This xBmt was completed by a member of The Brü Club as a part of The Brü Club xBmt Series in collaboration with Brülosophy. While members who choose to participate in this series generally take inspiration from Brülosophy, the bulk of design, writing, and editing is handled by members unless otherwise specified. Articles featured on Brulosophy.com are selected by The Brü Club leadership prior to being submitted for publication. Visit The Brü Club website for more information on this series.

Author: Cade Jobe

I’ve been trying to dial in a go-to Kölsch recipe for the hot Texas summers, which in my opinion should have a very light bready flavor with a medium-low bitterness and leave the palate with a crisp, vinous quality that accentuates the dryness. Previous versions have yielded comments on competition scoresheets suggesting previous batches have had a slight tang, or what one judge described as an “apple-like bitter ester.” I brew with local tap water and make adjustments to achieve specific target profiles. Due to my tap water being fairly alkaline, I end up using a decent amount of lactic acid to ensure the mash pH is in the appropriate range.

I’ve read that tasters are able to identify lactic acid in beer at levels above 1.5 mL/gal, and Martin Brungard offers the following on the Water Knowledge tab of his Bru’n Water Spreadsheet:

Lactic acid is readily available for brewing use, but it can produce a distinctive ‘tang’ in the flavor profile at high concentrations. Phosphoric Acid can also be used and it has little flavor effect since this acid is similar to the malt acids produced through mashing.

While contributor Malcolm Frazer’s xBmt comparing lactic acid to phosophoric acid returned non-significant results, I was curious to see if this might be the reason for the tangy characteristics perceived in my Kölsch and decided to test it out for myself!

| PURPOSE |

To evaluate the differences between beers made using either lactic acid or phosphoric acid to mash pH adjustment.

| METHODS |

The recipe for this xBmt was an iteration of one I’ve been working for awhile that’s almost, but not quite, there.

Fortitude Kölsch

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 20.3 IBUs 3.0 SRM 1.049 1.009 5.3 % Actuals 1.049 1.008 5.4 % Fermentables Name Amount % Pilsner (Weyermann) 9.5 lbs 95 Wheat Malt, Pale (Weyermann) 8 oz 5 Hops Name Amount Time Use Form Alpha % Hallertau 28 g 60 min Boil Pellet 3.6 Tettnang 16 g 60 min Boil Pellet 3.6 Liberty 14 g 5 min Boil Pellet 4.5 Yeast Name Lab Attenuation Temperature German Ale/Kolsch (WLP029) White Labs 75% 65°F - 69°F Notes Water Profile: Ca 94 | Mg 17 | Na 18 | SO4 150 | Cl 50 Download Download this recipe's BeerXML file

I started my #BrüDay by collecting the brewing water for the batch treated with lactic acid, as the beers were brewed consecutively but otherwise treated identically with the exception of the variable.

While the water for the first batch was heating up, I quickly tested it with a BrewLab kit to confirm the starting profile. Next, I used the Bru’n Water Spreadsheet to determine the additions needed to achieve my desired profile, adjusting both batches with either lactic or phosphoric acid to reach the same mash pH.

Next, I weighed out and milled the grains.

Once the water for each batch was at my target strike temperature, I mashed in then immediately made the respective acid addition.

Measurements taken at 15 minutes into each mash confirmed both had settled at a similar pH.

After each 60 minute mash, I sparged to collect identical volumes of wort that were subsequently brought to a boil. At the end of each 60 minute boil, I used my immersion chiller to quickly cool each wort.

Equal amounts of wort from each batch were transferred to sanitized Brew Buckets and set in my fermentation chamber to finish chilling.

Refractometer readings showed both batches hit the same 1.049 OG target. Once the worts had stabilized at my desired temperature of 60°F/16°C, the yeast was pitched. After 14 days of fermentation, hydrometer measurements revealed both beers had reached the same 1.008 FG. I cold crashed the beers overnight and fined with BioFine Clear before transferring each into CO2 flushed kegs. The filled kegs were burst carbonated then allowed to cold condition for 2 weeks before they were ready to serve.

| RESULTS |

A total of 23 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of the beer where lactic acid was used for mash pH adjustment and 2 samples of the beer acidified with phosphoric acid in different colored opaque cups then asked to identify the unique sample. In order to achieve statistical significance at this sample size, 12 tasters (p<0.05) would have had to accurately identify the odd-beer-out, and that’s exactly the number that did (p=0.048), indicating participants in this xBmt were able to reliably distinguish a beer acidified with lactic acid during the mash from one acidified with phosphoric acid during the mash.

The 12 participants who made the accurate selection on the triangle test were instructed to complete a brief preference survey comparing only the beers that were different. A total of 9 tasters reported preferring the beer made with phosphoric acid, 1 liked the beer made with lactic acid, and 2 people did not report a preference.

My Impressions: The night before serving the samples at a homebrew club meeting, my wife (who is no longer pregnant and can drink now! Yay!) and I took two semi-blind triangles tests. While we both chose correctly, I admittedly guessed on my second attempt. Several days after collecting the data, we both attempted a final test and failed. The beers were much closer in overall character than they were different, at least to my palate.

| DISCUSSION |

While Malcom’s original xBmt comparing the use of lactic and phosphoric acid to adjust mash pH failed to reach significance, such was not the case in my own comparison, as tasters were able to reliably tell apart beers made using either acid. One of the more obvious differences between the xBmts had to do with total amount of acid used– whereas Malcolm used 7.2 mL of 88% lactic acid and 4.1 mL of 75% phosphoric acid for a 5.5 gallon batch, I used 10.4 mL of 88% lactic acid and 108 mL of 10% phosphoric acid to achieve a similar mash pH. It’s possible this higher concentration of lactic acid helps to explain the discrepant findings, which would support the notion that lactic acid imparts a perceptibly different character than phosphoric acid when higher amounts are used.

In conversations with tasters following data collection, several of those who were correct on the triangle test said the beer made with phosphoric acid had more back-end flavor, which made it more preferable to them. Interestingly, while a couple participants noted perceiving certain common off-flavors including acetaldehyde and diacetyl, not one described a “tangy” character.

I found it interesting that 9 of the 12 correct tasters preferred the beer made with phosphoric acid. I don’t know what I don’t know, so I’m unable to come up with a satisfactory explanation for their preference or the difference in these beers. As for me, I’m not done tweaking my Kölsch recipe and plan to use phosophoric acid for mash pH adjustment in my next few batches, which I’ll enter in competitions and let subjective judging challenge the objective significant results of this experiment!

Cade Jobe is a Certified Cicerone and Certified Beer Judge (BJCP) living in Austin, Texas. He is a member of the Austin ZEALOTS who loves brewing and spending time with his wife, son, and two dogs named Juno and Jasper. Follow Cade on Instagram, Twitter, and UnTappd.

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

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