on to coffee extraction systems, we want to dedicate an entire chapter to espresso
machines – no one better than Paolo Dalla Corte could introduce us to this topic!
the characteristics that a coffee machine must have to extract the best espresso?
to start by saying that in my opinion, there is no perfect cup of espresso.
Evaluating coffee can be in great part objective from a technical point of
view, but there is also a very subjective component that makes the evaluation personal. That said, to list the main features that a coffee machine
must have to extract any type of coffee in the best way possible, we must first
see what does an espresso machine bring into the cup.
extraction systems, espresso machines apply thermal energy and mechanical
energy to the water. To ensure the best extraction, machines must have
thermal flexibility to adapt to any type of coffee and roasting on the
market. The higher the temperature, the more soluble parts of the coffee are released
into the water. Once we’ve found the right point of extraction - that is,
the right point of coffee solubility proportional to the amount of water - this
variable must be consistent. It seems like word play, but if we want this result
to be repeatable hundreds of times throughout the day, the temperature must be
as steady as possible, otherwise we risk not having the same result any
given cup. And once the barista finds his perfect cup, he wants this perfection
to be repeatable.
energy we apply is water pressure. Every time we brew coffee, we operate
a motor pump that generates pressure. It’s been found that the
ideal pressure to extract an espresso lies between 8.5 and 9.5 bar. We can
almost say that espresso isn’t a proper drink, it's the elixir of an emulsion.
the foundations of a coffee machine, but experience and evolution has highlighted
another important variable - pre-infusion. A feature already known in the 1960s and then underestimated for several decades. Only recently, with the coming of digital and manual flow regulators, has this
phase been re-evaluated as an additional variable that can be set for espresso
extraction. At the same temperature and pressure, pre-infusion allows you to
explore in more detail all the organoleptic properties of a single origin or a
is fundamental, as it prepares coffee for the actual extraction: depending on
the water flow we are going to apply, pre-infusion allows us to wet the puck faster or slower and apply pressure for a longer or shorter
amount of time. If done correctly, we can achieve different aroma intensity and body. And like
all variables, once the correct setting has been found there has to be the
possibility of repeating it over time. "
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