[JT]

I've chased after mash pH like a dog on a rabbit.  For me, chasing it in the mash is folly.  When I miss, I typically miss low (like .1 to .2 lower than expected).  This is using RO water and Martin's spreadsheet.  That said, it has always landed me in the acceptable range for converting starch to sugar and has avoided any harsh tannin flavors.  Once I collect my wort in the boil kettle, I'll bring it above 170 to stabilize the mash profile, then halt and take a reading.  It's much easier to dial in pH in the boil kettle.  After all, we're not drinking wort, there is still a lot of process left to make beer. 

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[curtdogg]

Sounds like maybe too low ph in the final product.  Do you have any baking soda? Pull a half pint and gently stir a tiny amount of baking soda in. Like 1/8 teaspoon. See if that changes it for the better

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With Jim's advice in mind I conducted a small experiment. I drew three samples of Oatmeal Stout with a FG of 1.012. Each sample was 200 milliliters at 60f. I added baking soda to samples 2 and 3 to increase pH and attemp to enhance flavor.

Sample 1. Is the control beer, it has a pH of 4.5.

Sample 2. Using 1/16 tsp of baking soda it brought the sample to a pH of 5.3.

Sample 3. Using 1/8 tsp of baking soda it brought the sample to a pH of 6.0.

Sample 1 has a thin appearance and mouthfeel with a subdued roast flavor and mineral like aftertaste. All in all it's not bad just not great.

Sample 2 has a slightly more silky appearance and mouthfeel. The roast flavor was very apparent and brought a smokey aftertaste with it. The smokey flavor lingers and creates an undesireble character that reminds me of the last oatmeal stout that went down the drain.

Sample 3 has the similar silky appearance and mouthfeel.  The roast flavor is slightly stronger than sample 2. The smokey aftertaste seems less intrusive but by no means pleasent and carries a slight cholate note with it.

After this experiment I can see now how the pH in the boil can affect the final outcome of the beer. With new knowledge gained I will keep trying to create a more satisfying Stout by doing  research and tweaking my recipe.

In conclusion I will be keeping the beer as is. I will be splitting the 3-gallon batch in two.
I will package one half as is to to see how carbonation and age effects it. I will add cocoa nibs to the second half to see what they can attribute to the beer.

Once again I thank all of you for your input.
Cheers

[klickitat jim]

Keep in mind that fermentation will further lower the pH. In other words boil ph might be 5.5, but final beer might be more like 4.5. 4.5 for a Stout seems a tad high to me. My pale beers end up there. My Irish dry stout finishes 3.8-4 and my American Stout finishes about 4.2-4.4. (From memory... could be off a smidge). This is actual finished carbonated beer that I tested after degassing.

Also, keep in mind that carbonation drops ph a little too because of carbonic acid. But not a whole lot.

[curtdogg]

Keep in mind that fermentation will further lower the pH. In other words boil ph might be 5.5, but final beer might be more like 4.5. 4.5 for a Stout seems a tad high to me. My pale beers end up there. My Irish dry stout finishes 3.8-4 and my American Stout finishes about 4.2-4.4. (From memory... could be off a smidge). This is actual finished carbonated beer that I tested after degassing.

Also, keep in mind that carbonation drops ph a little too because of carbonic acid. But not a whole lot.

Thanks Jim.
Do yo know what your pre boil pH is?
Do you add salts pre boil to achieve a certain range?

Curtis.

[klickitat jim]

Well, pre boil would be mash... so for me, about 5.4. That might drop to 5.2-5 post boil depending of several things, sometimes no change.

While in the past I did a lot of ph testing along the way, now i only worry about mash ph. The rest is handled by healthy vigorous fermentation.