Kettle pH adjustment calculation?

[SanPancho]

All I ask is for some insight on how you determined the best pH in your finished beer. I'm not asking for or expecting a written thesis. Or planning to write some sophisticated formulas. Just a bit more insight than 'higher than I'd like'. If you don't know for certain or don't want to share the thought process that's fine. Some people think mash pH is important while others don't. We can just leave it there.

last comment was directed at silver, not you. final ph is just personal preference for the most part. easy to do on your own with your favorite beer, especially the hoppy ones.

packaged beer should be under 4.5 for microbial stability, so thats generally considered the high end at most breweries. as most beers tend to fall in the 4.5ish to 4ish range on their own ( varies by yeast) thats generally the range you'll find most beers in when ready to drink. below that and you start getting a bit of "tart" character. (to me at least)

i simply added some acid to the keg when i felt something was a bit lacking. looked at my notes, saw that i was a bit high in ph after crashing and racking, so i figured it could be a bit muddled. instantly it popped. flavors were the same, just seemed a bit brighter, clearer, etc.

somewhat similar to the sulfate vs chloride changes in beer, in that lower ph seems to be associated with crispness and bright flavors, especially hops. and higher seems to work better in malty, darker and non hoppy beers. thats not saying there's any relation there- gypsum and cal chloride both lower pH. im just saying the perceived differences between them sort of mirror the high/low pH differences i get.

again, personal preference. try it out on your own recipes and see what you prefer.

 

[ScrewyBrewer]

@SanPancho thank you for explaining the process used. I’d imagine the best time to add the lactic acid would be before transferring the beer into a keg. I’d honestly never given this a thought before. Thank you for sharing.

 

[Silver_Is_Money]

... i simply added some acid to the keg when i felt something was a bit lacking. looked at my notes, saw that i was a bit high in ph after crashing and racking, so i figured it could be a bit muddled. instantly it popped. flavors were the same, just seemed a bit brighter, clearer, etc.

somewhat similar to the sulfate vs chloride changes in beer, in that lower ph seems to be associated with crispness and bright flavors, especially hops. and higher seems to work better in malty, darker and non hoppy beers. thats not saying there's any relation there- gypsum and cal chloride both lower pH. im just saying the perceived differences between them sort of mirror the high/low pH differences i get.

again, personal preference. try it out on your own recipes and see what you prefer.

And thus the other flavor variables that I attempted to integrate into a whole, and for which I was somewhat chided as being off topic, have reappeared as if on topic.

Would you ever consider the flip-side, as in adding baking soda to the keg if fermentation pH was 4 or below and you needed closer to 4.5 to achieve a particular desired set of flavor characteristics?

 

[SanPancho]

@SanPancho thank you for explaining the process used. I’d imagine the best time to add the lactic acid would be before transferring the beer into a keg. I’d honestly never given this a thought before. Thank you for sharing.

Don’t use lactic. It has its own flavor and can be like adding another variable into the mix. Phosphoric is generally considered flavor-neutral.

 

[Silver_Is_Money]

Don’t use lactic. It has its own flavor and can be like adding another variable into the mix. Phosphoric is generally considered flavor-neutral.

Don't tell this to the Germanic brewers. Weyermann goes as far as stating that most people generally prefer the benefits that come with lactic acid addition (in the form of acid malt).

 

[SanPancho]

Fair enough. Sauergut is gonna be lactic, so maybe Scotty can chime in on how much impact it makes flavor wise.

But my point is that if you want to see the difference between a beer at 4 vs 4.5 it’d be clearer to introduce only one change- ph. Lactic would be two changes possibly - ph and maybe flavor.

 

[Big Monk]

Don't tell this to the Germanic brewers. Weyermann goes as far as stating that most people generally prefer the benefits that come with lactic acid addition (in the form of acid malt).

You are missing the point here. Take any considerations about mash and kettle pH out of your head. What @SanPancho is discussing here doesn't have to take either of those into account. You could totally disregard mash and kettle pH until 10 minutes out, take a pH reading, and then make some assumptions and make an acid addition then.

What you are trying to do with a 10 minute or KO addition of acid is reduce the pH and ease the strain on yeast to have to do so on their own. Yeast have to first lower the pH of the beer to a certain threshold before fermentation proper kicks off. Acidifiying at KO speeds this process up and leads to healthier and more vigorous starts to fermentation.

Fair enough. Sauergut is gonna be lactic, so maybe Scotty can chime in on how much impact it makes flavor wise.

