There are two types of people in this world: those who brew with AeroPress coffee makers, and those who don’t. Those who do can be divided in two camps: followers of the traditional AeroPress ‘filter down’ technique, and those who turn it all upside-down and brew their AeroPress recipe inverted.
Traditional versus Inverted Brewing: Differences
For those unfamiliar with the AeroPress Original inverted method or AeroPress Go inverted method, the plunger is inserted into the brew chamber and stood on the counter, filter end up. Grounds and water are added, stirred, and allowed to steep. The filter and cap are installed and when the desired brew time is reached, the AeroPress coffee maker is flipped onto a mug then pressed.
In the traditional process, the filter is installed first, the brew chamber is placed onto the mug (filter down), coffee and water are added and stirred, then the plunger is fitted into the brew chamber and pressed.
Whether brewing with the inverted method or standard, the end goal is a delicious cup of coffee.
With every cup pressed, a choice is made between consistency and precision. If the cup brewed tastes good, the goal becomes the ability to repeat everything that allowed it to be good.
Origins of the AeroPress Inverted Method
Two pieces of technology brought the inverted method to the fore.
First Piece of Technology: Digital RefractometerFirst was the Extract Mojo digital refractometer, a specialized tool which measures total dissolved solids (TDS). TDS measures the amount of coffee solids dissolved into a beverage (meaning, how much of your beverage is water and how much is coffee flavoring). For most drip coffee drinkers, the ideal cup of coffee contains between 1.15% and 1.35% TDS. This is a very tight margin of 1/5th of 1%, and many coffee drinkers do taste a difference, especially between the upper and lower ranges of strength.
Second Piece of Technology: Digital ScaleThe second and most impactful piece of technology was the affordable digital scale. The increased availability of inexpensive, quality digital scales further opened the door for the inverted AeroPress method. Modern affordable scales are capable of accurately measuring mass to 1/10th of a gram, handing technically-minded coffee brewers the ability to develop highly precise recipes. The brew recipes language began to move from ‘scoops per ounce’ toward ‘grams per liter’ to describe ideal coffee-to-water ratios. Before scales, the gold standard recipe was one two-tablespoon scoop per six ounces of beverage. This worked well enough to produce a consistently enjoyable brew. However, if the scooped coffee is weighed, a scoop could range from eight to 11 grams. While this is only three grams, the percentage difference is sizable and hardly consistent. This recipe worked well when using an automatic drip brewer serving multiples of six ounces, but the standard home mug is eight to ten ounces and would need 1⅔ scoop for brewing a single serving.
Both the AeroPress Original and AeroPress Go scoops measure approximately 15 grams (+/-) of coffee, whole bean as well as ground.
Zeroing in on Ideal Brewing RatioUsing scales to measure the mass of beans, and scoops, and water, we discovered that dark roasted coffees were larger and less dense than medium and light roasts. Coffees grown in different countries and at different altitudes and climates tended to be different in size and mass. There are upwards of a hundred different botanical varieties of Arabica coffees with variations.
Averaging the scoops per serving recipe, and cross referencing that to the data set of preferred coffee strengths and extraction percentages, we can conclude that it is generally preferred that for every one-part of coffee, we should use 17 parts water. That is, the ideal ratio for brewing filter coffee (non-espresso) is 1:17 for the average cup, 1:15 for a stronger cup and 1:19 for a brew more mellow.
Brewing Ratio for AeroPress BrewingIn the context of AeroPress brewing, to brew a six-ounce (175 ml) cup of coffee, the recipe could be expressed several different ways: It is consistent (within an acceptable margin of error) to brew with one scoop of coffee + six ounces hot water. It is precise using a scale and the 1:17 ratio, to brew with 10 grams of coffee and 170 grams of hot water: 10 x 17 = 170. (It should be noted that with brewing volumes larger than the capacity of the AeroPress brew chamber, the effective brew ratio can range 1:10 to 1:13, and the resulting brew will be diluted to the strength of a 1:15-1:19 brew.)
Inverted AeroPress Brewing and Brewing RatioFor the coffee drinker looking for this level of precision and control over the repeatability of their brew process, using the AeroPress coffee maker in the traditional style (filter down) posed some problems. The first being the quantity of water that would drip through the filter. When combining such precise and controlled amounts of grounds and water, it was desirable that all parts remained together for the duration of the brew cycle. Essentially, what use was it to go to such lengths for control if gravity was going to change a 1:15 brew ratio to a 1:10 brew ratio? Turning the AeroPress coffee maker upside down and setting the plunger in place eliminated the drip-through variable and returned control of ration and steep time.
