The effect of mash pH on Final Gravity

[GallowsHillBrew]

Hi,

We just did a double batch of IPA. The one standard pale and the other black by cold steeping the strike & sparge water with patent black.
The mash temperatures were basically the same.

Before cold crashing the beers the black was at 1016 while the pale version was at 1020.

Can this be due to the black malt changing the pH?


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[porter]

What was the pH?

What was the pH of mash and finished beer for both beers?

Typically, mash pH affects enzymatic activity and therefore extraction/efficiency. As long as you are in the right pH range for good yeast health, your mash pH shouldn't affect yeast performance.

[BrewinLou]

Did you pitch the same yeast at the same rate? Did the yeast come from the same tank? There can be a definite change in yeast cell density from the top middle and bottom of a cone of yeast.

[jwalts]

It's plausible that mash pH could cause the difference. If you're not treating your water or mash with a source of acid, most of your mash pHs are probably higher than ideal. Dark malt lowers pH, and the ideal pH range for beta amylase (the enzyme that drives fermentability) is lower than the ideal pH range for alpha amylase. That means your Black IPA mash could be in a better pH range for fermentability than your normal IPA.

Mash pH is one possible cause out of several, though. Pitch rate, oxygenation rate, and yeast viability would be my first targets. BrewinLou brings up a great point about sampling location. My FV sample ports are nice & high, but they trap a lot of yeast. Whether it's due to excess yeast or because each sample is simply not representative of its entire batch, my gravities are regularly lower in the bright tank than the fermentation tank after correcting for temperature.

Joe

[GallowsHillBrew]

Thanks for the input guys.
Firstly... We did no pH measuring.
Both batches were pitched with the same amount of dry yeast. Fermentis S05. And the procedure, i.e. Aeration, etc was the same for both.
@jwalts - I think we need to treat our water a bit. Will measure the pH next time and make a more educated decision.


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