Author: Ray Found

I like to think of the different variables we can tweak as adjustment knobs on a big brewing control board, and the exBEERiment series as shining some light on those knobs I can turn for greater effect. If you’d asked me a couple years ago, I would have unhesitatingly claimed that mash temperature is a variable that has a profound impact on the final characteristics of a beer. In fact, as we were planning the first xBmt on the subject, I was convinced the batches would be easily distinguishable given how disparate the mash temperatures were. Similar to what I trust many experience when reading results that fail to confirm my beliefs, I would like have questioned the veracity of those results if it hadn’t been for the fact that I tasted them for myself during a stopover in Fresno while they were on tap. I could not tell them apart. Despite being fully aware of the 14°F/8°C difference in mash temperature, I not only failed a triangle test, but wasn’t even able to detect a difference when sampling the different beers side-by-side.

In follow-up discussions after those results were published, Nik Stevens of the Thunder Dog Brewery blog suggested an interesting hypothesis as to why these beers were so similar. In essence, the dextrins present in wort from mashes that favor alpha amylase are tasteless, not sweet as many expect, and will decrease fermentability, while wort produced from lower temperature mashes is highly fermentable, thereby reducing the amount of perceivable dextrins in the finished beer. Dan Paris from the In Bounds Brewing blog posited a less extreme difference in mash temperature may in fact produce beers that are more readily distinguishable by tasters.

It seems counter-intuitive that less extreme conditions might produce a greater difference, but the reasoning behind the hypothesis was intriguing enough to inspire a revisit of this xBmt!

| PURPOSE |

To evaluate the impact mash temperature has on 2 beers of the same recipe where one was mashed at 149°F/65°C and the other at 153°F/67°C.

| METHODS |

I wanted to make a beer for this xBmt that would really highlight any extra body or perceptible sweetness and went with a deliciously simple Pilsner recipe.

Czech It Out Pilsner

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 37.7 IBUs 3.6 SRM 1.058 1.011 6.2 % Actuals 1.058 1.009 6.4 % Fermentables Name Amount % Pilsner (2 row) (Gambrinus) 10 lbs 91.95 Vienna Malt (Gambrinus) 14 oz 8.05 Hops Name Amount Time Use Form Alpha % Hallertau Magnum 12 g 60 min Boil Pellet 12.1 Saaz 33 g 30 min Boil Pellet 3 Saaz 40 g 20 min Boil Pellet 3 Saaz 40 g 10 min Boil Pellet 3 Yeast Name Lab Attenuation Temperature Saflager Lager (W-34/70) DCL/Fermentis 75% 48°F - 59°F Notes Water Profile: Ca 55 | Mg 0 | Na 8 | SO4 45 | Cl 68



I began collecting the copious amounts of RO water required for this 20 gallon batch the day before brewing, it would later be adjusted to my target profile.

I brewed the following afternoon, milling the grain as my strike water was heating.

With the help of my little girl, I mashed in on the lower temperature batch, followed 25 minutes later by the higher temperature mash.

I came close to hitting my target mash temperatures of 149°F/65°C and 154°F/68°C, the higher temperature mash falling slightly lower than expected.

After 60 minute rests, I collected each wort in separate kettles that were placed over full-blast flames, both reaching a rolling boil quickly.

Following completion of each 60 minute boil, I quickly chilled the wort to about 80°F/27°C, the lowest I could get it with my balmy Summer groundwater.

My temperature controlled fermentation chamber would have to finish the task overnight.

Each batch was evenly split between two 6 gallon PET carboys, one for the xBmt, one for quenching the thirsts of a parched xBmt’r.

Hydrometer measurements showed the lower mash temperature wort landed an ever so slightly higher OG than the higher mash temperature batch.

The worts had stabilized at my target fermentation temperature of 56°F/13°C by the following day, at which point I pitched rehydrated Saflager W-34/70 yeast into each carboy. When I returned 36 hours later, I was intrigued to discover the lower mash temperature beers had begun to form a kräusen while the higher mash temperature beers hadn’t. An indication of a greater degree of fermentability, perhaps?

The following day, all of the beers appeared to be moving along nicely.

After 5 days, I began gently raising the temperature to 68°F/20°C where I held it for a few more days until signs of active fermentation were absent.

Hydrometer measurements at this point showed the lower mash temperature beer attenuated slightly more than the higher mash temperature beer.

The beers were then cold crashed, fined with gelatin, and kegged a few days later.

After a brief period of burst carbonation and a few days lagering in my keezer, both beers were clear, carbonated, and carried a beautiful golden hue.

| RESULTS |

Data for this xBmt was collected during an OC Mashups Homebrew Club meeting where 25 willing participants of varying experience level lent their palates to the cause. Each taster was served 1 sample of the lower mash temperature beer and 2 samples of the higher mash temperature beer in different colored opaque cups then asked to select the unique sample. In order to reach statistical significance with this number of participants, 13 (p<0.05) would have had to accurately identify the odd-beer-out, while only 6 (p=0.88) were able to do so. These results suggest tasters were unable to reliably distinguish between a beer mashed at 149°F/65°C and one mashed at 153°F/67°C.

My Impressions: While I found myself drinking more of the higher mash temperature beer, it likely had little to do with differences in character, as I readily admit to passing a triangle test just 1 of 3 times. I was also unable to distinguish between the beers when sampling them next to each other. If I hadn’t served myself, I wouldn’t have been able to tell which one I was drinking, I noticed no differences in body, head retention, lacing, or any of the other characteristics often attributed to elevated mash temperatures.

| DISCUSSION |

I’m compelled to believe the small 2.1% difference between the batches in apparent attenuation was likely a function of the variable, confirming what we know to be true about the impact of mash temperature. However, this difference did not appear to have a meaningful corresponding impact on the character of the finished beers, as neither a panel of blind tasters nor I could reliably distinguish a beer mashed at 149°F/65°C from one mashed at 153°F/67°C. While I’d never expect to taste a 0.001 FG difference, I certainly expected to see a bigger variance in OG as a function of the different mash temperatures, closer to the 0.003 difference BeerSmith projected.

This observation caused me to think about something that’s come up a few times in recent conversations, a concept referred to as “hot malt.” As it’s been explained to me, some modern malts are so robust in enzymatic activity that they convert fully, quickly, and easily. Such malts are fantastic for large scale commercial operations looking to cut costs by saving time with the process, though there’s some evidence an element of process control is sacrificed in that mash temperature seems to have less of an impact. This is a very new idea to me that I know very little about, so I’m hesitant to accept it as the sole explanation for the results of this xBmt, but I definitely think it’s deserving of a closer look.

These results provide further evidence that mash temperature may not be as powerful a “knob” when attempting to make a beer sweeter or drier, which is a huge diversion from convention as well as my my long-held dogma. On one hand, it’d be nice to know mash temperature isn’t as critical an issue as we’ve been taught, but on the other hand, I don’t like that it further removes me, the brewer, from the control loop. Perhaps this is part of the reason some brewers are drawn to using more unique base malts like Maris Otter, Golden Promise, and Vienna Malt, among others. Could it be that in addition to the purported flavor differences these “less advanced” malts allow the brewer more control over the wort from the mash tun? I don’t know, but I look forward to further investigation.

Whether you’ve experimented with different mash temperatures or just have thoughts about this xBmt, please share in the comments section below!

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