brewing coffee news

Ideal water composition for espresso extraction

The Coffee Science Education Centre (CSEC) in Australia tested the impact of a range of tap, artificially modified, and purified waters on the flavors of coffee in an espresso. The chemistry of the resulting brews and brew waters was analysed scientifically through gas chromatography with mass spectrometry, inductively coupled plasma optical emission spectrometry, a bank of photometers, and a series of pH/conductivity multi probes.

What a brilliant idea! I have long asserted certain differences in the flavors in a cup of coffee to the water used, but never really thought about it scientifically. Sometimes my favorite coffee tasted completely different when brewed at a friend’s home. Other times I simply couldn’t replicate the same great taste for a coffee I’d had at work in my home. I varied the recipe, tried to compensate for certain differences but never really solved the problem…

The study looked at how three elements of water affected flavours in extraction: hardness (the amount of calcium, magnesium, carbonate, and bicarbonate in water), pH levels, and total dissolved solids (TDS).

The biggest effect on flavour was achieved by modifying the hardness of the water

Dr Adam Carr of Seven Miles Coffee Roasters

They brewed an espresso on an industry standard machine from La Marzocco and then measured the concentration of chemicals in the coffee that are attributed to certain flavour characteristics, such as nutty/roasted (2-methylpyrazine), fruity (furaneol), vanilla/caramel (vanillin), and caffeine/bitterness (caffeine).

They found what I had sort of self-analysed by drinking coffee made with desalinated water, some mineral water and very hard (dH) water in my hometown in Bussum (dH around 9-10).

source: Seven Miles

Lessons learned:

  • Minimum hardness of 50 ppm for “best” flavors
  • Higher than 60 ppm has little effect on flavors
  • pH tends to concentrate flavors, much like salt enhances flavors in food
  • Higher pH tended to concentrate stronger flavours in coffee, though not to the same extent as hardness. However, higher pH levels also led to issues in the extraction process.
source: Reddit

Read the whole article to find out the recommended pH and what the effect on TDS was…


It just so happened that the water quality you want for coffee is what Sydney Water is pumping out of their stations!

Dr Adam Carr of Seven Miles Coffee Roasters
brewing coffee news

The math of brewing a better espresso

Scientists have finally answered a burning question of mine: why should an espresso be brewed in 25 +/- 2 seconds and use approx 15-22gr of dry coffee to yield 50ml of (a double) espresso?

Who came up with this rule and why? Not that I have a specific problem with it but it seems so arbitrary. Also, once you start to make espresso’s a day long, you’ll notice that it’s really hard to dial in the equipment a certain way and maintain those rules for every cup. Sometimes it’ll be 21 seconds, sometimes 29. The grinder is pretty accurate. The beans are practically the same. So where does this high variation come from?

Well, it turns out that brewing your espresso differently yields the same great taste and flavors while achieving this with much greater consistency and reducing the cost per cup of espresso!

How did they do it? Well, they started by reducing the process to a proper model with solid mathematics behind it. Brewing an espresso is basically fluid dynamics of a bed of particles. The “puck” being coffee grinds of varying sizes and water is pushed through this bed at a certain pressure.

These mathematics are very well understood and accepted. So the scientists started with this model, created equations for everything and solved the equations using differential equations. That resulted in a few parameters and then they found the optimal solutions.

Sounds easy enough but believe me the math is pretty impressive, yet their logic is sound.

Turns out if you lower the pressure to 6 bars instead of 9, use 7-15gr of dry coffee, ground more coarse then tradition tells you to and aim for an extraction of 8-15 seconds, you will get a beautiful espresso that is much easier to reproduce!

Don’t believe it? Read the articles:

brewing coffee news

Coffee Roasters in Netherlands already had the great idea to list as many local coffee roasters in the Netherlands with a webshop as possible, so that everyone who’s working at home #stayhome due to Corona crisis can enjoy the best coffee possible. Excellent!

Of course this leaves out those roasters who don’t have a shop (yet)…

Thankfully, already has an extensive list of coffee roasters in the Netherlands (and a list for Belgium). Yay! With these two lists together there is nothing stopping you from ordering fresh roasted coffee beans that suit your taste to brew at home.

hario v60
Hario V60 brewing fresh filter coffee