How much does water quality affect the preparation and sensory profile of espresso?
The Astoria Plus4You was the centre of an interesting experiment that lead to the evaluation of such factors. The results were published in the 46th summer issue of L’Assaggio, the sensory analysis magazine published by the Italian Tasters – Centro Studi Assaggiatori and managed by Luigi Odello.
Espresso preparation is influenced by the presence of chloride, of strange odours – particularly sulphites, which have a direct impact on the perception of flowers and fresh fruit – and by calcium and magnesium salts (lime), which determine water hardness. Given the importance of calcium in obtaining body, syrup and an elastic and stable cream, harder water generally favours the quality of coffee, but it also interferes with the need to maintain the efficient function of the machine.
In order to guarantee both results, some innovative methods have been developed, consisting of filters that associate lime protection to the removal of undesired substances, eliminating undesirable odours and controlling pH levels, thus not compromising the sensory quality of coffee or the machines’ mechanical parts.
The experiments used a variety of BWT (Best Water Technology) filters to obtain waters with different characteristics. These were fitted to Plus4You machines, using natural Arabica coffee, washed Arabica and Robusta. The espresso samples were subjected to sensory analysis by judges from the International Institute of Coffee Tasters – Istituto Internazionale Assaggiatori Caffè and analysis of the lipids and proteins was carried out at the Izsler laboratory in Brescia.
Through the use of mono-varied/multi-varied statistic techniques, the data – obtained using standard source water with different hardness levels and treated with various types of Bestmax filters – revealed an exact correlation between the various types of extraction water and the sensory profile of the espresso.
The most remarkable differences regarded higher-end coffee (in descending order: washed Arabica, natural Arabica and Robusta): the higher the quality of the blend used by the barista, the more consideration should be paid to the treatment of the water.
In particular, in the natural Arabica obtained with filtered water there is a higher perception of flowers and fresh fruit, nuts and spices; in the washed Arabica, this perception increases, especially with softer levels in the source water, otherwise there is a heightened perception of toasted and spicy notes. In the Robusta, the use of particular filters improves the perception of aromas like roast and spice, but it can also increase the perception of negative notes, like a taste of burnt, bitterness, sulphur and alkaline.
In general the best treatment is one that brings the water to a higher pH, which helps to obtain a better cream, body and aroma.
For deeper analysis of the results from the study, refer to issue 46 Summer of L’Assaggio.
