[tokai]

Optimal brewing temperature is ~93.0°C. So steam is too hot.

[messe]

Done properly, steam shouldn’t be going through the coffee grounds in a moka pot. The expansion of the air (and evaporation of the water as well admittedly) in the lower chamber pushes the hot water up through them.

[tokai]

If the water steams enough to rise the pressure its definitely not 93 degrees. Also the grounds are heated by the moka itself.

[smorgusofborg]

I would think that is the best brewing temperature at 0 bar? An espresso machine is going to reach higher temperatures and makes a good coffee.

https://www.valvesonline.com.au/references/steam-tables/