Burning the Coffee?

This is a phrase you see quite a lot, especially in more amateur circles (interpret that word as you will).  I am talking about this in relation to brewing coffee, though I have no problem at all using the word burnt as a descriptor.

Very early on you are told that you should never make coffee with boiling water because you burn the coffee, or that if you leave a loaded pf locked in you will burn it, especially if the puck is touching the shower screen.  It seems a curious choice of words, especially regarding a product that has recently (one hopes) seen incredibly high (400°F+)temperatures and lived to tell the tale.

It is easy to see how the error occurred and perhaps it is just pedantic of me to find the usage slightly irritating.  Hotter than ideal water is capable of extracting certain solubles that taste burnt.  However in the case of locking in a portafilter I think that it is a case of accumulating heat.  Whenever I look at a measurement graph of temperature from a Scace device the starting temp is always a little above ambient (lets say 30°C/86°F)and then as the brew commences it quickly rises (though still takes about 5-10 seconds to come up) before stabilising at the brew temperature (93°C/200°F) for the remainder of the extraction.  If I’ve left my portafilter in for a while the whole puck is much hotter at the start.  The rise from say 60°C/140°F to brew temp will be much shorter so one assumes there is more energy available for extraction, resulting in more solubles in the cup (both good and bad) for a given brew temp.  If we are obsessing about brew temp to 0.1°C then surely we need to obsess about the puck’s starting temp as well?

The other time we worry about burning the coffee (as an industry) is with the Americano.  Many people say you shouldn’t put boiling water on top of your espresso cos you will burn the coffee.  I don’t really think this is the case, as your boiling water is nowhere near the ground coffee that holds those nasty, burnt tasting solubles.  For me a stronger argument for water first, espresso second is down to aesthetics – your crema looks better, lasts longer and there is no splashing of the coffee from the pressured boiler water coming from your machines hot water spout.

Just a little rant/thinking out loud for a Sunday afternoon….

[tags]coffee, espresso, barista, brewing, brew temperature, scace, extraction[/tags]

3 Comments Burning the Coffee?

  1. Matthew Kolehmainen

    “If we are obsessing about brew temp to 0.1°C then surely we need to obsess about the puck’s starting temp as well?”

    Which is where the heating of the grinds from the grinder comes into play. Definitely something I’ve been thinking about. Will a 10 degree difference in grind temperature change anything in the final shot? Hopefully, I’ll be able to answer this in about two weeks (with the study group project).


  2. Jimmy

    Both you and matt raise interesting questions – however, one must ask – is the heat (and energy) as acted upon the bean in the case of radiant heat from a grouphead the same as the mixture of radiant heat and ‘kinetic’ energy of the burrs fracturing the bean?

    Actually this raised some interesting questions for me… time to do some ‘sperimenting.


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