Basically I get thrown any old beans at me from £8/kg to £30/500g.
I deal with 2 different machines and generally 4 different grinders. Its what bean gets chucked in thats the hard part.
I have to do roughtly 1:3 to 1:4 for unknown (cheap) beans. If they are actually labeled and have contact details on the bags (more common blends) I usually call them and generally they are 1:2 to 1:3.
Some are awful and spit out lol
Just thinking/hoping theres a easier way to get the best out of whats given
NewBoyUK Its what bean gets chucked in thats the hard part.
Subjectively, in terms of expectation (which may not be realistic) I can see this being hard. Objectively, not so much, if the output is achieved in normal time & EY
NewBoyUK I have to do roughtly 1:3 to 1:4 for unknown (cheap) beans. If they are actually labeled and have contact details on the bags (more common blends) I usually call them and generally they are 1:2 to 1:3.
I don’t see why cheap beans need a longer ratio, unless it is just to mute offensive flavours/intensity. Cheap, overly roasted beans tend to extract easily enough. Yes, many roasters suggest 1:2 to 1:3 ratios, but the bean can’t do it all by itself, some depends on whether the equipment will allow those beans to extract in those ratios. This you will be able to establish with repeated use of the 4 grinders.
You’re an engineer for the machines & grinders, not a fairy godmother for the roasting community. :-)
MWJB The DiFluid is absurdly cheap for the spec it quotes, but I’ve not tried it and have too many refractometers that I don’t/can’t use, already.
I wouldn’t say, “I lied.”, but blame unrestrained curiosity, late night wine drinking & ‘one click’ online purchasing…DiFluid R2 arrived today. I’ll post some thoughts over the coming week…immediately, I don’t like the spoon idea - 3ml pipettes recommended.
I await your 👍👎
I believe you can share results with people so may ask for a few…… if you dont mind
LMSC I’ve done 3 sets of 10 readings (V60 paper filtered drip, no syringe filtering of samples) with the VST LAB II and the DiFluid R2, Both zeroed at the same time & readings taken one device after the other in equivalent timeframe. I followed the VST protocol for the VST and the DiFluid protocol from their videos (the manual is not specific in this regard).
Test 1:
DiFluid average TDS after 10 reads 1.41, stdev. 0.007 (0.016 at 95% confidence).
VST Lab II average TDS after 10 reads 1.40, stdev. 0.006 (0.013 at 95% confidence).
Test 2:
DiFluid average TDS after 10 reads 1.42, stdev. 0.007 (0.016 at 95% confidence).
VST Lab II average TDS after 10 reads 1.38, stdev. 0.004 (0.010 at 95% confidence).
So far, so good, the difference in span between readings didn’t exceed 0.06%TDS, as both devices claim +/-0.03% accuracy, this seems fine…
Test 3 and the wheels seem to come off a little…
DiFluid average TDS after 10 reads 1.48, stdev. 0.008 (0.018 at 95% confidence).
VST Lab II average TDS after 10 reads 1.40, stdev. 0.007 (0.016 at 95% confidence).
So the variation in readings between devices is not a constant interval, As both are quoted as accurate to +/-0.03%TDS accuracy something seems adrift here as the difference in readings differed by up to 0.09%TDS (I, and no influencers that I am aware of, have the facility to check refractometer accuracy.) , However, the precision of the readings for both seem acceptable.
I then wondered whether the difference in protocol was causing the differences in the averages, so I repeated Test 3, using the VST protocol for both devices. So rather than plonking the hot sample onto the DiFluid lens and taking readings, I cooled the sample in an espresso cup then placed it on the lens.
Test #3 repeated with VST protocol for both devices:
DiFluid average TDS after 10 reads 1.44, stdev. 0.031 (0.069 at 95% confidence).
VST Lab II average TDS after 10 reads 1.42, stdev. 0.005 (0.012 at 95% confidence).
The DiFluid readings started at 1.50%TDS, dropping to 1.41, the VST only drifted between 1.41 to 1.42. But the DiFluid settled to 1.41. 1.41, 1.41 for readings 8, 9 & 10 (vs 1.41, 1.41 & 1.41 for the Lab II).
So I feel I have to start again, it seems logical that the plastic casing of the DiFluid may not be allowing samples to reach a steady state as quickly, compared to the steel peltier dish on the VST.
The DiFluid spoon (volume 0.65g) is a bit daft/messy. Printed instructions are scant, YT videos don’t offer any further info on taking readings,
I’m a bit disappointed that I’m having to explore a previously unmentioned test protocol seeng that this has been in the field for some months, but I’ll see what occurs over the next few days.
Data is here:
So for the difluid R2 i use the provided spoon to take the sample for filter and then put it on a tablespoon to let it cool down. The R2 definitely struggles to cool down the sample compared to the VST, temperature difference between zero and sample has a big effect on TDS (data from Jonathan gagne) with room temperature being 75f in the graph below
Following the pocket science workflow gives the most consistent results and it is still usable for the VST to make sure the temperature is stable (https://pocketsciencecoffee.com/2022/12/07/my-current-refractometry-workflow/)
Coffee Roaster. Home: Sage Dual Boiler, Niche Zero, Ode v2 (SSP), 1zpresso ZP6 Work: Eagle One Prima EXP, mahlkonig e80s, Mazzer Philos and lots more
InfamousTuba If this is DiFluid’s test protocol, they should say so somewhere?
