It is perhaps the most difficult and most misunderstood method of turning ground coffee into a delicious liquid. Historically, a single espresso shot was 7 grams of ground coffee producing 25 milliliters of liquid espresso in 25 seconds with very darkly roasted, low quality coffee beans. At best, this would give a rich, chocolatey flavor, but generally just tasted very bitter and smoky. Most espresso drinkers added sugar and/or milk to cut down on the bitterness.