Collecting mash samples and testing pH later.

[hellbent77]

I'm still learning pH meter use. When I brewed yesterday, I drew mash samples every 20 minutes and put them in a freezer. When I noticed the first two were frozen, I put them in the house on the counter to cool instead.

I didn't do the pH testing with a meter until the brewday was done, a few hours later. Do you think the pH of the samples changed in all that time?

Should I cool and test them right away next time? Is that what most people do?

I had expected 5.4 mash pH. The samples tested in the 5.6+ range. My expectations were based on Bru'n Water spreadsheet. I used RO, CaCl2, and no acid for Centennial Blonde Ale.

Not sure how to explain the divergence unless Walmart RO wasn't so good. Maybe the pH in the samples rose while sitting around? Or it could be any other countless potential errors.

I'm not stressing about this; the beer will be fine. I'm just trying to become a more reliable brewer.

Thanks.

 

[helibrewer]

The pH should not have changed. I check during the mash in case I need to make an adjustment. Without some crystal or dark malt, you should have had to add a little acid, I generally use about 1/8 to 1/4 lb of acid malt when brewing light beers with RO water.

 

[PlinyTheMiddleAged]

Hellbent,

I put together a test mash the other day - just one pound of grain and the right amount of distilled water with my salt additions (pickling lime, calcium chloride, etc). I pulled samples every fifteen minutes for the hour and all were within 0.01 of each other. Probably all grists behave a little different, but all of mine settled in very quickly.

For my test mash, I learned that Bru'N Water was about 0.19 higher than actual - this is going to be a RIS with a lot of roast malt. As a result, I'll make some adjustments to the salt additions prior to doing the real mash later this week.

 

[hellbent77]

The pH should not have changed. I check during the mash in case I need to make an adjustment. Without some crystal or dark malt, you should have had to add a little acid, I generally use about 1/8 to 1/4 lb of acid malt when brewing light beers with RO water.

Thanks for the reply. Good to be able to trust the meter tests then.

I felt I should have added some acid to follow AJ deLange's baseline recommendation. The Bru'N water spreadsheet changed my mind; predicting 5.4 without acid.

Just now I reviewed that spreadsheet and found a couple errors on my part. After corrections, it now predicts 5.5 pH without acid addition. That's pretty close to what I measured; maybe 0.5 to 1 low. That's close enough for me.

My confidence is restored in the spreadsheet, meter, and those baseline ecommendations.

There sure is a lot to learn about brewing!

 

[hellbent77]

Hellbent,

I put together a test mash the other day - just one pound of grain and the right amount of distilled water with my salt additions (pickling lime, calcium chloride, etc). I pulled samples every fifteen minutes for the hour and all were within 0.01 of each other. Probably all grists behave a little different, but all of mine settled in very quickly.

For my test mash, I learned that Bru'N Water was about 0.19 higher than actual - this is going to be a RIS with a lot of roast malt. As a result, I'll make some adjustments to the salt additions prior to doing the real mash later this week.

Do you do test mashes for every beer you brew or just for the unusual beers?

I haven't repeated too many recipes yet but might brew Centennial Blonde frequently if it turns out. Each brew will be my test and I'll tune it as I go.

I guess the lesson learned is that the spreadsheets should get me close if I don't screw up entering things. :smack:

 

[PlinyTheMiddleAged]

This was my first test mash. I did it because of the massive amount of roast malt. Other folks recommend holding the roast malts back and steeping them separate from the lighter malts to get better control on mash pH.

With my other lighter grain bills, distilled water, and salts, Bru'n Water usually gets me very close to my target pH. For this RIS grain bill, it didn't fair as well. But, I learned how to adjust the main mash from this test mash.

 

[ajdelange]

I'm still learning pH meter use. When I brewed yesterday, I drew mash samples every 20 minutes and put them in a freezer. When I noticed the first two were frozen, I put them in the house on the counter to cool instead.

I didn't do the pH testing with a meter until the brewday was done, a few hours later. Do you think the pH of the samples changed in all that time?

