RumRiverBrewer
Well-Known Member
Add it after adding water to my MLT with grain or add it to the water before heating it or ?
Thanks
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Need to add acid for alkaline water - How/when?
- Thread starter RumRiverBrewer
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I had not thought about this aspect before, but it would make a difference if you added acid before or after heating the water if that water had high alkalinity.
Heating drives off CO2 from the water and provides minor alkalinity reduction by consuming HCO3. Acid consumes (neutralizes) HCO3 directly.
In the case of all the brewing water calculators that I'm aware of, they are using the laboratory alkalinity and that was determined from an unheated water sample. In the case of Bru'n Water, the calculation of how much alkalinity needs to be neutralized is based on that lab alkalinity value and that equates to a calculated measure of acid. If the water is heated first, a portion of that bicarbonate that you intended to neutralize with the acid will have already been neutralized by driving off some CO2.
Therefore, I'd recommend that acid should be added to mashing or sparging water prior to heating the water significantly in order to avoid overdosing the water with acid and driving the ph and resulting alkalinity lower than desired.
Thank you very much for the question. It was food for thought!
Enjoy!
Heating drives off CO2 from the water and provides minor alkalinity reduction by consuming HCO3. Acid consumes (neutralizes) HCO3 directly.
In the case of all the brewing water calculators that I'm aware of, they are using the laboratory alkalinity and that was determined from an unheated water sample. In the case of Bru'n Water, the calculation of how much alkalinity needs to be neutralized is based on that lab alkalinity value and that equates to a calculated measure of acid. If the water is heated first, a portion of that bicarbonate that you intended to neutralize with the acid will have already been neutralized by driving off some CO2.
Therefore, I'd recommend that acid should be added to mashing or sparging water prior to heating the water significantly in order to avoid overdosing the water with acid and driving the ph and resulting alkalinity lower than desired.
Thank you very much for the question. It was food for thought!
Enjoy!
If you calculate the amount of acid you need to move water plus malt to the desired pH and then add that to just the water this will cause the pH to go well below the target pH (because the malt isn't there to buffer) and all the CO2 will fly off. This, on the one hand, consumes more acid than would be consumed for bicarbonate conversion than would be the case if the acid were added to the grist as the pH would never go below the target and the acid consumed in converting the last bit of bicarbonate (6.2% remains at pH 5.2) would still be available for moving mash. OTOH the alkalinity is higher if done this way as that 6% is still there. What actually happens depends on the titratable acidity of the particular malts being used. One would need to know that in order to do a calculation and that is a hard thing to find out. Doing some numerical experimentation modeling malt as a phosphate buffer shows that mash pH when all added to the water before mash in can be higher or lower than when added to grist depending on the ratio of alkalinity to buffering capacity of the malt. The shift isn't much, however (i.e. 0.1 or 0.2 pH). Those numbers can only be considered ROMs based on the sophistication (or rather lack thereof) of the model.
