So you’ve mastered pulling shots with your favorite espresso blend. But you didn’t become an expert home barista just to stay chained to one coffee. No, you want to try out the full breadth and depth of coffees–from those fudgy, nutty Brazils to the aromatic, enchanting Ethiopias.
But how do you make the switch without wasting a lot of coffee, time, and money? Today, we’ll teach you how to use the information on your bag of coffee to help you speed up the process. But first, the science!
Extraction and Solubility
Whenever you’re pulling a shot, you’re simply using water, an active solvent, to extract flavor compounds from a coffee, a roasted seed. What’s amazing is that all coffees, regardless of origin or roast, will go through the same stages of extraction. However, different coffees will go through those stages at different rates, depending on their solubility. For our purposes, we’ll define solubility by how relatively easy or difficult it is for water to break down the flavor compounds in any given coffee.
If a coffee is more soluble, it will require less water and time to extract well. If a coffee is less soluble, it will require more water and time to hit that sweet spot.
So what determines a coffee’s solubility and how can I predict if a coffee will extract slower or faster?
The two most important factors relating to solubility are density and cell structure. Remember, coffee beans are really just the roasted seed of the coffee fruit, so they’re full of plant fibers. How does a home barista find out how dense and strong a particular coffee is? Before you go rushing to your electron microscopes and graduated flasks, take a look at the bag sitting on your counter.
You’ll most likely see three important pieces of information on the bag: the roast level, the elevation, and the processing method.
The roast level has the greatest impact on solubility; the darker a coffee is roasted, the more soluble it becomes. This is because roasting affects both the density and cell structure of the coffee. If a coffee is roasted darker, more is cooked out of it and the bean becomes more fragile.
So what does that mean practically speaking?
If you’re switching to a coffee with roughly the same roast profile, try keeping your grind setting and recipe the same.
If you’re switching to a coffee that is darker than your last coffee, it will want to extract faster. Try adjusting your grind setting a little coarser and using less water to brew.
If you’re switching to a lighter roast, the coffee will want to extract slower. Try adjusting your grind setting a little finer and using a little more water to brew.
While our recommended espresso recipe works for most coffees, you may want to adjust your target recipe for roast level.
The next most important factor for solubility? Elevation. How high a coffee is grown will determine how dense the unroasted coffee will be. At higher elevations, there is a substantial difference in daytime and nighttime temperatures. During the chilly evenings, the coffee plant will send extra energy (sugars) into the seeds, so that it will have a greater chance of reproducing. This makes those seeds extra dense compared to coffees grown at lower elevations.
If you’re switching to a coffee with a higher elevation than your current bean, it will want to extract slower. Try using the same amount of water and coffee, but adjust your grind a little finer.
If you’re switching to a coffee grown at a lower elevation, it will be less dense and will want to extract faster. Keep the amount of ground coffee and water the same, but adjust your grind a little coarser.
After coffee cherries are picked at the farm, the growers have to remove the seed from the fruit so it can be roasted. The way they do it will have a big impact on the cell structure of the coffee.
There are three primary ways coffees are processed:
- Natural process
- Washed or Wet process
- Pulped-natural process.
The Natural process is the oldest method. After the coffee cherry is picked, they are left to dry with the full fruit intact, almost like a raisin. Once the fruit has dried, the seeds are popped out and sorted into bags and shipped to the roaster. This method produces coffees with vibrant berry flavors. Also, it tends to cause the most degradation of a coffee’s cell structure.
Natural Processed Coffee
The Washed or Wet process is a newer form of coffee processing. After picking, the bulk of the cherry is removed from the seed using a mechanical pulper. Then, the seeds are soaked in water to remove any remaining sticky fruit pulp. Flavor-wise, washed coffees tend to have lighter bodies with distinct, clear flavors; they will also have the strongest cell structure.
The pulped-natural process is the newest form of processing and it combines elements from both the Washed and Natural processes. Like a washed coffee, a pulped-natural will have most of its cherry removed in a pulper. Then, instead of washing off the remaining fruit pulp, the seeds are left to dry like a natural. These coffees tend to taste heavier bodied with a deeper fruit sweetness; in terms of cell structure, they’ll fall in between a Natural and Washed coffee.
If you’re switching to a Natural, the beans will want to extract faster. Try adjusting your grind setting a little coarser.
If you’re switching to a Washed coffee, they’ll want to extract slower. Try adjusting your grind setting a little finer.
If you’re switching to a Pulped-natural from a Natural, adjust your grind setting a little finer. If you’re switching to a Pulped-natural from a Washed, adjust your grind setting a little coarser.