Pros and Cons of Inverted AeroPress BrewingThe greatest strength of the inverted method is the high degree of technical control it gives. Precise brew ratios can be maintained. Turbulence, or stirring and agitation, can be regulated. Steep time can be kept in balance with the grind size. For this reason, the inverted method is growing in popularity with highly technical, precision-minded or data-curious coffee drinkers.
But it is not for everyone. There is a dramatic hazard of the AeroPress inverted method: plunger blow-out. If the plunger is not suitably inserted into the brew chamber, there is the risk that the silicone seal slips out when flipping the AeroPress unit upright. This is somewhat of an inevitability when inverting. Outside of hot water burns and the ensuing mess, consider the three following significant elements.
Second, and less of a problem, is the challenge of grounds that cling to the plunger when the AeroPress unit is turned upright. When grounds stick to the plunger, they become ‘stranded’ and no longer contribute flavor to the brew. This is like the problem of brew water dripping through in the traditional method. Stranded grounds can be reincorporated by giving a gentle swirl to the upright AeroPress chamber. The resulting agitation has minimal impact on the total extraction.
The third challenge is simply the possibility of dripping coffee onto the counter when flipping. Not a deal breaker. The easy fix is to turn your mug upside down onto the filter cap, lift the entire system and gently invert. Or keep a towel nearby.
Pros and Cons of the AeroPress Traditional Method
ProsThe most immediate advantage of brewing coffee with the traditional method is that it does not share the spill hazard of the AeroPress flip method. Another advantage is that if you are inclined to brew a light bodied cup with high flavor clarity using two or more AeroPress filters, the traditional method makes it significantly easier.
The most troublesome characteristic is the water that drips past the filter and does not extract coffee flavor. However, there are some techniques to reduce the impact of this bypass water. The most traditional use of the AeroPress coffee maker is to follow Alan Adler’s brewing method: one scoop fine ground coffee beans, water filled to the “one,” stir and immediately plunge. The stirring action has two impacts on the final cup. The agitation essentially shakes flavor compounds out of the grounds and into the beverage. Stirring also creates a current that reduces the amount of water that drips out into the cup. With Adler’s brewing method simulating espresso, the combination of fine grounds, tight coffee:water ratio, stirring, and immediate plunge nearly eliminates the drip through concern.
Inserting the Plunger EarlyFor a cup profile to be more similar to filter coffee, the brewing method calls for a larger ratio and medium-coarse grounds. This hazards more water dripping out. To slow the drip-through, stir while adding water then insert the plunger as soon as possible.
When seating the plunger, do not press it straight into the brew chamber; this will push water through the filter. Instead, angle the plunger at a 45-degree tilt and slowly insert it while rotating to vertical. This lets the seal sit lower inside the brew chamber without applying any evacuating force. Additionally, a small lift of the plunger creates a vacuum that stops all drip-through.
Drip-through and Brew Ratio ChangeThe undesirable effect of water dripping past the filter is not only that it changes the ratio of coffee and water in the brew chamber, but that there is a variable of chaos injected into the system. Let’s examine multiple hypothetical brews of an AeroPress brewing method that calls for 15 grams (or 1 loosely packed AeroPress scoop) and 210 grams of water (a 1:13 ratio).
Attempt #1: The water is added, stirred and the plunger is set within the first eight seconds and only 25ml of water dripped through. The effective brew ratio changes 1:12.3.
Attempt #2: All variables remain the same except it took three extra seconds to seat the plunger, yielding a total drip through of 45 ml. The effective brew ratio then becomes 1:11 and the resulting cups will have a perceivable difference in flavor and concentration. For some this will only be noticeable using the refractometer to measure the extraction yield and percent of total dissolved solids. But for the coffee drinker with a sensitive palate, the difference will be tasted.
Conclusion:Ultimately, the choice to brew traditional or inverted is a matter of preference, tolerance for variation, and openness to refining technique. The AeroPress upside down method gives control to the technical focused user. It reduces the chaos of variations in technique. Those who prefer the traditional method can hone their technique and create consistency. Either way, both methods are capable of brewing predictably and reliably great coffee with the AeroPress Original and AeroPress Go.
Keep Reading: What’s the Difference between AeroPress and French Press?