Comments on: Brew temperature

By: Scottlucey

Scottlucey — Tue, 30 Nov 2010 19:08:00 +0000

I’ve been exploring this topic lately b/c admittingly I’m curious just how serious managing heat w/ brewing water temp is. Surely I need a better thermometer (or do i?) but the studies I’ve been conducting have been 3 basic profiles water temp, 1-just off boil / 93c in the bed… 2-preheated kettle/brewer / 90-91c in the bed….. and intentionally cool / 85c in the kettle then 79-80c in the bed. Not surprising, results were somewhat linear, correlating hotter temps with higher extractions, but what I thought odd was that extraction %’s weren’t as drastically different as I thought they’d be. I was even able to produce a 19% extraction with the coolest temps… they didn’t taste great, but may seem ok if you’re only paying attention to ext% (which is why that’s not all one can value.)

From digging around I feel the main and maybe only principal on this topic is the correlation between sensory perception and temperature. Yes, there is a correlation between extraction% but from what I’ve done I’ve found those numbers aren’t solely able to signify quality.

Even in Scott Rao’s book ‘everything but espresso’ temperature is only one paragraph and with that citations from Ted Lingle’s brewing handbook as well as ‘experiments conducted by the author.’

With all this I can’t help but wonder if managing temps is really worth the external investments of hot-plates and other additional techniques that someone might incorporate into their brewing routine.

By: Chris Ilias

Chris Ilias — Thu, 25 Feb 2010 21:15:24 +0000

I've been thinking about this for tea for some time, and of course, it's equally valid for coffee. I started brewing tea at home inside a simmering pan of water. I figure it's about as controlled as I can get with the simplest of hardware.

By: Tom Jagiello

Tom Jagiello — Sat, 28 Nov 2009 11:15:59 +0000

just got my datalogger and made a few tests with it. It all really depends how you brew your coffee, is it with a boiler that can supply water at a steady temperature throughout the whole process, with slow flow and good dispersion, or is it using a kettle and pouring from it manually? I normally use an ordinary kettle to boil the water (not PIDed yet), transfer that to a metal jug, let it cool to around 92*C and pour. Today I measured the temperature under the coffee bed and it’s 85*C at the beginning and 82*C at the end, the coffee itself was 72*C. I know that it’s only one test, but I was curious if anyone did anything similar and what differences did he/she find.

Regards,
dsc.

By: Rasmus Helgebostad

Rasmus Helgebostad — Wed, 18 Nov 2009 15:20:08 +0000

James, just a quick note on the vessel: I usually preheat the brewing wessel with boiling water, then measure the temperature of that water before tossing it out. This to try to be as consistent as possible with vessel temperature before brewing. For french press I use a pre-heat temp of 80 degrees celsius, more because it’s easy replicable than anything else. Thoughts?

By: jeff verellen

jeff verellen — Fri, 06 Nov 2009 12:43:58 +0000

Erik, thank you for referring to that author. I have looked into him, and will read his work. Brewing longer at lower temperatures definitely changes the taste, but the amount of flavor seems comparable to classic methods. I think that some flavors can only be extracted if the brew is exposed to higher temperatures, but also, I think that deeper, earthier flavors can only come to their right if extracted at lower temperatures and longer times. The heat could have an adverse effect to that range of flavors.

By: AndrewF

AndrewF — Fri, 06 Nov 2009 04:39:14 +0000

I’ve often wondered if the people who say they prefer to french press their coffees, as opposed to brewing them in a vacpot, prefer it because of the lower temp the french press tends to brew at. If I start with a room temp french press (10 oz, glass) it brews around 185 F. I tried to see what the lowest I could get my vacpot to so I could compare the cups together, and could only get it to 192 F. I still want to try some other things to lower this temperture but this is certainly something to think about.

By: Erik Fooladi

Erik Fooladi — Thu, 05 Nov 2009 22:10:37 +0000

Jeff: time and temperature are linked in a complicated way, and would be differently so for different substances. Hence, the change in rates of extraction for various compounds with temperature will not be the same.

Consequence: coffee extracted at low temperature for longer time will inevitably have a different flavour than coffee extracted for a shorter time at a higher temperature.

A simple model experiment is to make tea and compare degree of astringency and bitterness. Steep the leaves in water at ambient temperature for as long as you like and see if you can make a tea that tastes as astringent and/or bitter as one that is overextracted for just a few minutes at high temperature.

For scientific studies on coffee extraction, look for references to Michael Spiro which has published loads on the topic for more than two decades.

By: Jeremy

Jeremy — Wed, 04 Nov 2009 05:16:08 +0000

Great. Now I won’t sleep tonight.

By: jeff verellen

jeff verellen — Sat, 31 Oct 2009 14:10:01 +0000

you are saying that output temperature from lets say a boiling water from a kettle to pouring that water on the ground coffee resulting in the brewing muck should be researched and clarified. This implies knowing the humidity, ambient temperature and temperature of the brewing device itself.

By: Cecil

Cecil — Sat, 31 Oct 2009 03:43:32 +0000

That different coffees will react well to some temps more than others is something we are used to. But there is a need to describe brew temps better than by the output temp, maybe a average temp at the start of brewing in the brew vessel. This would be less useful in espresso but more so in press or other types of brewing.

-C