Frozen coffee beans - espresso brew temperature?

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thoraxe

Postby thoraxe » Aug 08, 2018, 8:40 am

I searched around a bit and found various posts about freezing beans, but most were related to grind coarseness/fineness and extraction time/rate. However I didn't catch a lot of discussion about the actual brew temperature of using frozen vs. room temperature beans.

I'm just curious what people typically do -- higher temp? lower temp? differs by roast? I had read in one of the many blog posts / analysis of frozen beans that the temperature differential (temp of beans vs temp of water) is much higher and therefore you can go much lower temperature on the brew. But in my experience, the one time I had a lightly roasted coffee with "fruity" smells / flavor notes it was after I had cranked UP the temperature. But that could also have been technique issues.

Thoughts?

mike guy

Postby mike guy » Aug 08, 2018, 10:27 am

I don't change temp for frozen beans. The process of grinding the beans should raise the temperature enough where the brew temp isn't going to be offset when the hot water hits the beans. I don't think the grounds will be frozen anymore, and a hot portafilter temp will have way more thermal mass than the grounds. The brew temp will quickly bring the puck temp up where it shouldn't matter much. I haven't studied this enough, but I have been grinding from frozen for about 2 years and never really spent any effort adjusting temperature.

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HB
Admin

Postby HB » Aug 08, 2018, 10:37 am

thoraxe wrote:However I didn't catch a lot of discussion about the actual brew temperature of using frozen vs. room temperature beans... Thoughts?

Roasted coffee is basically really really dry wood. I doubt its initial temperature matters much, but it'd be easy to blind taste test with a helper weighing out the dose frozen/room temperature.
Dan Kehn

mike guy

Postby mike guy » Aug 08, 2018, 11:06 am

HB wrote:but it'd be easy to blind taste test with a helper weighing out the dose frozen/room temperature.


This is a more complicated experiment than probably seems on the surface. Grinding from frozen fairly drastically changes the grinder setting as grinding frozen beans shatters them and produces a lot more fines. This introduces two variables into the expiriment. 1. Repeatability of a brew recipe between the two trials. 2. The grind particle distribution will be different.

Even if you managed to produce a repeatable recipe that produced the exact same yield and brew time, the two grind distributions will be different enough that the TDS and EY will likely be different, which would probably account for the biggest difference in taste vs brew temp.

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LBIespresso

Postby LBIespresso » Aug 08, 2018, 11:45 am

Considering the relatively low water content of coffee beans I would think they will warm up to room temp or close to it just from grinding. Additionally the effect of the temp of a portafilter considering its mass should be much greater and how much attention do you pay to the temp of your portafilter?

I bet the act of freezing the beans and the difference in how they grind has exponentially more impact on taste and technique than the temp of your ground from frozen coffee.

But those are just the thoughts of a rambling non-scientist.

I look forward to reading responses from people much smarter than I.
LMWDP #580
"Be nice to people, even the sh!tty ones." Jason Sudeikis

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HB
Admin

Postby HB » Aug 08, 2018, 11:59 am

mike guy wrote:Grinding from frozen fairly drastically changes the grinder setting as grinding frozen beans shatters them and produces a lot more fines.

I've never tried it. But if the grind setting shift is that dramatic, it'd be easy to figure out how long it takes to reach room temperature conditions. I'd guess a minute or two, assuming the beans were spread out on a metal tray.
Dan Kehn

thoraxe

Postby thoraxe » Aug 08, 2018, 12:54 pm

I have an infrared thermometer. It would be easy enough to grind frozen beans into the PF and then stir the grounds and then measure the temp of the pile. I'll let you know when I make my next coffee.

gr2020

Postby gr2020 » Aug 08, 2018, 1:14 pm

I would think an important variable, one that we normally don't think about, would be the time the grounds sit in the PF. You're taking a (roughly) 450g piece of metal, at about 200F, and putting 18g of finely ground coffee into it. I would think the coffee doesn't stand a chance of staying significantly below the PF temperature for long.

thoraxe

Postby thoraxe » replying to gr2020 » Aug 08, 2018, 2:09 pm

Would be interesting to study. While it's "only" 18g of coffee, a lot of that space is air, likely even once compacted. That being said, from the time of tamp (when significant contact finally occurs) to the time of water hitting the puck is short (probably less than 30 seconds for me).

An easy test would be to grind into the PF, prep and tamp, take temperature, wait 15 seconds, take temperature, wait 15 seconds, take temperature.

Although you'd be measuring the temperature of the surface of the puck which is exposed to atmo, and not the "middle"/bottom of the puck.

I have a probe thermometer for meat, but that would likely be really tough to use to nail the mid-puck temperature.

thoraxe

Postby thoraxe » Aug 08, 2018, 2:47 pm

Freezer temperature - 0F
Bean temperature when I measured them into the measuring cup - ~20-30F
Temperature of grounds coming out of grinder chute - ~85F

So, this experiment (as inaccurate as it was with my poor Harbor Freight IR thermometer) "proves" that, at least as it relates to puck temperature and frozen beans, the fact that the beans were frozen likely doesn't matter for brew temperature.