PH Buffers or is there a chemist out there

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PBD
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PH Buffers or is there a chemist out there

Post by PBD »

Looking for help with building a Potassium Buffer.

This is specifically advised by our yeast manufacturer.

All articles I have read need a chemistry degree to understand. I have found only one readable article for a sodium buffer that had an easy to follow recipe eg to make a 10mM buffer add 0.xxxxxg per weight of water. But only useful for ale. We are vodka and gin distillers and fermenting using sugar washes at PH 5.2

Has anyone got a similar formula using monopotassium phosphate and dipotassium phosphate?

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Re: PH Buffers or is there a chemist out there

Post by Hügelwilli »

Is the 5.2 the pitching or fermenting pH?
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bunny
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Re: PH Buffers or is there a chemist out there

Post by bunny »

Pardon me, please.

If your yeast manufacturer advised you to use a potassium buffer maybe he knows how to assemble one. No?

My tap water has a pH of 7.5 but without any resolve to remain at 7.5.
Just yelling at it drops it down to the high 6s.(just kidding)
I use a hybrid Shady/Wineo recipe without any acid.
In a 14 gal batch I add 3T or more of CaCO3 powder and dangle a 2 lb mesh sack CaCO3 chips.
My starting pH is 7.7.
I pitch at 95f and within a hour is going almost full speed.
After 24 hours the pH is 4.3-4.5 and stays there through completion. (2-3 days)

Out of curiosity, how big are your batches and what recipe are you using?

If all else fails, take a trip out to Dover, bring you pail and shovel.
You will find what you need there.
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Re: PH Buffers or is there a chemist out there

Post by Hügelwilli »

Phosphate buffers are easy to work with. You have two solutions, that are very durable, and mix them in proportions that you can read from a table and you get the given pH. But although you can use them for relative high pH buffers (over pH 5.5), they are not very efficient at high pH, because phosphates are salts of phosphoric acid and this is a relative strong acid. The stronger the acid the less efficient (buffer capacity per concentration) is it for buffering a high pH.

I really don't understand, why they recommend those buffers.

For relative high pH I would recommend a citrate or malate buffer made from the acid and a base like sodium or potassium hydroxide.
If you know what you want (pitching pH and pH after fermentation), I am able to calculate such buffers.

In your other pH-thread you write, that your wash ferment has stalled although you added calcium carbonate. Honestly I doubt that this is what has happened. Calcium carbonate may not be the optimal compound for a buffer, but in any form (powder or egg shells or whatever) it prevents the ferment reliably from stalling. I think the ferment stalled because of other reasons and a buffer will not cure it.
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Re: PH Buffers or is there a chemist out there

Post by StillerBoy »

bunny wrote: Sat Jan 30, 2021 9:12 am In a 14 gal batch I add 3T or more of CaCO3 powder and dangle a 2 lb mesh sack CaCO3 chips.
My starting pH is 7.7.
I pitch at 95f and within a hour is going almost full speed.
After 24 hours the pH is 4.3-4.5 and stays there through completion. (2-3 days)
Now that's an interesting method of doing a sugar wash fermentation..

So you start the ferment with a 2 lb bag of calcium carbonate chips.. what amount is left after it is done in 3 days.. and what is fermentation temp during the 3 days..

Mars
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Re: PH Buffers or is there a chemist out there

Post by StillerBoy »

Hügelwilli wrote: Sat Jan 30, 2021 12:29 pm In your other pH-thread you write, that your wash ferment has stalled although you added calcium carbonate. Honestly I doubt that this is what has happened. Calcium carbonate may not be the optimal compound for a buffer, but in any form (powder or egg shells or whatever) it prevents the ferment reliably from stalling. I think the ferment stalled because of other reasons and a buffer will not cure it.
The other factor in a wash stalling is an un-stable fermenting temp, as fluctuating fermenting temp is murder on yeast.. and an un-stable temp will also cause other issues such as it will prolong the fermentation process, and reduce clearing ability at finish..

