pH question: Temperature compensation and efficiency

[MrHadack]

When I do a mash I typically use the Bru'n Water Spreadsheet to calculate any additions I need to make to achieve the water profile I want, but mainly to achieve the proper mash pH. In the past I have done mostly single infusion mashes. When I test the pH of my mash after 5 minutes, it is usually exactly at 5.4 pH as predicted by the Bru'n Water sheet. My efficiency is typically 70%.

This past weekend, since I did a decoction mash, I had a few different rests. At the first rest (95F) the pH of the mash was exactly as predicted. I had just bought two fresh bottles of calibration solution and opened them that morning to calibrate the Ecotest pH2 meter that I use. It was spot on, so I know this is accurate.

At the next rest, 122F, my pH level came in at 5.5. I know that temperature will affect pH readings. My meter is supposed to compensate for temperature fluctuations up to 122F. But just for fun I entered the information into this calculator. Sure enough, it corrected to 5.4 pH so I left it alone.

I continued this for each of the two saccharification rests. The pH reading kept rising, but at each temperature level (146F and 155F) the pH of 5.6 corrected to 5.4. So I never made any adjustments.

When done with the mash I sparged and took gravity readings. I took some after the boil and cooling process. To my amazement, my efficiency was my highest ever at 88%.

Wanting to replicate this success in the future I examined my notes and process for the day. I typically don't do protein rests. I know that will bump up efficiency and I will do them from now on. But would that cause an 18 point increase?

I also looked at the pH situation. My typical mash temp on a single infusion mash is 153F. A pH of 5.4 or 5.3 is actually as low as 5.1 when corrected for temperature. If my meter has been telling me I hit 5.4 on my past mashes, I think that means I have actually been out of range all this time and never knew it. I understand that the Bru'n Water Sheet will give you the predicted pH of the mash at room temp. And I have since learned that my pH meter will only correct for temperature up to 122F.

So here's my MAIN question:
Does this mean I should make adjustments to my water additions on the Bru'n Water Sheet until it says the room temperature pH of the mash is 5.6 to ensure the pH of the mash will be 5.4 / 5.3 when I get up to the Sacc Rest temps of 150F? I know my meter will read the pH as being 5.6 on brew day, but since it doesn't temperature correct up in that range, I can use the calculator I linked to earlier to ensure I am where I need to be.

Is this how other people do it, or are there better ways?

Thanks!

 

[helibrewer]

The Bru'n water program predicts the room temp pH. I sample, cool it in the freezer to about room temp and take my reading...the program has always been very accurate so I just do this as a spot check and don't take any other readings later in the mash.

10-20ml's cools very fast in the freezer to it doesn't delay my sample reading enough to worry about it. Maybe something about the decoction boosted your efficiency...

 

[BackAlley]

10-20ml's cools very fast....

2ml cool even faster, like as soon as it hits the sample cup almost. I think the pen type meters need nothing more than a thin layer.

 

[MrHadack]

The Bru'n water program predicts the room temp pH. I sample, cool it in the freezer to about room temp and take my reading...the program has always been very accurate so I just do this as a spot check and don't take any other readings later in the mash.

10-20ml's cools very fast in the freezer to it doesn't delay my sample reading enough to worry about it. Maybe something about the decoction boosted your efficiency...

It's been very accurate for me as well. I'm not really concerned so much about checking the pH later on, though I will use that cooling method to do so if needed.

What I am curious about is this: before you brew, when you use the spreadsheet to figure out your water additions and projected mash pH, do you shoot for a pH of 5.6 on the sheet? In other words, you know the pH at mash temps will be 0.2 or 0.3 lower than what the sheet suggests, so do you try to get the adjustment summary page of the spreadsheet to read 5.6 for the estimated mash pH to account for that?

 

[MrHadack]

Nevermind, I understand pH and room temperature stuff a little better now. If a sample of my wort cooled to room temperature checks in at 5.4 on my meter, I'm all set. No need to worry about it any further.

So I can check my pH during the protein rest before any conversion is taking place and make adjustments before it really matters.

 

[VladOfTrub]

If you are into decoctions try using low modified malt. It is a better malt than high modified when it comes to the decoction method. Phytase is cooked out of high modified during kilning. Some other stuff has been crystalized and inverted. High modified malt will only reduce PH to a limit. Then water or mash has to be doctored up with acid or something to further reduce pH. Low modified malt will gradually reduce mash pH as long as there's not something in the water to limit it. I use low modified malt and some sauer malt. Here's the way I do a tri-decoction. I dough in with cold water at 1qt/lb and let the mash rest for a couple of hours. This softens up the husk and helps get the starch bound in the husk out. Then, I fire the mash tun to hit 95-105F. Once the pH of the mash is about 5.6, I pull the 1st decoction. Then, go to a protein rest in the decoction kettle and then a rest at about 156-158 for conversion. A pH of 5.6 favors alpha enzymes. While waiting for the decoction to convert and boil. The pH of the main mash is dropping. After the 1st decoction has been boiled, I dump it into the main mash to hit a protein rest temp. Then as soon as temperature is stable, the 2nd decoction is pulled. The acid and protein rests are skipped in the 2nd decoction, I go to a 145F conversion temp. Because the pH is now in the beta band. What is taking place in the main mash tun, de-branching enzymes are beginning to convert starch even though gelatinizing hasn't taken place. The main mash temp is below optimum bata and alpha temps, but favors maltase and dextrinase enzymes. The phytase will be denatured, but the sauer malt will lower the pH during the rest to about pH 5.0. After the 2nd decoction has converted and boiled, I dump it back into the main mash for final conversion. The pH will rise when the 2nd decoction is returned. During main mash conversion rest, I'll thin down the mash. Because at 1 qt/lb, conversion takes too long. Fly sparging is a bear due to the mash liquid being thick with extract, if it isn't thinned down. After conversion the final decoction is pulled for mash out. The final conversion rest temp is based on protein rest temps. At the ending of conversion, pH is about 5. After sparge, boil and cooling, the wort, pH in the fermenter is about 5.5. Decent pH for Lager yeast. I use a 20 gallon Blichmann kettle and their false bottom for a lautertun. I reduced the size of the slot openings for decoction brewing.