Author: Brian Hall

Typically, the only time beer is deliberately frozen is for the purposes of distillation when making styles like Eisbock. However, with the widespread use of chest freezers and bypass thermostats as fermentation chambers and keezers, it’s not too uncommon to hear of a homebrewer who has frozen a carboy or keg full of beer, usually a result of accidentally leaving the temperature probe hanging outside the freezer.

While the dangers of freezing in a glass or pressurized container are fairly obvious, especially if said vessel is nearly full, there’s also quite a bit of concern about the effect freezing has on the perceptible characteristics of the beer. Does something occur during the conversion from a liquid to a solid then back to a liquid that noticeably impacts beer aroma, flavor, or mouthfeel?

On numerous occasions, I’ve forgotten about commercial beers I set outside during cold Anchorage winters for quick chilling, returning to discover undrinkable beer-cicles. My anecdotal experience is that, once thawed, the beers tasted just fine, no different than previous tastings. Curious if I was missing something, and inspired by the numerous stories of frozen beer gone bad, I decided to put it to the test!

| PURPOSE |

To evaluate the differences between a pale lager that was frozen for 5 days then thawed and the same beer that remained in a liquid state.

| METHODS |

Hoping to accentuate any impact freezing might have on beer, I chose to brew a simple pale lager for this xBmt.

Tundra

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 18.9 IBUs 3.9 SRM 1.045 1.011 4.4 % Actuals 1.045 1.008 4.9 % Fermentables Name Amount % Pelton Pilsner Style Malt (Mecca Grade) 9 lbs 90 Vanora Vienna-style Malt (Mecca Grade) 1 lbs 10 Hops Name Amount Time Use Form Alpha % Tettnang 22 g 60 min Boil Pellet 4.5 Tettnang 22 g 15 min Boil Pellet 4.5 Notes Water Profile: Ca 50 | Mg 7 | Na 5 | SO4 75 | Cl 60 Download Download this recipe's BeerXML file

I stirred up a couple starters of Imperial Yeast L17 Harvest a day ahead of time.

My first order of business the following morning was collecting the strike water for both batch, which I used my sous vide machine to heat.

As the water was warming up, I weighed out and milled the grain.

Due to kettle size limitations, I’m unable to brew 10 gallon full volume batches in a single vessel, so I performed 2 identical mashes at the same temperature.

Once the mash rests were complete, I removed the grain bags and allowed them to drip until the same volume was collected from each.

At this point, I combined the worts into a single kettle then proceeded with the boil, hops being added at the times stated in the recipe.

Following the 60 minute boil, I quickly chilled the wort before splitting it equally between sanitized Brew Buckets.

A hydrometer measurement showed the wort was sitting at my 1.045 OG target.

I pitched a yeast starter into each batch and allowed the beers to ferment at 52°F/11°C for a few days before gently warming it up over the course of 2 weeks. After a couple days at 68°F/20°C, fermentation activity had halted so I took hydrometer measurements confirming the same FG had been reached in both.

I swapped out the airlocks with BrüLoonLocks filled with CO2 and cold crashed the beers for a couple days. I then racked 4.25 gallons from each batch to separate CO2 purged kegs, making sure to leave room for the expansion that occurs when liquid freezes.

Both beers were fined with gelatin and left at the same temperature for a week before I placed one keg in my cool keezer and the other in my fermentation chamber controlled to 10°F/-12°C.

The beer froze. I left it alone for 5 days before moving it to a room temperature environment for thawing. The following day, with the beer fully melted and still very cold, I placed it next to its non-frozen counterpart in my keezer. Both were burst carbonated and allowed to condition for a week before they were ready to serve to participants.

| RESULTS |

A total of 22 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the frozen beer and 1 sample of the beer that was not frozen then asked to identify the sample that was unique. At this sample size, 12 tasters (p<0.05) would have had to correctly identify the unique sample in order to reach statistical significance; however, only 9 tasters (p=0.29) made the correct selection, indicating participants in this xBmt were unable to reliably distinguish a pale lager that was frozen for 5 days then thawed from one that remained in a liquid state.

My Impressions: With the exception of the fairly easily noticeable difference in appearance, I was unable to tell these beers apart, which was confirmed by various incorrect triangle tests. Even side-by-side and biased by awareness of the variable, these beers were the same to my nose and mouth. The beer was decent, not necessarily as crisp as I’d hoped for, but definitely tasty enough to consume amply.

|DISCUSSION |

Frozen beer is an issue that seems to be happening more often as the hobby of homebrewing grows, in fact John Palmer waxes poetic about his own experience with an icy Vienna Lager in How To Brew. Despite the myriad horror stories found in online forums, the results from this xBmt showing tasters were unable to reliably tell apart a pale lager that was frozen suggests such conditions had little impact on aroma, flavor, and mouthfeel.

While these findings may ease the minds of homebrewers prone to making minor mistakes, there is one issue that deserves consideration. Without proper conditions, freezing temperatures will impair yeast, rendering a good portion unable to metabolize sugar. For those who keg and force carbonate, this is a moot point, but brewers who bottle condition should consider adding some fresh yeast to ensure their beer carbonates.

The difference in clarity between the beers in this xBmt, slight as it may have been, was rather curious to me. Assuming it was chill haze, it seems plausible that it would have cleared up to at least the same level as the beer that wasn’t frozen once it warmed up, but that didn’t seem to be the case. Perhaps something about freezing creates a more permanent haze that, while noticeable with the eyes, doesn’t impact other perceptible qualities.

I’ve never personally had a batch of beer I made freeze on me, but the results of this xBmt have confirmed my experience with frozen commercial beers, namely that it doesn’t seem to have a negative impact on quality. I won’t be intentionally freezing beers because of this xBmt, though in the event I do so unwittingly, I won’t fret as much as I might have before.

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

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