exBEERiment | Impact Post-Boil Acidification With Sauergut Has On A German Pilsner

Author: Jordan Folks

There are various points throughout the brewing process where pH is said to be important, and while mash pH is the most discussed, many brewers mind the pH of the wort post-boil as well. When making paler styles absent of notably acidic roasted grains, such as Pilsner, acidification of the wort after the boil can help to expedite the pH reduction that occurs during fermentation, which some believe has a qualitatively positive impact on the finished product.

While reducing that pH is commonly done with exogenous acids such as phosphoric or lactic, adherents of the German Purity Law don’t have this option, as they can only use water, malt, hops, and yeast to make beer. A Reinheitsgebot-approved alternative for acid reduction is sauergut, which is essentially wort that has been soured through the use of the lactobacillus naturally present on brewing grains.

With one past xBmt suggesting post-boil wort acidification with lactic acid has a perceptible impact, and another showing tasters could distinguish beers where the mash pH was adjusted with either sauergut or lactic acid, I wondered if my standard practice of adding sauergut to German lagers at flameout was having a noticeable impact and designed an xBmt to test it out!

| PURPOSE |

To evaluate the differences between a German Pilsner where the post-boil pH was reduced with Sauergut and one where the post-boil pH was not adjusted.

| METHODS |

I brewed a simple German Pilsner recipe that I thought would allow any impact of the variable to show through. Big thanks to F.H. Steinbart for hooking me up with the malt for this batch!

Mit Pils

After collecting the full volume of filtered tap water for a 10 gallon/38 liter batch and adjusted it to my desired profile, which included acidification with sauergut to achieve the proper mash pH. While the water was heating up, I milled the grain.

Since this was a classic German lager, I decided to perform a step mash.

During the mash rest, I weighed out the kettle hop additions.

Once the mash was finished, I collected the wort and proceeded to boil it 60 minutes, adding hops at the times listed in the recipe. When the boil was complete, I ran approximately 2 liters/0.5 gallons of hot wort into fermentation kegs before adding enough sauergut to acidify one of them to 5.1 pH.

I then used my plate chiller to chill the rest of the wort during transfer to a cold break settling tank, which was placed in my chamber to finish chilling to my desired pitching temperature. A refractometer reading indicated I’d exceeded my target OG by 0.005 SG points. Meh.

With the wort chilled and clear of trub, I split it evenly between the two fermentation kegs, one of which contained sauergut, before taking pH measurements.

I then pitched two packs of Imperial Yeast L13 Global into each batch of wort.

The beers were left to ferment at 48°F/9°C for a week before I began very gradually raising the temperature to 60°F/16°C over the following 2 weeks, at which point I took hydrometer measurements the beers were at the same FG.

Subsequent pH measurements showed the batch dosed with sauergut post-boil ended with a slightly lower pH.

At this point, I gradually reduced the temperature of the beers to 32°F/0°C over the course of a few days, at which point they were pressure-transferred to CO2 purged serving kegs that were were placed in my keezer. After a 2 week lagering period, the beers were carbonated and ready for evaluation.

| RESULTS |

A total of 20 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of beer that was acidified with sauergut post-boil and 2 samples of the beer that was not acidified in different colored opaque cups then asked to identify the unique sample. While 11 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, only 8 did (p=0.34), indicating participants in this xBmt were unable to reliably distinguish a German Pilsner that was dosed with sauergut post-boil for pH reduction from one that was not acidified.

My Impressions: Out of the 5 semi-blind triangle tests I attempted, I correctly identified the odd-beer-out 2 out 5 times. To my palate, both beers had the same grainy and doughy malt notes with supporting hop bitterness and clean fermentation character. I detected no off-flavors in either of these beers, both were equally enjoyable.

| DISCUSSION |

While ensuring mash pH is within the purportedly ideal range has been shown to have a questionable perceptible effect on beer, some brewers have begun acidifying their wort post-boil as a way to improve the overall quality by decreasing “flabbiness.” Interestingly, tasters in this xBmt were unable to reliably distinguish a German Pilsner that was dosed with sauergut post-boil for pH reduction from one that was not acidified.

Considering the results from a past xBmt where tasters could reliably tell apart an American IPA that was acidified with lactic acid post-boil and one that was not, it’s possible the sauergut didn’t have the same flavor impact as the lactic acid. Another plausible explanation is that pale lagers don’t respond to post-boil acidification the same way American IPA does. Finally, while I make mash pH adjustments as a matter of course, and both beers were treated identically seeing as this was a post-boil split batch, I do wonder if the boil pH difference would have been more perceptible had I not acidified the mash.

As a rule of thumb, I always acidify my wort prior to yeast pitch, as it’s said to provide a variety of benefits such as reducing total fermentation time and encouraging complete attenuation, as well as providing flavor benefits. While the results of this xBmt didn’t necessarily support those claims, I’ll continue acidifying my lagers post-boil, even if just for insurance purposes, though I won’t stress if I forget this step in the future.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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