PH 5.2 + other salts

[Tiroux]

Hi!

I used in the past PH 5.2 to stabilize the ph. Works great!
Now I have many salts (Gypsum, Epsom, Baking soda, NaCl, etc) to ajust the water profil, with the help of beersmith water profile tool.

My question is: Can adding PH 5.2 can change the profile I obtain by adding my salts?

Exemple, it says that HCO3 affect the acidity of the mash, but since PH5.2 stabilize it, what happens..?

Thanks

 

[ajdelange]

I used in the past PH 5.2 to stabilize the ph. Works great!

Actually it doesn't work very well at all. It is a mix of monobasic and dibasic sodium phosphate which forms a buffer at about pH 5.9 in distilled water. When added to a mash the monobasic phosphate in the malt rebalances the ratio of mono to di basic in favor of mono which lowers the pH to which it tries to buffer but as the relevant pK for the monobasic/dibasic pair is 7.21 the mix has little buffering capacity (chemists never design buffers for pH more than 1 unit away from the acid/base pair pK).

My question is: Can adding PH 5.2 can change the profile I obtain by adding my salts?
Exemple, it says that HCO3 affect the acidity of the mash, but since PH5.2 stabilize it, what happens..?

5.2 will try to shift the pH down but since, as mentioned above, its buffering capacity is low, it won't have much effect. The pK for carbonic/bicarbonate is 6.38 so mash pH is closer than the phosphate pK so bicarbonate has a tremendous advantage and wins over the phosphate when even small amounts of bicarbonate (alkalinity) are present. Thus to use 5.2 to get mash pH into the desired region you would have to use so much that your beer would be loaded with sodium. There are much better ways to get mash pH into the correct range.

 

[Tiroux]

Ok. I had looked th ph during the mash and it was around 5.2...
So I should just skip the 5.2 or can it still help a little? (since I got the bottle, I should finish it..!)

So what should I look for to ajust my PH? I'm now a big chemistry freak, but I understand the importance of water profile, and that's what I have at home to adjust...
Table salt, NaCl
Sodium Bicarbonate, NaHCO3
Gypsum, CaSO4
Epsom, MgSO4
And I have some ascorbic acid

Thanks!

 

[ajdelange]

The most popular means for pH adjustment down (required in the majority of cases) are lactic acid in German beers in either the form of lactic acid itself or acidulated malt (see the Primer in the Stickies). For other beers phosphoric acid is doubtless the most popular. All of these are carried by home brewing suppliers.

To adjust pH up sodium bicarbonate can be used but most people want to limit sodium and use lime ('pickling lime' sold by supermarkets).