Lactic vs. Phosphoric Acid Taste Test

[teeWRX]

Lactic acid 88% is readily available to me, although for the first time I stumbled across 10% Phosphoric. Having read it's more neutral for flavor and as such, better for some styles of beer, I grabbed a bottle. But because of how much Phosphoric I need to use (have fairly hard water @ 152ppm Hc03) and the brand name on the bottle it's going to cost a bit more to use in the long run.

So I ran a simple taste test to see if I could even tell, but when me and the wife triangle tested both acids diluted in water, the Phosphoric is more noticeably "sour" than the lactic sample.

Please critique my experiment, maybe I messed up somewhere.

Had read 1.5ml/gallon of Lactic will put me just over the "perceptible taste threshold."
Which is ~0.4ml/L.

I used Beersmith to try and find a comparable dose of Phosphoric 10%. One recent recipe I had that used a nice round # of 10ml Lactic to reach pH of 5.36 in Beersmith would have required ~110ml Phosphoric 10% to reach the exact same pH. So i'm assuming I can compare the two at about 1ml to 11ml, but... you know what they say about assumptions. Maybe this is where I went wrong.

So I added 0.4ml Lactic 88% to 1L tap water & 4.4 ml Phosphoric 10% to a separate 1L of tap water. Both measured accurately using syringes, and even sucking some water in/out of the small 1ml syringe to make sure all the Lactic made it into solution.

Should I have used distilled water?

Or is it just possible neither of us mind the taste of Lactic at all?

Thanks in advance for any insight.

 

[Gnomebrewer]

152ppm bicarbonate isn't too bad. I doubt you'd notice a difference between lactic and phosphoric in a beer brewed with that. Maybe, possibly, in a very pale lager.

Also, this may be a bit pedantic, but HCO3 doesn't make your water hard (or soft). Hardness is to do with the Ca and Mg in your water. Your water has moderate to high alkalinity at 152ppm HCO3. It is quite possibly also hard due to Calcium.

 

[teeWRX]

152ppm bicarbonate isn't too bad. I doubt you'd notice a difference between lactic and phosphoric in a beer brewed with that. Maybe, possibly, in a very pale lager.

Also, this may be a bit pedantic, but HCO3 doesn't make your water hard (or soft). Hardness is to do with the Ca and Mg in your water. Your water has moderate to high alkalinity at 152ppm HCO3. It is quite possibly also hard due to Calcium.

Right! Alkalinity, my mistake. I think its still moderately hard? (Ca=50ppm, Mg=2ppm)

That was my tentative plan, save the phosphoric for my lighter styles. But having tasted them and finding the lactic addition less noticeable or offensive to my palate, should I just forget the Phosphoric all-together? Or did I just conduct a faulty taste test?

 

[Gnomebrewer]

I find the taste of lactic acid to be quite pleasant. I'm happy to use either. If you use lactic acid in pale beer and notice off flavours from lactate, change to phosphoric. I seriously doubt you will though. To throw some number in:
152ppm = 152ppm/61ppm/mEq/L= about 2.5mEq/L
88% Lactic acid has about 11.45mEq/mL (to pH of 5.4)
Therefor you need about 0.22mL of 88% lactic acid per liter of water to counter all of the waters alkalinity.
That's about 0.83mL per gallon.
The consensus here
https://www.homebrewtalk.com/forum/threads/lactic-acid-how-much-is-too-much.637716/
is that 1mL per gallon is unlikely to be noticed, so you're fine with your water providing you don't need to much extra to counter the alkalinity of your malt (WRT target mash pH), but remembering as well that you don't need to further acidify your sparge water. Summing that up, you're only possibly going to go above the taste threshold on a high-gravity very pale beer.

Or another method:
Braukaiser did a study on the taste threshold of lactate in beer, which can be read here
http://braukaiser.com/wiki/index.php/Lactate_Taste_Threshold_experiment
It shows that there is quite a bit of variability depending on the taster and the beer, but that below 400ppm Lactate is unlikely to be detected in beer.
Lactic acid has a mass of 90.08g/mol.
88% lactic acid has 880g of lactic acid/L, which is 880g/90.08g/mol = 9.77mol of lactic acid, which dissociates to provide 9.77mol of lactate in solution.
Lactate has a mass of 89.07g/mol, so 9.77mol has a mass of 9.77molx89.07g/mol = 870g.
So, each liter of 88% lactic acid provides 870g of lactate, which means each mL provides 870mg.
Therefore, 1mL of 88% lactic acid in a litre provides 870ppm of lactate.
400ppm lactate (braukaiser's taste threshold) equates to 400ppm.mL/870ppm= about 0.46mL of 88% Lactic acid per litre of beer.
In gallons, that 0.46mL/l x 3.8l/gallon = 1.75mL of 88% lactic acid per gallon, or more than double what you'd be using to counter the alkalinity in your water. The caveat there is that some people with perceive the lactate at lower levels.