Extraction yields with the new precision baskets (Weber, SWorks, Wafo, Pesado, etc.)

#1: Post by **gscace** » July 13th, 2023, 10:04 am

Hi there:

We have 9 pages of comments on the Unibasket, with only anecdotal evidence that the basket is better. How exactly is it better? Has anyone verified higher extraction yields via refractometer, and is that data available for us to see? A link to Pesado's basket is on one of the pages. I looked at it, and Pesado claims higher yield but shows no data. Let's see it.

-Greg

Moderator note: Split from Experience with Weber Unibasket

#2: Post by **baldheadracing** » July 13th, 2023, 10:43 am

gscace wrote:We have 9 pages of comments on the Unibasket, with only anecdotal evidence that the basket is better. How exactly is it better? Has anyone verified higher extraction yields via refractometer, and is that data available for us to see? A link to Pesado's basket is on one of the pages. I looked at it, and Pesado claims higher yield but shows no data. Let's see it.

It's on my list, but I have to design a suitable experiment first. I'd like to be able to tease out the difference between flow and basket design.

For example, leaving the unibasket aside, if a basket has bigger holes than an identical basket with smaller holes, then one has to grind finer to get the same flow rate. Is this 'better' in and of itself? I think that I can come close to testing this with, say, VST-15 vs. VST-25, although headspace would be different.

Bringing in the Unibasket, I'd want to compare it against a basket that had the same flow so the same grind size could be used between the baskets. I have some 'worn-out' old baskets to go through. Hopefully one of those will come close to the unibasket's flow. (I had been hoping that the VST-25 would be that basket.)

ETA: Lance Hedrick did have some EY numbers in his basket test. Start at 10:00 for EY methodology; 11:25 and 12:03 for the results. (I'm not posting the results so Lance gets the views/watch minutes and hopefully subscriptions.)

July 13th, 2023, 1:54 pm

Hey thanks for embedding the video. That was really interesting. So the answer to my original question is that Lance measured about 5% more yield, and I get that this is presumably due to improved flow through coffee around the perimeter of the basket.

#4: Post by **Jeff** » July 13th, 2023, 2:05 pm

That theory is consistent with some of the beliefs emerging from other discussions. At least as I've been following the impressions and talking with people directly, it seems that the presently preferred third-generation baskets have in common relatively parallel sides with minimal corner radius and that the perforations extend closer to the edge of the basket than many of the second-generation options. While from 2020, Stéphane RIbes looked at radial extraction in second-generation baskets. Adding filter paper to those noticeably improved both overall EY as well as mitigating the reduction in EY observed closer to the walls of the basket. While this doesn't prove anything about third-generation baskets, it is suggestive of a mechanism.

July 13th, 2023, 2:38 pm

I mapped out extraction inside filter baskets both top to bottom and radially. I presented the top to bottom results in 2017 at SCA Coffee Expo in a talk I gave on espresso extraction, and did the radial work shortly after at the request of Carimali, S.p.A., for whom I work as a consulting engineer. I'm quite interested in the straight-sided approach with holes to the perimeter as it's a practical approach to saving coffee by using less ground coffee while holding beverage strength constant. 5% isn't a lot when we leave a third of the dissolvable solids inside a spent puck. But it's a start.

July 14th, 2023, 3:09 am

If you are able to share, did your radial work show similar results to the oft quoted Ribes data?

July 14th, 2023, 6:57 pm

In general, my data shows that residual coffee (undissolved) after brewing is about 50% greater around the perimeter compared to the center, given a saturated center core being around 16 gm and perimeter around 24 grams. That's a rather arbitrary slicing, chosen because that is the size tubing I had on hand with which to make a coring device. An example of coffee left in core and perimeter is 4.0 % yield vs 8% in the perimeter portion for an average yield in the cup of 21.4%. The arithmetic holds up pretty well - 21.4% in the cup plus 0.4*4 plus 0.6*8 equals 27.8% dissolved material, which falls within the realm of what we can expect for dissolvable solids in coffee. The .4 and .6 values refer to the weight fractions of center core and perimeter compared to their combined weight.

-Greg

#8: Post by **baldheadracing** » July 14th, 2023, 7:39 pm

gscace wrote:In general, my data shows that residual coffee (undissolved) after brewing is about 50% greater around the perimeter ...

Was that result with a slanted/rounded basket or a VST-like straightish-sided one?

#9: Post by **PIXIllate** » July 14th, 2023, 8:47 pm

gscace wrote:In general, my data shows that residual coffee (undissolved) after brewing is about 50% greater around the perimeter compared to the center, given a saturated center core being around 16 gm and perimeter around 24 grams.
-Greg

Thank you for sharing Greg. It seems like your findings roughly agree with the Ribes experiment.

July 15th, 2023, 7:56 am

baldheadracing wrote:Was that result with a slanted/rounded basket or a VST-like straightish-sided one?

I used VST and IMS precision baskets of various types including flat and rounded bottom ones. I don't prefer ridged baskets so all were ridgeless. The work was part of an effort to increase the extraction yield of Carimali traditional machines and included changes to the group design, as well as discovering which components seemed preferential. The trend of center extracting more efficiently than perimeter exists for all configurations that I tested and for all machines that I used. I have benchmark machines in my lab that I can use to make comparisons and they all behave similarly.

-Greg