Mars
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Re: PH Buffers or is there a chemist out there

Post by NZChris »

PBD wrote: Fri Jan 29, 2021 12:33 am We are vodka and gin distillers and fermenting using sugar washes at PH 5.2
Why so high? I only control pH that high when I want to encourage bacterial infections to create flavors in high ester rums, the exact opposite of what I want to happen when making gin and vodka.

If you are having trouble fermenting to completion because of a finicky yeast, maybe you need another yeast supplier?
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Re: PH Buffers or is there a chemist out there

Post by PBD »

Not sure which question are for me or in respect to others who have commented.

We are new distillery, so go easy on me please :-)

As we use bought-in GNS in the grain range, the sugar range is small batch currently whilst we test demand.

To answer questions:

1. We ferment in 60L and 120L batches.
2. We use Fermentis C-70 yeast.
3. I do not see any temp issue. Held between 21 and 24 C.
4. We kick off ferment at 5.2 PH
5. PH drops to 3 - 3.5 by 24 hour point. Point on ferments stalling is this reason, not because of Calcium.
6. Currently add Calcium Carbonate to get it back to 5.2 The ferment immediately starts off again. I have been told recently to not take it up so far. eg get it back to 4.5
7. I have been told to try starting it off at 5.8 or 6 ph so that it doesn't drop so far and hence will not stall at all and no need to add Calcium.
8. One question was why not ask Fermentis? I have, but sales guys just say what I have said, but I cannot get the detail or recipe. I am still chasing, believe me.
9. Question on end PH. I haven't measured this to be honest. Just checked and finishing 5 to 5.2ph. This would be sensible because of addition of CC to raise them back to 5.2 after 24 hours.

Maybe I am worrying over nothing, Start at 5.8 and it might not stall, or need to just add a little CC. But whilst we are small, I wanted to get it correct. I am open to ideas and advise, but I would rather automate with a buffer than have to manually manage ph. If there is a buffer, I would just like to understand how I calculate it. I am open to using a different buffer than Potassium, but was advised by Fermentis because Potassium is a yeast energiser.

Help and all advise appreciated. Hopefully I have answered all questions.
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Re: PH Buffers or is there a chemist out there

Post by Hügelwilli »

Again, if you already use CC, you won't have problems with the pH of a normal ferment. Almost every yeast ferments at pH 3. Did you write somewhere what's fermenting? Is it grain? Then perhaps the conversion didn't work well? Or is it sugar and water? Then perhaps there are not enough nutrients in the wash? Or perhaps the wash is simply finished dry? Where you know it has stalled? Gravity measurement?
I would like to read the recipe and protocol of the whole process.
But I know this was not your question. You want to calculate a buffer. A buffer for a relative high pH fermentation (not the right pH for vodka BTW).
Buffers can't be calculated with a simple formula, because the anions of the acids form equilibria. Only iterative calculations are possible. This means you need a computer program what tries to estimate the ingredients for the buffer with the given properties and then it calculates the properties of the estimation and then corrects its estimation again and again until everything is right. You can find such tools online with google "online buffer calculator". But those tools are not customized for distillers, because there is simply not much need for calculating buffers for fermentation. Not customized means those tools calculate ingredients we don't use and they calculate mol instead of gramm and so on. The only one tool for distillers I know is that I have build together with other distillers:
https://hobbybrennen.ch/Rechner/pHPuffer.html
It is in German language. But easy to understand.
One example:
Select "Citratpuffer: Berechnung der Zutaten" (Citrate buffer: Calculation of ingredients).
You want to ferment 100l wash between pH 5.2 and 4.2. So you allow it to drop by 1. So you have to type 5.2 "gewünschter pH" (desired pH) and "Absenkung des pHs um" 1 (dropping of the pH by 1).
You estimate that the unbuffered ferment would drop to pH 3.0. This means you need 1 "Pufferkapazität..." (buffer capacity). 1 means 1 millimol/liter H+ (= pH 3.0).
And 100 "liter Maische" (liter wash) of course.
Then you get the buffer calculated. For example:
28.2 grams anhydrous citric acid and 14.7 grams potassium hydroxide.
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Re: PH Buffers or is there a chemist out there

