Author: Malcolm Frazer

I use the same multi-step but simple process every time I make water adjustments for a beer. Based on the style, I select my preferred water profile, calculate the mineral additions, then check to see what the mash pH is predicted to be. Relying on my moderate alkalinity (~145 ppm) municipal water for at least some portion of the brewing liquor, my mash pH is often higher than I prefer, which I remedy by using liquid acid.

Readily available at local homebrew shops, 88% lactic acid is a popular option for pH adjustments due to its low cost, effectiveness, shelf stability, and relative safeness. Phosphoric acid is also used commonly by homebrewers for pH adjustment, though it’s maligned by some due its reaction with calcium, and it’s also a bit weaker at the commonly available 10-15% strength. While the decision of which acid to use is likely made without much forethought by many homebrewers, both react in their own idiosyncratic ways that are worthy of consideration. For example, phosphoric acid adds flavor neutral phosphate that precipitates out a small amount of calcium, thus lowering the total calcium potential in the beer, which can have a negative impact on yeast health and beer clarity. Lactate ions, on the other hand, may have a noticeable flavor impact when used in higher amounts.

As a brewer who uses water with a decent level of alkalinity to make beers with low mineral character, I came to rely on liquid acid to achieve my target pH. While I developed a personal preference based on my own system and experience, I began to wonder if acid type contributed to the character of the beer and decided to put it to the test!

| PURPOSE |

To investigate the differences in beers produced using the same recipe and process where pH adjustments to the mash were made with either lactic acid or phosphoric acid.

| METHODS |

I chose to brew a simple Kölsch-style beer to test this variable, a recipe I’ve used many times and one of my favorites to have on tap at home. While I typically dilute my water with 60% distilled when brewing this beer in order to reduce the mineral content and total alkalinity, I opted not to dilute for this xBmt, as this would require me to use higher amounts of acid to counteract the alkalinity of my tap water and hit my target mash pH. Ultimately, my goal was to amplify the potential impact of the respective acids.

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 70 min 22.4 IBUs 2.6 SRM 1.041 1.008 4.3 % Actuals 1.041 1.008 4.3 % Fermentables Name Amount % Pilsner (2 row) (Gambrinus) 7.75 lbs 88.57 Wheat Malt, Ger 1 lbs 11.43 Hops Name Amount Time Use Form Alpha % Perle 24 g 70 min Boil Pellet 6.5 Hallertauer 14 g 10 min Boil Pellet 4.1 Perle 8 g 1 min Boil Pellet 6.5 Yeast Name Lab Attenuation Temperature German Ale/Kolsch (WLP029) White Labs 75% 65°F - 69°F

I made a single large starter about 24 hours before I planned to split it between the two batches.

I then crushed the grain in preparation for the following morning’s brew.

The next morning, I heated the strike water, readied the different acids, and staged the hops.

I started the phosphoric acid mash 20 minutes before the lactic acid mash to make managing things easier. While a difference of 1°F/0.6°C is likely negligible, my hunch is the temperatures were within a few tenths of each other.

Using the Bru’n Water spreadsheet, I determined reaching my target mash pH of 5.4 would require 4.1 mL of 75% phosphoric acid and 4.5 mL of 88% lactic acid. Using a medical syringe, I measured out the suggested amounts, added them to their respective tuns, and took confirmatory pH measurements 15 minutes into each mash.

While the batches were mashing, I collected sparge water and acidified each to pH 6.0 using 2.4 ml of 75% phosphoric and 2.7 ml of 88% lactic acid. I proceeded to batch sparge each batch then it was flame on!

Both beers were boiled for 70 minutes, during which hops were added at the appropriate times, then they were chilled and OG readings taken.

The yeast starter was equally split between each fermentor followed by a 60 second dose of pure O2, then they were left to ferment at 62°F/17°C for 3 days before I gently began raising the temperature to 68°F/20°C over the next week.

Fermentation activity absent at the 10 day mark and hydrometer measurements confirmed both beers had dropped to the same expected FG.

Well attenuated and no demonstrable off-flavors present, I cold crashed over night, fined with gelatin, then kegged the beers.

After a week in my keezer, they were clear, carbonated, and ready to serve!

| RESULTS |

A total of 23 people participated in this xBmt, all blind to the variable of investigation. Each taster was served 1 sample of the beer acidified with lactic acid and 2 samples of beer acidified with phosphoric acid in opaque cups then asked to identify the one that was different. 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, though only 11 participants (p=0.11) were capable of doing so, suggesting this panel of participants were not able to reliably distinguish a beer made with lactic acid from one made with phosphoric acid.

But it sure was close. Because of this, and the fact others may choose to use a different standard to determine significance, I thought I’d share the post-triangle preference ratings of the 11 correct participants. In prudence, I caution anyone from imbuing this data with much meaning since the results did fail to reach significance. When asked which sample was preferred, 4 selected the beer acidified with phosphoric acid, 1 liked the sample acidified with lactic acid more, 1 reported they couldn’t detect a difference, and 5 had no preference despite noticing a difference.

My Impressions: I’ve tended to use phosphoric acid for pH adjustments since I always perceived a butter-like aroma from lactic acid itself and was concerned of it carrying over to the beer. This bias likely played a role in my perception of a similar buttery character in the beer made with lactic acid, despite the fact it went through a lengthy diacetyl rest. I was sure I’d be able to reliably pick the unique sample in “blind” triangle tests, yet I failed my first attempt, an indication they weren’t as different as I thought. However, in later trials, I was consistently able to detect the different beer, a task that became easier for me as the samples warmed. Were they strikingly different? No, but knowing what to look for and tasting both beers multiple times made the differences more obvious to me.

I trust the data from our panelists and believe prior research findings are valid, perhaps I am just swayed by my bias and slow to change. More experiments are needed for me to completely accept that there is no difference at least to my impression. Great, now I feel like a science denier.

| DISCUSSION |

It’s been said that the flavor threshold for lactate is approximately 300-400 ppm, which corresponds with Kai Troester’s experiment findings where he concluded it’s difficult to detect lactate at a level of 400 ppm or below. The results of this xBmt provide even further confirmation since the beer made with lactic acid contained approximately 433 ppm of lactate by my calculation (7.2 ml at 88% in 5.5 gal) and yet was not reliably distinguishable from the beer made with phosphoric acid. As such, it can be said with at least some degree of confidence that brewers can use either lactic or phosphoric acid without risk of impacting beer characteristics in an appreciable way.

Prior to this xBmt, I’d avoided using lactic acid primarily because every time I opened a bottle I was greeted with an intense buttery aroma, and the thought of that going into my beer made me cringe. Kai’s findings in conjunction with information gleaned from Martin Brungard regarding the potential positive impact lactate ions can have on beer certainly reduced my concern, the results of the present xBmt serving to push it down even further. I certainly look forward to ongoing investigation of this variable, perhaps using water with different levels of alkalinity, but as for me, I’ll no longer hesitate to use either lactic or phosphoric acid for pH adjustments.

One last note– some may view these results as being too close to imply anything meaningful, and that’s perfectly fine, use whatever standard you choose to interpret the findings. However, it’s important to remember that the amount of acid I used to hit my desired pH, while not terribly extreme, was pretty high given my intentional use of moderate alkalinity water. Using my normal 60/40 blend of distilled to tap water, the amount of acid required to hit the same pH is markedly lower, presumably making detection even more difficult.

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

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