exBEERiment | Impact Pre-Boil Acidification Has On A Czech Amber Lager

Author: Jordan Folks

Acidity is something brewers pay attention to at various points in the brewing process, adding a small amount of exogenous chemicals to achieve a desired pH. While mash pH seems to get a majority of the focus, many brewers opt to adjust the wort as well, which is believed to improve the flavor profile and stability of the finished beer. Standard practice involves making these adjustments, usually with acid to reduce the pH, immediately following the boil and before yeast pitch; however, some have found success by acidifying the sweet wort prior to the boil.

There are several reasons brewers claim wort acidification is important, from counteracting the pH increase from dry hopping to reducing the risk of contamination. However, objective evidence regarding the organoleptic differences between pre- and post-boil acidification is a bit vague, so anecdote is mostly what we have to rely on. Ashleigh Carter, co-founder and head brewer of Bierstadt Lagerhaus, has made known her preference for pre-boil acidification, presumably because it’s said to encourage better protein coagulation and result in a beer with cleaner bitterness.

As a lover of all things Bierstadt, I view Ashleigh Carter as one of the best brewers in America, so when she shares her brewing wisdom, I tend to take it at face value. Until I learned that Ashleigh was a fan of pre-boil acidification, I was doing what most of the other brewers I know do by dropping the pH after the boil. Curious to find out if the point at which wort is acidified has a notable impact, I decided to test it out for myself.

| PURPOSE |

To evaluate the differences between a Czech Amber Lager where the wort pH was reduced pre-boil and one where the pH was reduced post-boil with the same amount of acid.

| METHODS |

I went with a simple Czech Amber Lager recipe for this xBmt, as I felt it 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!

A Hundred Versus In Ragtime

After collecting the full volume of filtered tap water for two 5 gallon/19 liter batches, adjusting each to the same desired profile, and getting them heating up, I milled the grain.

Since this was a classic Czech lager, I decided to perform a step mash with at 60 minute rest at 146°F/63°C followed by a 15 minute rest at 156°F/69°C.

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

Once the mashes were finished, I removed the grains and set both controllers to heat the worts up, at which point I took a preliminary pH reading.

Based on this and the volume of wort, I determined 4.5 mL of 88% lactic acid was needed to drop the wort to my desired pH and added that amount to one batch of wort.

Another measurement taken after the acid addition showed a noticeable drop in pH.

The worts were boiled for 60 minutes before being quickly chilled with my JaDeD Brewing SS Coil Hydra IC.

At this point, I added the same 4.5 mL volume of 88% lactic acid to the other batch of wort.

With the worts transferred to separate fermentation kegs, I took refractometer readings showing they were at the same OG.

Once the worts had chilled to 48°F/9°C, I pitched identical amounts of Imperial Yeast L29 Lookr slurry into each batch.

The beers were left to ferment at 50°F/10°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 indicating a very small difference in FG.

At this point, I gradually reduced the temperature of the beers to 32°F/0°C over the course of a few days then pressure-transferred them to CO2 purged serving kegs that were placed on gas in my keezer. After a 4 week lagering period, the beers were carbonated and ready for evaluation.

| RESULTS |

A total of 24 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of beer with the pre-boil acid adition and 2 samples of the beer with the post-boil acid addition in different colored opaque cups then asked to identify the unique sample. While 13 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, only 8 did (p=0.58), indicating participants in this xBmt were unable to reliably distinguish a Czech Amber Lager where the wort pH was adjusted with acid prior to the boil from one where the wort was adjusted with the same amount of acid after the boil.

My Impressions: Out of the 5 semi-blind triangle tests I attempted, I correctly identified the odd-beer-out just once, which is a true indication of my experience – I perceived these beers as being identical in every way, and they were excellent examples of the style!

| DISCUSSION |

Brewers interested in making the best beer possible are wont to pay attention to as many details as possible, and while mash pH is widely focused on, many have also adopted the practice of adjusting the wort pH. This typically occurs after the boil and before yeast pitch, though some brewers claim that wort acidification prior to the boil results in an improved bitterness profile and clearer beer. Interestingly, tasters in this xBmt were unable to reliably distinguish a Czech Amber Lager where the wort pH was adjusted with acid prior to the boil from one where the wort was adjusted with the same amount of acid after the boil.

There are a few considerations that come to mind when analyzing this data, the first of which is one that comes up often – perhaps it’s a matter of scale. It’s possible the impact of pre- and post-boil additions is stronger as batch size increases. Another potential explanation is that the acid addition had an identical impact on the beers, rather than no impact, which would suggest the point at which it was added had no meaningful effect.

Seeing as I was unable to tell these beers apart, which aligned with the blind participant results, I’m not convinced the time at which wort pH adjustments are made really matters that much. However, given the results of a prior xBmt showing tasters could tell apart a beer where the wort pH was adjusted post-boil from the same beer where the wort was unadjusted, I’ll continue employing this practice, likely sticking to post-boil additions only because it’s what I’m used to.

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

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