All coffee enthusiasts say it, in his or her best Hermione Granger voice, “it’s eSpresso, not eXpresso!” While this is true, let’s help educate, not shame. Nevertheless, now that we’ve got the pronunciation down, what exactly is it?
What is Espresso?
Espresso is a method of brewing coffee. It is not a type of bean or a type of roast. This method consists of highly-pressurized hot water being forced over coffee grounds, resulting in a very concentrated cup of coffee. One shot of espresso makes one ounce. But most coffee shops will use a double portafilter basket, producing two ounces, or two shots of espresso. On top of this, people do have different recipes and methods. Some people use a 1:1 coffee-to-water ratio, while others use a 1:3 ratio. Some people will pull 14 grams, while others pull 21 grams. Some people will extract for 20 seconds, while others 35. Most though, generally speaking, will pull two shots of espresso at a coffee-to-water ratio of 1:2, using 18 grams (dose) of coffee to make 36 ml (yield) of espresso in about 25-30 seconds (time).
Another defining factor of the espresso brewing method is the pressure at which the water is forced through the coffee grounds. For true espresso, near-boiling water (about 200F) is forced through coffee grounds at 9 bars of pressure, which is about 130 pounds per square inch. This mechanical pressure that is applied extracts soluble and insoluble solids and gases, resulting in, hopefully, a tasty shot of espresso.
There are many other factors to consider when correctly pulling a shot of espresso. The size of the grind plays a significant factor. As has been mentioned before, the larger the grind size, the longer it takes to extract the good qualities from the coffee beans. Espresso, then, being pulled at around 27 seconds, is a very fast brewing method. Therefore, the grind size is going to have to be quite fine.
Water temperature plays an important part as well. 195-205 is the ideal rage for properly brewing espresso. A general rule is that the darker the roast, the closer the water should be to 195; and the lighter the roast, the closer it should be to 205. Correct temperature is important for proper extraction: a cooler temperature will not extract properly, resulting in a sour cup, while a temperature that is too hot will burn the coffee grounds.
Tamping pressure is also very important to consider. Tamping is the act of exerting pressure with a tamper onto the coffee grounds that are inside the portafilter, resulting in a compact “puck” of coffee. Making the grounds compact is essential for the forced hot water to extract all of the coffee, rather than finding the path of least resistance, over-extracting some grounds, while under-extracting others. The pressure at which one compacts these grounds will also affect the grind size that is needed for pulling a shot within the proper time period of 25-30 seconds.
Espresso truly is a super easy and extremely difficult thing to do properly. The task of pulling a shot of espresso is pretty easy, but maintaining all of the correct variables and doing so consistently is a task that takes a long time to nail down. So if you are wanting to jump into the espresso-making world, give yourself grace, because it is not likely that you will be a professional in just a couple of months.