Italian moka pot coffee

see also:

• the perfect coffee when camping
• photography and camping main index page

• the classic Italian moka pot is an extremely popular way to make concentrated black coffee (not as concentrated as true expresso cough though and without the crema)
• the lazy Italian traditional way heats it until you hear it spluttering away and then you pour it out into small cups and possibly add a teaspoon of sugar per cup as there will be bitterness which many people actually like
• for the modern thoughtful OCD coffee maker, there are many recipes to reduce this bitterness - but if you are camping , you will probably be happier just doing it the lazy way

• there are 3 main components to a moka pot:
  • the “boiler” base which holds the water and generates the pressure when heated to force water up to the top and through the coffee grounds
  • the “coffee basket” (the grounds holder)
  • the top reservoir which has a filter at the bottom, a seal and a central pipe through which the coffee percolates up and out of the top (plus a lid to stop it spluttering all over the place and making a mess)
• the mechanics of it:
  • heating the water heats the air mass above the water which expands and pushes the hot water down and up through the central pipe into the coffee grounds and thence up into the top reservoir
  • it is the coffee grounds and the perfect seal of the top with the bottom part that creates resistance to the water and allows a high pressure to build up
    • if too much resistance due to either too fine a grind or too much tamping then it will fail
    • if not enough resistance due to channels forming in the grounds or the grounds are too coarse, only steam will come out and you will eventually lose all pressure
    • if the seal between the top reservoir and the bottom is not perfect, steam and/or coffee will escape reducing the pressures and prevent the coffee percolating up
      • this critical seal can be compromised by either:
        • presence of coffee grinds between the two parts
        • not tightening the top enough
        • dents in the rim of the coffee basket - hence avoid tapping the rim to clean the old coffee out as this will damage it!
        • the seal under the top reservoir may be damaged or missing
  • if a blockage occurs then there is a pressure relief valve in the bottom part to avoid it exploding - this should be tested to work every few weeks of use by pushing the ball bearing in or by pulling it out against its spring with fingernails

• use cold water
• perform the critical steps outlined above
• they usually create a central heap going above the top of the coffee basket and let the top flatten it out
• leave on heat until you hear spluttering then turn it off and serve it

• bitterness arises from the last part of the coffee to percolate out which is generally the hottest part and it is thought the hot temperature is what is extracting the bitterness
• some will also add an additional filter (eg. an Aeropress filter) to the bottom of the top reservoir (wet it to make it stay there while you invert the top to screw it onto the base) - this reduces the amount of particles percolating up as these also contribute to unwanted flavours
• ensure water is good quality and not hard - use bottled water if tap water not good enough
• these OCD coffee makers will generally weigh the water and coffee to ensure consistency, and may measure the temperature of the water coming out at the top, carefully adjusting the heat throughout the process, finally, in addition to a taste test without sugar, they may measure the output volume, the total dissolved solids (TDS) and calculate extraction ratio, etc to ensure they are being consistent.
  • it seems that an extraction ratio of 22-23% is perhaps ideal for Moka pots - going over 25% seems to give it more unpleasant flavours
  • generally use a dark roast in particular when making milk based coffees or you want a strong rich coffee

• Youtube: James Hoffman - The Ultimate Moka Pot Technique (Episode #3)
  • the lighter the roast the finer you need to grind it to get a good extraction from it, but still coarser than expresso and use the maximum amount of water up to the valve
  • a less filled boiler will brew earlier with a lower brew temperature and is best used for darker roasts to get stronger richer brews
  • use freshly boiled water (use a tea towel to hold the base to screw it together)
• add water:
• for light roasted coffees:
  • add hot (NOT boiling) water to just under the level of the valve
• for dark roasted coffees:
  • add room temp water 20mL or 1cm less than the level at the valve - this will allow the water to rise earlier at a lower temperature and give a stronger brew with higher TDS but overall less extraction and less volume brew ¹⁾
    • for more consistency you can weigh the water to ensure it is always the same volume and it allows you to experiment with known coffee:water ratios and grind size to get your best results
  • NB. if using a 4-6 cup pot, you can use hot water to speed up the process
• consider using a paper filter
  • this will give a higher extraction with the dark roast method as it increases resistance, pressure and brewing time for a more balanced brew
  • for lighter roasts, it will filter out the fine particles and improve flavour clarity
• if using an electric hob, pre-heat it
• if using induction, choose a low heat below half power
• if using gas use a low flame on the smallest burner
• consider using an adapter plate for both gas and induction
• ideally, gently heat the pot with the lid OPEN WHILE CLOSELY WATCHING IT - as soon as the coffee starts to flow, reduce the heat to as low as possible or remove from stove to prevent too rapid a process, then take it OFF the heat just before it finishes flowing otherwise it will splash everywhere and your coffee flavor will be impacted
• if the flow stalls prematurely, add a little more heat for a few seconds until flow re-starts, then remove again - “heat surfing” ²⁾
• if it does start spluttering, quickly run the base under cold water to stop further bitterness
• if serving into multiple cups, stir the coffee before serving it to ensure each cup gets similar brew
• serve it as soon as possible as the pot is hot and can cause more bitterness if it remains in the pot