Piggybacking on the comment above, there will be an added flavor component to a KO addition of Sauergut because there is a larger volume of acid being added (orders of magnitude higher, i.e. hundreds of ml). This is a staple nuance flavor in many continental lagers.

But my point is that if you want to see the difference between a beer at 4 vs 4.5 it’d be clearer to introduce only one change- ph. Lactic would be two changes possibly - ph and maybe flavor.

This is true. If you are dosing a finished beer with acid to assess the flavors, you'll want a more flavor neutral acid just to be safe.

 

[ScrewyBrewer]

Yeast have to first lower the pH of the beer to a certain threshold before fermentation proper kicks off. Acidifiying at KO speeds this process up and leads to healthier and more vigorous starts to fermentation.

I know that yeast begin fermentation once they enter their anaerobic state. After all the oxygen in the wort has been consumed. I also thought pH was lowered by yeast during the course of active fermentation. I didn’t think pH was a precursor or a prerequisite to active fermentation.

 

[mabrungard]

What you are trying to do with a 10 minute or KO addition of acid is reduce the pH and ease the strain on yeast to have to do so on their own. Yeast have to first lower the pH of the beer to a certain threshold before fermentation proper kicks off. Acidifiying at KO speeds this process up and leads to healthier and more vigorous starts to fermentation.

That is not necessarily the main reason for performing a late- or post-boil pH adjustment. DMS removal is aided by boiling at higher pH. My research indicates that German brewers tend to target a modest kettle pH of around 5.4 and dose with saurergut late in their boil to bring the wort pH down several more tenths to suit the yeast and the resulting beer flavor.

There is nothing wrong with employing lactic acid in your brewing as long as the lactate content is kept below around 400 ppm, which is the taste threshold for typical tasters. However, some tasters are particularly sensitive to lactate and the lactate limit might need to be tightened for them. Lactic acid is a minor yeast nutrient.

 

[Big Monk]

I know that yeast begin fermentation once they enter their anaerobic state. After all the oxygen in the wort has been consumed. I also thought pH was lowered by yeast during the course of active fermentation. I didn’t think pH was a precursor or a prerequisite to active fermentation.

The pH drop occurs in the lag phase IIRC.

I consistently mix up my yeast terms and when I say "Active Fermentation" i'm typically talking about the beginning of the Exponential phase.

 

[Big Monk]

That is not necessarily the main reason for performing a late- or post-boil pH adjustment. DMS removal is aided by boiling at higher pH. My research indicates that German brewers tend to target a modest kettle pH of around 5.4 and dose with saurergut late in their boil to bring the wort pH down several more tenths to suit the yeast and the resulting beer flavor.

Very true. I neglected to mention the DMS removal benefits.

Sauergut is a different animal than mineral acids due to the volume added and the nuance flavors. Also due to the fact that larger brewers are constantly re-innoculating the Sauergut culture with fresh wort, it differs in fundamnetal ways from Sauermalz.

All very interesting stuff when you get down to it.

 

[Silver_Is_Money]

An interesting read on the factors which contribute to yeasts ability to reduce wort pH during fermentation. Per this article up to 30% of the pH reduction witnessed is due to still unknown causes.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/j.2050-0416.1976.tb03739.x

 

[Silver_Is_Money]

Ongoing research is at play to develop strains of saccharomyces cerevisiae which produce lactic acid as a fermentation byproduct. That may lead to an interesting beer fermentation future.

 

[ScrewyBrewer]

An interesting read on the factors which contribute to yeasts ability to reduce wort pH during fermentation. Per this article up to 30% of the pH reduction witnessed is due to still unknown causes.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/j.2050-0416.1976.tb03739.x

@Silver_Is_Money based on this 1976 study it seems the majority of pH drop from 5.2 to 4.2 occurs over the course of the first 24 hours. During the initial lag phase if the chart legends are correct as the gravity drops from 1.040 to 1.012.

 

[ajdelange]

Yes, the yeast immediately go to work trying to adjust the pH to a value they like in order to make it easier for them to do their real jobs. I brew in stainless steel fermenters so I can't see whats going on inside. A plummeting pH in the first few hours, well before visible CO2 emission, is great reassurance that the ferment is underway.

 

[Big Monk]

Yes, the yeast immediately go to work trying to adjust the pH to a value they like in order to make it easier for them to do their real jobs. I brew in stainless steel fermenters so I can't see whats going on inside. A plummeting pH in the first few hours, well before visible CO2 emission, is great reassurance that the ferment is underway.

