The act of making espresso is simple. There is a bit of technique involved, but generally the physical movements required to prepare a shot of espresso can be taught in a matter of a few minutes. What makes an espresso actually taste good has more to do with the recipe you use. Knowing how to effectively adjust your recipe to improve flavor is not always common knowledge among enthusiasts. Eliminating variables wherever possible makes it easier to understand what is actually going on, so I always recommend keeping the dose consistent.
The Dose, sometimes called the “input” is simply the weight of the ground coffee in your portafilter basket. If you don’t know the weight, grab a kitchen scale that can measure in grams. You will want to fill the basket with the amount of ground coffee that the manufacturer recommends, and it is usually printed or etched on the side of the basket somewhere. For example, here at Corvus we have 18-gram portafilter baskets so all of our recipes use that dose. Sticking to this weight within a gram or two is a really good idea.
Funny things start to happen when you play around with the dose. Let’s take a step back and think about what’s actually happening in the portafilter when you brew an espresso (forgive me if this gets a little nerdy!) First, boiling hot clean water hits the top of the coffee bed. Then, it’s forced under pressure to navigate its way through seemingly infinite pathways through the coffee grounds, and we hope it does so as evenly as possible as it grabs and dissolves flavor along the way. As it’s doing this though, that clean boiling water is dropping temperature and turning into espresso so that by the time it reaches the bottom of the coffee bed grounds are being brewed into espresso with espresso! Increasing or decreasing your starting dose changes the depth (and the shape of the coffee bed) that the water has to travel through. This is going to change the time the water takes to get through the coffee bed, increase difference between the temperature at the top and bottom changing the types of flavors extracted along the way and many other things I can’t even think to name! Don’t worry, I won’t bore you with the Noyes-Whitney equation…
Keeping your starting dose consistent will simplify your life and get you to a delicious, dialed-in shot of espresso much quicker. You’ll also be able to understand and nail down the other more easily controlled variables and how they change the way your shots taste—things like grind size, total brew time, and how much espresso you decide to brew or the yield; more on that later!