Fancy a 'perfect espresso'… https://www.theguardian.com/food/2023/dec/06/scientists-claim-to-have-discovered-secret-to-perfect-espresso

Every time I read a Guardian article it reminds me why I don’t read The Guardian.

Anything that quotes 'scientists' is clickbait.

RDT is at least 18years old to my knowledge. CH Hendon didn't discover it.

"Now we know what grind settings to use to make reproducible espresso, we can start to try to understand what factors give rise to sensory differences in coffee taste.” ![Giphy - Season 4 Wow GIF by The Office](https://media1.giphy.com/media/b8RfbQFaOs1rO10ren/giphy.gif?cid=bb77869fjpqxrds1embymrlnuwtdexkqawnp1rw4eyeilyl0&ep=v1_gifs_search&rid=giphy.gif&ct=g)

> @"MWJB"#p57438 RDT is at least 18years old to my knowledge. CH Hendon didn’t discover it. The clue is in the 'Ross' Droplet Technique - attributed to David Ross in 2005. You'd think the oik (calling them a journalist is an insult to the noun) would do a bit of homework.

So, according to Joshua Méndez Harper, an assistant professor of electrical and computer engineering at Portland State University, grinding coffee has a lot in common in pyroclastic flow.

If you're a volcanologist, everything has something in common with pyroclastic flow.

https://imgur.com/7HkfqE1 Old Guardian https://imgur.com/a/fTSwJQE New Guardian and author of piece about espresso

> @"MWJB"#p57438 RDT is at least 18years old to my knowledge. CH Hendon didn’t discover it. Where did anyone claim Hendon discovered RDT? The paper agues that RDT results in a smaller peak grind distribution, longer extractions and higher extraction yields. The article effectively says the same in more general terms. I'd not seen any of the other claims made in this paper used as justification for RDT before, aside from causing less static mess.

RDT = Ross Droplet Technique Come from an old post on alt.coffee in 2005 from somebody called David Ross. Ah I see I'm late.

New grinding technique for 'perfect espresso'

JHCCoffee

Thank-you kindly for your research and the video, which I will watch at my earliest opportunity. Might you define what you mean by “extraction time”. Is this the number of seconds required to reach a given EY%, all other factors being equal? Or the total time duration of the shot? Were all other variables kept constant, including dose, grind, brew ratio, temperature, pressure?

If the shot time decreased AND the EY went up as a result of RDT, the RDT may have caused greater flow (ml/sec), which may have resulted in greater EY, as faster flow can extract more from from the surface of boulders. Just guessing as I am not a coffee chemist.

Emc2

JHCCoffee The extraction time was the time it took to achieve the desired brew ratio for the coffee which was 1:2.5. The constant variables were temperature, grind setting, dose. I tried to keep the flow rate between 2-2.5 ml/sec after preinfusion. I don’t have a Decent so there is an element of variability there. I used the paddle of the Lelit Bianca to adjust the flow.

The pressure was therefore variable. I did try grinding finer to compensate for the shorter extraction time when it occurred but this didn’t improve things (not discussed in the video). The reason I didn’t explore this further as it’s impossible to return to the exact previous settings for grind size.

Shot time never reduced with WDT. I used WDT for every experiment except for the one comparing RDT+WDT and RDT alone. RDT had a variable effect on shot times depending on the roast and the volume of water used.

JHCCoffee

JHCCoffee If the shot time decreased AND the EY went up as a result of RDT, the RDT may have caused greater flow (ml/sec), which may have resulted in greater EY, as faster flow can extract more from from the surface of boulders. Just guessing as I am not a coffee chemist.

@Emc2 My typo! Sorry! I meant RDT and have corrected my post text. Does the above make sense to you?

Emc2

JHCCoffee That makes more sense! You could be correct. I only looked at impact on flavour.

MWJB

Emc2 at 25:51 your visual says, “Less water & leaving the beans until water is absorbed, both increase extraction…”. Should this not read, ‘increase extraction time’?

Emc2

Yes you are right. I’ll make a note in the description.

MWJB

Emc2 Sorry. I should have said, “Increase speed of extraction.” (Less time).

DavecUK

giampiero If i remember well many years ago Formula one engine use to spray water to mix with benzine to increase power,

I “think” from talking to my late father, who was a flight engineer (Lancaster’s) during WWW2…water injection (actually water/methanol mix) was to prevent preignition on the 2 stage superchargers, so they could run higher boost pressures without in supercharger detonation problems. It cooled the charge..the methanol has a lower evap point and added extra cooling.

It was used for take off when they had a full bomb load.

So it indirectly increased power, but by allowing much higher boost pressures to be used. Which is probably what the formula one was doing back in the day.

JHCCoffee

@DavecUK

Is it advisable to use RDT in the Niche Zero?

Will it cause rust or corrosion?
Clogging?
Any negative impacts on the grind or on taste?
Any other reasons why NOT to RDT?
Any other risks?

Cuprajake

niche told me one spray

dfk41

Is adding one drop to the grinds, not proof that the real issue is atmospheric? Obviously in colder months, the central heating is on which I think, generally increases static?

MWJB

dfk41 The study & commentators since suggest varying amounts (several drops) per dose, I think they monitored humidity in the paper. Seems that it is more roast level related.

Generally, I have a question/query:

How much of the RDT moisture is retained in the dose after grinding, so is an 18g dose now assumed to be 18.72g/17.28g total for (instance) in the PF?

Emc2

MWJB the scale I used to measure the weight after grinding is only sensitive to 0.1 gm. With the 20 microlitre and above doses, the weight was slightly more than what went in. In the range of 0.1-0.3 gm. It’s not sensitive enough though so these are probably not accurate estimates.

MWJB

Emc2 Thanks, but without Stripping & sweeping out the grinder between doses, how can we begin to answer the question. The % of additional RDT moisture in the actual dose is still a bit of a mystery?

(Aren’t your milligram scales able to hold 20g?)

Emc2

MWJB I’m relying on memory and in hindsight I should have weighed the grinds with the 0.01 gm scale. Why is it a mystery? The small amount of water should mix with the grinds.

MWJB

Emc2 Yes, but if you don’t know how much RDT water makes it through the grinding process, you don’t know how much coffee you have in your dose. Not enough difference to mess with ratios, but 4% more/less mass that isn’t coffee confuses extraction results (generally speaking, not really relevant to your testing, but as you had the scales to test, it’s something you could look at? …if it interesting you that is).

tompoland

Great video thanks for the effort @Emc2

Emc2

MWJB Will do. For now, I think I’m going to take a break. I had so much coffee while testing that I couldn’t sleep!

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