Faux espresso and milk drinks with the Moka Pot

This is generally aimed for getting as close to espresso as possible with the moka pot (assuming you want to make espresso-based drinks like latte, americano etc afterwards). You cannot replicate straight espresso shots: in those the large amount of crema does play a significant role in the taste; but for everything else - this is your guide.

Gear tips

Stainless steel 2-cup pot. Burr grinder. Scale with 0.1g resolution

Why

Stainless steel can make a huge difference. Aluminium has a higher heat transfer / lower heat retention, which makes it more difficult to control. Its certainly possible to use, but there is less margin for error. Its also harder to use the method where you turn off the heat mid way to maintain even flow, since aluminum cools much faster and will release all the heat quicker. Another benefit is that stainless steel is not that sensitive to cleaning solutions, you can soak it in Cafiza once every month or two to get all the stale coffee out.

Another thing that is slightly different in the aluminum pot: the coffee will warm up a bit more before water gets in contact with it. Because of that, slightly lower starting temperatures are desireable - once in contact with the coffee the water will

There is plenty of info on why a burr grinder is important on the net, so I'll leave that out. As long as it can go espresso and a bit below it shoud be okay - even if its not too adjustable. The Hario mini-mill or Porlex will do on a budget, although the coffee will be a bit bitter due to fines. The Aergrind or Lido will do much better with less fines so you can grind even finer with them. Caveat: bigger pots require more coffee (25g or more for a 4 cup) and it might be too cumbersome to hand-grind that much.

Why use a 2-cup pot, not one of the bigger ones? They have different physical properties so they produce different coffee - I'm not sure if they're capable of producing espresso-like intensity. I have the 4 cup Venus, and its simply unable to produce any coffee with the grind size and tamp properly adjusted for espresso.

Coffee

Grind about as fine as for non-pressurised espresso machines. 15g coffee for a 2-cup moka pot when using a darker roast, up to 18g for light roast. Tamp, but not too hard. Fresh grind is important for taste, but preground can be OK.

A good starting grind size on the Aergrind would be 1:1 to 1:6, depending on how new your Aergrind is and whether you are using a dark roast (finer) or light roast (coarser). For comparison, espresso range is 1:2 to 1:8 and turkish is somewhere at 0:7 to 1:1. No I am not crazy - read below.

Why

I know your concern. If you grind finer than espresso AND tamp, nothing is going to come out and the pot will definitely explode, will it not?

The short answer is, not if you leave some space above the puck.

The long version is, there is a very big difference between an espresso machine and a moka pot:

• For espresso, we tamp the puck with 30 pounds of weight. That's only about 0.5 bars of pressure in a 58mm basket. The real "tamping" comes after we put the portafilter in the machine, compressing that puck even further as the coffee swells. As the density increases, the pressure increases, all the way up to 9 bar or 500 pounds equivalent!
• In the moka pot, 1.5 bars of pressure are pushing the puck to expand and swell from below. That works as long as there is some space above the puck. As it expands, its density decreases. There is no way any amount of initial tamping will compare to the 9 bar "tamp" of the espresso machine, so we actually need to grind finer to achieve the same intensity and to achieve any sort of minuscule pressure. But if there is no space for the puck to swell and expand, then the pressure will indeed increase too much!

Tamping is also necessary to achieve even distribution. Without tamping, the water will mostly go through the easiest parts and mostly avoid the more difficult parts, resulting with uneven extraction and less intensity. You will notice that if you don't tamp, the coffee will "shrink" to the tamped size (somewhat bigger, since it swells) after the water goes through it. Not tamping just makes that shrinking less controlled.

How much to tamp? Not too much - about 2kg-5kg (4-10 lbs) of pressure should be enough. We're mostly aiming for evenness, not pressure. You will have to tweak it yourself to get the desired strength, keeping in mind it will depend on the grind size.

If the coffee is tamped too hard but the tamp is uneven, there is risk of channeling. The water might push through part of the coffee and then proceed to go through there. Usually this happens on the sides, and you might get bitter (since the sides where channeling occurred over-extracted) and watery (since a lot of the coffee didn't get extracted) tastes. Its not as bad as channeling in espresso due to the lower pressure, but its still noticeable.

You can try to find a plastic cap that fits the size of your pot's filter basket and use it to do the tamping. My solution was to 3d print a tamper with the proper diameter for my 2-cup Venus, but you don't have to go THAT far. Anything that is flat and approximately the same diameter (could be 2/3 the diameter, not a big deal) will do the job with several light tamps (i.e. NSEW tamp)

Its still a good idea to take the following two safety precautions:

• Always check if the safety valve is able to move by pressing it from the inside and wiggling it a little bit before pouring in water. Seal the pot tightly!
• More importantly, always leave at least a couple of mm of empty space above the tamped coffee - never ever overfill the basket. This gives the coffee space to swell upwards, which in turn ensures that pressure wont grow too much. At the very least, after tamping you should remove any excess coffee with a flat knife.