Yes, most probably. The reactions that go on in the mash tun take quite some time to complete in some cases - as long as an hour or even more. This depends on the malts involved and the acid/base source.

Should I cool and test them right away next time? Is that what most people do?

Yes and yes.

 

[ajdelange]

That's pretty close to what I measured; maybe 0.5 to 1 low.

That's pretty good!

 

[hellbent77]

That's pretty good!

Good to know. I will quit struggling to get Bru'n Water to predict exactly what I measured; especially since delayed testing probably fouled the measurement anyway.

Many thanks to all for the guidance!

 

[PlinyTheMiddleAged]

I haven't repeated too many recipes yet but might brew Centennial Blonde frequently if it turns out. Each brew will be my test and I'll tune it as I go.

That's a good way to do it as well. Just keep good notes on your mash parameters - water, salts, and pH. If you brew the same beer again, consult your notes and make adjustments. That's what I usually do too. But the grain for my RIS was more expensive than my usual grain bills. I wanted to get close on my first try.

Good luck with your brew!

 

[PlinyTheMiddleAged]

The reactions that go on in the mash tun take quite some time to complete in some cases - as long as an hour or even more. This depends on the malts involved and the acid/base source.

AJ,

I understand that the reactions that alter pH take some time to happen. This brings up a question that you've probably been asked before - at what point in time should we hit the target pH; beginning, middle, or end of mash? As a hypothetical example, if I'm shooting for 5.40 and the reactions reduce pH by 0.20 over a one hour period, what should I be looking for when I measure pH - 5.40 at the beginning? (I don't know if the 0.20 change is realistic or not; I just pulled that number out of the air as an example).

Thanks in advance!

 

[ajdelange]

That is, of course, a very good question to which I do not have a definitive answer. pH approaches its final value asymptotically in most cases so that most of the shift has taken place after about 20 minutes. Though there may still be creep after that the amount of change is going to be quite small relative to what took place in the first 20 minutes or so after strike. As a consequence of this I generally look about 20 - 25 minutes in though I do measure and record before and after that point in time.

The amount of shift seems to depend on how dramatic the pH change for the individual malt components is going to be. For example, if sauermalz with an intrinsic (DI mash) pH of 3.6 is being used to adjust the pH of some pale ale malt with an intrinsic pH of 5.7 it takes much longer for the acid from the sauermalz to be completely absorbed by the base malt that it seems to if the same pH adjustment is achieved with a caramel malt of 5.4. Note the use of the phrase 'seems to'. I don't have formal data on this.

 

[hellbent77]

That is, of course, a very good question to which I do not have a definitive answer. pH approaches its final value asymptotically in most cases so that most of the shift has taken place after about 20 minutes. Though there may still be creep after that the amount of change is going to be quite small relative to what took place in the first 20 minutes or so after strike. As a consequence of this I generally look about 20 - 25 minutes in though I do measure and record before and after that point in time.

The amount of shift seems to depend on how dramatic the pH change for the individual malt components is going to be. For example, if sauermalz with an intrinsic (DI mash) pH of 3.6 is being used to adjust the pH of some pale ale malt with an intrinsic pH of 5.7 it takes much longer for the acid from the sauermalz to be completely absorbed by the base malt that it seems to if the same pH adjustment is achieved with a caramel malt of 5.4. Note the use of the phrase 'seems to'. I don't have formal data on this.

I wondered if the sample's pH changes after it is taken and is sitting for some time in a freezer, refrigerator, or on a counter. There is some grain in the sample.

 

[ajdelange]

Although I have never experimented in a way that exactly reproduces those conditions I think the answer is most probably that the pH does shift with time. The colder conditions may retard the reactions so that the change might be smaller over a given time interval.

 

[hellbent77]

Although I have never experimented in a way that exactly reproduces those conditions I think the answer is most probably that the pH does shift with time. The colder conditions may retard the reactions so that the change might be smaller over a given time interval.

That's logical.

I'll test right away in the future.