Has anyone tried this Baca drops method for their water recipe?

I haven't tried it, but think it might be an interesting experiment for some.

The video muddles the chemistry a little so some geeky explanation might be useful . . .

His concentrates, which he calls "10000x" are all formulated at levels of hardness (GH) or of alkalinity (KH) of 10,000 ppm CaCO3 equivalent. So his GH (CaCl2 MgCl2, Epsom) solutions are all 0.1 mole/liter and his KH (KHCO3) solution is 0.2 mole/liter. (Note that Ca++ and Mg++ are divalent, and K+ is univalent, so that's why you need twice the molarity of the potassium to get the same chemical equivalence.)

For example if you had 100 ml squeeze bottles you want to put 0.01 moles Epsom (MgSO4 * 7 H2O) in the bottle. Epsom has a molar mass of 246.5 g/mol, so you'd need about 2.5 grams of Epsom salt. Anhydrous calcium chloride (CaCl2) has a molar mass of 111.0 g/mol you'd need about 1.1 grams of that in the 100 ml bottle.

For the KHCO3 you need 0.02 moles, and the molar mass of KHCO3 is 100.1 g/mol, so you need about 2.0 grams of KHCO3 in the bottle.

Those bottles, in measures of CaCO3 equivalent are now at 10000 ppm as CaCO3 (ppm and mg/L here amount to the same thing). Each ml of that concentrate contains 10 mg of CaCO3 equivalent. With his bottle he gets about 40 drops per ml so that's 0.25 mg (CaCO3 equivalent) per drop. Then to calculate the GH or KH equivalent in the final shot you divide that by the shot volume. He pulled 48 ml (0.048 liter) turbo shots, and 0.25 mg / 0.048 liter = 5.2 mg/L (as CaCO3) per drop.

You would need to adjust your own mix to allow for the drop volume. Some droppers may give you much larger drops. And typical shot volumes are smaller.


P.S.
The "Baca" here is a credit to a participant (bacafreak) on the Espresso Aficionado discord server.

Wow, I just published a question asking if people added water drops directly into their shots. Is there any need to add the drops in the portafilter instead of the glass?

Earthy wrote:Is there any need to add the drops in the portafilter instead of the glass?

It's not really known. You will see statements to the effect that "coffee tastes the same whether water minerals are added before or after brewing" attributed to Samo Smrke, who is a respected coffee researcher. I think that's based on this Lance Hedrick interview a few months back: http://www.youtube.com/watch?v=-_8fXToQ1dg (skip to 8:13 for that part of the discussion.)

It does make sense that the effect of alkalinity on buffering of acids would be the same whether minerals were added before or after brewing. I suspect that's what the study that Samo Smrke was discussing in that video was about. Note that he said it was a purely chemical analysis and not a sensory study.**

With respect to calcium and magnesium there's not much certainty what if anything they do to affect extraction. It's fairly clear that they don't really affect extraction yield as measured by refractometer, but there seems to be sensory differences, but no clear agreement about what those differences are.

P.S.
The video was discussing Lotus drops, which is a commercial coffee water mineral additive geared primarily toward brewed coffee. See Lotus Water experiences

** [edit addition] Searching through Dr. Smrke's instagram posts I found a link to a student paper by Tove Bratthäll that is probably the one he was talking about: https://www.diva-portal.org/smash/get/d ... TEXT01.pdf . That study was about divalent cations and not alkalinity, and the measurements were GC-MS analysis of three important coffee acids. Here's the paper's conclusion:

Available scientific literature regarding water composition and coffee brewing has been reviewed
and a substantial gap between the scientific community and the specialty coffee community has
been identified. In this study, a rough model for analysis of non-volatile coffee constituents with GC-
MS was developed, paving way for further research in the field. Experimental data suggest that
calcium and magnesium do not increase the extraction of organic acids. At concentrations
recommended for coffee brewing, there was no observed effect, while at high concentrations,
calcium and magnesium added pre- and post-brew, significantly (p<0.00001) reduced the levels of
malic and citric acids, as measured by GC-MS.

** [another edit addition] Also on this idea of adding minerals before vs after brewing it's perhaps worth mentioning a 2019 BeanScene magazine article discussing an experiment by Australian coffee scientist, Dr. Monika Fekete: https://www.beanscenemag.com.au/the-pow ... e-tasting/ . She used 12 samples using three different coffees, blind tasted by 13 expert tasters, who failed to detect a difference between brewed coffee that had hardness minerals added to pure water before brewing vs added afterward to coffee that had been brewed with pure water. (Their added mineral content was 150 ppm CaCO3 equivalent, half calcium and half magnesium.)