Post by NZChris »

PBD wrote: Sun Jan 31, 2021 6:25 am1. We ferment in 60L and 120L batches.
2. We use Fermentis C-70 yeast.
3. I do not see any temp issue. Held between 21 and 24 C.
From the C-70 Product information sheet
optimal fermentation temperature: 25-33°C
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Re: PH Buffers or is there a chemist out there

Post by NZChris »

PBD wrote: Sun Jan 31, 2021 6:25 am Maybe I am worrying over nothing, Start at 5.8 and it might not stall, or need to just add a little CC. But whilst we are small, I wanted to get it correct. I am open to ideas and advise, but I would rather automate with a buffer than have to manually manage ph. If there is a buffer, I would just like to understand how I calculate it. I am open to using a different buffer than Potassium, but was advised by Fermentis because Potassium is a yeast energiser.
To me, its sounds like you are looking for a complicated solution for a simple problem. Have you read this? https://homedistiller.org/forum/viewtopic.php?t=64169
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Re: PH Buffers or is there a chemist out there

Post by Saltbush Bill »

Bumping the temp up will help just to begin with........try running it on the higher side of the range.
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Re: PH Buffers or is there a chemist out there

Post by StillerBoy »

PBD wrote: Sun Jan 31, 2021 6:25 am 3. I do not see any temp issue. Held between 21 and 24 C.
There is an issue with un-stable temp if your fermentation fluctuate between 21 - 24 C.. yeast do not like fluctuating temp..

Secondly base on Chris stated on the C-70 yeast range of 25 - 33 C, and you're fermenting below its range, not good for the yeast..

Try to stabilize your fermentation temp range for the mid range of that yeast at 29 - 30 C and keep it stable, and see what the result are..

Also your starting Ph should be around 5.5 at start and adjusted for a 4 - 4.2 at the 12 and 24 hrs marks..

Doing those two things should stabilize your ongoing issues..

Mars
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Re: PH Buffers or is there a chemist out there

Post by bunny »

--Stiller Boy--
My pH used to dive to low 3s in short order and pretty much quit.
I thought I would try without the acid and with a high, but weak, pH.
It seemed to work with the CaCO3 chips at the very start of the fermentation.
It worked so well for me that is now what I do every batch.
The pics show a sack of chips that was used in the last 4 ferments.
The pH is a little lower than the first batch so I will refill the sack.
The clean sack is the first sack that I actually weighed the contents.
It's a fair amount more than the eyeball amount I normally put in.

My temps range from low to mid 90s
P1050114.JPG
P1050116.JPG
P1050118.JPG
This batch is about done and starting to cool down. (2 1/2 days)
Will rack in a day or two.
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Re: PH Buffers or is there a chemist out there

Post by Sulaiman »

I'm a hobby chemist that does not drink, so I can only comment on sugar washes and distillations,
(about 20 so far).

My experiments with buffers failed
- either costing too much or not working well.
Im sure this was due to my inexperience rather than the process,
I gave up on buffers because as I learned here,
Calcium carbonate is excellent;
it has very low solubility pH7 and above,
and is only really involved in the fermentation at lower pH levels,
the lower the pH the faster it reacts,
the calcium carbonate does a good job of neutralising acidity - without fear of adding too much, only as much as required is consumed.
(ok, maybe a very very small bit extra - difficult for me to determine)

Even with calcium carbonate, when the wash is oxygenated
(at the start of fermentation/reproduction of if aerated at almost any time during the fermentation)
the pH will drop rapidly - too quickly for the calcium carbonate to keep up, but it will catch up.

