Espresso and espresso based drinks are notoriously difficult to get right. I see very often in commercial environments, baristas pulling shots that will never be reproducible. There is no weighing of the starting mass, end mass or timing of shot length. This is quite probably true of most home scenarios too. Therefore, I thought it would be worthwhile writing about the three most important considerations in producing espresso:
Dose, Yield and Time.
Consider making an espresso to be akin to baking or cooking. You need a recipe. You need to begin with something, end with something and it will take a period of time for the process to happen. In our industry we focus on the dose as our beginning and the yield as our end point.
The espresso dose should not change once you decide on your recipe. It must stay consistent, through weighing in, in order to create a consistent drink mass. The dose mass governs the size of the drink you wish to have. A large espresso needs a larger dose. A small espresso needs a smaller dose. You should not consider changing the dose in order to change the balance of flavour, shot time or strength of drink. Only change the dose if you need more or less espresso.
This consideration on dose mass should be applied to your milk based drinks too. If you require a greater balance of coffee to milk, use a larger dose. Conversely, if you prefer the balance shifting towards milk, use a smaller starting dose mass. You could use this methodology when choosing your cup size. Greater the total volume of cup may require a larger dose according to taste. As a rule of thumb, I tend to use between 17g and 19g as my dose for the majority of my drinks and design our Jones espresso blend to suit this mass for most milk based drinks.
In summary, only change the dose mass when choosing the size of your espresso – big or small.