Water

I usually fill to right under the safety valve. In the Bialetti Venus 2-cup thats about 95 grams.

Preheat the water to 70 C / 160 F. Alternatively, 2/3 boiling water with 1/3 tap water is a good starting point.

Don't use cold water. Don't use boiling water.

Exception: Use cold water in the brikka. It works differently.

Why

Contrary to popular belief, the water in the pot is not boiling when the coffee starts coming out. The temperature depends heavily on the initial temperature of the water and is governed by both the idal gas law for the air part and vapour pressure laws for the vapour part. According to this paper and confirmed by an experiment, if the initial temperature of the water is cold, you can expect extraction temperatures to be in a range as low as 60-70 C / 140-160 F!

Pre-heating to boil on the other hand will result with temperatures that are way too high. The equations from the above paper tell us that the vapour pressure relies on a sufficient temperature differential to work. With some pots there will even be extraction problems as the water will not be able to push through properly. The escaped water creates a sort of a "vacuum", and if the initial amount of air is too small, the air component of the pressure will drop as many times as the volume of it drops (ideal gas law) as water starts coming out.

The Bialetti Brikka is different. It has a valve that prevents coffee from coming out before it develops sufficient pressure (and therefore temperature). The Brikka should be filled with cold water.

Extraction

Around 1 minute from first coffee to finish. Flow should be fairly consistent but gradually increasing.

• Once you get about 20g in the pot (half of the end result, 1/3 of the maximum), remove from heat.
• Before any sputtering starts (when the coffee stream turns lighter / yellowish), pour into a cup immediately. You should get 35-40g from the 2-cup pot.
• Discard the rest (about 20-25g in the 2-cup pot).

Why

This is the trickiest and most important part of using a Moka pot. The main goal is to to stop the extraction at the right time to prevent most of the superheated steam from extracting burnt tastes from the coffee at the end.

Extraction time can be controlled by changing the heat strength. The flow should be fairly consistent but increasing as the time goes by. If you are getting early periodic squirts, it means the grind is too fine, the tamp is too hard or most likely the amount of coffee is too much (the pot cannot push through the coffee). If extraction stops at half of the volume you expect, you probably overfilled with water above the safety valve or the initial water was too hot (or both).

Feel free to play around with turning off the plate half-way / putting the gas on the lowest setting. That should help prolong the brew time.

Once you get about 1/3 to 1/2 of the target extraction (in the Venus that just about covers the protruded bottom fully, plus 5s-10s), remove the pot from heat. If you don't do that, the flow will speed up too much making it very difficult to time the pouring right. Removing from heat should result with a continuation of an even flow. If you get some stalling, feel free to return it back to the heat for a couple of seconds then remove it again, but in general it shouldn't be necessary (a couple of extra seconds of extraction is okay)

Most importantly, pour the coffee out of the pot before sputtering starts happening (usually when the "yellow foaming" phase begins, but that depends on the coffee). Allow the sputtering phase to end up in the pot (about 1/3 of the amount), then throw that away - its not going to be useful at all. If this ends up in your cup, you will get the most common problem with moka pot coffee: over-extraction (due to too much water) and burnt taste (due to steam passing through the grounds once all water goes through).

Any sputtering you allow in the pot contributes to the burnt taste. When the water gets near boiling temperatures, bubbles of steam will start forming. Some of the bubbles escape through the funnel and create gurgling. For example, if the initial temperature of the water is too high, gurgling will begin very early and burnt tastes are practically guaranteed!

Variable control

This section lists all the variables you can control in the moka pot and what effect they have on the variables you want to control.

Variables you want to control:

• extraction time <- affected by grind size, amount of coffee in basket, initial water temperature, stove heater strength
• extraction pressure <- affected by grind size, amount of coffee in basket
• extraction temperature <- affected by grind size, amount of coffee in basket, initial water temperature
• brew ratio <- affected by amount of coffee in basket and pot size

Variables you can control and how they affect those you want to control:

amount of coffee in basket

Affects:

• brew ratio
• extraction time (inversely)
• extraction pressure (proportionally)
• extraction temperature (proportionally)

Tip: Just do this first to adjust the brew ratio. Then it will no longer affect everything else. Remember to measure the output coffee, not the input water. Somewhere between 2:1 and 3:1 should be nice, for example, with 15g coffee grounds you want to get around 35-45g of coffee liquid.

grind size

Affects:

• extraction pressure (smaller grind -> higher pressure)
• extraction time (smaller grind -> longer extraction time)
• extraction temperature (smaller grind -> higher temperature)

Tip: I would go as low as possible without activating the pressure safety valve, causing channeling or causing gurgling before 50ml get extracted. Once any one of those events happen, go a notch up and focus on even tamp.

