Water is a vital compound to life as we know it – whether it is forming an ecosystem, making up around 60 per cent of the human body or comprising the lifeblood which keeps numerous biological systems running. However, water plays an immensely important role in coffee farming, harvesting, production and consumption – and not just as a key component of the drink itself.
This much is somewhat self-evident – water is needed in order for coffee plantations to survive. A coffee bean is effectively a seed – and seeds need water to grow. In the majority of cases, farms are situated in sub-tropical areas of the world, where surprisingly water may be scarce. Without water – at the right volume, at the right time – the whole farming process would struggle to get off the ground.
Water is also critical at the cherry-processing stage if they are to be what is called 'wet processed' or 'washed' beans. While dry processing sees the cherries spread out and dried in the sun, for washed beans the pulp is removed from the cherry after harvesting before being washed away using water, along with the outer layer of mucilage. After being rinsed, the wet-method beans are then dried themselves. The water is, in most cases, then cleaned before being put back into the environment.
Once the cherries have been farmed and milled, when it comes to testing green beans as part of the quality control process, moisture content is one of the key factors to be analysed. Variations in the moisture content of green beans will affect not only how well they survive in transit from the country of origin, but also the roasting profile and dynamics, cupping process and flavour of the finished product.
Why? Well, first of all, water packs weight and so as importers ourselves and for roasters who buy the beans, nobody wants to pay for excess water.
According to the College of Tropical Agriculture and Human Resources at the University of Hawaii at Manoa, if a bean deviates from, say, 12 per cent moisture content by one percentage point, this would represent 1lb more or less of water across a 100lb bag of coffee. Therefore, with 11 per cent moisture content, an extra 100lbs of coffee would be required per bag to make up the correct weight, were 12 per cent preferable.
Furthermore, in the vast majority of cases, beans are being shipped internationally from far and wide. Too much water can cause the beans to sweat in shipping containers, which in turn can cause mould – a catastrophic problem in transit and thereby one that absolutely must be avoided at all costs.
However, it can also affect the flavour if there is too much moisture, causing the coffee to become musty.
At DR Wakefield, therefore, we stipulate an acceptable level of moisture in the bean and rigorously test all of our imports to ensure they do not fall below our standards.
The finished product
Cole McBride from Seattle, who came second in America's Northwest Regional Barista Competition this year, wrote in Barista Magazine about the seemingly obvious importance of water quality to the final product.
"Water makes up 98 per cent or more of brewed coffee and 95 per cent of espresso, which basically means that water and coffee have a strong relationship," he said.
How exactly can water itself change and affect the taste of a cup of coffee? While water is for all intents and purposes a neutral substance, its pH level can vary ever so slightly – above pH 7 and it will be more alkaline, below 7 and it will be more acidic. Typically, the closer to true neutral (7) that water can be, the better.
The barista warned of the dangers of iron in water. "Iron is terrible for coffee," he said. "Preparing coffee with water that contains concentrations as low as 10mg per litre will affect not only the flavour but also the colour of the coffee."
Other trace substances in water – such as calcium, sulphur, chlorine and magnesium – can also have an affect on the taste profile. Therefore, it is essential that those roasting beans in order to produce the finished beverage also take into account their own water filtration process as this will affect the coffee flavour too.