hacking new coffee techniques with an aeropress
This recipe comes from the heart and soul of a pandemic-weary government bureaucrat, desperate for a break after 4 virtual meetings in a row.
I love coffee, and I love playing around with different ways of making it - especially if they’re manual. But almost all coffee, especially if I’m starting from whole bean, takes some time to make. A few months into the pandemic, I worked out a recipe for an espresso which can be squeezed into 5 minutes between meetings. As an added bonus, it can pull a crema(ish) out of oily medium or dark roast coffees - more on this later.
It works by combining a number of factors:
We’ll start with the basic recipe, and then break down each component and how to adjust it. Note that the measurements I give here are approximate - there’s no need to overthink things (despite my domain name) and this is meant to be made in a hurry, after all. This recipe is can be very easily tweaked according to taste with a little bit of coffee knowledge.
Now that we know the recipe, let’s talk about adjusting it.
The aeropress scoop holds roughly 12 grams of coffee, with a heaping scoop coming to 14-15 grams. However, this depends on the density of the coffee. Lighter roasts tend to be more dense, so therefore 2 scoops results in more coffee. Dark or super dark roasts (if you’re into that kind of thing) are less dense so 2 scoops results in less coffee.
This can be compensated for with the amount of water, but I normally pour it on autopilot. Instead, I use the steep time to adjust - cutting the time a bit for light roasts before they get too acidic.
The water temperature is pretty variable. In general, I prefer to use fairly hot water compared to my normal aeropress recipe, which uses water at about 90 C. That said, the coffee to water ratio is so high that it’s very easy to overextract, so I use lower temperature for dark roasts. I’ll do light roasts at 98 or 99 C, medium roasts at 96, and dark roasts at 94. I sometimes make a super dark roast, for which I’ll go down as low as 92 and 93, and my medium-dark blend gets water at 95.
In general, the literature agrees that coffee extracts best in water that’s between 90 and 96 F. I’ve dialed the recipe in to account for the water cooling as you pour it, but the in-situ temperature (taken about 15 seconds into the steep), is between 85 and 93 C - lower for dark roasts. This tastes fine to me, but using higher temperatures than I’ve listed here for medium and dark roasts is completely defensible.
If you adjust the amount of water used, keep in mind that dosing more water (like if you prefer to fill the areopress 3/4 full) will result in a higher in-situ steep, while less water will be a lower temperature.
Coffee snobs all agree on using filtered water. Where I live, the water is naturally pretty soft so I don’t bother, but if you sometimes get odd tasting coffee switching to filtered water is a good idea.
Because the coffee to water ratio is so high for a fine grind, it’s critical to dial in the steep time. It’s very easy to overextract with this recipe. My steep time is 45 seconds to a minute, but I normally come in at the shorter half of that window. In the morning, the steep time is defined as “the amount of time it takes me to get my cereal and yogurt together for breakfast”.
If you have a regular problem oversteeping, it might be easier to increase the water used for the steep. The more water that is used, the larger the window for getting good extraction becomes.
The biggest eyebrow raiser in the entire recipe may be the use of both a paper and metal filter. The reason is to keep some of the sediment out of the cup, but a coarser grind (with longer steep time) could be used with just the metal filter. This would allow the oils in the coffee to come through, if you’re into that sort of thing. However, it would inhibit crema formation.
I recommend playing around with the speed of the plunge. Plunging faster increases pressure, but I’ve found that the result is larger, less table bubbles in the crema. The smaller the bubbles, the better.
The crema is a layer of foam that develops on the top of an espresso. It’s created by coffee lipids emulsifying under pressure, trapping air bubbles. I use the paper filter to increase the pressure and get more emulsification. And I can, with oily roasts, get a sort of crema. It’s good enough to fool my partner who knows nothing about coffee, but coffee snobs will tell you it’s not a “true” espresso. Simply put, you can’t get the same level of pressure with an aeropress that you can with a true espresso machine.
A true crema is quite stable - it can last for several minutes and up to an hour or so - and characterized by small air bubbles. The crema from this recipe is not as stable and has larger air bubbles, disappearing in a few minutes. I’ve been able to impact the bubble size by changing the speed at which I plunge. Speeds to slow result in no bubbles, while too fast result in large bubbles that are unstable. Finding the sweet spot takes practice and changes depending on the bean.
The secret to getting a crema with this recipe is the fact that the aeropress is filled to only by 1/2 - 2/3 full. The room in the aeropress above that is filled by air, and when the air is pushed through some pressure, it pulls extra water and lipids out of the coffee. The lipids encase some of this air, creating bubbles as they come out of the Fello Prismo attachment.
Because the physics and chemistry underlying crema formation in traditional espresso are the same as my recipe takes advantage of, the taste of either crema is very similar - to me it tastes fatty and creamy with a very pleasant bitterness. I can get that flavour to stick around by creating a latte before the crema falls apart - the foam from the steamed milk capture the coffee lipids but is much more stable.