pH change from protein to sacc rest

I almost always do single infusions and have my water and recipes down to where I know what to add (salts and acids) to get to 5.4-5.6 every time. Today, I was doing two batches with protein rests since I was using raw wheat (never again btw LOL). I was a little surprised to see my pH during the protein rest at 5.1 (cooled to room temp). Thinking the large amounts of raw wheat might have thrown my usual calculations, I was about to find some chalk or baking soda. But when I took the pH reading at the sacc rest, it was the usual 5.5.

One pH reading at the protein rest was not long after dough in, so maybe it hadn't stabilized. But the other had been doughed in for awhile. Both batches had identical numbers at identical rests (5.1/5.5) with identical brew water and grists. I can't find any mention of this phenomena anywhere. Anyone ever seen the same thing or have any theories?

I know pH is dependent on temp., but all samples were cooled to room temp.

That is an odd finding. A review of Malting and Brewing Science shows an opposite response for pH and temperature. But, that was for identical mashes at differing SACHARIFICATION temperatures (135F to 150F). So your results comparing a protein rest temp and a sacharification temp rest difference is interesting.

I look forward to hear from others with their thoughts.

Can you say what water you used and what you did to it? This is not for me but so others can help better. IIRC AJ has mentioned that pH 'creep' can happen when using sauermalz/lactic and I've seen it when I use them as well. Like for a decoction you might expect the pH to drop a little during the boil but if you used a decent amount of acid the pH can actually creep up during the decoction boil.

pkeeler said:

One pH reading at the protein rest was not long after dough in, so maybe it hadn't stabilized. But the other had been doughed in for awhile. Both batches had identical numbers at identical rests (5.1/5.5) with identical brew water and grists. I can't find any mention of this phenomena anywhere. Anyone ever seen the same thing or have any theories?

I know pH is dependent on temp., but all samples were cooled to room temp.

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This would be my suspicion. With raw wheat, the goodies (pH contributers) inside are pretty tightly bound up. In a malted grain these compounds are easier to dissolve. I'm not sure why the pH would be low at first though. I would think it would start out higher and then drops as the organic acids etc. dissolve out. I'm assuming your mash water starts at or above your target mash pH.

pjj2ba said:

This would be my suspicion. With raw wheat, the goodies (pH contributers) inside are pretty tightly bound up. In a malted grain these compounds are easier to dissolve. I'm not sure why the pH would be low at first though. I would think it would start out higher and then drops as the organic acids etc. dissolve out. I'm assuming your mash water starts at or above your target mash pH.

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I like that hypothesis. Malting is a form of mashing in the kernel and that raw wheat would be undergoing its first conversion from starch to sugars while malt is partially converted. This has got to involve heavy-duty phosphate chemistry and that is definitely AJ's domain. I hope he chimes in.

Can you say what water you used and what you did to it? This is not for me but so others can help better. IIRC AJ has mentioned that pH 'creep' can happen when using sauermalz/lactic and I've seen it when I use them as well. Like for a decoction you might expect the pH to drop a little during the boil but if you used a decent amount of acid the pH can actually creep up during the decoction boil.

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My well water is pretty poor in minerals. Basicall 2 ppm of Ca and Mg and 2 ppm of bicarbonate. What took me awhile to figure out is that there is a lower limit to how much you can push pH down with salts. I'm not sure of the chemistry (no more alkalinity to neutralize?), but the newer calculators will show my water never going lower than 5.5 pH, even with more CaCl or CaSO4. So I have started adding a bit of acid. Use salts down to 5.5-5.6 then put in lactic acid to get between 5.4-5.5.

For this batch, I used ~5 gal. of my well water, added 1/2 tsp of CaCl and 1/4 tsp of CaS04 and 2 ml lactic acid (88%).

I haven't done a wit for years but went back and looked at old records and found that raw wheat didn't have any unusual effects WRT mash pH. I have noted that wheat beers (using wheat malt) and sauermalz tend to have lower pH than all barley malt beers but certainly not as dramatically so as posted here. The pH "creep" phenomenon has been referred to in this thread and it will produce "creep" of that magnitude but I've only ever seen it when sauermalz is involved. I note that OP used lactic acid and I don't know if that exhibits the same creep as the acidified malt but that would be the best explanation I could offer at this point.

Thanks for the guesses. It is kind of cool to have seen something weird. I won't be able to replicate it, because the recipe was such a PIA on my present equipment that I won't be doing it again LOL

One more thing I would add...Both times when the pH was 5.1, the mash liquor was cloudy white, like milk not quite mixed with water. Later, when it read 5.5, it looked like normal mash liquor.

Interesting. I'll be sure to take some measurements next time I brew my hefeweizen.