How does one conduct a test mash?

[bitteritdown]

I'm curious how one conducts a test mash. (Assuming a test mash is done to determine the mash pH and the amount of acid/alkalinity one must add to correct said pH.)

Any pointers or details on the entire test mash process would be appreciated.

 

[cire]

I would do 3 simultaneous mini mashes, each of 50g of grist with differing degrees of alkalinity adjustment.

Below dates back to days when a pH meter was a major investment.

 

[Silver_Is_Money]

Scale down your entire recipe across the board by a factor of 100 and mash it using water sourced or made up just as for that which is intended of your actual mash. Then check the pH at about 20 minutes into the mini-mash. The measured mash pH will notify you if you need to acidify or add a base, but extra work (resolved in one workable way by "cire" as seen directly above) is required to specifically quantify the amount of acid/base required. Titration of the scaled down sample to the desired target mash pH is another way.

Or alternatively, mash each individual grist component separately using 50 grams of crushed malt in 150 grams distilled water. Then for each component check the pH at about 20 minutes into the Congress mash. This will yield each of the individual grist components DI_Mash pH's. Then put your actual DI_Mash pH data and actual water data into software which is capable of receiving this information. The output will inform you of the batches need for acidification or the addition of base, and how much.

The benefit of the former method is that it will give you a direct indication of how to treat your current batch. The benefit of the latter method is that you can subsequently make any recipe you like from any mix of your measured components by utilizing their individual DI_Mash pH data (provided that your software is capable of accepting your discovered DI_Mash pH data).

 

[ajdelange]

Or alternatively, mash each individual grist component separately using 50 grams of crushed malt in 150 grams distilled water. Then for each component check the pH at about 10-15 minutes into the Congress mash. This will yield each of the individual grist components DI_Mash pH's. Then put your actual DI_Mash pH data and actual water data into software which is capable of receiving this information. The output will inform you of the batches need for acidification or the addition of base, and how much.

This gives you half the information you need. You must also make a minimash of each grain with an increment of acid (paler malts) or base (colored malts) and measure the pH's of those mashes too. Now you have the DI mash pH and the slope of pH with proton surfeit/deficit. You really need to make multiple measurements with enough acid/base increments to determine 2 -3 coefficients as pH does not, in general, vary linearly with acid/base addition. If you don't want to do this extra work just assume the linear term is 40 mEq/kg. The pH estimate is more sensitive to pHDI than to the buffering terms and 40 seems to be the average for most malts.