The Impact of Storage Temperature on Beer

By Ray Found, Brulosophy.com

This homebrew experiment was originally published on Brulosophy.com.

It’s well known that temperature is positively correlated with reaction rates– as the warmth of a particular environment goes up, so too does the rapidity with which certain reactions occur. In the case of beer, these reactions are commonly associated with negative characteristics such as oxidation and staling, perhaps one reason refrigerated shelf-space is so zealously sought after by beer distributors and brewers, though likely secondary to consumer preference for “beer I can drink right now.”

Less of an issue for homebrewers due to our smaller batch volumes and usually, ahem, quicker consumption, storage temperature remains a concern for those who bottle condition and don’t have the capacity to store 50 bottles in a cool environment. Prior to making the switch to kegging my beer, this was certainly something I considered, as my garage fridge was often filled entirely with bottles, only to leave more sitting warm in a spare closet. With the birth of my son, that spare closet ceased being “spare” and my bottle storage space was dramatically reduced.

My switch to kegging wasn’t prompted so much by a desire for cold storage, but for the ease and convenience of the process when compared to bottling. However, I felt the quality of my beer improved, specifically that it was fresher, crisper, clearer, and more aromatic (especially IPAs) than when I bottle conditioned. I attributed these improvements as being due to the beer remaining at a consistently cool temperature post-fermenation, never rising above the setpoint of my cold keezer.

Could storage temperature really make that big of a difference, or did my love for kegging bias me in favor of the beer such that I invented a difference that was really all in my head?

Purpose

To evaluate the differences between a beer stored in a cool environment and the same beer stored in a warm environment over the same period of time.

Methods

This was not actually the intended xBmt on this brew day, but due to a miscalculation on my part, I had to rethink things last minute and was forced to test a post-boil variable.

Bohemian Pilsner Homebrew Recipe

Recipe Details

BATCH SIZE BOIL TIME IBU SRM EST. OG EST. FG ABV
5.5 gal 60 min 37.2 IBUs 3.8 SRM 1.052 1.012 5.2 %
Actuals 1.052 1.013 5.1 %

Fermentables

NAME AMOUNT %
Pilsner (2 Row) Bel 10.25 lbs 95.35
Vienna Malt (Gambrinus) 8 oz 4.65

Hops

NAME AMOUNT TIME USE FORM ALPHA %
Hallertau Magnum 11 g 60 min Boil Pellet 12.1
Saaz 30 g 30 min Boil Pellet 3
Saaz 37 g 20 min Boil Pellet 3
Saaz 37 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

Starting a day ahead, I collected the full volume of water for this 20 gallon batch, catching it just in time!

I weighed out and milled the grains while my strike water was heating.

After transferring the slightly overheated strike water to my MLT and allowing for a brief preheat, I stirred in the grains to hit my target mash temperature.

I let the mash rest for 60 minutes, stirring occasionally to ensure good conversion.

At the end of the mash, I collected the proper volume of sweet wort and brought it to a rolling boil.

Hops were added during the 60 minute boil, after which I quickly chilled it to a few degrees above my groundwater temperature.

A hydrometer reading at this point confirmed I’d hit the OG predicted by BeerSmith.

1.052 OG

I transferred equal amounts of the chilled wort to two 6 gallon PET carboys that I placed in my fermentation chamber to finish chilling to my desired fermentation temperature of 60˚F/16˚C.

Once there, I pitched 2 rehydrated packs of Saflager W-34/70 into each each fermentor.

It took about 24 hours for both beers before I noticed fermentation activity.

The beers fermented similarly over the following week, at which point I raised the temperature in the chamber a bit to encourage complete attenuation. With signs of fermentation absent around the 2 week mark, I took hydrometer readings and observed both had attenuated identically.

1.013 FG

I proceeded with cold crashing, fining each with gelatin, then transferring to kegs. After purging the headspace in both kegs and leaving just enough CO2 to seat the lids, I stored one keg in a 35˚F/2˚C refrigerator while the other was placed in a closet in my house that maintains a temperature range between 68-73˚F/20-23˚C. The beers were left alone for a month before I moved them to my keezer, allowing them to thermally equalize for 2 days before burst carbonating. Even after another month of lagering in my keezer, the beers maintained a fairly dramatic difference in appearance.

Left: warm storage / Right: cool storage

Results

In total, 20 people of varying experience levels participated in this exBEERiment. Each taster was blindly served 1 sample of the beer stored warm and 2 samples of the beer stored cold in different colored opaque cups then asked to select the unique beer. At this sample size, at least 11 accurate selections were required to achieve statistical significance, though 12 accurate selections were made (p<0.05; p=0.013). These results indicate tasters in this xBmt were indeed able to reliably distinguish a Pilsner stored in a warm environment from the same Pilsner stored in a cold environment.

A brief comparative evaluation of only the two different beers was completed by the 12 participants who made the accurate selection on the triangle test, all remaining blind to the nature of the xBmt. The warm storage beer was preferred by 5 tasters, the beer stored cold was preferred by 2 tasters, 4 people had no preference despite noticing a difference, and 1 person reported there was no difference between the beers.

My Impressions: Whether skewed by bias or not, I really can’t say, but these beers hit right on what I expected them to taste like. The cold storage beer seemed to lose some life as it aged, but it remained quite clean, crisp, and enjoyable. On the other hand, I perceived the beer stored warm as having the characteristic sweet/cloying character I frequently associate with old or oxidized beer. While not entirely unpleasant, it lost many of the characteristics I expect in a typical Pilsner, bur rather possesses an impression of sweetness more reminiscent of a less phenolic Belgian Pale. Unlike prior xBmts, these beers genuinely echoed my expectation near perfectly, validating my belief that storage temperature matters.

Discussion

The fact tasters in this xBmt were able to reliably distinguish a beer stored warm from the same beer stored in a cold environment provides additional support to the accepted notion that storage conditions do indeed have an impact on beer, which has many implications. As mentioned previously, craft brewers want to get their beer into the mouths of drinkers in the best form possible, though their ability to do so is hindered by the limited amount of refrigerated shelf space in stores carrying their product. Moreover, homebrewers who bottle condition and don’t have the ability to store all of their beer in a cold environment will, in all likelihood, experience flavor drift over the life of each batch. The solution? If there’s a good one, I’d love to hear it.

I thought it was curious that only 2 of the 12 correct participants preferred the cold storage sample, which was my clearly preferred, while 5 liked the beer stored warm better. My hunch is this was more a function of the fact tasters weren’t aware of the style of beer they were drinking and hence chose the one with more overall character, or maybe some people actually do enjoy whatever it is aging in a warm environment does to beer.

I personally believe beer, in general, is a product best served fresh and, save for a few rare exceptions, decreases in quality with age. This even goes for styles many believe require aging such as strong Belgians and clean lagers. Ultimately, as someone who keeps all the beer I make in a cold keezer, it’s good to know it will likely live a little longer than if it were sitting a warm closet.

Homebrewers Association
Homebrewers Association