Dark Beer Problems..

[ajdelange]

What is to be made of the reports from people who have measured Porter and Stout mashes in the range of 4.9 to 5.0 pH?

What can I say. I wasn't there. All I can say is that their experience is different than mine has been and try to figure out why the discrepancy. Often, if it is found, it is a bad pH reading.

Would not an approximately 5.5 gallons (to the fermenter) size batch that measures within this pH range and weighs in at ballpark 11-13 Plato need ballpark about a TSP of baking soda? (which from various sources would weigh from 4.4 to 4.9 grams)

That's going to depend.

When I did Irish stout I always used 10% roast barley, 10% flaked barley and the rest Maris Otter. When I put those numbers into the new spreadsheet with water of alkalinity 70 (which is where my water usually falls but it can go higher or lower) with a mash thickness of 1.27 qts/lb with water with calcium hardness of 60 and magnesium hardness of 50 it predicts pH of 5.59. I always got right around that in the mash tun which would cause me to post statements to the effect that perhaps some stout brewers should be thinking about adding acid rather than alkali. This, of course, was not well received but then reports started coming in from other brewers who were seeing the same results.

Now we should keep in mind that the parameters of the malts I used in the prediction spreadsheet were measured by me on the malts I was using so naturally I got good results.

Using the numbers above no, a stout with those numbers does not need bout a tsp of baking soda. In fact, if you want a pH like 5.5 or 5.4 you are going to need acid - not base. Now if you increase the roast barley to 20% of the grist and want pH 5.5 you are going to need some bicarbonate. Assuming that you are mashing at the 1.27 thickness with 3.5 gal DI water with enough CaCl2 in it to get you about 50 mg/L Ca++ you would need about 2.1 grams (2/5 tsp?). Increase the roast barley again to 30% of the grist (ick, but I'll bet someone has done it) and now you are going to need about 6.2 g sodium bicarbonate.

And what to make of the OP, who claims to have hit 5.5 pH on the nose after adding 4.4 grams of baking soda?

Again, I don't know what to say other than to observe that unless the malts he is using are substantially more acidic than the malts I know of that I have assumed to be similar or unless the sodium bicarbonate he is using has been adulturated with some neutral substance that isn't possible. Whenever someone who has used a spreadsheet gets a pH reading that is right on the nose I know immediately that the reading is probably not a good one because that just doesn't happen (but you'd be amazed at how many people report that Brun water always predicts mash pH to 0.01). So in this particular case, as I always do when something is fishy, suspect the pH reading as it so often turns out to be the case. I've certainly been led down the garden path by faulty pH readings. It took me quite a while to master the art of using a pH meter. I don't see why it shouldn't take others some time too. But I can't say it is a faulty pH reading because I just don't know. If the pH reading is good then we have to find a lot of acid somewhere to balance that 4.4 grams of bicarbonate,

Plus (over on my "What is the most Baking Soda you ever added.." thread) forum member dmtaylor recently posted that he has measured Stouts that mashed at as low as 4.8 to 4.9 pH, and Martin recently stated that by his personal measurement Reaper's Stout (not too insanely loaded with roasted malts) mashes at ~4.9 pH.[/QUOTE]Again I have no idea what to say other than that there is an explanation. I don't know what it is. Perhaps they had 30% roast barley. Perhaps they screwed up a pH measurement. Perhaps their dark malts are appreciably more acidic than anything I or Kai or Joe Walts have ever measured.

There is no question that one can formulate grists that will require bicarbonate (or other alkali) in order to hit mash pH and there is this "mommily" going around that stouts taste better if mashed at higher pH. So if people are shooting for 5.6 or even higher and using high percentages of highly acidic malts they are going to need bicarbonate.

 

[ajdelange]

Thankfully, there is plenty that you've done. But I question that your admonition to stop adding chalk really had much effect

I was not nominating my self for an award here.

...since only a small portion of the chalk actually dissolved and reacted with the weak acids in a mash.

And then what happens to the rest? Depending on how fine the crystals are some will doubtless be filtered out by the lauter bed but the rest will make it through into the boil where, slow though the reaction may be, it will continue to absorb protons thus raising kettle pH. That which doesn't react in the kettle will pass on to the fermenter where, slow though the reaction may be, it will absorb protons secreted by the yeast for the purpose of establishing the pH they like. This makes them work harder at acid production than they other wise would have to. Less energy available for making beer. Finally, evidently, some gets carried over into the finished product as I've had people report beer that "tastes like a chalk board" back in the days before we got smart about chalk. So the significance of getting rid of chalk is perhaps greater than you were aware of. Plus, it's not only chalk that I tried to dissuade people from using - it was alkali in general. Most stouts and porters do not require alkalinity. When it is used mash pH goes high and beer flavors are muted. That's true in a stout just as it is in any other beer.

My experience is that brewers trying to avoid an excessive pH drop had little success with chalk. My data and Kai's data point to a result that shows that the best you can achieve with even a massive chalk addition was around 0.1 unit increase.

How far you can go depends on how much chalk you add. There is no fundamental limit on the possible pH increase. It is a question of how long you are willing to wait to get it. I have reported here that I have found the reaction between chalk and acid (strong acid too - it doesn't have anything to do with the acid strength AFAIK) carrying on for more than 24 hours.

While some stouts and porters don't have to be brewed with high alkalinity mashing water, most do benefit from the resulting elevated wort pH produced by water that does have readily-available alkalinity.

Not sure what you mean by "readily available" alkalinity. No actually, I think I do. Bicarbonate alkalinity is readily available becuase it reacts fast. Chalk alkalinity is not readily available because it takes forever to react. BTW I shout mention that I don't thing its the reaction of chalk that is so slow. I think it is the dissolution. If one were to dissolve it in sulfuric acid, for example, I'm sure it would be "readily available". Interesting thought. Put some chalk in a beaker, add some water, add sulfuric (or hydrochloric or lactic...) acid. Let the acid dissolve the bicarbonate and let the mixture stand long enough for the disolution to complete. Make up to volume and bottle. You now have a solution of calcium ions, bicarbonate ions and sulfate (or the anion of whatever acid you used). Have to think about that one.