51 replies to this topic

[MtnBrewer]

I can see I'm going to have to figure this out on my own

I don't know what you want me to say. The pH doesn't rise because you haven't done anything to cause it to rise. A rock in your yard doesn't move unless you push it.

[ThroatwobblerMangrove]

I don't know what you want me to say. The pH doesn't rise because you haven't done anything to cause it to rise. A rock in your yard doesn't move unless you push it.

check my edit - I was ultimately referring to the risk of tannin extraction. I honestly have no background in chemistry so I have clue as to "why" anything really happens.

[MtnBrewer]

edit: so apparently higher temperatures accelerate tannin extraction not b/c of pH but in addition to it - is that correct?

Tannin extraction requires two things to happen: 1) pH > 6.0, 2) temperature > 170°F. Those numbers are not like an on/off switch. You don't suddenly get massive tannin extraction at 6.1 & 171°F. But generally speaking if neither of these conditions exist, tannin extraction will be very minimal to none at all. Since the mash should be in the vicinity of 5.2 pH, then there should be no tannin extraction.

[ThroatwobblerMangrove]

Tannin extraction requires two things to happen: 1) pH > 6.0, 2) temperature > 170°F. Those numbers are not like an on/off switch. You don't suddenly get massive tannin extraction at 6.1 & 171°F. But generally speaking if neither of these conditions exist, tannin extraction will be very minimal to none at all. Since the mash should be in the vicinity of 5.2 pH, then there should be no tannin extraction.

is this an "and" condition or an "or" condition? is the idea that if you keep the pH in check you can raise the temperature all you want with no issues? what about if the pH is off but the temperature stays low?

[denny]

Actually there is a correlation but it goes the other way. The higher the temperature the lower the pH. This is true of a mash but is not true in general. If you want to try it out, take a pH reading of your mash say at around 100°F and then another at room temperature. The second reading will be higher.

But does temp actually change the pH, or simply the reading of it? For instance, if you let a hot sample cool, the pH reading rises, but does the actual pH?

[denny]

is this an "and" condition or an "or" condition?

AND

is the idea that if you keep the pH in check you can raise the temperature all you want with no issues?

Yep.

what about if the pH is off but the temperature stays low?

Low meaning under 170? Not a problem AFAIK.

[MtnBrewer]

But does temp actually change the pH, or simply the reading of it? For instance, if you let a hot sample cool, the pH reading rises, but does the actual pH?

Yes, it actually changes the pH. There is also the effect of temperature causing a measurement error due to non-linearity of the probe but that's not what I'm talking about. There is an actual pH change with temperature due to more H⁺ ions being available.

[denny]

Yes, it actually changes the pH. There is also the effect of temperature causing a measurement error due to non-linearity of the probe but that's not what I'm talking about. There is an actual pH change with temperature due to more H⁺ ions being available.

Cool! Thanks so much for the clarification.

[zymot]

Here is BYO's MR Wizard's take on tannins and decoction.Mr Wizard's Decoction Mash & Tannins

[MtnBrewer]

Here is BYO's MR Wizard's take on tannins and decoction.Mr Wizard's Decoction Mash & Tannins

Thanks for the link. I hadn't considered the protein-polyphenol reaction before but now after reading that it makes perfect sense. Also, the bit at the end about lagers actually being a little bit astringent is good food for thought.

[Jimmy James]

Almost all buffering systems experience changes in pH as temperature either rises or drops, so mash pH would change and from poking around a bit it seems that the pH may drop as temp increases. Not sure how we got on this topic but I've never found tannin extraction to be an issue for decoctions.