Higher pressure and smaller grind produce stronger intensity and flavor.

You will need to readjust initial water temperature and heater strength after you change grind size.

initial water temperature

Affects:

• extraction temperature (higher initial water temperature -> higher extraction temperature)
• extraction time (higher initial water temperature -> longer extraction time)

Tip: Good starting point is 70C. You can get that by mixing 2/3 boiling water with 1/3 cold water. Don't go above 80C or below 40C. If you go above, gurgling happens earlier. Gurgling destroys the taste - makes it burnt. If you go below, extraction temperature will be too low - expect sour or even bland taste. Also, the pressure will be able to grow even more, meaning you might need to remove the pot off heat sooner - otherwise it will extract faster due to higher pressure.

stove heater strength

Affects:

• extraction time (higher heat -> shorter extraction time)

Tip: Should be fairly low; aim for approximately 50-90 seconds extraction time for 2 cup pots (so around 1 minute, maybe a bit more). Too long and the taste will be bitter, too short and it will be sour. I've used several different approaches here, with the fastest and laziest one being using maximum heat on the plate, turning it off immediately the moment i see coffee coming out, removing from the plate when the coffee covers the bottom fully (Venus) or reaches the bottom of the spout (Moka)

Variable limits

• brew ratio - limited by size of basket, only few grams of variability in amount of coffee. Easier to control amount of water going in, but very different from amount going out!
• pressure - when safety valve starts releasing steam, maximum pressure is reached.
• temperature - not limited to 100C: temperatures above 100C possible in end phase due to pressure; steaming also possible. Lowest you can get is probably around 55C / 130F, if you start with refrigerated cold water.
• extraction time - longer is always possible, shorter only up to a point - too high stove heat will overheat the pot, warm up the coffee in the basket, get coffee grounds in your liquid

Misc info

One cup is 30ml (~1 oz actually). This is based on single-shot espresso. Yep, a 2 cup pot producing only 60ml (~ 2 oz) of coffee is perfectly fine. It should've been called a 2 shot pot.

My 2-cup Venus produces between 35ml and 45ml, about the right amount for a double-shot of espresso. This goes perfectly with 160ml-195ml (5.5 - 7 oz) milk to make a very strong latte.

What are the differences from real espresso? Strength-wise there will be no difference if the grind is fine enough and the tamp is strong enough. Taste-wise, the moka pot will highlight slightly different taste notes than the espresso. I tend to get slightly more of the fruity, floral and earthy notes in the moka, and slightly less of the sweet / caramelly / chocolate notes, but its hard to say how much - the differences are very subtle!

Washing the pot with soap is important, but it will alter the taste for a short while. Washing once per week is enough. Use a gentle soap and don't put in the dishwasher. With the steel pots you can use a cafiza bath to soak it (not sure about the rubber however - I remove it before the soak)

Milk

You can get great results with a handheld milk frother using the technique demonstrated in this video:

If you try it and fail to get good results, don't give up! It might take a couple of weeks to get it just right.

The result will have the right texture and the taste will actually be better than steamed milk. Art is also totally doable, though I can only do hearts (latte art is actually damn hard!)

The typical steps would be as follows

• pre-heat to about 135F (55C) in microwave
• pour into classically shaped milk pitcher with a spout (this is actually very important, the wider-bottom shape of the pitcher helps a lot throughout the process... 350ml to 450ml are good sizes for a single cup of latte)
• follow video tutorial but place pitcher on stove and put a clip on thermometer in it and warm until 155F / 65C while frothing.
• frother angle in the pitcher is important. The whirpool needs to be slightly tilted sideways such that milk from the upper layers gets pushed into the lower layers (hence the angle).
• position of frother should be such that you don't hear the aeration sound. Angle and off-center positioning and help with this. Depth should be just enough so you don't hear the aeration sound, but not much more. Too deep and the whirpool will start to go away - too shallow and the aeration sound will be back.
• after frothing, tap & swirl as shown in the video. It might not look like it, but swirling is extremely important for getting the right consistency throughout the milk.
• then the procedure is the same as with steamed milk: when pouring, make sure that the pitcher is first far away from the cup for the first 2/3 of the pour; then drop the pitcher as close to the cup as possible without dipping it into the coffee to pour the art. Tilting the cup lets you get closer to the surface. Look online for how to do various patterns (its not obvious at all)

The pitcher shape is important for proper incorporation of foam into the milk. It helps both in the frothing phase (after initial aeration) and for the swirling. The spout shape helps with pouring art.