figure 10_option b: A cation exchanger with two bound sodium ions (Na+) exchanges these for a magnesium ion (Mg2+)
When the filtrate is heated (for example, in a brewing unit), it splits into sodium hydroxide, which is also known as caustic soda, and carbon dioxide.
Figure 11: Sodium ion (Na+) react with hydrogen carbonate (HCO3+) to form sodium hydrogen carbonate (NaHCO3), which decays into caustic soda (NaOH) and carbon dioxide (CO3) when heated.
The newly created sodium hydroxide increases the pH of the wet coffee grinds, which swell and become compressed. The hot (brewing) water therefore takes longer to flow through, prolongs extraction time, and removes more constituents that resist dissolving therefore increasing overall extraction. The water still contains hydrogen carbonate, which buffers the coffee acids. This can enhance both the roasted aromas and the bitterness of the coffee.
The roasted aromas and increased bitterness result in a coffee flavor that is often referred to as “typically Italian.” Those who do not enjoy this flavor decarbonize the filtrate to substitute hydrogen ions for part of the sodium ions in the water. Fewer sodium ions and hydrogen carbonate are then available, which reduces the roasted aromas and bitterness allowing the sourness to better develop.
Figure 12: Softening reduces the calcium (Ca2+) and magnesium ions (Mg2+) in the water and increases the sodium ions (Na+) without affecting the amount of hydrogen carbonate (HCO3+) present. This can increase the perception of the coffee’s roasted aromas and bitterness.
Total Demineralization
This involves the use of both cation and anion exchangers. The process of demineralization almost eliminates the cations and the anions. Reducing these minerals prevents adverse effects on the coffee’s flavor balance. In sensory terms, such chemically pure water isn’t ideal as it can leave coffee with excessive sourness and weak aromas.
To let the aromas unfold while reducing the coffee acids, specific minerals must be present. This is usually achieved by mixing the filtrate with unfiltered water from the same source, via a bypass. The downside is that added unfiltered water may contain undesirable components like chloride or sulphate.
Figure 13: Total demineralization reduces the amount of minerals in the water. This typically also improves the balance of flavors in the coffee.
Reverse Osmosis
In reverse osmosis (RO), water is pressed through a membrane with pores so small that only miniscule water molecules can pass through. The minerals and organics dissolved in it are too large to pass, so the filtrate is almost pure water (H2O). The drawback is that (like total demineralization) it yields sub-optimal water for coffee. It’s therefore a good idea to add a small amount of unfiltered water to the filtrate via a bypass.
A better solution is to install a post-mineralization filter so that only acceptable amounts of the desirable calcium and/or magnesium ions and hydrogen carbonate enter the filtrate.
Figure 14: Reverse osmosis eliminates almost all minerals and organics from the water. This reduces the extent to which these substances detract from a a balanced coffee flavour.
Mineralization
When coffee is made with almost mineral-free water, coffee acids dominate the flavor. This is offset by adding a small amount of calcium and/or magnesium ions and hydrogen carbonate to enhance the balance of flavors and reduce sourness. With RO, mineralization is an alternative to a bypass and even superior to it in purely sensory terms, as it only channels the desired minerals into the filtrate. Many mineralizing filters use grains of stone containing calcium, magnesium, and carbonate. When they come into contact with slightly acidic water, they are dissolved. It therefore makes good sense to insert a further, pH-reducing filter (such as a decarbonization filter) ahead of the mineralization so that a sufficient quantity of the minerals is dissolved.
Figure 15: Water is mineralized by intentionally adding calcium (Ca2+) and magnesium ions (Mg2+) and hydrogen carbonate (HCO3+) to it. This can enable the extraction of more aromas from the coffee, reduce acidity and thus achieve a balanced coffee flavor.
All Filters Are Not the Same
Despite the similarity of names and terms used by water filter manufacturers, the processes involved can produce different coffee flavors. Marcel Schauss, “coffeeologist” and a member of BRITA’s field service for professional filters in Germany, explains:
When talking with customers, I’m often asked why a competitor’s filter gives coffee a different flavor even though it uses the same technology. This often causes confusion.
The quality of the filtrate can be influenced by the device’s settings and size. Take decarbonization, for example: the water composition can vary depending on the amount of ion exchanger in the filter cartridge, the filtration rate, the buffering agent used, and the proportion of unfiltered water added via a bypass. Conversely, two different filter technologies can yield comparable water compositions and sensory properties. It’s always necessary to find out whether the filter technology per se is meant or they’re talking about a particular make of filter for a special application. A filter really is more than its technology.
For more information on BRITA Professional please visit our website: Professional Filter for business customers I BRITA
To view and download the whitepaper published by BRITA on this topic, click here.
On the BRITA Group:
With total sales of 656 million euros in business year 2021 and 2,321 employees worldwide (of which 1,263 are in Germany) the BRITA Group is one of the leading companies in drinking water optimisation and individualisation. Its long-established brand BRITA has a leading position in the global water filter market. The family-owned company based in Taunusstein near Wiesbaden is represented by 30 national and international subsidiaries and branches as well as shareholdings, distribution and industrial partners in 69 countries on all five continents. It has production sites in Germany, the UK, Italy and China. Founded in 1966, today the inventor of the household water filter jug develops, produces and distributes a wide range of innovative drinking water optimisation solutions for private (water filter jugs, on-tap systems and BRITA Integrated Solutions for small and large electric appliances by renowned manufacturers) and commercial use (hotel sector, restaurants, catering and vending) plus mains-fed water dispensers for offices, schools, restaurants and the hygiene-sensitive care sector (hospitals, care homes). Since 2016 BRITA has been working with Whale and Dolphin Conservation (WDC) to protect the world’s oceans from plastic waste, and as such to protect whales and dolphins.
