Ever see us scratching down numbers when we make your espresso? Here's why! Learn what all our "barista scratch" is about!
It's all about the numbers! Every shot we pull is judged based on four numbers that together tell us how the shot will taste. I suppose we could sip your espresso before giving it to you, but alas, this is more accurate and socially acceptable. :)
The first number is what baristas call the "dry-weight." Dry-weight refers to the weight, usually in grams, of the dry ground espresso beans. The ground coffee is then tamped into a portafilter basket and called a "puck." Changing the dry-weight is the easiest way to make adjustments to the overall product, the espresso. While the easiest, the changes made here are usually fairly small and produce minor "tweaks" to the final results. Example, a barista may change their dry-weight from 20g to 19.8g. The resulting coffee should also change by a matter of decimals. For a standard double shot of espresso, doppio, the dry-weight should be 1/2 of your final product weight. As in, 20g of dry coffee should pull 40g of espresso. But before we talk about the final product, lets talk about brewing.
Two of our four numbers are related to the time it takes to brew the coffee we just weighed. The first, is a barista's "pre-infuse." Pre-infuse refers to the length of time that water is first introduced to the dry-weight and allowed to soak in before full extraction begins. Think of turning a sink faucet on just barely to lightly wet a rag compared to turning the faucet all the way on. The first one is like a Pre-infuse, where water slowly wets the beans and brings them to the temperature of the water. The ground coffee begins to open up and loosen when the water soaks it. When this happens, Carbon dioxide is released forming bubbles. This first step of extraction we call the "bloom." You can't really see it when using an espresso machine, but it is named such because of how the grounds and water bubble up and "bloom" when using a pour-over for example.
Preparing them for extraction, which is like the full-on faucet and will send the water through the ground beans pulling their loosened flavors and particles out into the water. Coffee. The Pre-infuse is the most complicated number we'll talk about here and even more complicated to control. As a barista, one can choose, to some level, how long they pre-infuse. But this takes skill and a feel for what is needed to produce the results one is wanting. The machine and the beans are only a few of the factors that play into a changing pre-infuse time. As a rule of thumb though, our baristas aim for a pre-infuse time between 8-12 seconds. A fast, or "hard" pre-infuse, can ultimately slow your total extraction time. A longer, or "soft" pre-infuse, can ultimately speed up your total time. Pushing the water through an already well soaked puck is easier than pushing it through a still semi-dry puck. This has to do with flow. By increased pressure, (a hard pre-infuse), the puck is more compressed making the flow slower. A soft pre-infuse results in less pressure thereby not compressing the puck as much. Less compressed = higher flow. It can be a lot to think about, but when you simplify your goals and the basic concepts of more or less coffee, it will soon be as easy as riding a bike! However, many espresso machines do not allow the barista to personally control the pre-infuse time. These are considered automatic machines. A manual machine, in essence, allows the barista to adjust water flow by hand where as automatic machines are set to a pre-programmed pre-infuse. With an automatic machine, it is still possible to get your ideal numbers by playing with other variables, just pre-infuse is not one of them. This means it takes longer to dial in. With pre-infuse as an option, a barista can adjust on the fly and compensate for any other minor changes or errors made. An automatic cannot.
Now that the puck is soaked, we start another time count. "Extraction time" starts when the set max water flow is allowed to hit the puck and begin pulling the coffee through. In our opinion, and many other baristas', the extraction time should be exactly 27 seconds. If the shot pulls in less than that time, the espresso will taste sour, a sign of under extraction. If the shot takes longer than 27 sec. to pull, it will taste bitter, a sign of over extraction. The goal is to hit the dead middle where the espresso will taste sweetest and the flavors are most balanced. This brings us to our forth and final number.
"Wet-weight" is what we call the weight of the espresso. This is the good stuff that you drink! Or it should be good stuff if all your numbers were right on. Remember back to our dry-weight. I mentioned that the ration between dry-weight and the final wet-weight is 1:2. 20g of coffee beans should produce 40g of espresso in your cup.
In our minds, the perfect shot should be a 1:2 weight ratio, in 27 second, with a pre-infuse of 8-12 seconds. We take note of these numbers when we pull your espresso to constantly monitor the quality of taste you receive. There are many other variables we play with, but in the end, the goal is to get great tasting coffee.
So, with four numbers, we regulate and tweak each and every shot to produce the best taste possible and pour as much accuracy and dedication as we can into the art and science of it. We encourage you to put us to the test and ask for our numbers next time we make your coffee!