Espresso Myths Demystified-- The Dead Espresso Shot

https://arvicaf8aa.doodlekit.com/blog/entry/13934433/how-long-will-an-espresso-shot-last

Crema is the layer of foam that usually sits on top of an espresso that has in fact simply been pulled. The typical rule in coffee making is that as quickly as the crema disappears from an espresso, the shot is