How our senses contribute to our understanding of water and coffee

understanding coffee

BRITA Head of Organoleptic Department Birgit Kohler on how BRITA’s sensory lab contributes to our understanding of water and coffee.

Water quality has a massive influence on the quality of your cup of coffee. You can ruin your favourite coffee by choosing the wrong water, but you can also enhance the flavour experience by using the “right” water.

Birgit Kohler is the Head of Organoleptic Department at BRITA.

To achieve a consistent and perfect water quality, you need a good understanding of the water composition. That’s why BRITA has a special department dedicated to taste.

Taste is measurable and organoleptic testing is a particular scientific field. On the basis of more than 100 different standards for organoleptic testing, together with my team in the BRITA Organoleptic Analysis Department, I choose a suitable methodology for every question that needs to be answered. Sometimes several methods are necessary to answer a rather simple question.

In organoleptic testing, it is never about a single person’s perception. Instead, we work with specially trained groups of testers, the so-called panellists. Anyone who attends a testing has successfully completed extensive taste trainings and has to prove their sensory skills in recurring counter tests.

During these panel meetings, the panellists mainly taste water, but also tea and coffee. A beverage like water, which seems to be not very spectacular at a first sip, offers an unexpected variety of sensory experiences.

Our tastings and research are conducted in a state-of-the-art sensory lab, inaugurated in 2015, which has been designed to allow us to work independently and effectively.

Artificial light and a minimal design keep the atmosphere neutral, ensuring our surroundings remain constant and don’t influence how we perceive taste. The tasting room can accommodate up to 12 testers at once with testing booths adapted to suit each test, so we can work collaboratively without disrupting each other.

The test results then flow into various projects and products at BRITA. Ultimately, the goal is to improve water’s taste, not just in theory but also in practice, because everyone should enjoy great flavours. This work builds our own understanding of water flavour and composition, as well as that of the wider community. With other departments of BRITA, the Organoleptic Analysis Department even helps produce educational material for the coffee and food industries.

Some years ago, most people were neither aware of the sensory dimensions of coffee nor the impact of water on coffee. But water for coffee has become more important within the past few years. We are on a journey. We still have some way to go, but we’re heading in the right direction.

From my perspective, the future is in enabling more and more people to understand the effect of water on coffee. Even though it might seem complicated at first, in my experience, it’s a pretty easy introduction to chemistry. This is especially true for sensory-skilled people, because they can instantly taste the difference. 

There are three main parameters that impact the sensory of water: minerals, organic compounds, and substances from water treatment. Each also have a critical impact on the flavour of a coffee.

Minerals influence the coffee extraction and can interact with extracted substances. 

In my opinion, the most important factor for a good taste in coffee is the mineralisation of the water. Water without minerals (distilled water) extracts different substances from the coffee grounds compared to water with lots of minerals.

The most important minerals occurring naturally in drinking water include calcium, magnesium, sodium, and potassium, as well as chloride, sulphate, and – most importantly – hydrogen carbonate.

Depending on the overall mineral content in water, hydrogen carbonate is also called “carbonate hardness”, “buffer capacity”, or “alkalinity”. No matter which name, when there is a lot of hydrogen carbonate in the water, it influences extraction and reacts with the fine caffeic acids. The coffee can taste unbalanced and even flat. 

Organic substances can be perceptible in the taste of coffee.

Organic substances include plasticisers, residues of plant protection agents and solvents, but also natural substances like algae metabolites. 

Organic matter in drinking water is highly controlled and many of these substances, such as pesticides, have very strict limit values. However, some of these substances are perceptible in taste even in tiny quantities. 

One example is geosmin, a natural algae metabolite, tiny amounts of which can produce an earthy-musty taste reminiscent of beetroot. Geosmin is also formed in coffee beans when they are incorrectly dried or if they are exposed to excessive moisture in storage. 

Many of these organic contaminants can arise as off-flavours in water as well as coffee.

Water treatment substances can influence extraction and become perceptible in coffee.

Certain substances are deliberately added to treat water, for example, chemicals to eliminate clouding (turbidity) or chlorine for disinfection. 

Only a very small amount of chlorine is used in tap water but combining it with organic residues can give water an unpleasant odour and unpalatable taste. Depending on the binding partner, chlorine has different taste qualities and threshold values.

If the water to be used for the coffee already smells of chlorine, it’s very probable that the coffee will also take on a chlorine-like aftertaste. Even if chlorine is not perceptible in the water, there can still be reactions with the delicate coffee aromas.

The “perfect water” for coffee really needs to be filtered. Even if the mineralisation level is OK, you need to make sure that there is nothing else, like chlorine or geosmin, potentially influencing the taste of your cup.

In a country as large as Australia, there is not just one level of water quality that applies to the whole nation. It really differs from region to region. For instance, Victoria is considered to have a lower mineralisation that other states like Western or South Australia. This can mean the same coffee can taste different in two cities, which is something coffee roasters or suppliers should be mindful of when operating across state lines.

In general, mineralisation in Australia is not too high compared to Germany, for example. But the use of chlorine is necessary to treat water and the pipe systems are very long, which can cause additional compounds to build up. This may lead to several off-flavours in water that requires high-quality filters to purify at the point of use.

The ideal water composition for coffee would not contain organic compounds or substances from water treatment. When it comes to minerals, instead of lacking these “ingredients”, it just needs to be the right amount. It might sound simple, but a good quality filter is all you need to achieve a consistent water quality. 

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This article appears in the June 2021 edition of BeanScene. Subscribe HERE.
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