Importance of Alkalinty

[nman13]

So I've read a lot about the fact that Alkalinity is simply a "buffer" and nothing more. Which means that the more Alkalinity in your water, the more acid you will need to reduce the PH.

If this is the case and all that alkalinity does is serve as a buffer then in theory should it not matter how much alkalinity is in your water when brewing a style whose water profile calls for a low amount of Alkalinity ? In other words, assuming you are able to add enough acid to lower mash PH to the desired range of the style (without getting off flavors from the acid) then shouldn't it not matter how Alkaline the water is for the final product?

 

[mabrungard]

You are sort of correct. However when there is a lot of alkalinity in the water, it also means there is also a lot of other ions in the water that are likely to also affect taste and brewing performance.

I see that you recognize the potential for the acid's anion to create off flavors. Although there are some acids that are more flavor neutral than others, eventually you will reach a concentration that any of them will be tasted.

Starting with modest alkalinity water of say less than 150 ppm as CaCO3 is more likely to produce acceptable results. Starting with alkalinity even lower is better yet.

 

[SpeedYellow]

Realize that this buffer will also impede your yeast in reducing the pH to where they may want it. I've heard it said that ale yeasts are better able to cope with the alkalinity, which makes sense from at least an historical perspective. So in other words, "high" alkalinity may be a problem with lagers, even if you've hit your mash pH.

 

[nman13]

I see that you recognize the potential for the acid's anion to create off flavors. Although there are some acids that are more flavor neutral than others, eventually you will reach a concentration that any of them will be tasted.

On the topic of Acid causing off flavors, I currently use 25% phosphoric acid. At what amount will 25% Phosphoric acid produce off flavors assuming a 5-6 gallon batch that includes acidifying the mash and sparge to appropriate levels.

 

[J187]

On the topic of Acid causing off flavors, I currently use 25% phosphoric acid. At what amount will 25% Phosphoric acid produce off flavors assuming a 5-6 gallon batch that includes acidifying the mash and sparge to appropriate levels.

Phosphoric has a considerably higher taste threshold than lactic, and lactic is still pretty high... with Alk under 150ppm you aren't going to taste a lactic addition that is enough to get you to target PH. Phosphoric is even higher than that. Don't worry about the whole Calcium precipitation thing either, if it were to happen, it would be a minor change in Calcium and it's a rare occurrence from what I understand. Having said that, my alkalinity is pretty low and I use lactic.