Efficiency and pH

[brian320fo]

I recently started stirring my mash (among other things) and increased my mash efficiency from about 75% to about 90%. So I scaled my recipes accordingly. The one thing I noticed though was that my pH levels dropped from about 5.45 to about 5.2 (at room temp). Can I assume that the higher efficiency of extracting sugar also means a higher efficiency of extracting acid? Do spreadsheets like Bru'n Water assume a particular mash efficiency? Does anybody know the effect of mash efficiency on pH? I figured since I scaled my recipes that the pH would stay about the same. Maybe I just need a new pH meter....

Thanks

 

[Yooper]

I recently started stirring my mash (among other things) and increased my mash efficiency from about 75% to about 90%. So I scaled my recipes accordingly. The one thing I noticed though was that my pH levels dropped from about 5.45 to about 5.2 (at room temp). Can I assume that the higher efficiency of extracting sugar also means a higher efficiency of extracting acid? Do spreadsheets like Bru'n Water assume a particular mash efficiency? Does anybody know the effect of mash efficiency on pH? I figured since I scaled my recipes that the pH would stay about the same. Maybe I just need a new pH meter....

Thanks

No. Efficiency is not impacted much by pH, and the difference in efficiency between 5.2 and 5.45 wouldn't be at all an issue.

The differences in the pH have to do with the amount of alkalinity in the water and the amounts of acids in the grains, and of course other ingredients.

 

[brian320fo]

No. Efficiency is not impacted much by pH, and the difference in efficiency between 5.2 and 5.45 wouldn't be at all an issue.

The differences in the pH have to do with the amount of alkalinity in the water and the amounts of acids in the grains, and of course other ingredients.

Thanks Yooper. But my question is really "is pH effected by efficiency"?

 

[Yooper]

Thanks Yooper. But my question is really "is pH effected by efficiency"?

No.

What does affect the pH is the alkalinity of the water and the grain used, and the mash thickness (especially with alkaline water).

 

[mabrungard]

is really "is pH effected by efficiency"?

Maybe, but its got to be minor. The incremental effect could only be due to the extra extract being placed into solution by the finer grind that may be the root of the increased efficiency. As noted by the OP, that increase in efficiency amounts to something like 20% more of that malt being made available for reaction. I suppose that might make a minor difference in pH.

One question I have is: is this extract efficiency or system efficiency? Extract efficiency is measured as the maximum wort gravity produced in the tun with respect to the water/grist ratio. The Braukaiser website has a nice chart of gravity vs. water/grist ratio that helps you decide how your extract efficiency is. System efficiency is the gauging of how much of the extract actually makes it into the kettle. That is affected by how you sparge or runoff.

With all that said, I don't think that pH really effects extract efficiency very much. I do think that pH does affect the conversion of extracted starch into sugars.

 

[brian320fo]

One question I have is: is this extract efficiency or system efficiency?

This is mash efficiency, which I guess is the same as extract efficiency. This is the amount of sugar extracted from the grain and put in the boil kettle as a percentage of total sugars in the grain. I just noticed a sudden jump in mash efficiency with just stirring the mash in my recirc system to loosen up the grain bed. When the efficiency jumped, the pH dropped. I was just wondering if I was extracting more acid.

Thanks for your replies!

 

[PlexVector]

I recently started stirring my mash (among other things) and increased my mash efficiency from about 75% to about 90%. So I scaled my recipes accordingly. The one thing I noticed though was that my pH levels dropped from about 5.45 to about 5.2 (at room temp). Can I assume that the higher efficiency of extracting sugar also means a higher efficiency of extracting acid? Do spreadsheets like Bru'n Water assume a particular mash efficiency? Does anybody know the effect of mash efficiency on pH? I figured since I scaled my recipes that the pH would stay about the same. Maybe I just need a new pH meter....

Thanks

No. Efficiency is not impacted much by pH, and the difference in efficiency between 5.2 and 5.45 wouldn't be at all an issue.

The differences in the pH have to do with the amount of alkalinity in the water and the amounts of acids in the grains, and of course other ingredients.

Maybe, but its got to be minor. The incremental effect could only be due to the extra extract being placed into solution by the finer grind that may be the root of the increased efficiency. As noted by the OP, that increase in efficiency amounts to something like 20% more of that malt being made available for reaction. I suppose that might make a minor difference in pH.

