Traditionally, espresso was made with a sensory approach that would take months or even years to master. It required baristas to develop a sensitivity to the appearance of the grind, the volume of coffee in the basket, the speed and time at which it was extracted, and the appearance, smell and taste.
Moving forward in time, and through the development of tools and technology, we have replaced our sensory approach to espresso production with a scientific recipe of numbers, scales, refractometers and pressure. These tools have helped baristas achieve quality control and simplified our lives by providing useful facts and figures to work with.
I believe the future of quality espresso extraction comes from marrying sensory abilities with measurable variables.
If you follow a recipe exactly and your coffee still tastes bad, what do you do? Before you call your supplier to complain, consider the variables that can impact the extraction and flavor outcome and adjust accordingly. These can include humidity, temperature, time since roasting, light, air, tamping and pressing technique, equipment functionality and cleanliness, dose volume, grind size, bean origin, roast type, heat, and milk pouring technique.
The three main factors for good espresso extraction include:
• Dose: quantity of coffee, generally measured by weight in grams.
• Grinding: size of the coffee particles, in relation to grinding or fineness.
• Time: duration of coffee extraction.
Everyone has their own method of calibration. Tom Hespe of Toby’s Estate has over 20 years of experience in the coffee industry. For single origins, he likes to dose a little less than for blends and uses a bare group handle to get a better view of the pour. He also likes to take things to the extreme, pulling super-fast and then super-slow shots to experience the full range of flavors the coffee has to offer. He also recommends calibrating with a few people, as you can bounce ideas off each other and get some interesting results.
Now, to produce a complete and balanced espresso shot, let's understand the four stages of extraction:
1. Initial extraction. This lasts approximately one to 12 seconds, also known as ristretto. This stage is responsible for achieving dark, rich, syrupy notes in the cup.
2. Extraction of the medium. This occurs about 12 to 22 seconds into the shot. It is responsible for achieving equilibrium in the glass.
3. Diluting the shot. This is the final stage, starting at 22 seconds, and is where the color of the extraction is light and the flavor is a little bland.
4. Yield. This is the last phase where the volume of espresso coffee is extracted.
These times are just a guide. You may have a bean that really comes alive when dosed a little higher and tighter, running up to 40 seconds, and that’s OK too. You may be using a different grinder where faster shot times are the norm. The point to understand is how each stage of extraction impacts flavor.
How espresso extraction correlates to flavor.
Now let's identify the main sensory factors in espresso extraction:
• Pour speed. Did the espresso come out of the group handle in a spurt or did it drip super slowly and take a long time to form a steady stream?
• Color. Has the color changed well over time or has it lightened too quickly?
• Aroma. Does the espresso give off a pleasant aroma or is there a metallic/pungent note? Smell can be difficult to assess due to the fact that coffees are roasted from light to dark and this will impact the overall aroma.
• Flavor. Look for a balance between acidity, bitterness and sweetness.
• If your espresso tastes bitter, the grind may be too fine. You may have put too much coffee in the basket or left the shot in for too long.
• If your espresso tastes sour, the grind may be too coarse, the dose too low, or you stopped pouring too soon.
Unless you’re using a volumetric machine, you’ll need to learn when to stop the shot. We don’t need to get too technical about this. When the shot starts to “go blonde” and the stream wobbles or gets thinner, that’s a general sign that you’ve fully extracted the coffee. I encourage you to play around with this to find what works for you, stopping at different times and tasting the coffee.
If you're using a volumetric espresso machine that stops when a certain amount of water has passed through the coffee, you still need to watch the appearance of the coffee so you can adjust the dose and grind correctly, and not just run on autopilot and sacrifice flavor.
Now that you know how to adjust your espresso, leave a comment about how yours is coming out.
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