Baking Soda Effect on Flavor

[JstnMoyer]

I am sharing the outcome what I expect to be too much baking soda added to the mash AND fermented beer (shame).

I brewed a tweaked Old Rasputin imperial stout clone recipe in January. Recipe is here.

About 10 minutes into the mash, I got a pH reading of ~4.8 using pH strips (shame) near room temp so I added 1 tsp of calcium carbonate. 10 minutes later, I got the same pH reading. Understanding that calcium carbonate takes a while to dissolve, I decided to add .5 tsp of baking soda. I ended up hitting my pre boil gravity of 1.080 .

Fermentation was complete within 3 days using Wyeast German ale yeast. I then added 1 oz wet bourbon soaked oak chips to primary. I left the spent bourbon behind.

8 days into primary, I took a pH reading with a pH strip and got mid 4s (4.4 to 4.7). Since I didn't yet understand that pH is practically irrelevant at this stage, I added another 1/4 tsp of baking soda to the fermented beer. This pH chasing inspired me to buy a pH meter... so I measured the pH again before bottling 16 days post brew and got 4.88.

The outcome: Drinking the resulting beer 2 months post brew day, I can perceive an astringent harshness in the flavor that reminds me of soap. It covers some of the nice roasted malt and sweet caramel flavors that also exist in the flavor. This astringent harshness also exists in the aroma but this beer has a prevalent hop aroma that is pleasant. There is a lingering bitterness on the palate. I know there is a chance that this harshness in could be from the oak chips but after sampling a stout that I intentionally added extra baking soda to in the glass, the same off flavor came out. Could this be from less than 2 tsp of baking soda to a 4.75 gallon batch?

I brewed this for my wife for her birthday and she actually likes it. I will keep aging it and drink it over the next year. I have brewed twice since and I am putting more effort towards taking accurate pH readings during the mash and improving pH adjustment methods early in the mash.

 

[brewdude88]

Depending on your starting water profile, you may have driven your sodium to high with the baking soda.

I typically leave post fermentation ph alone, letting the yeast drop it to where it wants. I do make sure my post-boil ph is within the 5.0-5.2 range for most of my beers.

Just make sure you cool your mash and kettle samples close to room temp before taking a reading with your calibrated meter.

 

[Silver_Is_Money]

You likely drove the HCO3- bicarbonate ion concentration way too high, leading to astringency and possibly tannins extraction. An ale should finish at between 3.9 and 4.1 pH. 4.88 pH is way too high. pH strips are a notoriously poor means of measuring pH, and on top of that (as in adding fuel to the fire) measuring at only 10 minutes into the mash is likely to yield a false low pH. I believe the general trend with pH sticks is to read a pH lower than actual. 4.8 pH is a quite rare occurrence, but is admittedly possible. Best is to use a pH meter, pull a sample at 30 minutes into the mash, cool the sample to 68 degrees F., and take the pH reading.

You (or more specifically, your yeast when introduced) want the Wort to be ideally pH 5.2 post boil and cooling. With 5.0 - 5.2 pH being the range of acceptability here. A room temperature measured pH of 5.4 pre-boil will likely transition to ~pH 5.2 post boil.

If your sodium ion level was moderately low before adding all of that baking soda, it is doubtful that sodium was a negative. Brewers of yore documented positive flavor contribution results for rather shockingly high levels of sodium.

As to baking soda, 2 TSP is a lot. 27-28 grams of baking soda is sufficient to neutralize a whopping 1 kilogram (2.20462 Lbs.) of Acid Malt to a pH of ~5.4. Your addition of 2 TSP is on the order of 10 grams.

 

[couchsending]

Wise move on the pH meter. Now just make sure you know how to store and calibrate it effectively.

There could be a lot of things going on with this beer. 10g of baking soda is a ton of baking soda.

1.080 done in 3 days... temp controlled?

pH is totally relevant at every step of the process. But different numbers mean different things at different times. Understanding pH and taking numerous readings at different stages of the process will help you understand a lot more about your beer and if there is an issue where things started to go sideways.