Author: Jake Huolihan

There are many components brewers focus on when it comes to converting starches from grain into fermentable sugar, from the various mashing methods and temperatures to the amount time the grist in left to mash. Influenced by numerous factors such as grist composition, water source, and liquor volumes, mash pH is another aspect I see come up fairly often. Brewers have widely accepted an ideal mash pH within a range of 5.2 to 5.6, though my research hints that it may not be so cut and dry. In his book, Brewing Science and Practice, Dennis Briggs notes the optimal mash pH may be different depending on the desired outcome. For instance, according to Briggs, if the focus is solely on saccharification, a mash pH bet 5.3 and 5.7 would be preferable because it provides the shortest conversion time; however, if optimal extraction from the malt is the goal, the brewer would be better off employing a mash pH of 5.2 to 5.4.

I’ve never knowingly mashed a beer lower than about pH 5.2, though I recently heard a rumor that one of my favorite breweries recommends mashing at pH 4.5 and was inspired to try it for myself!

| PURPOSE |

To evaluate the differences between a beer made with a notably low mash pH and the same beer made with a mash pH accepted to be in the normal range.

| METHODS |

I’ve seen anecdotal reports of certain commercial lager breweries employing low mash pH floating around the internet, and while I was unable to substantiate these claims, I decided to brew a clean Pilsner for this xBmt.

pHilsner

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 32.7 IBUs 3.1 SRM 1.046 1.011 4.6 % Actuals 1.046 1.01 4.7 % Fermentables Name Amount % Weyermann Pilsner Malt 10 lbs 90.91 Oats, Flaked 1 lbs 9.09 Hops Name Amount Time Use Form Alpha % Hallertau Magnum 15 g 60 min Boil Pellet 14 Hallertau 15 g 30 min Boil Pellet 4.5 Hallertau 15 g 5 min Boil Pellet 4.5 Yeast Name Lab Attenuation Temperature Southern German Lager (WLP838) White Labs 72% 50°F - 55°F Notes Water Profile: Ca 50 | Mg 0 | Na 8 | SO4 50 | Cl 50 | HCO3 16 | pH 4.45/5.33

Two days prior to brewing, I made a giant liter starter with 2 packs of WLP838 Southern German Lager yeast, the volume determined by my preferred pitch rate calculator.

I began preparing for brewing by collecting pure RO water the a day ahead of time.

After adjusting the water for both batches with the same amount of minerals to achieve my desired profile, I introduced the variable by adding 19 mL of 88% lactic acid to the low pH batch, which the Bru’n Water Spreadsheet predicted would result in a mash pH of 4.5.

Staggering the batches by 20 minutes to save my sanity, I started off my brew day by firing up the burner under one of the kettle’s of strike water.

I measured out and milled the grains for both batches as the strike water was heating.

Each batch was mashed in and settled at the same target temperature.

I took pH readings at 15 minutes into either mash and found the low pH wort was at pH 4.5 as predicted by Bru’n Water while the normal batch was sitting at a cozy pH 5.3.

After each mash finished a full 60 minute rest, I proceeded to collect the full volume of sweet wort using the no sparge method.

Both worts were boiled for 60 minutes with hops added at the times listed in the recipe.

Out of curiosity, I pulled samples for pH measurement from the worts as they neared the end of the boil and noticed both experienced a very slight drop.

At the conclusion of each boil, the wort was rapidly chilled to slightly warmer than my currently chilly groundwater.

Hydrometer measurements at this time revealed the low pH wort achieved a slightly higher OG than the normal wort, which went against my expectation that low pH would hinder mash efficiency.

I racked the chilled wort to corny keg fermentors and placed in my cool chamber to finish chilling down to my target fermentation temperature.

I returned a couple hours later and found both batches had stabilized at my desire 50°F/10°C. After decanting the supernatant from the cold crashed started, I split and pitched equal amounts into either fermentor. I also added 10 drops of Fermcap-S to both batches in hopes of staving off a crazy blowoff. The beers were both happily bubbling away when I checked on them 24 hours later.

Hydrometer readings 7 days into fermentation showed the beers still had some fermenting to do, so I raised the temperature to 56°F/13°C to encourage complete attenuation. Subsequent hydrometer measurements taken over a few days 3 weeks later confirmed FG for both batches had been reached. Interestingly, the difference in FG between the batches was similar to the difference in OG, making me wonder if perhaps low pH encouraged increased extraction of unfermentable sugars.

I took final pH readings at this point and was quite startled to find out that both had settled at a very similar spot.

With the beers finished fermenting, they were pressured transferred to serving kegs then cold crashed, fined with gelatin, and carbonated.

When it came time to present the beers to tasters for evaluation, both were clear, carbonated, and looking quite tasty.

| RESULTS |

A panel of 22 people with varying degrees of experience participated in this xBmt. Each taster, blind to the variable being investigated, was served 2 samples of the normal pH beer and 1 sample of the low pH beer in differently colored opaque cups then instructed to select the unique sample. With the given sample size, a total of 12 (p<0.05) correct selections would have been required to achieve statistical significance, though only 7 tasters (p=0.64) chose the different beer, just about what’s expected assuming tasters were picking at random. These results indicate tasters were unable to reliably distinguish a beer produced with a lower than recommended mash pH from one produced with a normal mash pH

My Impressions: My experience on multiple triangle tests with these beers was the same as the xBmt participants, no better than what could be accounted for by random chance, which was very surprising to me as I’d developed a strong belief they’d be easy to distinguish based on the results of previous water chemistry xBmts. The beers were good, though I seem to pickup a noticeable sulfur note whenever I ferment with WLP838 Southern German Lager yeast that leaves me longing for the cleaner lagers I make with Saflager W-34/70.

| DISCUSSION |

A difference of pH 0.88 may not seem like much on the surface, but considering the pH scale is logarithmic, such a difference means the low pH mash was nearly 9 times more acidic than the normal mash. Putting it this was makes the results of this xBmt, that tasters were unable to reliably distinguish the low mash pH beer from the normal mash pH beer, a tad more more interesting.

The first thing that comes to mind are claims regarding the impact mash pH has on beer character, namely that crispness is associated with lower pH while higher pH can produce “flabbiness.” This presumes mash pH in some way carries through to the finished beer, which was not demonstrated in this xBmt. Not only did a beer that had 19 mL of lactic acid added to the mash taste the same as a similar beer without acid, but they ended up at nearly the same post-fermentation pH, which supports the idea that yeast stops working once beer pH is outside of the optimal range. This might explain why the low mash pH beer finished with a higher FG, the yeast simply puttered out once the pH floor was hit, suggesting fermentation serves as an equalizer or sorts.

If the observed differences in OG and FG between the batches are are indeed a real function of the variable, it provides evidence that extraction may be negatively correlated with mash pH, whether it effects flavor or not. Interestingly, every prior water chemistry xBmt that achieved statistical significance involved differences in mineral composition. With this in mind, if reports I’ve heard of a certain commercial lager brewery mashing with a low pH are true, I’m compelled to believe they do so not for purposes of flavor, but perhaps the behind-the-scenes impact it has.

The fact I genuinely couldn’t taste a difference between these beers coupled with the amount of lactic acid required to achieve such a low mash pH, I’ve no plans to change my current process of mashing between pH 5.2 and pH 5.6. I’m now more curious than ever to continue exploring the limits of mash pH and the impact it has on beer.

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

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