Author: Marshall Schott

There are many off-flavors beer can possess such as diacetyl and dimethyl sulfide (DMS), commonly described as imparting butter and cooked cabbage character, respectively. Through centuries of trial-and-error as well as scientific research, brewers have been able to hone in on what creates these undesirable characteristics, leading to the development of methods that help us to avoid them, for example raising the temperature at the tail end of fermentation for a diacetyl rest or boiling wort long enough to drive off DMS and its precursor, SMM.

Another off-flavor brewers try to avoid is astringency, which is arguably more of a mouthfeel thing than it is a flavor, often manifesting as a mouth-puckering sensation that is sometimes confused for intense bitterness. In addition to this harshness, I tend to experience a slight tightening in the jaw muscle just beneath my ear lobes and my tongue is left feeling sort of fuzzy. For those curious what I’m talking about, an easy way to experience astringency is to make a cup of black tea using a teabag per the instructions then remove the bag and squeeze the absorbed liquid into your mouth.

A high mash pH is said to be an obvious culprit of astringency in beer, as it is purported increase the extraction of tannins from grain husks. While malt is pretty magical stuff in its ability to correct for brewing water with out of whack pH, some brewers are forced to rely on manual acidification to ensure they their mash in the recommended pH range pH 5.2 to 5.8. Having judged many a beer I felt had an astringent character that I presumed stemmed from water chemistry issues, I was curious to see how I’d experience a beer mashed with an intentionally high pH and put it to the test!

| PURPOSE |

To evaluate the differences between a beer made with a notably high mash pH (6.39) and the same beer made with a mash pH accepted to be in the normal range (5.17).

| METHODS |

In planning out the recipe for this xBmt, I wanted to make sure there was enough malt so that the high pH water had more to extract tannins from, so I designed a fairly simple IPA using some leftover hops I had in my freezer.

A Stringent IPA

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 52.3 IBUs 7.3 SRM 1.059 1.015 5.8 % Actuals 1.059 1.012 6.2 % Fermentables Name Amount % Pale Ale Malt (Rahr) 13 lbs 95.41 Victory Malt 10 oz 4.59 Hops Name Amount Time Use Form Alpha % Columbus/Tomahawk/Zeus (CTZ) 10 g 60 min First Wort Pellet 13.1 Azacca 15 g 20 min Boil Pellet 13.7 Columbus/Tomahawk/Zeus (CTZ) 10 g 20 min Boil Pellet 13.1 Loral 30 g 2 min Boil Pellet 9.2 Simcoe 30 g 2 min Boil Pellet 11.6 Loral 30 g 3 days Dry Hop Pellet 9.2 Azacca 20 g 3 days Dry Hop Pellet 13.7 Simcoe 15 g 3 days Dry Hop Pellet 11.6 Yeast Name Lab Attenuation Temperature Flagship (A07) Imperial 75% 60°F - 72°F Notes Water Profile (Standard pH): Ca 95 | Mg 0 | Na 8 | SO4 104 | Cl 93 | pH 5.2

Water Profile (High pH): Ca 201 | Mg 0 | Na 8 | SO4 104 | Cl 93 | pH 6.4

I whipped up a single starter of Imperial Organics A07 Flagship yeast a couple days ahead of time that would later be evenly split between batches.

I started collecting RO water the afternoon before brew day, as the process takes a few hours.

Later that evening, I continued my preparations by weighing out and milling the grains for each batch.

With equal amounts of brewing liquor in separate kettles, I adjusted each to have as similar of mineral profiles as possible while also producing the intended pH spread. This required the use of 7 grams of pickling lime for the high pH batch and 5 mL of 88% lactic acid for the standard pH batch.

Given the calcium content in pickling lime, that was the only other component besides pH that ended up being different.

First thing the following morning, I hit the flame under the standard pH brewing liquor, staggering the start of the high pH batch by about 20 minutes.

With the help of a couple cute brewing assistants, I mashed in the entire volume of water, performing my standard no sparge method.

Thanks to BeerSmith’s accuracy, both batches hit a similar mash temperature.

I let the mashes rest for 60 minutes, stirring each on every 20 minutes in the hopes of improving efficiency.

At 15 minutes into either mash rest, I pulled samples to measure the pH, which showed the adjustments I made did what they were supposed to do.

To say I was nervous would be an understatement.

At the conclusion of each mash rest, I collected the sweet wort and put it over the flame until a boil was reached.

I noticed the high pH wort had much large protein chunks during the boil compared to the standard pH wort, which I thought was curious as I’d always read a better hot break was achieved when the wort was in the “correct pH range.” Once each wort boiled for 60 minutes, they were quickly chilled to a few degrees warmer than my tap water.

