Brew temperature

October 27th, 2009

This, shockingly enough, isn’t about espresso.  It is about brewed coffee, and the fact that brew temperature is completely wrecking my head.  We talk a lot about brew temperature but what we are really talking about is water delivery temperature.

I love my Uber boiler, I love the control and the delivery temp stability.  With this, however, has come the painful and embarrassing realisation that it doesn’t matter.  Alright, that is perhaps an overstatement – temperature has massive influence on the quality of the brew, that is undeniable.  I may love the control of the Uber, but having a consistent and controllable temperature really just shifts the problem from the exit spout to the vessel underneath.

Espresso has a rare advantage as, despite being the most finicky and frustrating brewing method, when it comes to brew temperature we can be pretty sure it is close to the delivery temperature.  We’ve enclosed the brewing space and have a lot more consistency that way.  Put a Scace device in and measure and the number you get is as close as we can measure what the coffee would be subjected to during the brewing.  With a french press this is all very different.

Once you open up the brew environment a lot more factors suddenly influence the brew temperature.  The distance from exit to vessel, the temperature of the press itself, the material of the press, the level of insulation, the size of the press and the ambient temperature will all influence the brew temperature: the temperature of the coffee and water as they steep/brew.

In the filter brewing sector/literature we generally see a prescribed brew temperature of 92-96c measured at spray head.  We don’t see much on actual brewing liquid temperature.  Surely a plastic brew basket will create a hotter brew than a metal pan?  Will a recently used hot pan brew hotter than the first brew of the day – despite stable water delivery temperatures?  Is there any research on this?

I’d like to create a few experiments with the Extract Mojo looking at the effect on brew temperature across the brew (though I’d appreciate any help from other people out there?).  Does starting temperature matter more than total temperature spent?  If my brewing vessel radiates heat quicker – because it is wider – can I match a better insulated brew by starting hotter?

I have a few simple experiments in mind that I shall try and perform and post about during the week.  In the mean time any and all thoughts are welcome!

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