One question I have is: is this extract efficiency or system efficiency? Extract efficiency is measured as the maximum wort gravity produced in the tun with respect to the water/grist ratio. The Braukaiser website has a nice chart of gravity vs. water/grist ratio that helps you decide how your extract efficiency is. System efficiency is the gauging of how much of the extract actually makes it into the kettle. That is affected by how you sparge or runoff.

With all that said, I don't think that pH really effects extract efficiency very much. I do think that pH does affect the conversion of extracted starch into sugars.

But would not the pH be affected by stirring? In other words the mash was stratified.

 

[Qhrumphf]

I look at it in terms of "conversion efficiency", which mash pH, mash temp, mash time, and grain crush are the primary driving factors, ie how much sugar is created in the mash, and then "lautering efficiency", which is how much actually makes it into the kettle, which is determined by system design and mash/sparge processes. As Martin said, other factors like crush increasing conversion efficiency might slightly impact the mash pH, but they're probably minor. I'm guessing you're not getting a good consistent first reading, and as a result the second reading seems odd. Stirring the mash should increase the lautering efficiency, but not the overall impact overall mash pH unless the mash wasn't stirred enough at first to be consistent for the the inital reading.

 

[brian320fo]

Thank you for your replies. It's very much appreciated.

 

[mabrungard]

This is mash efficiency, which I guess is the same as extract efficiency. This is the amount of sugar extracted from the grain and put in the boil kettle as a percentage of total sugars in the grain.

Nope! What you just described is the System Efficiency. Things like the fineness of the crush, the length of the runoff, and the use of a mashout temp step affect system efficiency.

I'm more inclined to say that one of those factors improved your yield and not pH. But, do try and get your mash pH in the right range. That should always help your beer flavor.

 

[brian320fo]

Nope! What you just described is the System Efficiency. Things like the fineness of the crush, the length of the runoff, and the use of a mashout temp step affect system efficiency.

I'm more inclined to say that one of those factors improved your yield and not pH. But, do try and get your mash pH in the right range. That should always help your beer flavor.

Thanks Martin. One more quick question. If my efficiency does increase and I rescale my recipe to accommodate this, should I also proportionally rescale the amount of acid malt I'm using? From what I've read here so far the answer would be "No" because the efficiency doesn't effect the pH so I'll need the same amount of acid malt to hit my target pH.

 

[doug293cz]

Kai Troester has this to say about pH and efficiency:

Near their temperature optimum the amylase enzymes have a pH optimum between 5.4 and 5.7 when the pH of a cooled mash sample is measured (5.4-5.6 pH for beta amylase and 5.6-5.8 pH for alpha amylase [Narziss, 2005]). This was also confirmed in the limit of attenuation experiments. Outside this pH range the enzymes still work, but not as well and the mash doesn't convert as quickly or, if the rest time is not long enough, won't convert and the conversion efficiency will suffer.
...
Many brewers see a jump in brewhouse efficiency once they correct the mash pH. This is the result of improved conversion efficiency. On information about how to estimate and correct mash pH see Understanding Mash pH.

So, apparently the pH mainly affects the rate of starch to sugar conversion, and might affect total conversion if the mash time is too short for completion at the lower rate.

It's also plausible that the rate of conversion could affect the measured mash pH, if the measurement is taken early in the mash. It seems reasonable that if the pH of the mash changes over time, then the rate of that change might be correlated to the rate of conversion. A low conversion rate might require longer into the mash time for the pH to stabilize than a fast conversion rate. Conversion rate is highly affected by crush coarseness (large grits convert slower), and temperature (higher temps give faster conversion.)

Another thing that increases conversion rate is agitation (stirring or recirculating.) The sheer forces speed up the diffusion limited processes (gelatinization probably being the most important.) So, when you added stirring, you probably got more complete conversion in your alloted mash time, meaning your conversion was not complete with your old process. The faster conversion may have allowed your mash pH to stabilize earlier than when you didn't stir. Now, if your pH sample time was prior to pH stabilization with your old process, and after (or closer to) stabilization with your new process, then the increase in efficiency could give you a perceived change in pH.

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