Espresso is a coffee beverage made using hot water under pressure
and served in a preheated cup. If made correctly espresso has a top layer of
crema (golden foam).
Espresso is made by a barista (master coffee maker). For the best quality espresso a barista must be concerned with the following four things:
A clean espresso machine controls the temperature, pressure and volume of water passing through the coffee grounds. It is extremely important that your espresso machine be kept clean and in good working order to get the best quality shots of espresso.
The blend is a combination of single origin coffees from around the world. These are blended because a single origin on it's own does not provide all the flavors and aromas necessary for a good quality espresso. For this reason, roasters often blend several coffees together to achieve the full taste and aroma they desire.
The coffee grinder crushes the beans into small particles for brewing. There is no "perfect" size. The barista adjusts the size of the grind based on the time of the shot "pulls". The optimum shot time for a double shot of espresso is between 18 and 24 seconds.
The barista controls the tamp. The tamp is performed with a "tamper" that is used to press the coffee grounds into the portafilter. The tamp must be level and consistent.