An excellent quality blend of coffee is not in itself a guarantee that you will obtain a perfect espresso. Besides the expert hand of the experienced barista, another important factor to take into consideration is the water, which accounts for 98% of the drink. The quality of the water is indispensable in order to obtain a good extraction. Normally, we tend to use water straight from the tap connected to the mains system, but it is important to remember that it may contain some undesirable components, with the risk that the quality of the coffee may be compromised. This is the reason why many water treatment systems have been developed. Let’s take a look at how they work.
Water treatment for softening, eliminating impurities and improving its properties
For the extraction of a good espresso, you need fresh water, with a good flavor and free from any odors which could have a negative effect on the flavor of the drink. Furthermore, its components should preserve a good balance of minerals: calcium, for example, which gives the water body and stimulates the formation of the protein lattice, thus determining the presence of a consistent cream.
Water from wells, rivers, springs or lakes is not made up simply of pure molecules of hydrogen and oxygen: indeed, there may also be heavy metals or polluting substances dissolved in it such as hydrocarbons, as well as forms of life like bacteria and micro-organisms. In the past, the aim of water treatment was, above all, to reduce the quantity of particles that led to the formation of limescale. Today, the aim of these treatments is to, on the one hand, guarantee the elimination of harmful particles, and on the other hand, to ensure that the water still has the ideal characteristics for consumption and the preparation of coffee.
Resin softeners: how do they work?
There are some systems available which can improve the quality of the water and be easily inserted between the water network and the espresso machine. These are softeners, in other words appliances created to prevent calcium deposits and ensure that the equipment and water purifiers that filter the water making it safer and good to drink, last longer.
The resin or ion exchange softeners improve the quality of the water by eliminating the positively charged ions, for example those of calcium Ca2++ and magnesium Mg2+, by allowing the water to flow over a bed of resins contained in a tank. These resins retain the Calcium or Magnesium ions and exchange them by releasing Sodium ions, which are completely soluble. The ability of the resins to perform this exchange tends to run out in a short time: this is why it is necessary to regenerate them regularly by removing the salts retained and supplying them with sodium chloride (coarse kitchen salt). There are two types of resin softeners: manual and automatic.
In the case of manual softeners, the regeneration of the resins can be performed at intervals which vary according to the hardness of the water. In general, this should happen every 26-33 pounds of coffee for the softeners which use 2.2 pounds of salt. The regeneration activity takes about 30 minutes, during which the coffee machine must not be used in order to avoid contact with the salty water. This activity is carried out by allowing a brine mixture of water and salt to flow through the cylinder, and can be stopped once the water coming out no longer tastes salty.
These work on the same principle as the manual softeners. The regeneration though, in this case is carried out automatically at planned times and deadlines via a timer, which can be analog or digital. Normally, the machine can also continue working during the regeneration. The operator just needs to add some rock salt every so often in the appropriate tank.
Reverse osmosis for water treatment
Reverse osmosis systems are used when there is continuous demand for pure water, minimum bulk and low costs for assistance and maintenance. The process is based on the use of semi-permeable membranes which allow the water to pass through and retain 99-99,7% of the ions it contains.
This method allows the polluting particles to be completely eliminated, even of the very smallest dimensions, as well as viruses, bacteria and general impurities, thus guaranteeing absolute bacteriological purity. However, once the water purification by reverse osmosis removes all the fundamental characteristics of the water, it becomes necessary to install a cartridge filter which reintroduces the essential elements, before using it in the coffee machine.
What are cartridge filters?
The difference between these filters and the ion exchange ones lies in the type of resins used and the addition of filter cartridges, placed on the filter head. These contain mixing mechanisms between carbonized and non-decarbonized water, filtered both mechanically and with active carbons: they allow both macro particles and residual organic particles of water to be filtered, as well as reducing the content of chlorine and heavy metals such as lead, zinc and copper. Cartridge filters also act on discoloration and on the organoleptic improvement of taste and odor.
The advantage, in comparison with the more traditional resin method, is that it is not necessary to add salt for the resin brine, but simply change the cartridge regularly, as well as having the possibility to remove both impurities and water hardness.