Wort samples at this point exemplified the previously mentioned observation regarding hot break. At first, I thought the high pH wort was slightly darker than the standard pH wort, but later realized the difference was a function of turbidity.

I took another measurement of the cooled wort that showed the high pH batch had dropped quite drastically since the mash.

A refractometer reading revealed both batches had achieved the same exact OG, suggesting mash pH had no effect on efficiency. I did not expect this.

The same amount of chilled wort was racked from each batch into separate stainless Brew Buckets, which were placed in a temperature controlled chamber to finish chilling.

It took 4 hours for both worts to stabilize at my desired fermentation temperature of 66°F/19°C, at which point I evenly split the yeast starter between the batches.

I realized after pitching the yeast that I’d left the wort sample sitting on my workbench, the trub in both had settled out, but I decanted the clear portion from each for another comparison.

Within 12 hours of pitching yeast, both beers were showing signs of active fermentation, and they proceeded identically for the following 3 days, which is when I dry hopped and bumped the temperature up to 72°F/22°C. I returned 4 days later and noticed both beers appeared to be finished fermenting, which hydrometer measurements confirmed.

I reduced the temperature in the chamber to 32°F/0°C, fined with gelatin 20 hours later, then kegged the beers 2 days after that. I placed the cold beers in my keezer where they were hit with 45 psi of CO2 for 20 hours before I reduced the gas to serving pressure. They were allowed to condition for 3 more days before I collected data, at which point they maintained a very similar appearance.

Out of curiosity, I took a final pH measurement of the finished beers to discover a difference did remain, though the beer were closer than I expected, a testament to the buffering ability of yeast during fermentation.

| RESULTS |

A panel of 20 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 high pH beer in different colored opaque cups then instructed to select the unique sample. With the given sample size, a total of 11 (p<0.05) correct selections would have been required to achieve statistical significance, though only 8 tasters (p=0.34) chose the different beer, indicating tasters were unable to reliably distinguish a beer produced with a higher than recommended mash pH from one produced with a normal mash pH.

My Impressions: I was convinced from the moment I agreed to brew this xBmt that the beers were going to be different, and sure enough, upon first non-blind sip of each, I was absolutely certain the high pH sample was more harsh. I held off on triangle testing myself until I started to notice participants routinely selecting the wrong sample. I had 3 different friends serve me 5 semi-blind triangles at various times, out of which I was correct only twice. No shit, I’m not sure I’ve ever focused so hard in my life on anything, and still my performance was not better than chance. After sharing my shock with one friend, he offered to pour me samples side by side to see if I could tell them apart that way, both in clear glasses. Knowing that I had a 50% chance of getting it right, I threw in the towel after a few minutes of focused evaluation, as I didn’t feel like pretending I detected a difference when I really just guessed.

As for the beer, meh, it was okay, certainly not a dumper. I’m not sure I’m as big of a fan of using Victory in IPA as I used to be, and that hop combo didn’t really seem too exciting either.

| DISCUSSION |

With over 10 years and hundreds of batches under my belt, I feel like I have a decent grasp of most aspects of brewing, and while I didn’t really start down the rabbit hole that is water chemistry until the last few years, I’ve done more reading on the subject than I ever did anything in grad school. It’s likely this that’s responsible for the confidence I had that this xBmt would return significant results, the high mash pH beer possessing an easily noticeable astringency not perceived in the beer mashed with a more acceptable pH. The first sign that my convictions might be wrong came when I poured myself a couple samples prior to collecting data and they looked exactly the same, an observation that went against my expectation of the high pH beer being darker than the standard pH beer via non-enzymatic browning. I figured this darkening effect might take some time and, based on a couple preliminary sips, was certain there was a difference between the beers.

As participants started taking the triangle test, it became obvious many struggled to distinguish the unique sample, with post-survey comments regarding how similar they were leaving me completely baffled. It was at this point I attempted multiple triangle tests and discovered they tasted like the same damn beer. You’d think I’d be immune to this phenomenon by now, but nope. Not only were participants unable to reliably distinguish the high pH sample from the standard pH beer, but I couldn’t either, which in addition to reminding me how strong bias is, caused me to reconsider what I thought I new about mash pH.

When looking at these results in light of those from the xBmt on the impact of low mash pH, it seems lower mash pH might slightly improve enzymatic activity while a higher pH has minimal effect based on OG readings, which could help to explain reports from homebrewers claiming to have experienced increased efficiency once they began adjusting their water profiles. I also thought about the boil pH xBmt that returned non-significant results and wondered if intentionally raising the pH even higher might have produced the expected astringency. Ultimately, I’m yet again left with more questions than answers and anticipate ongoing exploration of this fascinating variable.

If you have thoughts about this xBmt, please feel free to share in the comments section below!

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