Mash pH with steeping and cold-steeping dark grains.

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cheesemoney

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I'm looking for advice for a few scenarios for a Russian Imperial Stout. I live in San Diego and have fairly hard water with high residual alkalinity. I'm looking to reduce astringency. I brew BIAB but this isn't really BIAB specific.

Scenario 1: Cold Steep Dark Grains and Add to Fermenter or Late in Boil
Cold steep all dark grains over night in the fridge (doubling the dark grain bill as is often recommended with cold steeping). Add these cold-steeped grains either to the kettle at flame-out or to the fermenter once the kettle wort is cooled. When brewing a typical 6 gallon base-malt batch I'll usually add 5 ml lactic acid to get the appropriate ph. Not sure what happens to the fermenter ph when I combine this acid-treated base-malt mash with the cold-steeped grains.

Scenario 2: Steep Grains at End of Mash
I always mash base malts for 90 minutes before doing a BIAB mashout at 168 for 20 mins (since I'm not sparging, just squeeze the hot bag and get all of the liquor). I could add the dark grains at 80 mins and then pull them with the rest of the grains after the mashout. I am not sure how to balance the base-malt pH (which would have to be treated with lactic acid) with the pH lowering properties of the dark grains when added 80 mins into the mash. The idea would be to reduce the amount of time exposing the dark grains to high temperatures. But how does one balance pH?

Of course I could always just mash the dark grains along with the base malts for the entire 90 minutes and probably wouldn't have to add any lactic acid at all. But again I'm trying to reduce astringency. I get the importance of mash pH, but I don't have an understanding of boil pH and fermenter pH.

As a follow up question, does pH need to be checked when cold-steeping? I.E. do I need to treat the water that goes into the fridge with the dark grains (and can I use diluted water here)?
 

mabrungard

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If the water has high alkalinity, separate steeping is probably not needed or beneficial. You typically need those dark grains in the mash to help bring the pH down to a desirable level.

My question is: what are you doing to reduce the pH and alkalinity of the mashing water and a sparge addition (if one is used)? I'm hoping you know how to acidify your water to reduce that alkalinity.
 
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cheesemoney

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It's BIAB so I don't sparge. Like I said, when I don't use dark grains I just add a bit of lactic acid (about 5 ml to 10 gallons of water for a 6 gallon batch).

I realize that dialing in a proper pH with dark grains reduces tannin extraction, and realize that tannins are mostly a product of temp and pH, but I like the Gordon Strong analogy regarding using freshly brewed coffee or coffee that's been heated all day. I notice that when I steep cold tea it tends to taste better than heating tea and then cooling it in the fridge.

The question really becomes, can one combine cold-steeped grains with the properly pH mashed base malts at the end of the boil or later? Or will the steeped grains lower the pH so much (say if added to the fermenter) that it will negatively affect fermentation?
 
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