Making fine espresso is a game of variables and to get control of those variables requires a bunch of measurements. Within this content we will go over the basic measurements, why they are important, some starting points and ranges for the measurements. We will find out what the heck a bar is and go through this topic to the end to find out how all of this plays into grind size adjustment, which is perhaps the most critical variable.
So, why do we measure all these things when making espresso? Like we mentioned at the top, espresso is a game of variables. It is important when playing with these variables to maintain consistency. So when you make adjustments to one variable, you want to keep the other consistent. That allows you to judge the effect of a single change.
If you are using a popular coffee maker that uses coffee capsules, to produce coffee then you can read the following measures just for your information. If you own or thinking to buy an espresso machine then measurements will be more applicable to you.
So the measurements we are concerned with are:
For weight, we are measuring the dose of coffee in the portafilter. For a standard double espresso, most people will use around 17-18 grams of coffee.
The most accurate way to measure it is with a scale. So tear it out with the portafilter grind and weight it. If you don’t have a good accurate scale, you can just grind into a double-shot basket, over-fill a bit and level it off.
Obviously, this method is not as accurate as a scale but this method usually puts you in a good range and if you fill in level the same way every time, you should get a dose that’s fairly consistent.
Other options for consistent dosing our grinders with built-in timing functions and there are even grinders what automatically grind to a preset weight.
Espresso and temperature
For temperature, we want to know the temperature of our brew water. This can be a little tricky depending on the type of machine you are using.
Whatever machine type you are using, make sure it’s fully warmed up and the portafilter is locked into the group when not in use so it’s warmed up as well.
For espresso and most coffee methods, we want a brew temperature at 195-205 F (90.5-96 C) degrees.
On dual boiler machines with PID control it’s easy just to set the temperature you want and when everything is warmed up that is what you will get.
For coffee machines with heat exchange boilers, flushes are used to adjust the temperature.
In these machines, the initial shot of brew water is almost always above 205 F degrees. So prior to attaching the portafilter, brewing is turned on briefly to flush out the over temperature water. Typically, it flushes for a few seconds beyond the point when the water coming from the group has calmed down indicating that it’s below boiling point.
From there you can adjust brew temperature by continuing to flush for a few more seconds to go cooler or a few less for a hotter brew temp.
On single boiler machines or entry-level coffee machines with thermo-block boilers temperature control as well even trickier. It’s not unusual for these machines to have brew temperature swings of 10 degrees or more, depending on where they are in the heating cycle. Now there are ways to manipulate brew jumps on these but those techniques are pretty machine specific and evolve a bit of guesswork. The best basic advise we can give is to fully warm up these coffee machines with the portafilter in the brew group. Give the machine a short flush and then brew shortly after the machine indicates it’s back up to brew temperature.
Espresso and pressure
For brewing pressure some machines, typically higher-end ones will have a gauge that reads in bars. Now if you are not familiar with the pressure measured in bars, 1 bar is the atmospheric pressure at sea level, which is about 14,5 pounds per square inch. 8-9 bars pressure is a minimum of what we are looking for when brewing espresso.
Now if your espresso machine does not have a brew pressure gauge, don’t worry as you can use extraction timing to determine if you are in a proper brewing pressure range.
When timing, measure the time it takes to produce slightly over 2 ounces (or 60 millimeters) of espresso. What we are looking for is a range of 20-30 seconds from the 1st drip of espresso to make that double shot of a little over 2 ounces or 60 millimeters.
Brewing pressure and extraction time are controlled by slight adjustments to grind size and dosing way, and to a lesser extent by things like prefusion and brew temperature.
Now if time is under 20 or over 30 seconds work with grind size first while keeping the coffee dose consistent. Go finer to slow the extraction and coarser to speed it up. After adjusting grind you can adjust the dose to fine-tune your espresso shots as well as temperature.
At the end assuming you are working with a quality holding coffee, grind size is the most important factor when making espresso. Being able to consistently control other variables like dosing weight and brew temperature, allow you to dial in a grind size that produces the best possible espresso from the coffee you are using.