Mash pH and temperature snafu

[Hush_Poopy]

Soo.. I had a series of brain farts during a brew session yesterday and I'm not sure how its going to affect the finished product (apologize in advance for so such a long post). First - some pertinent info:

• batch size: 5 gal
• Recipe = chocolate milk stout
  
• MLT = 10 gal round igloo cooler w/ false bottom
• Mash @ 152 for 60 mins. target pH = 5.46
• Batch sparge @ 168

Now, here's what happened:

1. mashed in and hit 153. all is well
2. checked pH after 5 mins. pH = 5.95
3. recognizing that i needed to take action to bring the pH down, I added 1/8th tsp of baking soda to the mash, stirred up real good and let it sit. Yep, that's right. I added baking soda instead of lactic acid. I seemingly forgot that acid lowers ph and baking soda raises ph.
4. checked pH again after another 5 - 10 mins or so. pH = came down to 5.77 somehow
5. since the pH had come down some, i thought i was making progress. I added another 1/4 tsp of baking soda, stirred and let it sit.
6. checked pH again. pH = came down to 5.71
   
7. while baffled that double the amt of baking soda from the first addition didn't bring down the pH twice as much, I still thought i was making progress (and still not recognizing i should have been adding acid instead of baking soda). this time i added 1/2 tsp of baking soda, stirred and let it sit.
8. Then it hit me... I should have been adding acid, not baking soda!
9. Using the BeerSmith Mash pH tool, I determined that I needed to add 5 ml of lactic acid to go from current pH to target. I added the 5 ml of lactic acid, stirred it up and let it sit.
10. checked pH again. pH came in at 5.47. Woohoo!
11. A lot of time was consumed with the above mayhem and by this point, there was only about 10 mins left in the original 60 min mash. I decided to mash for an additional 30 mins to try and give the grains some time at the correct pH (not sure if this would even have any beneficial effect since so much time was already spent at the wrong pH).
12. 30 mins later, i decide its time to conclude the mash and take a temp reading. I guess with all the opening of the lid, stirring and such - the mash temp had dropped down to about 139 or so.
13. I drained the MLT, sparged and went on about my day. The rest of the brew process went very smoothly.

So... What do you all think is going to happen to the finished product as a result of the baking soda vs acid shenanigans and the large temp loss?

Thanks for your input!

 

[EDF713]

I think you'll make beer and be surprised how well it turns out, and next time you'll remember. Brulosophy did an exbeeriment on mash ph, read it and you'll feel better.

 

[mongoose33]

What's your procedure for measuring pH? In almost all instances it needs to be measured at room temp (say 65-75 or so). Are you measuring it while still hot?

Not only will that give you inaccurate readings, it'll shorten the life of your pH probe.

It takes me 3-5 minutes to cool a sample to room temp, and I do that by using "frozen" whiskey glasses and small beakers. I pour the hot wort into the whiskey glass and because it has a lot of thermal mass and is very cold, it brings the temp down pretty quickly. I pour between whiskey glass and beaker, checking w/ a thermometer until it his about 70. Then I check pH.

No way on earth I could be measuring pH accurately as quickly as you are.

Another issue: I don't check pH until 15 minutes; also, I only do that after stirring to ensure a homgeneous mash. If you're just grabbing something off the top, who knows what it would be?

Typically I need to use some lactic acid to balance the pH, depending on the grain bill. I'm rather surprised you'd need to do much with acid given the dark malts you were using.

How is it going to taste? I have no idea. But it would help in the future if you dial in this measuring of pH and make sure you're doing it according to Hoyle.

Good luck, I hope it turns out for you.

 

[Hush_Poopy]

Thanks for the feedback! I'll checkout the brulosophy exbeeriment on mash ph - don't think i've seen that one before.

Here's how I have been measuring the mash ph: i remove a sample from the top of the mlt by dipping a little plastic cup (shot glass size) in and filling about half way up. Next, I cool the sample to room temp by placing the cup in an ice bath and swirling it around. Its not much liquid, so it cools quite quickly. Once the temp hits 75, i dip my ph meter right in the plastic cup.

I have NOT been stirring the mash before removing the sample. That's a good tip - i'll definitely start stirring before removing the sample in the future! thanks!

Also, I've read conflicting info on 'when' a ph measurement should be taken. Think I've seen everywhere from 5 mins to 20 mins - its a touch confusing to me. I was thinking that the sooner i identified a need for adjustment, the sooner i could take action, thus giving the grains more exposure at the desired ph... But i guess that all goes out the window if my measurements aren't accurate.

I did a quick a google search on Hoyle and pH measurement, but didn't see anything obvious. Could you point me in a direction on that one?

thanks again for the help and feedback!

 

[RM-MN]

It takes 15 to 20 minutes for mash pH to stabilize. By that time a good portion of the conversion has already taken place. Take notes on what you have for mash pH at 20 minutes and use that info for the next brew session because it really is too late then to have a lot of effect.

 

[The_Bishop]

That's not entirely correct; you are not merely correcting the pH for mashing purposes, but to get a proper kettle pH which will effect hop utilization and perception, as well as break formation, clarity, yeast health, and finished beer flavor/stability. pH has more far-reaching consequences than you are taking into account.

 

[ESBrewer]

I think you should measure at the beginning (at 5min when everything has been mixed will be fine) and at the end of the mash. When you know (from experience) that the pH will change during the mash you can make the corrections at 5min to reach the zone you're looking for. As you can see it will be impossible to reach a stable pH throughout. Brewing is about being able to repeat it the same way and being in the right ballpark / getting it correct on average.

 

[ScrewyBrewer]

That's not entirely correct; you are not merely correcting the pH for mashing purposes, but to get a proper kettle pH which will effect hop utilization and perception, as well as break formation, clarity, yeast health, and finished beer flavor/stability. pH has more far-reaching consequences than you are taking into account.

I take my mash pH readings 20 minutes into the mash as well, cooled down to ~75F. It takes wort pH a good 20 minutes to stabilize, about the same amount of time it takes the mash enzyme activity to favor either alpha or beta amylase, based on mash temperature. Predicting and then getting the correct mash pH within the first 20 minutes should always be your primary goal. It has been my experience that when mash pH is correct, kettle pH is also correct, for the vast majority of beer styles.