several of us have been talking about and and or doing a higher mash PH, then lowering in the kettle preboil.
For example, light lagers in the 5.4-5.5 range for mash, then lowering to 5.1 in the kettle.
There must be an exact formula to be used for post mash wort reduction - xxml lactic or phosphoric acid = xxPH reduction per/gal wort?
Maybe… but I’d worry about water composition and grist/wort composition because those things will affect buffering capacity which will affect how much acid you need to add to drop X pH units. But maybe it won’t matter so much such that a ballpark figure could be found? I don’t know.
It’s never that simple with pH, unfortunately. It will depend on the amounts of any ions/salts that have the capacity to buffer any pH changes.
What will probably get you in a closer ballpark would be to figure it out in Brun’water as if you added it to the mash. Say you wanted to mash at 5.4, then lower it to 5.1 preboil. I’d figure out how much acid needed to get to 5.4, but then I’d also figure out how much to get to 5.1. I’d add the difference between the two into the kettle. It may take some tweaking to get to an exact number, but I bet you’ll be in the ballpark.
Eric, that seems like it may be a plausible start. I was thinking just adding a small amount, like a mL or 2 to the kettle. It’d drop the pH, maybe not to 5.1, but it would help I’m sure.
yeah I havent been able to make that work. I think perhaps what you mention, basically not all wort created equally has an impact on how much acid is required to drop one wort vs. another.
additionally, as Martin mentions in the software notes, adding acid to hot vs room temp has different impact…the hot being more impactful and lowering PH greater than the software predicts…if I understnad it correctly.
perhaps it is just a bit of a PITA , and will just have to add 1ml at a time to see how its lowering a given wort.
I hear ya. interesting though if what Eric said:
“It’s never that simple with pH, unfortunately. It will depend on the amounts of any ions/salts that have the capacity to buffer any pH changes.”
if that’s correct, you’d think even Kai’s formulas would not apply to kettle PH lowering from wort to wort…given different mineral composition. Looking at my notes on different batches, it has been different amounts of lactic for different brews - only constant was about 8gal preboil wort.
In a post, Jim had specified using X ml of lactic 88% for a 6.x gallon batch (lager/pilsner I think) to end up at 5.0pH BK. Using his value, and factoring it down for my batch size I ended up at 6.4ml for 5.25G to be added to BK (mash/sparge were 5.5ph - pilsner 8.75lb grist). At preboil, I added the adjusted lactic amount and pulled sample, cooled to room temp, and was at 4.97pH (±0.05) - pretty darn close considering I was just “winging it”. I don’t have any tasting notes since it won’t be kegged until this coming week. FWIW.
I think there may be a generalized rule of thumb that could be discerned from the link jim posted, real world experiences, and grist amounts. Then some small adjusting up/down for general composition of beer water/minerals/etc. Perhaps an open document (google docs etc) where folks could record some basic values that over time could help to flesh out a general formula. Then again, it’s rarely that easy in brewing
That crossed my mind, but… analogy time. Lets say every car gets somewhere between 125 and 205 miles per gallon. We want to know how much is needed to get from coast to coast. A chart of experiences would only be helpful if you found a guy who had everything exactly like you have, down to how much change is in the cup holders. We still wont know exactly what we would need for our particular trip.
A safe but time consuming method would be Kens idea of 1ml and test, 1ml and test. Or take Kai’s low end and go from there. Or what I did, take the average and go for it. I probably got lucky.
By the way, you got lucky too. Kai’s figures are not based on volume of water, just pounds of grain bill. The average for lactic 88% was .175 ml per pound grain bill. Ten pounds would be 1.75 ml per .1 pH drop. Its puzzeling why the water volume doesn’t seem to matter until you think about it. 10lbs grain in 10 gallons has less buffering but more water than 10lbs grain in 5 gallons. Also its total volume we’re dealing with, so if a person has more equipment loss between the mash tun and the boil kettle they will need less acid than the total volume. Same in the keg. If you toss out a gallon and only keg 5, or drink a gallon before using acid… see the point?
So basically what you’re saying, Jim, is that there is no way to come up with a solid formula. Shoost! I could just ballpark it I suppose and add a couple mL to the kettle…lowering it even just a little would probably make a difference for the better, no? Just spit ballin’. Not sure I actually feel comfortable flying blind like that.
The point I see is starting to look like stars in space :D. Certainly more complex that it might appear, BUT let’s look at what Martin has done with BrunWater. It’s my understanding that he’s not providing actual titration values for specific malts (malt colors) but rather using the color and type of malt as a proxy to get very well within the ballpark. It’s then up to us to dial-it-in using our own equipment/meters. Perhaps, given the fact that pH reduction takes exponentially more-and-more quantity for that same .1pH reduction, we can find a nicely defined “safe” zone based on certain criteria (BK volume, grist amount, etc) such that a person could start at the low end of the zone and incrementally work their way to the sweet spot… but there are those stars again
I dont know if anything can be expected per se. There’s some theories. Kai has said years ago that pH effects hop utilization much the way temperature and specific gravity does, I think he claims that 5.0 will be smoother? Maybe? Lower pre boil pH is supposed to effect break, so better clarity? Maybe? And the other is that yeast will lower the ph so they can more easily uptake and release… stuff. Manually lowering it ahead of pitching is thought to help them. Again, maybe.
Looking at Kai’s chart, converting ml to tsp, your 11.15 lb grain bill would need 1.1-1.5 tsp of 10% phosphoric to drop the ph from 5.43 to 5.33. Again, volume of wort doesn’t matter so long as you are dealing with the total volume and not just a portion of it.
Thanks for posting. I have 88% Phosphoric acid. I’m thinking I’d add 1 or 2 mL. But I’m not sure I’m comfortable flying blind. And I suppose, depending on the beer style, you wouldn’t need to add as much? Say, for darker worts vs lighter worts?