I would expect a craft distiller to keep constant manual control of the processes - otherwise the 'craft' part should be replaced with 'factory'
... or is that too naive of me?
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Re: PH Buffers or is there a chemist out there

Post by atarijedi »

This is quite late to the game, and I don't know how much "self promotion" is allowed in this forum. But you can check out a video on the youtube channel StillBehindTheBench, on creating buffers. It has all the math and everything right there. I help with that channel.

So what you would need to do, in order to create a buffer is find a potassium salt, that will disassociate into the potassium ion and a conjugate acid/base.

For instance, potassium citrate will disassociate into a potassium ion, and a citrate ion. The citrate ion is a conjugate base of citric acid. So you would need to calculate how much citric acid and potassium citrate to add in order to hold a certain pH.

If you wanted to use a potassium phosphate, the phosphate would be the conjugate base, and the acid you would pair it with, would be phosphoric acid.

Also remember that you need to adjust the pH, preferably with a different acid, before adding the buffer, for it to work properly.
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Re: PH Buffers or is there a chemist out there

Post by Hügelwilli »

I like the channel but I have to say that I think the calculations in this video are wrong.

A friend of mine posted questions in the comments there and some answers sounded not plausible. And because I was just starting to work on a javascript buffer calculator with a total different way of calculating the buffers, we discussed it and I got confused by those answers. I wasn't sure anymore about my way of calculating the pH and buffers. Therefore I decided to ask similar questions in a chemists forum and got confirmed there that the answers of the guy of this channel were wrong.

I could post more details. But I don't know, if it is a good idea. It's up to you, atarijedi.
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Re: PH Buffers or is there a chemist out there

Post by Sporacle »

NZChris wrote: Sun Jan 31, 2021 12:24 pm
PBD wrote: Sun Jan 31, 2021 6:25 am1. We ferment in 60L and 120L batches.
2. We use Fermentis C-70 yeast.
3. I do not see any temp issue. Held between 21 and 24 C.
From the C-70 Product information sheet
optimal fermentation temperature: 25-33°C
I have used the C 70 in my molasses washes and it defiantly doesn't like the low end temps, I set my temp to around 31 and it seems to go OK.
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Re: PH Buffers or is there a chemist out there

Post by Teddysad »

In my experience you have two factors.
1 In most fermentations pH will fall due to the CO2 mixing with water to form carbonic acid. It is rare for the pH to rise by itself during a ferment process. Thus other than initial setting of the starting pH an acid (pH lowering) element is not required.

A buffer by its nature resists changes in both directions up and down.

2 The key is to get a starting pH and hold things at that level which generally means resisting or working against the drop in pH.
This is where the calcium carbonate comes in. If present in the ferment it will do just that resist the fall. However it is not ideal for raising the pH where it has already fallen. For this many use sodium bicarbonate although I far prefer potassium bicarbonate to avoid the adverse affect the sodium has on the yeast.

However if you do want a citrate buffer there are calculators online which use sodium citrate dihydrate and citric acid together to make the buffer
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Re: PH Buffers or is there a chemist out there

Post by Stonecutter »

Is it possible [the salesman] could have been referring to potassium
Chloride by chance? Just a shot in the dark. This might be a problem though..

Hügelwilli wrote: Sun Jan 31, 2021 9:49 am But I know this was not your question. You want to calculate a buffer. A buffer for a relative high pH fermentation (not the right pH for vodka BTW).
Buffers can't be calculated with a simple formula,
because the anions of the acids form equilibria.
Only iterative calculations are possible.
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Re: PH Buffers or is there a chemist out there

Post by bluefish_dist »

While I can’t do the chemistry for it, i used 1:1 citric acid and calcium carbonate by weight as a buffer. The more I would add prior to fermentation, the less drop I would get. I usually adjusted to get a drop to around 4 in the first 24 hrs. Then adjust with cc as needed to keep it above 4.
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