Can I use a 50 Hz device in a 60 Hz power frequency?
The 60 Hz represents the frequency at which the voltage in the wire oscillates. Heating elements don't care about this, and neither do most electronic components as they turn this alternating current (AC) into constant (DC) direct current anyway. 

If this is an all-singing, all-dancing, computer controlled extra-fancy espresso machine then I'd steer clear, though, as there's a remote chance you've one of the few devices where the cycles-per-second makes a difference. If it just uses power to heat an element you should be fine.

Disclaimer: operating the device outside of the region it's designed for will certainly void the warranty, and coffee in excess isn't good for you anyway.