Tuesday 03 October 2023

BY PAOLO DALLA CORTE – Tecnica caffè: alkaline infusions and unwanted guests. Neglecting machine cleaning and maintenance. Taking care of boiler water

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Up until the invention of continuous pouring espresso machines, lever technology was based on one single water circuit that supplied water for brewing groups, steam and infusions – the boiler water circuit. A constant water demand allowed boiler water to be changed several times a day, with a subsequent balanced content of salts.

When continuous pouring machines entered the market, water circuits doubled: one supplied coffee brewing groups, the other provided steam and hot water for infusions. In the former, water is changed very frequently, proportionally to the number of espressos produced. In the latter, on the contrary, the opposite happens: water for infusions has a very limited demand – its greatest part is used for producing steam, which in its turn creates the milk foam for many drinks, such as cappuccino.

It is interesting to note that steam supplied by the steam wand is free of mineral salts when it is condensed to its liquid state – this means the salts have deposited in the boiler, adding up to those normally contained in the incoming water that maintains the normal boiler water level.

Incoming water has usually a pH of about 7 – according to law, water pH can vary from 6.5, slightly acid, to 9.5, alkaline. However, the constant use of steam for cappuccinos soon brings water pH to very high values, up to 11-12, which are very far from those of the so-called “light waters”, so appreciated for their poor Sodium content (high levels of Sodium could cause health problems in sensitive persons). This explains the importance of a complete water change in hot water/steam boiler to be carried out at least 2-3 times a week or, even better, every day. This problem has been very common since the Seventies, but it has always been neglected by machine manufacturers, particularly in case of low cost models.

In order to carry out such maintenance, the machine must be equipped with a semi-automatic boiler cleaning cycle, just like ours are. If this function is missing, the difficulty of boiler water change can be compared to oil change in a car: it is better to have it done, to avoid any possible damages (but how can one even think of asking a technician for help several times a week, if not every single day?). Finally, if water in the steam boiler is changed every day, outgoing water can be used, for example, for the cleaning of the bar floor.

If this maintenance is accurately carried out, baristas can be certain they will offer their customers high-quality infusions that taste good and do not cause health problems – it is therefore a simple, yet fundamental operation.

Getting rid of residues on and under the machine
During the day, steam and coffee powder mix, along with a certain amount of dust present in the air, forming deposits on surfaces all around the espresso machine and grinder. At the end of the day, it is also important to remove the layer of coffee fat residues that has deposited on the cup warmer rack. If this operation is not carried out and the periodical alternation of cups is not done, cups in the last rows could turn yellow due to the deposits accumulated over time. Also in this case, it is important to carry out a daily cleaning of the rack and of the upper part of the machine with a special degreasing spray in order to avoid having cups that seem clean but are not.

Let’s observe, then, what happens under the machine, where dirt and heat create the ideal environment for the formation of moulds and the proliferation of unwanted guests, such as cockroaches. According to the USA law, coffee machine feet must be at least 120 mm high; in Italy the standard measure is 40 mm: not much, but enough to allow the surface to be cleaned with a brush or cloth.

This cleaning must be included in the daily cleaning operations as well: an uncaring attitude can cause damage or lead to the need of disinfestations, thus affecting the bar/café’s image.

Stop neglecting the water softener
Finally, I would like to focus once again on the importance of drinking water treatment when its hardness exceeds 10°F. It is mainly carried out with water softeners in which special ion- exchange resins catch Calcium and Magnesium ions and release Sodium ions. If they reach saturation, however, they are not able to clean the water any more and, if they are not regenerated with common salt, they let mineral salts flow and crystallize when water is heated.

The most harmful salt is Calcium, because it creates calcifications that alter machine functioning until it is impossible to extract a good coffee….and the technical service is called urgently because “the machine doesn’t work”!

The picture in this page shows a “souvenir” that has recently been delivered to our machine shop: a group full of limescale that – strangely enough! – poured an extremely pale coffee. I agree on the fact that we – roasters and manufacturers – must be more committed in raising baristas’ awareness of the importance of taking care of their “jewels”, since their machines provide a good part of their income.

However, users themselves must be aware of the fact that the maintenance and cleaning of their devices play an essential role in the production of a good espresso: a personal responsibility not to be delegated to third parties, a sign of their commitment and will to make that longed-for quality leap of which just few examples actually exist.

The economic aspect must also be taken into account: when the machine is too encrusted, it is usually withdrawn from the bar (and temporarily replaced with another machine), then completely disassembled and cleaned with special decalcifying acids. Who should pay for this operations or – like in our case – for a maintenance that is carried out in loco, in which damaged parts are substituted without hindering the user’s work?

Unless in case of manufacturing defects, the “you break it, you pay for it” rule should be in force – this way, high costs would certainly make baristas take greater care of their machines.

I would like to conclude with an idea that is not much widespread in Italy: quality, functionality and performance of a device are proportional to its price (this is true in at least 95% of cases), not to the maintenance costs it needs during its operating life.

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