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Effect of bean origin and temperature on grinding roasted coffee (2016) (nature.com)
71 points by WMCRUN 34 days ago | hide | past | favorite | 19 comments

For those interested in this sort of thing, James Hoffmann[0] has some really well presented videos about coffee, the making and iterating on, from the perspective of someone who's been working with and around coffee for a while (he was a world barista champion in 2007[1])

He's recently been making a series called Weird Coffee Science[2], where he looks at and tests scientific papers and weird ideas floating around.

[0]: https://www.youtube.com/channel/UCMb0O2CdPBNi-QqPk5T3gsQ

[1]: https://youtu.be/_DwZV17bek4

[2]: https://www.youtube.com/playlist?list=PLxz0FjZMVOl1Dmfogt84Q...

Comments like yours are why Hacker News is such an important part of my daily reading. I did read your comment and then immediately thought: where else could I get such an interesting suggestion on a "generic" / "casual" topic like this?

Thanks for the links. I am an avid coffee drinker and I will check these out.

On Reddit? The coffee subreddit is pretty active, James Hoffman is also active there.

Beat me to it!

After watching that video I started microwaving my beans. It made such a huge improvement in the quality of my pour-overs that I've never stopped.

For the extremely coffee curious: I typically brew a V60, 25g coffee, 1:16 ratio, beans microwaved 45 seconds on high (950W rated output microwave). Baratza Virtuoso grinder.

Not to nitpick - but none of that info has as big an influence on the taste of your coffee as the one crucial bit you left out: What's the coarseness setting of your Baratza?

(For comparison purposes, I usually use 30g coffee, 1:17, grinder at 19, V60, 205F water. Most of these I can fiddle quite a bit with before you really notice, but the grinder setting really matters)

I originally left that out as it can vary based on the density of the coffee being used, and in addition grinders vary not only brand to brand, but quite a bit between various grinders even of the same model. I've disassembled my Baratza many times for repairs/cleaning, and changed the burrs once. I'm fairly certain that I would get a noticeably different grind size than a brand new Baratza Virtuoso at the same setting. That being said, here's the extra details:

For my 25g, 1:16, I typically use around a 12 grind setting (can change +/- 1 depending on the density of the coffee), and typically see around a 3m15s total brew time including a 30 second bloom.

I typically brew light roast, and brew at a whopping 100C (212F), also at the suggestion of James Hoffman - Info here: https://youtu.be/K_r5kpXPRYo

@riknos314 and @groby_b, can you guys describe your pouring process? Do you guys agitate your coffee? Do you guys continuous pour or pulse pour? If the latter, what's the amount of water used for each pulse?

I do 25g, 1:14 w/ a bit of water to taste at 205 F, coarseness at 21 +/- 1 on an Encore with a V60. The reason I'm asking about your pour is I seem to get a sludgy sediment for my final pulse if I do anything < 20, and even then my extract time exceeds 3m unless I agitate with a stick.

I'm fairly certain nothing is wrong with my grinder (in fact I had an unrelated reason and got it back from their repair center last week) and it's still doing this so I'm betting it's my technique that's flawed.

Sludgy sediment is usually an indicator of insufficient filtration. But while coarseness does vary across machine, getting that at 21 indicates there's something wrong - you shouldn't get that fine of a grind.

I've been there, so maybe you made the same mistake that I made when I had that problem: When you clean the Barratza and take out the white plastic thingamabob, it goes back in two different ways, smoothly. But if your little orange marker isn't towards the front, on the right hand side, your grind will be much too fine :)

I usually do an initial pour to allow the grounds to outgas - about 70-90 grams, pouring from the middle out, in a spiral.

Then two separate pours of ~220g, slow, outside in - I essentially use the water to agitate the grounds a bit by rapidly pouring the last half in tight circles at the center.

And for the people reading this and think "those coffee peeps are weird" - yes, we are. The taste differences are minute. Can't speak for others, but I mostly do it because I like a ritual, I'm happy with any number of pour styles as long as I get my coffee ;)

The reason I picked this particular ritual is because a) I swear it tastes just a tiny bit better, and b) I learned it in a tiny coffee shop in Colombia that I loved to pieces, and so every time I make coffee I'm reminded of that trip.

Looks like the white plastic thing is in the right place. I'll try and up my ratio and try the two pours of 220g tomorrow. Thanks! :)

Measured total extraction time this morning, so you can compare - 30 seconds for the first outgassing pour, 1:00 for the second pour (first 220g), 1:15 for the third pour.

I usually pour without timer - since I don't like agitation, it's not like a timer makes the water go faster :) - but that's pretty consistent with the last time I measured. That was a total pour time of 2:52. (I keep lab notes. I decided to just fully nerd out on my coffee a while ago)

> I originally left that out as it can vary based on the density of the coffee being used, and in addition grinders vary not only brand to brand, but quite a bit between various grinders even of the same model.

Indeed, even among grinders that are the same grinder; I just replaced burrs on my Vario and it’s a different machine. I wouldn’t be surprised if disassembling/reassembling the machine, without replacing any parts, might affect the performance depending on how much you squint.

I've tried across three Barratzas, and I'd argue the difference was at most one or two notches between them. They seemed fairly consistent to me (except when I messed up assembly, see above) but maybe I just got lucky.

Whoa. 12 for a pour over seems... strong. Now I'm really curious how I'll like microwaving those beans, since we seem to have very different tastes.

God, I'd kill to just hang out in a coffee shop and sample through all the different approaches with a bunch of coffee lovers. (Sorry, cabin fever speaking ;)

Wait a second, I thought the paper’s conclusion was the beans should be cool not warm?

I think he concluded that both - cooling or heating the beans before grinding leads to better extraction


Interesting, seems like he is validating the findings of the paper that grinding cooler beans produces more fines and you should strive for fines and derive the rest of your technique around optimizing the fines.

In the industry, this paper has long been known as 'the grinder paper'. Matt Perger (one of the authors, and a World Brewers Cup champion) provides a good layman's explanation: https://www.baristahustle.com/blog/the-grinder-paper-explain...

Nice. Are you in the industry, by any chance, or do you simply know about it?

Curious to see if you have other unknown things to share for a layman like me.


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