• trouble-shooting too much steam and spluttering at start causing poor extraction
  • don't tamp the coffee or over-fill it!
    • tamping creates too much resistance for the low pressure in a moka pot, forcing water to find the path of least resistance and causing uneven extraction. Instead, fill the filter basket with coffee and gently level it out, perhaps with a light shake or tap—never compress the grounds
    • too much coffee will result in the top effectively tamping it down
    • coffee may only start coming out when temperatures at the top are over 70degC instead of 50-60degC which results in bitter coffee
    • the only time tamping it is advisable is if you are using a very coarse grind
  • use the correct grind size
    • The ideal grind is slightly finer than table salt but coarser than espresso. Too fine a grind can compact and block the flow, again leading to channeling. Too coarse, and the water passes through too quickly, under-extracting the coffee. Avoid blade grinders, use a burr grinder for more even grinds.
    • eg. Femobook A2 lithium powered grinder use grind setting 6 seems to work very well
      • grind setting 10 seems to give under-extracted weak coffee with start temp ~55degC and end temp ~85degC
      • grind setting of 5 seems OK
      • grind setting 3 not as nice I think for a medium roast but is more like expresso grinds
  • ensure even coverage of coffee
    • After adding coffee to the basket, gently shake or tap the basket to distribute grounds evenly. Some users recommend using a distribution tool (like a WDT—Weiss Distribution Technique tool) to break up clumps and ensure an even bed, but avoid pressing down
  • ensure basket is dry before adding the coffee
    • A wet basket can cause grounds to stick unevenly, leading to an inconsistent bed density and increased risk of channeling. Always dry the basket thoroughly before adding coffee
  • clean the pot regularly
    • Blockages in the filter or buildup in the pot can disrupt water flow, creating uneven pressure and contributing to channel formation. Disassemble and clean all parts, especially the filter and silicone seal, to maintain optimal performance
  • use gentle heat to avoid to rapid a pressure build up

• great for simplicity, price, ergonomics and durability but low pressure 1 to 2 bar (100 to 200 kPa) so minimal crema and not as concentrated as an espresso
• ensure you have the best size for your need - 1 “cup” equates to ~40mL of brewed coffee and uses about 5-10g ground coffee per cup
• you need 20g or just under a 1/4 cup of coffee beans to fill a 3 cup (150mL base) Moka pot (or a 4 cup Bialetti induction)
• ?2 cup uses 150mL water in base to output ?120mL coffee using 20g or just under a 1/4 cup of coffee beans

• 2 cup uses 130mL water in base to output 100mL coffee using 15g coffee (output may vary 80-100ml depending upon method) diameter top of base is 56mm
• 4 cup uses 180mL water in base to output 150mL coffee using 20g or just under a 1/4 cup of coffee beans, diameter top of base is 63mm
• 6 cup uses 320mL water in base to output 280mL coffee
  • gentle heat, eg. setting 5 of 12 on a kitchen induction stove until it starts percolating out then drop to 3 then turn off when almost fully done
    • for 4 cup, if using cold water, takes 5.5 min for 1st stage then 1.5min for last stage, if using near boiling water, takes 2.5 min for 1st stage then 1.5min for last stage
      • adding a paper filter and using cold water took 4.5min for 1st stage then only just over 1 minute for last stage
      • changing to grind of 3, using hot water, takes 2min 20sec to start brew at 64degC, then further 2min to finish
• the Venus version has a very annoying deep rim in the top chamber which needs special attention for cleaning
  • see Youtube - how to clean a Bialetti Venus

• incorporates a weighted valve as a pressure regulator on top of the nozzle that allows pressure to build up inside the water tank in a manner similar to a pressure cooker.
• As pressure builds up more quickly in this method (since there is much less leakage of vapour) compared to the standard moka pot, it reaches the level required for water to rise through the ground coffee in a shorter time. However, the weighted valve allows pressure to accumulate and temperature to rise somewhat further before the liquid bursts through the nozzle.
• The result is coffee brewed at a higher pressure and temperature than the standard pot, making it more similar to espresso and therefore with more visible crema, but still not the same as a pumped espresso.

• “1 cup” = 40-60mL brewed coffee and uses 6-7g of ground coffee which is similar amount to that used in 1 shot of expresso if using a standard Bialetti pot
• always aim to be filling the coffee basket for the best results and this means choosing the right size pot for how many cups you want to make
• don't try just making 1-2 cups in a 4-6 cups size pot - it will taste terrible
• your brew volume usually is about 2/3rds of the volume of water you put into the boiler
• for a single person wanting a double shot, use a 2 cup pot
• see https://www.youtube.com/watch?v=jWWVi25oLNA