You’ll see from my tests there was no issue with the VST precision using their protocol. I’m not sure why Gagne would be measuring samples at such high temperatures?
@MWJB It isn’t difluids protocol, they aren’t the best at providing good protocols and information. So it means using a different protocol which is a bit annoying instead of being able to use the same one.
Gagnes temperature starts at his room temperature of 75f (23.9c) and goes up to 90f (32.2c) which is warm but not that hot
Coffee Roaster. Home: Sage Dual Boiler, Niche Zero, Ode v2 (SSP), 1zpresso ZP6 Work: Eagle One Prima EXP, mahlkonig e80s, Mazzer Philos and lots more
InfamousTuba Sorry, the chart said, “Sample temperature”, rather an ambient temperature.
The whole article is a bit long winded so I did just pick out the figure, here is the full thing: https://coffeeadastra.com/2019/09/21/measuring-coffee-concentration-with-a-0-01-precision/
Coffee Roaster. Home: Sage Dual Boiler, Niche Zero, Ode v2 (SSP), 1zpresso ZP6 Work: Eagle One Prima EXP, mahlkonig e80s, Mazzer Philos and lots more
InfamousTuba It is sample (not room) temperature according to the article, but no one would do this in real life (after reading VST’s instructions)..
No one would use those instructions, they are from quite a few years ago. It does say room temperature was 75.7f just under the figure that I copied here
Coffee Roaster. Home: Sage Dual Boiler, Niche Zero, Ode v2 (SSP), 1zpresso ZP6 Work: Eagle One Prima EXP, mahlkonig e80s, Mazzer Philos and lots more
InfamousTuba The instructions were written by the guy who innovated the method by which a refractomer is used to read coffee TDS, produced the first coffee refractometers & set the precision & accuracy specs. They still work.
@MWJB That is the technique I follow with the VST but the difluid (and the atago) don’t have the same temperature correction that the VST does, VST can account automatically for temperatures between 15-40c. That is the difference between a <£200 device and a £700 device, you do get some better features and they might be worth it for some users
Coffee Roaster. Home: Sage Dual Boiler, Niche Zero, Ode v2 (SSP), 1zpresso ZP6 Work: Eagle One Prima EXP, mahlkonig e80s, Mazzer Philos and lots more
Thx folks for the insight.
Three more tests now added, same protocol for both devices.
Stir coffee sample and place a teaspoonful into an espresso cup/shot glass to cool. For all devices this sample will need syringe filtering if espresso, French press, cupping, Aeropress, or pour over made with very fine grinds (e.g. any brews with significant suspended solids, or for absolute best results for all methods).
Calibrate with distilled water left on the lens for 1;00. Clean lens with lint free cloth/science wipe.
Add sample to refractometer (3 drops to VST, 6 drops to DiFluid R2), wait 1:00. Now would be a good time to start tasting your brew, if cool enough,
Start readings, I took 10 from each.
The averaged difference in TDS between the devices was +0.03%TDS higher with the DiFluid. Which is reasonable as both claim +/-0.03%TDS accuracy..
The stdevs in readings were:
DiFluid R2: 0.007, 0.010, 0.005 - 0.007 averaged and 0.016%TDS extrapolated to 95% confidence level.
VST Lab II: 0.007, 0.070, 0.070 - 0.007 averaged and 0.016%TDS extrapolated to 95% confidence level.
So, as far as this test can tell they are equivalent with this protocol. In terms of workflow, the VST Lab is quicker to stabilise and reached the average reading in 3-5 reads (I wouldn’t be too concerned about whether the reading recorded was 0.01%TDS out). The Lab II I used has been replaced by VST for the more accurate & precise Lab III.
This makes the DiFluid R2 quite a step up from the Atago & Amtast offerings in terms of performance. The workflow isn’t as smooth as the VST Lab series but I guess at the price difference, that’s a fair trade off. The Atago workflow is much slower due to the rolling display.
MWJB Exciting, extremely useful and awesome work!
The comparative results are very interesting.
Looking at your sheet, I am amazed to see the test 3 for the Peruvian coffee at room temperature / 23+C on par with each other.
Based on your results, this device is enough for home baristas even for filter, IMO. Of course, as you had suggested, syringe filter is recommended for the best outcome. Would that still be required even for filters like Clever (short and long steps), V60 and Hario Switch?
Thank you for the great piece of work. 🙏🏽
LMSC Whether you need to syringe paper filtered brews is more related to grind size used, so for 12% 400Kruve (probably a little finer than that too) and coarser, I wouldn’t bother. Though I have seen recommendations to brew pour over at very fine settings (like 40-45 on Niche). I wouldn’t recommend this myself, but if you were to do this, you would see significantly elevated readings, maybe by a couple of %.
If you were doing some kind of professional study/science then syringe filtering everything is recommended. If, on the other hand, you wanted a ‘finger in the air’ idea of extraction for Aeropress/very fine Clever/Switch steeps & very fine V60 pour over brews, you can still obviously take readings, but best to state whether syringe filters were used and take any unusually high EY readings with a pinch of salt.
Aeropress filters and holder have some gaps that let silt through, hence why syringing is always recommended.
