Adjusting pH during Mash

[luke2080]

While past experience and the Bru'N Water spreadsheet told me my latest mash pH should have been around 5.2-5.3, 10 minutes in my pH read 4.8.

I had a couple of baking soda additions during the mash to raise the pH up to 5.2 for the IPA I was brewing. What I haven't yet read (and the "Water" book is staring at me from the bookcase, children don't let me read...) is:

What is the impact of adjusting the pH during the mash?

If the pH is too low (or high) for 30 minutes before I can correct it, is it too late for proper enzyme activity? Per Brukaiser, it seems not. But what is meant by 1-2 pH units 5.1 to 5.2 as 1 unit, or 5.0 to 6.0?

From http://braukaiser.com/wiki/index.php?title=How_pH_affects_brewing

As long as the difference between the optimal and actual pH is low (1-2 pH units) the effect of pH on the enzyme activity is reversible since the enzyme is not permanently damaged (denatured). In practice this means that pH can be corrected even after dough-in and little or no enzymes will be lost as a result of a suboptimal initial pH. But once the pH is adjusted to an adequate level these enzymes will get a later start. At that point some of them may have already been denatured as a result of the heat before they got a chance to work at an optimal pH. This is especially true for the more heat liable beta-amylase and limit dextrinase. If the pH is substantially far from the optimum the enzyme can also be denatured, but that is difficult to achieve in brewing.

The above tells me it is reversible (if I'm close enough, but I'm unsure of that unit of measure) but also that at some point it is too late. What is that point, and can it be corrected by mashing longer?


I ended up at a pH of 5.2 at 50 minutes into the Mash, starting at 4.8 10 minutes in, thanks to adding baking soda. 3 total additions of 1 tsp, so slowly climbing to that mark.

I stopped the mash to mash-out at 70 minutes. I did end up with 80% efficiency, and the beer has finished out to 2 points above the beersmith estimate. Any thoughts on the impact my terrible mash day will have? This is an IPA. First taste (while green, warm, and not carbed) was not what I would call an IPA. But I also only seem to taste bitterness out of Sculpin these days.

 

[JonM]

Something doesn't sound quite right. How are you measuring your pH? Are you sure your reading was accurate? Assuming your measurements are accurate, how did you get down to 4.8? Did you have a lot of acid in the mash?

 

[luke2080]

Forgot to point out, I have a Milwaukee electric pH reader, that I calibrated at room temp while the strike water was heating. This was the third time brewing in three weeks, no issues. I won't rule out my pH meter being shot, I'll keep an eye on that next time. But I believe it is accurate.

My question is less on what I did wrong or my pH reader, but on the impact of late pH adjustments to the mash. Especially when/if you do start too far out of range. I take readings to help me adjust for a mistake, but I don't truly know the impact of those real time adjustments.

 

[JonM]

Well, assuming everything was mixed thoroughly and there weren't concentrations of baking soda in one part of the mash, it should be okay.

I'm still curious how you got to 4.8 in the first place. Last IPA I did with a traditional IPA grain bill, even with something like 4 or 5 ml of 88% lactic acid, I only got to 5.4something.

 

[mabrungard]

It is fairly unusual to get a pale malt grist to a room temperature pH of 4.8 without adding a huge amount of calcium salts or acid. You are probably doing something wrong.

 

[trentm]

My question is less on what I did wrong or my pH reader, but on the impact of late pH adjustments to the mash. Especially when/if you do start too far out of range. I take readings to help me adjust for a mistake, but I don't truly know the impact of those real time adjustments.

Since you came out with the expected efficiency, your pH adjustment apparently worked. My guess is that Kai is considering 0.1 as a pH unit or since 5.2 is the low end of optimum, 5.0 may still be OK. I don't think you denatured the enzymes as 4.8. The next question is flavor impact of that adjustment. Baking soda has a lot of sodium. Assuming your mash had 3.5 gallons of water and a teaspoon of baking soda weighs 7 grams (http://bakerbettie.com/), according to Bru'n Water you would have added 144.6ppm sodium to your mash. I hope the 3 additions of baking soda = 1 teaspoon and not 3 tsp total. 144.6ppm sodium is too high and may have a flavor impact. However that amount will get diluted with your sparge water and assuming it is sodium free and you used 5 gallons, that would dilute the sodium to ~60ppm. Still too high IMO but should not ruin the beer. What was you kettle pH?

 

[WiscBrewer]

I'm new to using a pH meter so take this with a grain of salt. I recently read that you need to swirl the probe slightly on the solution you're measuring to get an accurate reading. I wasn't doing that initially but do now. Did you do that?

 

[luke2080]

You are probably doing something wrong.

A daily occurrence.

I hope the 3 additions of baking soda = 1 teaspoon and not 3 tsp total. 144.6ppm sodium is too high and may have a flavor impact. However that amount will get diluted with your sparge water and assuming it is sodium free and you used 5 gallons, that would dilute the sodium to ~60ppm. Still too high IMO but should not ruin the beer. What was you kettle pH?

I had actually grabbed the 1/2 tsp, so 1.5 tsp total in a batch that was 10.5G after boil. I am worried about the impact to flavor, as it seemed to lack the bitterness of past IPAs after fermentation. The adjustments I did obviously worked, at the likely expense of desired taste. Normally if I'm unsure, I err on the side of a high pH and add in some Acid Malt, but I had none on hand. Was still an unexpected result to be that low to start, must have made an incorrect addition somewhere.

 

[luke2080]

I'm new to using a pH meter so take this with a grain of salt. I recently read that you need to swirl the probe slightly on the solution you're measuring to get an accurate reading. I wasn't doing that initially but do now. Did you do that?

Interesting. I've actually read the opposite. I do give it a little swirl to start though, and let it sit while it settles for a reading. It seems to give the final reading quicker.

 

[ClaudiusB]

Interesting. I've actually read the opposite. I do give it a little swirl to start though, and let it sit while it settles for a reading. It seems to give the final reading quicker.

My Hach pH meter has a built in stir plate for the samples to be measured.

 

[Gavin C]

I had a couple of baking soda additions during the mash to raise the pH up to 5.2 for the IPA I was brewing. ..

Don't do any intra-mash adjustments.

By the time mash pH has stabilized to the point where good data can be obtained regarding the pH value it's too late to do anything. Most conversion will already have taken place.

Making adjustments to early is likely be to the detriment of the mash and final beer.

All my mash adjustments are preplanned premash.

Record data.

Adjust future adjustments/mashes acordingly.

After a few brews just like with equipment you will get the chemistry dialed in.