Miele CVA 2660 - Manual (Page 85)

Pressure is important as it releases the
suspended particles in the coffee which
give it its aroma. If the pressure is too
low, the aroma cannot develop fully. If it
is too high, it releases tannin and a
bitter flavour. Pressure is also important
for creating the crema.
Pre-warming the cups prevents the
espresso from cooling too quickly.
Roasting is very important for the
flavour and caffeine content of the
espresso. Roasting releases the
ethereal oils which create the aroma
and flavour. A darker roasting gives a
more concentrated aroma, but burns off
more caffeine. So the darker the roast,
the lower the caffeine content. Lightly
roasted beans have a more acidic
flavour, and dark roasted beans taste
more bitter.
The caffeine content of espresso is
only a third or a half the caffeine
normally found in coffee. The darker the
roast, the less caffeine the espresso will
contain.
Water hardness can affect the flavour
of the espresso.
Glossary
85