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General Category => General Homebrew Discussion => Topic started by: jared long on April 26, 2011, 07:38:03 PM

Title: adjusting mash pH post dough-in
Post by: jared long on April 26, 2011, 07:38:03 PM
this earlier discussion regarding target mash pH (and using mash 5.2 to achieve this) got me thinking...

if i were to skip using 5.2, take a reading after dough-in and found that my mash pH was off, could i adjust at that point?  if so, what with?

Title: Re: adjusting mash pH post dough-in
Post by: gordonstrong on April 26, 2011, 07:42:56 PM
If you need to adjust it down, add phosphoric acid.  If you need to adjust it up, add your charcoal-filtered but unboiled source water.
Title: Re: adjusting mash pH post dough-in
Post by: tom on April 26, 2011, 07:56:13 PM
Gordon,  some prefer lactic acid to phosphoric.  I think they mentioned that the phosphoric can precipitate out some of the calcium.  Any thoughts?
TIA, Tom
Title: Re: adjusting mash pH post dough-in
Post by: mabrungard on April 26, 2011, 08:14:51 PM
Gordon's recommendation only applies if your tap water has high alkalinity.  If its low in alkalinity, then adjustment with an alkalinity producer such as lime or baking soda is OK after mash in. 

Phosphoric acid is perfectly fine for pH adjustment.  There is a myth circulating that adding phosphoric acid causes more calcium precipitation in the mash.  Since wort typically contains on the order of 1% (which is 10,000 ppm) phosphatic compounds, adding a 100 ppm of orthophosphate ions to the mash is not going to appreciably change the amount of precipitation of calcium in the mash. 
Title: Re: adjusting mash pH post dough-in
Post by: johnf on April 26, 2011, 08:18:36 PM
Gordon,  some prefer lactic acid to phosphoric.  I think they mentioned that the phosphoric can precipitate out some of the calcium.  Any thoughts?
TIA, Tom

The phosphate added by phosphoric acid is a drop in the bucket compared to that in the malt. Since phosphate is flavor neutral lactic will be preferred by those who like the taste of lactate or care about the reinheitsgebot.
Title: Re: adjusting mash pH post dough-in
Post by: tom on April 26, 2011, 10:15:10 PM
Thanks guys!
Title: Re: adjusting mash pH post dough-in
Post by: hopfenundmalz on April 27, 2011, 01:56:34 AM
I have found that pickling lime is an effective way to raise the pH.  Thanks Martin.
Title: Re: adjusting mash pH post dough-in
Post by: malzig on April 28, 2011, 03:13:46 AM
There is a myth circulating that adding phosphoric acid causes more calcium precipitation in the mash.  Since wort typically contains on the order of 1% (which is 10,000 ppm) phosphatic compounds, adding a 100 ppm of orthophosphate ions to the mash is not going to appreciably change the amount of precipitation of calcium in the mash.  
Doesn't that supposition imply that 100 ppm of calcium wouldn't make any substantive difference in phosphate concentration, either?  Yet that small amount of calcium seems to make a measurable dent in the phosphate concentration as seen in the mash pH.  I would think that that would indicate that most of those 10,000 ppm of potential phosphate compounds is already complexed and unavailable.  For example, the majority of the phosphorus in grain is in the form of Phytin and probably unavailable to further react with soluble calcium.