I've re-purposed my old ColorpHast strips for this purpose. Since the reading doesn't need to be precise, they merely show me that the pH is dropping.

 

[cire]

@SanPancho For what styles of beer are you doing this and what are your natural and target pH?

Finished lager pH is usually 4.4 to 4.8 while European ales between 3.8 and 4.2. However it would seen more common for American ales to finish between pH 4.2 and 4.4 which makes me wonder if the yeasts are different and or the mineral levels are the reason for the difference for ales.

My last brew, a popular Scottish style of the last century, was pH 5.39 into the boiler and pH 5.29 out. While it was liquored back for reasons of gravity, which would have produced a very marginal reduction in pH, at racking the beer was pH 3.82.

That beer was fermented with a heavy cropping top fermenting ale yeast from a now defunct brewery which always finishes below pH 4.

 

[couchsending]

Final beer pH depends on a lot of things. Yeast will drop it to a certain point but pH will often
rise even without DH additions, I believe FAN content can have a big impact on that pH rise
at the end of fermentation.

 

[cire]

I've not found beer pH to change much after racking, unless of course there is something else at work in it.

 

[couchsending]

It generally bottoms out before fermentation ends and climbs at the very end or soon after active fermentation ends. Just had a Pale Ale that I measured at 4.38 at FG then chilled to 58 for two days to get yeast to flocc and harvest before DH. It was 4.48 before DH addition. I didn’t take a PH measurement any earlier in fermentation, wouldn’t surprise me if it was lower than 4.38 at some point.

 

[cire]

Think I've never measured pH during fermentation, so thanks for that information which is new for me.
I don't know what DH is, but would find pH 4.48 or even 4.38 very high for a finished pale ale. Do you use a low mineral liquor profile, i.e. < 100 ppm Ca?

 

[phishie]

What we have traditionally done is as follows:

1.) If using Sauergut, we used it at a rate of 30 ml/kg of malt to drop the pH 0.1, IIRC. This was handed down from Kolbach and is documented in Kunze's text. 30 ml/kg is the boil addition rate (or kettle addition).

2.) Mineral acids were a bit trickier at first. You have to make a few assumptions, one being that the buffering is the same from mash to kettle to knockout. Ultimately, what I settled on was a combination of Brun Water's mash acid calculations and Riffe's mash acid calculations, extrapolated to cover kettle and knockout additions by re-calculating the RA for each step. For instance:

Kettle pH (using Acid) = Mash pH (Measured) + (pH/RA Slope (l/mEq) * RA (mEq/l))

KO pH (using Acid) = Kettle pH (Measured) + (pH/RA Slope (l/mEq) * RA (mEq/l))

where:

pH/RA Slope (l/mEq) = 0.17

RA (mEq/l) = -( Acid Strength (%) * ( Acid Density (kg/l) / Mol. Weight ) * 1000 * ml of Acid ) / Corresponding Volume (l)

It's not perfect because we don't know the actual buffering of the kettle wort or KO wort so we have to assume, but it will get you in the wheelhouse if you need to park the carriage in a hurry.



While I am a "sum of all parts" kind of guy as well Larry, in this case it doesn't matter. You can totally disregard the mash and kettle predictions one may develop and just take a reading before knockout and use my approximations from above to get a fairly decent, if not totally precise, estimation of knockout pH.

For the guidance in 1.), what percentage acid Sauergut is assumed? I often see people talking about 1% or 2% Sauergut.

 

[SanPancho]

Sorry @cire , missed your question earlier.

I dont care about european styles or guidelines at all. Pretty much all american styles, some bastardized uk styles, and sours. So mine are based off what i see around me and hear from others.

Most of the time i only adjust the lagers that get tons of hops. Sometimes ill adjust other beers if i feel theyre a bit flat, typically the hop bombs.

I have never been able to track down the info but i read once that the acidification by yeast is related to the speed of reproduction. So ales will tend to create more acid than lagers, hence the higher typical ph in finished lagers. Ive been meaning to test this out on a warm fermented lager as i assume it should acidify more at higher temps and speeds. TBD.

Again, this is personal preference. But often a .1 or .2 change in final ph can have a big impact in flavor.

 

[ajdelange]

I also thought pH was lowered by yeast during the course of active fermentation.

It is.

I didn’t think pH was a precursor or a prerequisite to active fermentation.

And that's why pH reduction isn't a precursor. The yeast will supply the acid needed to establish a pH they are comfortable with. But in so doing they are distracted from fermenting sugar into alcohol and flavor compounds which is what we prefer they do.